S %
19 (2006)
10
Albany Thicket Biome
David B. Hoare, Ladislav Mucina, Michael C.
Rutherford, Jan H.J. Vlok, Doug I.W. Euston-Brown,
Anthony R. Palmer, Leslie W. Powrie, Richard G.
Lechmere-Oertel, Şerban M. Procheş, Anthony P.
Dold and Robert A. Ward
Table of Contents
1 Introduction: Delimitation and Global Perspective
2 Major Vegetation Patterns
3 Ecology: Climate, Geology, Soils and Natural Processes
3.1 Climate
3.2 Geology and Soils
3.3 Natural Processes
4 Origins and Biogeography
4.1 Origins of the Albany Thicket Biome
4.2 Biogeography
5
6
7
8
9
10
Land Use History
Current Status, Threats and Actions
Further Research
Descriptions of Vegetation Units
Credits
References
542
544
544
544
545
546
547
547
548
548
549
550
550
565
565
List of Vegetation Units
AT 1 Southern Cape Valley Thicket
AT 2 Gamka Thicket
AT 3 Groot Thicket
AT 4 Gamtoos Thicket
AT 5 Sundays Noorsveld
AT 6 Sundays Thicket
AT 7 Coega Bontveld
AT 8 Kowie Thicket
AT 9 Albany Coastal Belt
AT 10 Great Fish Noorsveld
AT 11 Great Fish Thicket
AT 12 Buffels Thicket
AT 13 Eastern Cape Escarpment Thicket
AT 14 Camdebo Escarpment Thicket
550
551
552
553
555
556
557
558
559
560
561
562
563
563
L. Mucina
Figure 10.1 AT 8 Kowie Thicket: Kowie River meandering in the Waters Meeting Nature
Reserve near Bathurst (Eastern Cape), surrounded by dense thickets dominated by succulent
Euphorbia trees (on steep slopes and subkrantz positions) and by dry-forest habitats housing
patches of FOz 6 Southern Coastal Forest lower down close to the river.
541
S %
1.
Introduction: Delimitation and Global
Perspective
Following the earlier work of Acocks (1953), the structurally
unusual vegetation of the semi-arid river valleys of the eastern
seaboard of South Africa was described as Valley Bushveld. This
nomenclature probably followed the colloquial term used by
the agriculturalists, mainly livestock farmers, who found it a
largely impenetrable thicket which had to be ‘opened-up’ to
allow access to domestic livestock (cattle and goats). According
to Acocks, this comprised ‘a semi-succulent thorny scrub 2–3
metres in height’.
Rutherford & Westfall (1986) classified the biomes of South
Africa on the basis of dominant life-form combinations
(Raunkiaer 1934, Cain 1950) and climatic features. Therefore,
the areas now considered here to be the Albany Thicket Biome
were classified by them as Savanna on the basis of the dominance of phanerophytes associated with, on average, hemicryptophyte co-dominance (Rutherford & Westfall 1986), although
they acknowledged the existence of a variety of life-form combinations. This view continued in the work of Scholes (1997),
who mapped the vegetation of the discussed region as a part
of the broad-leaved Savanna. Following White & Moll (1978)
and Cowling (1983), some evidence for its classification as a
distinct structural and floristic unit was presented, and this provided justification for the later recognition of the Thicket Biome
(Low & Rebelo 1996, 1998). Rutherford & Westfall (1986)
noted that many parts of the areas classified here as Thicket
Biome, namely Spekboomveld and the Fish River Scrub, Addo
Bush and Sundays River Scrub forms of Valley Bushveld (Acocks
1988), had vegetation co-dominated by phanerophytes and
chamaephytes. This corresponds to a ‘missing biome’ that they
suggested may be recognised in the future. This concept is formally adopted here. Recent analyses, primarily within the STEP
project (Cowling et al. 2003), have confirmed that the climatic
uniqueness (Robertson & Palmer 2002) and peculiar vegetation
structure resulting from a unique combination of constituent
growth forms (Vlok & Euston-Brown 2002) as well as floristic
diversity (including high regional endemism) justify its recognition as a biome.
The term ‘Albany Thicket’ is a concept recognised by the WWF
(Olson et al. 2001, Burgess et al. 2004) where this vegetation type (‘ecoregion’) is listed as a part of the broader category (biome) ‘mediterranean forests, woodlands, and scrubs’,
thus, as a part of the Cape Floristic Region—a misplacement
that partly reflects the transitional nature of the biome. The
same WWF categorisation does not recognise a global thicket
biome. Various thicket formations in Africa, Madagascar, Asia,
Australia and the Americas are spread over four different
biomes. In Africa, patches of typical thicket are included in two
other ‘biomes’: ‘montane grasslands and shrublands’ (e.g. Jos
Plateau forest-grassland mosaic), and ‘tropical and subtropical grasslands, savannas, and shrublands’ (e.g. Somali Acacia–
Commiphora bushlands and thickets). Worldwide, other thicket
types are classified as ‘tropical and subtropical dry broadleaf
forests’ (see Olson et al. 2001). In terms of vegetation structure and climate at least two other regions qualify as analogous to Albany Thicket. These include the thickets of the Chaco
straddling the border areas between Argentina and Paraguay
in South America (Lewis 1991, Cábido et al. 1992, 1994) and
the Didiereaceae-rich semideciduous thickets (also called dry
forests) of southern and southwestern Madagascar (Koechlin
et al. 1974, Grubb 2003). Madagascar spiny thickets, largely
equivalent in vegetation structure to southern Africa’s Albany
Thicket, are classified under ‘deserts and xeric shrublands’.
542
Albany Thicket Biome
19 (2006)
Table 10.1 Major correspondence between vegetation
units and STEP vegetation types (Vlok & Euston-Brown
2002). Those STEP units are listed which have at least 80%
of their area within the vegetation units and do not necessarily constitute a high proportion of the vegetation unit (these
proportions are given under the headings in the description of each unit). Only Gouritz Valley Thicket is (much) less
than 80%.
Vegetation Units
STEP
AT 1 Southern Cape Valley Thicket
Gouritz Valley Thicket
AT 2 Gamka Thicket
Gamka Arid Spekboomveld
Gamka Spekboom Thicket
Oudtshoorn Karroid Thicket
Baviaans Spekboom Thicket
Baviaans Valley Thicket
Bethelsdorp Bontveld
Groot Arid Spekboomveld
Kleinpoort Karroid Thicket
Gamtoos Arid Spekboomveld
Gamtoos Bontveld
Gamtoos Thicket
Gamtoos Valley Thicket
Kromme Forest Thicket
Otterford Forest Thicket
Vanstadens Forest Thicket
Sundays Noorsveld
Elands Forest Thicket
Koedoeskloof Karroid Thicket
Kremlin Grassland Thicket
Motherwell Karroid Thicket
Sundays Spekboom Thicket
Sundays Spekboomveld
Sundays Thicket
Sundays Valley Thicket
Zuurberg Fynbos Thicket
Grass Ridge Bontveld
Albany Spekboom Thicket
Albany Spekboomveld
Albany Thicket
Albany Valley Thicket
Ecca Bontveld
Salem Karroid Thicket
Shamwari Grassland Thicket
Thorndale Forest Thicket
Geluk Grassland Thicket
Hamburg Dune Thicket
Kiwane Dune Thicket
Nanaga Savanna Thicket
Paterson Savanna Thicket
Zuney Strandveld
Fish Noorsveld
Crossroads Grassland Thicket
Doubledrift Karroid Thicket
Fish Spekboom Thicket
Fish Thicket
Fish Valley Thicket
Hartebeest Karroid Thicket
Buffels Thicket
Buffels Valley Thicket
Kei Thicket
Mountcoke Grassland Thicket
Escarpment Thicket
AT 3 Groot Thicket
AT 4 Gamtoos Thicket
AT 5 Sundays Noorsveld
AT 6 Sundays Thicket
AT 7 Coega Bontveld
AT 8 Kowie Thicket
AT 9 Albany Coastal Belt
AT10 Great Fish Noorsveld
AT11 Great Fish Thicket
AT12 Buffels Thicket
AT13 Eastern Cape Escarpment
Thicket
AT14 Camdebo Escarpment Thicket
Escarpment Spekboom Thicket
S %
19 (2006)
Perhaps also the Somali-Masai thickets as described by White
(1983), the so-called ‘Vine Thickets’ of Australian Queensland
(Webb 1978) and succulent-rich thickets of northern Venezuela
and Colombia (Matteuci 1987) could be viewed as part of the
global subtropical succulent-rich thickets.
the equatorial and tropical regions of Africa, and Addo Bush
(Acocks 1953) is similar to certain thickets of the Arid Lowveld
(Acocks 1953, 1988) in the Mpumalanga Lowveld, northern
KwaZulu-Natal and parts of Swaziland. The Albany Thicket also
has a unique phylogenetic and biogeographic origin and is
transitional between Nama-Karoo and the subtropical regions
of the eastern seaboard of southern Africa.
Thicket in the valleys from the other side of the Great Kei River
to the Thukela River in KwaZulu-Natal are not recognised here
as being part of the Albany Thicket Biome (the Great Kei River
Valley does contain some mapped Albany Thicket). In fact, this
is a gradual transition from the characteristic bimodal rainfall,
with no seasonal period of pronounced drought of the Albany
Thicket to the summer-rainfall areas with dry winters typical
of the Savanna Biome. Also in terms of species affinities, an
increasing number of typical savanna species occur along this
gradient towards the northeast. Woody elements of strandveld units to the west, including parts of the west coast, are
not regarded as part of the biome despite their recognition as
thicket by some authorities (e.g. Cowling 1984). The current
delimitation of the Albany Thicket Biome closely follows (in most
parts) the set of core (‘solid’) thickets of STEP (Vlok & EustonBrown 2002) (Table 10 1). Much of the area of STEP’s mosaic
thickets is not here included in this biome, although small
parts of some of them are incorporated where the evidence
for belonging to an adjacent biome (Forest, Fynbos, Savanna,
Grassland, Nama-Karoo and Succulent Karoo) appeared unwarranted. Valley Bushveld and Spekboomveld (Acocks 1953) of
the Eastern Cape are similar in structure to thickets found in
L. Mucina
L. Mucina
Rainfall can occur at any time of the year in Albany Thicket,
which occurs in a climatic interface between an all-year rainfall
zone in the west and a stronger summer-rainfall zone in the
northeast (Schulze 1997). Thicket vegetation is considerably
fragmented and displaced by renosterveld and fynbos in the
winter-rainfall zone and by grasslands and savanna in the summer-rainfall zone (Vlok & Euston-Brown 2002). The climate in
itself is not the primary selective force for this pattern, but rather
the fire regimes that are determined by seasonal precipitation.
Evidence for this lies in the occurrence of outliers of thicket vegetation in fire refugia in the winter- and summer-rainfall zones.
Although it is tempting to think that thicket is also differentiated by occurring mostly on deep soils rich in nutrients, it is
not limited to or restricted by any particular soil type (Vlok &
Euston-Brown 2002). The clumping of the vegetation is another
distinguishing feature and appears to be strongly facilitated by
below-ground animal activity (termite mounds, active mole rat
colonies, aardvark burrows, earthworm activity). The clumps
show elevated levels of C, Ca, K, organic and moisture content
when compared with the adjacent soils (Palmer et al. 1988).
Figure 10.2 Spekboomveld dominated by Portulacaria afra (Didiereaceae) in the Ecca Pass (north of Grahamstown, Eastern Cape).
Figure 10.3 Euphorbia triangularis (Euphorbiaceae) at road from
Addo to Zuurberg Inn (Eastern Cape)—a flagship species of the Albany
Thicket Biome.
Albany Thicket Biome
543
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2.
Major Vegetation Patterns
Thicket, according to a dictionary definition, is a tangle or dense
growth of shrubs or trees. This is a physiognomic or structural
description of a type of vegetation that may be found in many
geographical areas. The term ‘Thicket’ (uppercase ‘T’) refers to
the Biome, whereas ‘thicket’ (lowercase ‘t’) refers to a structural type of vegetation. Within several biomes there may be a
wide variety of structural vegetation types found which would,
through high densities of woody plants, qualify as ‘thicket’ (see
for instance chapters on Fynbos and Savanna in this book).
The vegetation of the Albany Thicket Biome is described in
general as a dense, woody, semisucculent and thorny vegetation type of an average height of 2–3 m (Acocks 1953, Everard
1987), relatively impenetrable in an unaltered condition. During
his journey of 1776–1777, Paterson found this vegetation
impenetrable except along elephant tracks (Dyer 1937). It
comprises a broad spectrum of physiognomic types reflecting
gradients in climate, geology, soil and herbivory. The Albany
Thicket Biome consists of various major vegetation types, and
the wide variety of plant communities, with varying structure
and species composition, has posed a challenge for researchers
attempting to describe it. Acocks (1953, 1988) recognised four
vegetation types currently classified as thicket, namely Valley
Bushveld, Noorsveld, Spekboomveld and False Karroid Broken
Veld. His thicket also contains small patches of other vegetation
types that are embedded within thicket, e.g. Coastal Forest and
Thornveld, Alexandria Forest, etc. Acocks also subdivided Valley
Bushveld into valley thicket, scrub and Addo Bush. Typical valley
thicket may be tall or low and may be composed of different
proportions of succulent and nonsucculent plants. Following
Acocks (1953), Martin & Noel (1960) described this vegetation
as a Succulent Woodland Formation, with two subformations,
the taller ‘sub-succulent woodland’ and the ‘low succulent
scrub’. In an effort to contextualise the vegetation relative to
its origin, White & Moll (1978) included it in their TongalandPondoland Regional Mosaic, as it was part of the vegetation
with strong tropical affinity. This affinity was attributed to the
presence of genera such as Acacia, Brachylaena, Carissa, Euclea,
Grewia, Pappea, Ptaeroxylon, Rhoicissus and Ziziphus, which
were able to extend down the coast due to the influence of the
warm Agulhas Current. This led to incorporating the notion of
the subtropical origin of the flora into nomenclature. Cowling
(1983) recognised the floristic uniqueness of the regional vegetation and coined the term Subtropical Transitional Thicket,
which had two formations, the mesic ‘Kaffrarian Thicket’
and the xeric ‘Kaffrarian Succulent Thicket’. In further floristic research in the Subtropical Transitional Thicket, Everard
(1987) described the Albany region as comprising two formations, the ‘Xeric Succulent Thicket’ formation which could
be distinguished from the ‘Mesic Succulent Thicket’ because
of its higher proportion of succulents (29% as opposed to
24% for the Mesic Succulent Thicket) and lower proportion
of woody taxa (39% as opposed to 48%). The floristic data
collected by these researchers were further supplemented by
local-scale research in the Great Fish River Valley (Palmer 1981,
Palmer et al. 1988) where gradients in species composition and
structure were described. These were further elaborated upon
by Evans et al. (1997), providing landscape-scale descriptions
of the vegetation units. They described Tall Succulent Thicket
(TST), Medium Succulent Thicket (MST) and Short Succulent
Thicket (SST) of the Great Fish River Valley (Evans et al. 1997).
MST is dominated by the leaf succulent Portulacaria afra, which
comprises the most extensive version of the thicket, synonymous with subsucculent woodland of Martin & Noel (1960).
SST, characterised by the dominance of Euphorbia x bothae,
544
Albany Thicket Biome
19 (2006)
is represented by our Great Fish Noorsveld and is structurally
similar to our Sundays Noorsveld, being shorter in height (1–2
m) and having a lower standing biomass than the MST. The TST
is associated with cooler, moister southern aspects, comprises
taller emergent Euphorbia species, and has a greater standing biomass than either the MST or the SST. Noorsveld (Acocks
1953) is a uniform, 1–2 m high scrub dominated by Euphorbia
coerulescens, known as noors. Spekboomveld is dominated by
Portulacaria afra (spek: Dutch word meaning bacon), thus referring to the apparent delicacy of the plant. Other vegetation
found in the Albany Thicket Biome includes mosaics of thicket
clumps and grassland, and various secondary vegetation types,
including grassland and thornveld. Vlok & Euston-Brown (2002)
also point to examples of a gradient of plant species turnover
within the biome from the Buffels to the Gamtoos Rivers.
There is a wide range of growth forms and a high diversity of
plant species, including leaf and stem succulents (Figure 10.2
and 10.3), deciduous and semideciduous woody shrubs and
dwarf shrubs, geophytes, annuals, grasses, and a high diversity
of plant species (Cowling 1983). The understorey typically hosts
a relatively high diversity of dwarf succulent shrubs and forbs
(mainly Crassulaceae and Aizoaceae), many of which are locally
endemic and rare (Cowling 1983, Johnson et al. 1999, Vlok &
Euston-Brown 2002, Vlok et al. 2003). Perennial grasses are
often prevalent inside the clumps, with Panicum maximum, P.
deustum and numerous Eragrostis species being found. The
wide range of growth forms and taxa in Albany Thicket is a
reflection of the transitional nature of thicket vegetation, being
an interface between various types of forest, sclerophyllous
shrublands, karoo and grasslands (Cowling 1984, Palmer 1990,
Everard 1991, Kerley et al. 1995, Vlok & Euston-Brown 2002).
A distinct guild of spinescent woody plants occurs in certain
types of thicket, that develop recurved branches once the plants
are more than 1 m tall and continue to produce the recurved
branches even when mature (deurmekaarbossie; Vlok & EustonBrown 2002). This unusual growth pattern results in an impenetrable barricade of thorny branches, because adjacent plants
become entwined as they mature. Seeds of all woody species
of this guild are contained within edible fruits and are bird-dispersed. The initial establishment of the woody species of this
guild with their spinescent, recurved branches is followed by
the growth of vines (often poisonous, wind-dispersed species)
within the bush clumps. These often spinescent lianas further
become interwoven within the individual bush clumps, to form
the impenetrable vegetation so typical of, for example, Sundays
Thicket. Once the matrix of shrub, grass and herb species is well
established, herbivores play an important role in maintaining
growth form richness.
There are insufficient data to describe major patterns of alpha,
beta and gamma diversity in thicket vegetation fully, but a local
study (Birch et al. 1999) gives some indication of alpha diversity
in this vegetation. Within the MST, the alpha diversity in the
clumps is higher (approx. 28 taxa per plot, range 15–44) than
outside the clumps (using data from Birch et al. 1999), but the
changes in diversity between clumps are low (total number of
species in 58 plots was 195). Clump diversity in SST is 25 taxa
per plot. TST contains 30 taxa per 100 m2 plot.
3.
Ecology: Climate, Geology, Soils and
Natural Processes
3.1
Climate
Albany Thicket is found in semi-arid areas of the Eastern and
Western Cape, with 200–950 mm MAP (Vlok & Euston-Brown
S %
19 (2006)
AT 1 Southern Cape Valley Thicket
mm
AT 2 Gamka Thicket
mm
°C
75
399 ^^
>2A
30 2A4G
33
17.1 4
20 >2E
3U
>75
10
>2A6 1900 ^^
0 >2D>D
72
50
25
0
75
25
0
; 7>2> ; ; 2 D @?5
AT 3 Groot Thicket
AT 4 Gamtoos Thicket
mm
°C
75
299 ^^
>2A
30 2A4G
35
16.7 4
20 >2E
19 U
>75
10
>2A6 2256 ^^
0 >2D>D
81
50
25
0
50
25
0
AT 6 Sundays Thicket
mm
°C
75
259 ^^
>2A
30 2A4G
36
18.3 4
20 >2E
5U
>75
10
>2A6 2288 ^^
0 >2D>D
82
50
25
0
25
0
AT 8 Kowie Thicket
mm
°C
75
452 ^^
>2A
30 2A4G
32
17.8 4
20 >2E
3U
>75
10
>2A6 1861 ^^
0 >2D>D
76
50
25
0
25
0
AT 10 Great Fish Noorsveld
mm
°C
75
677 ^^
>2A
30 2A4G
27
17.8 4
20 >2E
2U
>75
10
>2A6 1730 ^^
0 >2D>D
72
50
25
0
50
25
0
AT 12 Buffels Thicket
mm
°C
75
449 ^^
>2A
30 2A4G
32
17.1 4
20 >2E
7U
>75
10
>2A6 1916 ^^
0 >2D>D
77
50
25
0
655 ^^
>2A
30 2A4G
27
17.7 4
20 >2E
2U
>75
10
>2A6 1695 ^^
0 >2D>D
74
50
25
0
; 7>2> ; ; 2 D @?5
AT 13 Eastern Cape Escarpment Thicket
AT 14 Camdebo Escarpment Thicket
mm
°C
520 ^^
>2A
30 2A4G
30
16.0 4
20 >2E
16 U
>75
10
>2A6 1964 ^^
0 >2D>D
75
; 7>2> ; ; 2 D @?5
°C
75
; 7>2> ; ; 2 D @?5
0
420 ^^
>2A
30 2A4G
32
18.2 4
20 >2E
3U
>75
10
>2A6 1859 ^^
0 >2D>D
78
; 7>2> ; ; 2 D @?5
AT 11 Great Fish Thicket
25
°C
75
; 7>2> ; ; 2 D @?5
50
517 ^^
>2A
30 2A4G
30
17.5 4
20 >2E
3U
>75
10
>2A6 1843 ^^
0 >2D>D
75
50
; 7>2> ; ; 2 D @?5
AT 9 Albany Coastal Belt
75
°C
75
; 7>2> ; ; 2 D @?5
mm
334 ^^
>2A
30 2A4G
34
17.5 4
20 >2E
8U
>75
10
>2A6 2134 ^^
0 >2D>D
80
50
; 7>2> ; ; 2 D @?5
AT 7 Coega Bontveld
mm
°C
75
; 7>2> ; ; 2 D @?5
mm
460 ^^
>2A
30 2A4G
32
17.1 4
20 >2E
7U
>75
10
>2A6 1967 ^^
0 >2D>D
76
; 7>2> ; ; 2 D @?5
AT 5 Sundays Noorsveld
mm
°C
75
; 7>2> ; ; 2 D @?5
mm
267 ^^
>2A
30 2A4G
36
16.9 4
20 >2E
13 U
>75
10
>2A6 2396 ^^
0 >2D>D
81
50
; 7>2> ; ; 2 D @?5
mm
°C
°C
75
352 ^^
>2A
30 2A4G
34
15.9 4
20 >2E
25 U
>75
10
>2A6 2302 ^^
0 >2D>D
80
50
25
0
; 7>2> ; ; 2 D @?5
Figure 10.4 Climate diagrams of Albany Thicket Biome units. Blue bars show the median
monthly precipitation. The upper and lower red lines show the mean daily maximum and minimum temperature respectively. MAP: Mean Annual Precipitation; APCV: Annual Precipitation
Coefficient of Variation; MAT: Mean Annual Temperature; MFD: Mean Frost Days (days when
screen temperature was below 0°C); MAPE: Mean Annual Potential Evaporation; MASMS: Mean
Annual Soil Moisture Stress (% of days when evaporative demand was more than double the soil
moisture supply).
2002; see also Figure 10.4). Two prevailing climate systems (allyear rainfall to the southwest and summer rainfall to the northeast) converge in the region, resulting in all-year rainfall, with
spring and autumn maxima (Aucamp
& Tainton 1984). All the Thicket vegetation units have nonseasonal rainfall,
with optima in March and October or
November. The increase in summer rainfall to the northeast corresponds with a
change in vegetation towards grassland
and thorn-tree savanna; the increase
in winter rainfall to the southwest corresponds to a gradual replacement by
fynbos. In these two zones interannual
variations in climate, in combination with
different fire regimes and substrate factors, may lead to temporal species turnover and changes in dominance between
thicket species and those from adjoining
biomes.
Rainfall is unreliable, with an average
coefficient of variation of 25–36% (as
low as 18% at the coast and along the
escarpment, and as high as 40% in
Gamka Thicket), and droughts of several months are common. There is a
25% chance of not receiving 80% of the
mean rainfall in any given year (Aucamp
& Tainton 1984). In addition to this
unpredictable rainfall regime, the inland
region experiences high temperatures in
summer (exceeding 40°C on occasion)
and low temperatures with frost (0 to 64
days) in winter. The dominant plants in
these inland regions reflect this harsh climate, with a high degree of succulence
and sclerophylly. The larger shrubs and
trees are deep-rooted, and plants with
storage organs are common. Studies
on primary productivity in thicket have
shown that the life strategy in most species appears to be one of slow growth
(Aucamp & Tainton 1984).
Thicket vegetation growing close to the
coast experiences less extreme climatic
variability due to the influence of the
ocean. Coefficients of variation here are
usually lower than 30% and the number
of days of frost fewer than 10 per year.
There also tends to be a higher annual
rainfall, with the vegetation less succulent, and there is a lower degree of leaf
sclerophylly and more predictable growth
rates.
Vlok & Euston-Brown (2002) suggested
that fog may be important even in arid
thickets, with a high incidence of bark and
ground lichens.
3.2
Geology and Soils
The dominant geological feature in the
region occupied by the Albany Thicket
Biome is the east-west trending Cape
Fold Belt. These mountain ranges consist
mostly of the folded strata of the Cape
Supergroup, of which the sandstone and quartzite of the Table
Mountain and Witteberg Groups (Ordovician to Silurian and
Devonian, respectively) are biogeographically important (Gibbs
Albany Thicket Biome
545
S %
19 (2006)
L. Mucina
Russell & Robinson 1981) in that they
typically support outlier populations of
fynbos and renosterveld within a matrix
of thicket. Early Karoo Supergroup
sedimentary rocks, namely the Dwyka
and Ecca Groups, are also folded in the
northern margin of the Belt, where they
overly the Cape Supergroup rocks. The
main folding event took place around
250 mya. Another significant topographical feature is the escarpment which consists mostly of the fine-grained sediments
of the Beaufort Group of the Karoo
Supergroup. These rocks of Permian and
Triassic age are also intruded by Jurassic
Karoo Dolerite dykes and sills that
formed in association with the break-up
of the supercontinent Gondwana. This
rifting of South America from Africa
also resulted in the formation of halfgraben structures within the Cape Fold
Belt that formed the Cretaceous depo- Figure 10.5 AT 6 Sundays Thicket: Spekboomveld (Portulacaria afra) with a herd of last
Cape elephants (Loxodonta africana) browsing in the Greater Addo Elephant National Park
sitional basins for the Uitenhage Group
(Eastern Cape).
sediments. This sequence includes Enon
conglomerates as well as other finergrained clastic sediments. During the Tertiary Period, times of
nonflammable succulent component with a potentially flamrelatively high sea level caused the peneplanation of large areas
mable field layer (Vlok & Euston-Brown 2002).
between the coast and the mountains. As the sea level dropped,
Albany Thicket has historically supported a high diversity and
the accelerated erosion resulted in the dissection of the plains
density of indigenous herbivores, ranging in size from duiker
by a series of large river valleys such as the Fish, Sundays and
to elephants (Skead 1989). Early accounts of the travellers and
Gamtoos. It is these large valleys that gave rise to the name
explorers in the region report high numbers of elephant (see
‘Valley Bushveld’, as thicket vegetation is restricted to their
references in Stuart-Hill 1992). The high nutrient status of the
slopes and floors. Recent deposits of shallow marine sandstones
vegetation and proximity of many perennial rivers suggest that
and coastal dunes are present along the coast in many parts as
these large herbivores were permanent residents (Stuart-Hill
a result of more recent fluctuations in sea level.
1992) and support the hypothesis that herbivory has played an
The soils derived from these rocks vary considerably over a
important role in shaping vegetation and ecosystem propervariety of scales, closely tracking the underlying geology and
ties (Kerley et al. 1999b). The impact of indigenous herbivory
topography. The fine-textured rocks of the Karoo Supergroup
has been reflected in the evolution of the plant species, many
typically give rise to deep, well-structured soils. A repeated cat- of which are well defended against browsing (Everard 1987,
ena pattern of shallow rocky soils on upper slopes and deep
Haschick 2002). Midgley (1991) and Stuart-Hill (1992) describe
fine-textured soils in the valley floors is evident in the series of
the potential impacts of large herbivores through herbivory,
river valleys through the Eastern Cape. The more coarse-tex- trampling and dunging, and suggest that large mammals were
tured rocks of the Witteberg and Table Mountain Groups are
the primary patch disturbance agents in Albany Thicket prior to
typically found in sharply folded mountain systems, and the
their extirpation in the 1800s.
combination of steep slopes and the high percentage of quartz
Megaherbivores, such as elephants and rhinos, seem to be
sand gives rise to coarse, unstructured soils that are shallow
important in maintaining the structure of thicket vegetation
and nutrient-poor. Much of the fine-scale pattern in the vegeta(Stuart-Hill 1992), although they do impact on the diversity
tion is likely to be attributable to the interaction of climate and
of the dwarf succulents (Johnson 1998, Johnson et al. 1999,
pedology (e.g. Palmer et al. 1988).
Cowling & Kerley 2002). Stuart-Hill (1992) demonstrated the
role that elephants play in maintaining vegetation structure and
3.3 Natural Processes
promoting asexual recruitment of Portulacaria afra in Albany
Thicket (Figure 10.5). Elephants encourage coppicing in woody
Albany Thicket shows little annual fluctuation in its relatively
shrubs and promote the development of a skirt around P. afra
high perennial cover or biomass, irrespective of the relatively
plants. Sigwela (1999) and Sigwela et al. (2004) showed how
high coefficient of variation in mean annual precipitation or
significantly more seeds are dispersed by indigenous herbivores
with droughts that may last months or even years (Aucamp
than by goats. There have been several previous studies that
& Tainton 1984). This general resistance to drought probably
examine the impact of goats and indigenous megaherbivores
involves several mechanisms such as below-ground storage
on biodiversity and ecological processes. Most of the earlier
organs, sclerophylly, CAM photosynthesis and succulence. work was done from an agricultural production perspective,
Unlike other semi-arid ecosystems such as savannas and cer- where the vegetation was viewed primarily as a resource for
tain Mediterranean-type shrublands, intact Albany Thicket does
browsing animals (Aucamp & Tainton 1984). There are two key
not support a regular or widespread fire regime (Kerley et al. vegetative traits that contribute to degradation of the Albany
1999a). The combination of the low availability of fuel and the
Thicket. Firstly, despite a high standing biomass, Albany Thicket
high degree of succulence has largely excluded fire from Albany
has a low annual production, thus giving a false impression of
Thicket (Kerley et al. 1995). However, the occurrence of fire may
the amount of forage available for animal production (Aucamp
be increasing in degraded areas due to the replacement of the
& Tainton 1984). Another is the very slow recovery periods of
546
Albany Thicket Biome
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19 (2006)
the main forage species such as P. afra, which can take up to
18 months to recover from 50% defoliation by goats (Aucamp
& Tainton 1984). Also, the feeding behaviour of goats, both as
individuals and as herds, differs from that of indigenous herbivores (Danckwerts 1984, Stuart-Hill 1992). Goats are gregarious
animals and tend to feed in groups around individual plants and
vegetation patches, leading to very high localised impacts. They
also damage the structure of bush clumps by browsing from
the sides and exposing the interior to the forces of desiccating
winds and erosion by water (Stuart-Hill 1992).
4.
Origins and Biogeography
4.1
Origins of the Albany Thicket Biome
The Albany Thicket Biome is part of a poorly defined global
Subtropical Thicket Biome, characterised by subtropical, semixeric conditions. Such conditions became globally important
during the Eocene characterised by climate both colder and drier
than the usual (Zachos et al. 2001). Hence one can expect that
it was this period when most thicket plant lineages originated.
In support of this hypothesis, Cowling et al. (2005) have shown
that many plant groups characteristic of thicket vegetation (as
well as associated insect taxa) are of Eocene age, although both
older and more recent taxa currently represent important thicket
components. This timing is confirmed by both palynological
evidence (Boureau et al 1983, Salard-Cheboldaeff & Dejax
1991) and recent calibration attempts (Davies et al. 2004).
Ebenaceae, two clades of Celastraceae, Sapindaceae,
Didiereaceae (currently including also Portulacaria) and
Cotyledonoideae (Crassulaceae) can be reasonably listed as
those families well represented in the Albany Thicket Biome
which diversified most likely in the Eocene (Cowling et al.
2005). Generally, these are taxa endemic to, or most diverse
in, semixeric African vegetation. Many other clades will probably be added to this list as more well-dated phylogenies
become available.
Some of the succulents and geophytes are of more recent origin
(Klak et al. 2004, Procheş et al. 2006), presumably dating back
to the more pronounced mid- to late Tertiary aridification. These
are groups that are generally centred in the arid southwest of
southern Africa (Nama-Karoo and Succulent Karoo Biomes), but
have clades typical of the Albany Thicket Biome, indicating a
retrocolonisation of a semixeric environment from fully xeric
conditions. Examples are several clades within Aizoaceae and
within Asteraceae, specially the tribe Senecioneae (Cowling et
al. 2005).
The geographic origins of Albany Thicket are poorly understood,
and southern African fossil sites of relevant age are few. The
fossil woods from Bogenfels (Namibia) indicate an assemblage
more similar to present savanna or arid bushveld than to the
Albany Thicket (Bamford 2000). Older sites, such as the pollen flora of Banke in Namaqualand (Cretaceous/Early Tertiary,
Scholtz 1985) show no clear evidence of thicket elements. The
Umzamba site in the Eastern Cape (of similar age) contains a
variety of fossil woods, some belonging to the Euphorbiaceae,
more likely typical of forest sites (Bamford 2000). The assemblages that can be quite clearly associated with the present-day
Albany Thicket taxa come from other parts of the African continent, mainly from East Africa, such as the variety of woody
plants of Ebenaceae, Celastraceae and Oleaceae occurring in
Eocene to Miocene deposits from Ethiopia, Uganda and Egypt
(Laudoueneix-Dupéron & Dupéron 1995). Recently, Schrire et
al. (2005) have suggested that those plant forms characteristic
of a global ‘succulent biome’ (covering also the parts of global
Subtropical Thicket Biome) first appeared during the Eocene in
the region of the Tethyan Ocean (the Mediterranean Sea being
a remnant of the latter), in conjunction with the aridification
that affected this region more drastically than others. This area
is likely to have represented the cradle of the Fabaceae. An
early branch that supports this hypothesis is the tribe Detarieae,
which includes the southern African endemics Schotia and
Umtiza. A northern origin is also supported by the Tertiary
records of typical thicket genera such
as Ehretia and Rhoicissus from Europe,
where they are now extinct (Gottschling
et al. 2002, Ingrouille et al. 2002). The
above evidence may suggest that the
Albany Thicket Biome may represent a
relict formation with deep roots in the
Eocene.
L. Mucina
Another set of taxa are likely to represent true Gondwanan relicts, and therefore are of Mesozoic age, although they may
have adopted a semixerophytic habit only during the Eocene or
later. These are the cycads of the genus Encephalartos as well as
Cussonia (Araliaceae) and Strelitzia (Strelitziaceae; Figure 10.6),
all having their closest relatives in South America, Madagascar
and Australia.
Figure 10.6 Strelitzia reginae (Strelitziaceae)—a flagship beauty among South African plants
(near Ecca Pass north of Grahamstown, Eastern Cape).
Currently, several centres of semixeric
and xeric plant diversity can be distinguished on the African continent (including Madagascar), the most important
being the Succulent Karoo Region, the
thicket vegetation of the Eastern Cape,
the KwaZulu-Natal/Limpopo high diversity zone, several smaller centres in East
Africa, the Horn of Africa (including the
Island of Socotra), the Mediterranean
Basin, and southern and southwestern
Madagascar. Three of these areas appear
to have been most important in harbouring the earliest branches in various
semixeric lineages, namely the Succulent
Karoo Region, the Eastern Cape and
Albany Thicket Biome
547
S %
western Madagascar. Various groups appear to have colonised
large parts of the continent having originated in one of these
three areas. The southern African-Madagascan semixeric connection is particularly interesting, given that Madagascar has
been separate from the African mainland since the Cretaceous.
Nevertheless, the distance was never large enough to prevent
multiple crossing events by wind-dispersed as well as bird-dispersed plants (Grubb 2003, Pell 2004). At the same time, temporary aridification events during the Tertiary (and recent ones
associated with Pleistocene glaciations) may have facilitated
exchange events between southern Africa and the Horn of
Africa and consequently the entire Mediterranean region along
an arid corridor, even in groups with limited dispersal abilities
(see Axelrod & Raven 1978).
The floristic uniqueness of the Albany Thicket Biome, marked
by a significant contingent of local endemics, suggests an uninterrupted existence in its current geographic distribution area.
However, variations in size may have been great. The absence of
endemic vertebrates—as would be expected given the relatively
large area covered by the biome—strongly suggests that thicket
vegetation suffered several constrictions in recent times, most
likely associated with Pleistocene glacial cycles (see Cowling
et al. 1999). Then the Albany patch may not have been much
larger than other vegetation patches of similar composition
growing under different climatic conditions in fire-free pockets
along the eastern escarpment of southern Africa and the Great
Rift Valley. The establishment of a relatively large nonseasonal
rainfall and fire-protected area in the Eastern Cape may have
allowed it to expand to its current extent.
Browser pressure and the unreliable arid climate of the region
have probably been the driving forces in the evolution of Albany
Thicket since the Last Glacial Maximum (LGM), 18 000 to 21 000
years BP (Palmer 1990). Yet, in the face of the impressive array
of indigenous herbivores (not even considering arthropods),
Albany Thicket appears to show little fluctuation (in recent decades) in standing biomass over short periods of time (Aucamp &
Tainton 1984). This feature sets it apart from most of the other
herbivore-driven systems, such as savannas (Scholes & Walker
1993) and grasslands (O’Connor & Bredenkamp 1997), where
the herbivores (Owen-Smith & Danckwerts 1997), fire, and climate (Schulze 1997) are primary determinants of plant biomass.
In Albany Thicket, indigenous herbivores do reduce plant biomass, but the overall patch structure is retained (Cowling &
Kerley 2002). In spite of the widespread and varied defences
employed by plants, and their apparent resistance to herbivory,
the onset of domestic herbivory was the catalyst to degradation
of the Albany Thicket ecosystems.
4.2 Biogeography
The Eastern Cape flora corresponds with the convergence of
five of White’s (1983) phytochoria (Cowling 1983, Cowling &
Campbell 1983), namely the Cape Region, the Karoo-Namib
Region (later subdivided; see chapter on Succulent Karoo in
this book), the Maputaland-Pondoland Regional Mosaic, the
Afromontane Region and the Kalahari-Highveld Regional
Transition Zone. As a result, the flora has been described as
complex and transitional and the convergence of these phytochoria in the Eastern Cape has led to a huge ‘tension’ zone
(Cowling 1983). No less than 21 of 70 national Acocks (1953)
Veld Types are represented in the Albany area, which constitutes
the core of the Albany Thicket Biome. Subtropical MaputalandPondoland forests enter Albany Thicket from the northeast
along the coast, penetrating up the river valleys after the establishment of warmer wetter conditions that followed the LGM
(Palmer 1990). The succulent and dwarf shrublands of the
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Albany Thicket Biome
19 (2006)
Karoo-Namib phytochorion penetrated down the river valleys
from the arid interior and graded into the forest and thicket.
Afromontane (afrotemperate) forest elements are found from
the sea level forests to the forest pockets in the interior mountains, possible refugia from the LGM. Cape fynbos elements are
well represented on the infertile soils derived from the Cape
Supergroup rocks (Cowling 1983). The relative distributions of
these phytochoria are held in balance by environmental drivers
such as climate and, more recently, land use. The result is a
mosaic of plant communities with different or mixed chorological affinities (Cowling 1983).
The Albany Thicket is the Eastern Cape biome supporting the
highest number of endemic taxa. It forms the core of the socalled Albany Centre of Endemism (Van Wyk & Smith 2001).
Some authors (e.g. Gibbs Russell & Robinson 1981) consider
the Albany region to have relatively low levels of endemism
in comparison to the rich centres of endemism elsewhere in
southern Africa. Many of the species in the Albany Thicket
Biome are considered to have their centres of distribution elsewhere, and it has been suggested that the region does not have
a strongly characterised flora (Gibbs Russell & Robinson 1981,
Hoffman & Cowling 1991). However, endemism in this region is
probably grossly under-estimated (Van Wyk & Smith 2001) and
the region represents a centre of endemism for karroid succulents (Hoffman & Cowling 1991, Van Wyk & Smith 2001), most
of which are restricted to the thicket vegetation in the region.
High percentages of endemism are reported for the families
Asclepiadaceae, Crassulaceae, Euphorbiaceae and for several
families of the Asparagales (see Smith & Marx 1990). High
numbers of local endemics are known to occur and Cowling
& Hilton-Taylor (1994) report 51 Red Data taxa, 200 endemics
and 2 000 taxa in the Albany hotspot, an area that corresponds
broadly with the Albany Centre of Endemism (Van Wyk & Smith
2001). An analysis of threatened species in the Albany Centre
of Endemism (Victor & Dold 2003), which includes the Albany
Thicket, indicates that 180 (61%) of the species evaluated have
a very narrow distribution range. This list does not include all
endemic taxa, but is similar to the 200 endemics reported by
Cowling & Hilton-Taylor (1994) and 205 by Lubke et al. (1986)
that give an overall estimate of 10% endemism for the Albany
Centre of Endemism. There are many more near-endemics (with
about 90 listed in the descriptions of the vegetation types of
the biome). Van Wyk & Smith (2001) report 365 endemic/nearendemic succulents in the Albany Centre of Endemism; inclusion of nonsucculents would expand this list considerably and
indicates that 10% endemism is probably an under-estimate.
Vlok & Euston-Brown (2002) provide a list of 322 out of 1 588
species (20%) in subtropical thicket that are endemic. The
endemics of the region are a mixture of palaeoendemics and
neoendemics, with few endemic genera and no endemic families (Van Wyk & Smith 2001).
5.
Land Use History
Prior to the arrival of colonial settlers in the early 1800s the
region was sparsely populated by humans. Most human activity
was concentrated along the Sundays River Valley, the principal
source of perennial water in the area. Early travellers described
the area as an unbroken expanse of dense thicket north of
Uitenhage (Skead 1989). Initially, domestic stock was restricted
by the high densities of ticks (carrying the fatal heartwater disease) and difficultly of access for the stock associated with the
very dense bush, and the limited perennial water (A. Rudman,
personal communication). Later, the use of dips and boreholes
allowed farmers to increase their stock densities and enter into
S %
19 (2006)
new areas of thicket. This trend resulted in the opening up of
large areas of thicket. More recently, an increasing number of
farmers are switching from stock to game farming (Smith &
Wilson 2002) as reduced availability of forage and increased
variability in forage production make stock farming less profitable and sustainable.
Current Status, Threats and Actions
The current Albany Thicket vegetation is highly transformed and
shows high levels of degradation (Lloyd et al. 2002, Palmer et
al. 2004). Of the untransformed Thicket, only 11% is still in
pristine condition and 60% is severely degraded (Lloyd et al.
2002). Approximately 7.3% has been transformed. The factors
responsible for degradation and obliteration across the biome
include cultivation in the moister regions, herbivory by livestock
in the drier regions and urban settlement along the coast (Lloyd
et al. 2002). The pressure on individual species, likewise, is high.
Of the 126 species threatened with extinction in the Albany
Centre of Endemism, the major threats, in decreasing order of
importance, are illegal collecting, urban residential development, industrial development, alien plants, agriculture (including browsing/grazing), medicinal harvesting and forestry (Victor
& Dold 2003).
Current land use pressure on thicket vegetation includes primarily urbanisation, agriculture and afforestation/alien trees
L. Mucina
Considering that thicket has historically
been exposed to a range of indigenous
herbivores, from duiker to elephants,
sometimes in very dense populations
(Skead 1989), it is interesting to note
why it collapses so rapidly in the face
of domestic herbivory. The production potential of Albany Thicket is easily destroyed by domestic herbivory due
to a combination of the feeding behaviour of goats (Stuart-Hill & Danckwerts
1988) and the slow growth rate of the
plants (Aucamp & Tainton 1984). StuartHill (1992) shows how goats feed into
the sides of bush clumps, exposing the
interior and reducing essential vegetative
recruitment. In comparison, indigenous
herbivores that browse from the top of
the bush clumps, encourage vegetative
recruitment. If damaged by over-utilisation, the woody component of the
vegetation does not recover within management time frames (Stuart-Hill 1992).
In comparison to other woody and
herbaceous systems, such as savannas,
removal of the woody component does
not necessarily lead to a more produc-
6.
J.P.H. Acocks
With the arrival of the first European settlers in the early 1800s,
began the extirpation of megaherbivores (elephant and black
rhino) and significant reductions in the populations of small
(e.g. duiker) and medium-sized (e.g. bushbuck and kudu)
herbivores (Kerley et al. 1999b). Since then, the high-quality
forage available in intact Albany Thicket has been used to support extensive pastoralism. Goats were the most successful
domestic species in the region since they were able to make use
of the high biomass of browse. Despite its long history of herbivory, Albany Thicket has not displayed resilience to domestic
herbivory and there is much evidence to show that commercial
pastoralism has led to ecosystem-level degradation (Aucamp &
Tainton 1984, Hoffman & Cowling 1990, Moolman & Cowling
1994, Kerley et al. 1999a, b). Approximately 92% (7 500 km2)
of Albany Thicket in the Eastern Cape has been degraded to
some degree over the past 200 years (Lloyd et al. 2002). Much
of this degradation occurred decades ago when there was little understanding of sustainable stocking levels in Albany Thicket. Anecdotal
accounts suggest that government-recommended stocking rates during the
1950s were at least 20-fold those of
today. Furthermore, it seems that some
thicket farmers deliberately over-stocked
goats to open up the dense bush, as
much of the biomass was inaccessible to
other stock, and high levels of tick-borne
heartwater disease were associated
with dense bush (A. Rudman, personal
communication). Thus, the area is now
dominated by grasses and ephemeral
forbs, with remnant trees and pockets of
thicket (Figure 10.7).
tive grass understorey. The herbaceous layer is not a reliable
source of forage, as its production closely tracks rainfall patterns (Stuart-Hill 1992).
Figure 10.7 AT 3 Groot Thicket: Fence-line effect in the Spekboomveld near Willowmore
(Eastern Cape), 13 km south of Beervlei Dam. To the right of fence small trees and shrubs of
Euclea undulata, Pappea capensis, Rhigozum obovatum and Lycium oxycarpum are left. Photographed by J.P.H. Acocks in the 1950s (above top) and in 1998 (above). See also Acocks (1979,
Figure 8).
Albany Thicket Biome
549
S %
(Cowling et al. 2003). Two urban areas constitute a significant
pressure on surrounding vegetation, namely the Nelson Mandela
Metropole (including Port Elizabeth) and environs and the corridor spanning Buffalo City (East London) and the Amathole
range (Cowling et al. 2003). The Nelson Mandela Metropole
is considered to constitute a significant urbanisation pressure
on the surrounding landscape and therefore on biodiversity
(Cowling et al. 2003). Coega is a specific nucleus of urban
sprawl due to the development of the Industrial Development
Zone that will result in the attraction of large populations of
people to the surrounding areas. The Albany Thicket vegetation
types from this node most at threat are Coega Bontveld and,
to a lesser extent, Sundays Thicket. Further northeastwards,
Buffalo City and its extensions towards Bisho constitute a threat
to Buffels Thicket, but this vegetation is more widespread in
areas removed from this threat.
A recent report detailing the effects of climate change on vegetation in South Africa (Rutherford et al. 1999, WWF 2001)
did not treat the Albany Thicket as a separate biome. However,
according to modelled climatic scenarios over the next 50
to 100 years, the area occupied by Thicket vegetation would
undergo a major shift in climate, becoming warmer with fewer
days when soil moisture and temperature are suitable for plant
growth. Only the extreme western and eastern portions of the
biome would be less affected. Fynbos would extend slightly
eastwards, suggesting that bimodal climate conditions will also
move eastwards shifting Albany Thicket in that direction. On
the basis of this type of analysis, it is possible that there might
be a significant loss in area of the Albany Thicket types that
do not occur in the kind of habitat available in these eastern
regions, for example steep-sided river valleys. Predictions are
that approximately 20% of the area where Portulacaria afra is
found, would become unsuitable for this species under modelled scenarios of climate change (Robertson & Palmer 2002).
The worst-affected areas are likely to be the coastal region
around Algoa Bay, almost at the core of the biome, as well as
the Keiskamma River Valley and areas to the south of GraaffReinet (Robertson & Palmer 2002). Climate change effects are,
however, more complex, and it is likely that changes in the variability of climate parameters will have as big an influence on
the survival and distribution of species as changes in the mean
values of parameters (O’Connor & Roux 1995).
A number of megaconservancy networks (MCNs) and expanded
parks have been proposed or are in the process of being established within the biome, including the Fish-Kowie MCN, the
Gqunube-Amathole MCN, the Kei MCN, the Gouritz-Little
Karoo MCN, the Baviaanskloof MCN and the Addo-Camdebo
MCN, many of which include existing reserves. Despite the formation of these new conservation areas, conservation of the
variety of Thicket vegetation will not be achieved without the
establishment of new protected areas that conserve unprotected types of Albany Thicket. One of the major conservation initiatives in the biome area is the expansion of the Addo
Elephant National Park, which began in 1997 and is still under
way, made possible by funds from the government (DEAT) and
foreign donors (primarily the Global Environmental Fund). The
park is currently 148 000 hectares in extent (December 2004)
and will eventually cover 240 000 hectares to become South
Africa’s fourth largest National Park.
Large areas of Albany Thicket degraded by overgrazing and invasive alien plants require a substantial restoration effort for the
achievement of both pattern and process conservation targets
(Cowling et al. 2003). The Working for Water Programme may
restore the function and biodiversity of the catchment through
the systematic eradication of alien invasive plants. However,
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Albany Thicket Biome
19 (2006)
rehabilitation efforts to restore Albany Thicket vegetation are
likely to be very labour-intensive and require long-term investment of resources (Todkill 2001). Much of the degraded thicket
was Portulacaria afra-dominated and the re-establishment of
this species is necessary to begin to restore the vegetation.
However, this is costly and unlikely to be undertaken by private land owners. Due to the high carbon-storage ability of
Portulacaria afra-dominated thicket (Lechmere-Oertel 2003),
the opportunity exists to initiate restoration through the international carbon credit system (Cowling et al. 2003).
7.
Further Research
The main focus of the research in the Albany Thicket Biome
appears to have been on the agricultural potential of these
areas and the contribution that Thicket may make towards
animal production, both domestic (e.g. Aucamp 1976, 1979,
Aucamp & Tainton 1984, Danckwerts 1984) and wild (e.g.
Cowling & Kerley 2002), as well as on the influence of grazing
and browsing on thicket structure and function (e.g. LechmereOertel 2003). Two ‘Valley Bushveld Symposia’ (proceedings
published in 1991 and 1996) generated much interest and
data on the economic and conservation aspects of the Albany
Thicket Biome.
Earlier studies (Dyer 1937, Story 1952, Acocks 1953, 1988,
Archibald 1955, Lubke et al. 1986) were broad in nature, but
provided a good first approximation of vegetation patterns.
Some detailed studies have been undertaken, e.g. Cowling
(1984), Everard (1987), Palmer (1988), Birch et al. (1999), Judd
(2001), but most of these are concentrated in specific areas
and have been undertaken at different levels of intensity. There
is an urgent need for detailed floristic studies on the different
vegetation units within the Albany Thicket Biome to provide
baseline information on diversity, structure and species composition, as well as on the distribution of individual species and
the relationship between the different parts of the Biome. Two
major universities located in the region (the Nelson Mandela
Metropolitan University in Port Elizabeth and the Rhodes
University in Grahamstown) are the institutions that should take
the lead to deal with these challenges.
Recently, the Subtropical Thicket Ecosystem Planning Project
(STEP) was an important measure in identifying ecologically
uniform areas on the basis of remote-sensed data and environmental parameters. The STEP (Cowling et al. 2003, Pierce et al.
2005) identified a number of research priorities of an ecological
nature, including the need to identify dynamics within different Thicket types, how these dynamics compare in intact and
degraded forms of Thicket, what the biological indicators of
ecosystem health are in different Thicket types, what they mean
and how they can be used in monitoring programmes, to what
extent different Thicket types are dependent on herbivory by
different guilds of indigenous herbivores for the maintenance
of biodiversity and ecosystem health, and what processes are
essential across all spatial and temporal scales for the long-term
maintenance of Thicket biodiversity.
8.
Descriptions of Vegetation Units
AT 1 Southern Cape Valley Thicket
Aloe Scrub (Muir 1929). VT 23 Valley Bushveld (44%), VT 46 Coastal
Renosterbosveld (39%) (Acocks 1953). LR 63 South and South-west Coast
Renosterveld (86%) (Low & Rebelo 1996, 1998). BHU 93 Gouritz Mesic
Succulent Thicket (74%) (Cowling & Heijnis 2001). STEP Gouritz Valley
Thicket (63%) (Vlok & Euston-Brown 2002).
S %
19 (2006)
Distribution Western Cape Province: The core of the distribution is in river valleys of the Goekoe River (between Riversdale
and Still Bay) with the largest patch in the Gouritz River Valley
(between Herbertsdale and the Gouritzmond) and is found in
unmapped smaller patches of the Groot Brak and Klein Brak
Rivers as well as the Kaaimans River (here at its easternmost
limit). Towards the west this vegetation is found (unmapped)
in valleys of the Duiwenhoek and Slang Rivers and reaches its
westernmost limits of distribution in the Breede River Valley.
Altitude 20–200 m.
Vegetation & Landscape Features Steep slopes of deeply
incised valleys of rivers flowing mainly in a north-south direction
and dissecting the Southern Cape coastal peneplain. Mediumsized to tall (3–5 m), dense thicket composed of sclerophyllous (often spinescent) evergreen shrubs (e.g. Euclea, Grewia,
Gymnosporia, Putterlickia, Rhus, Sideroxylon, Tarchonanthus)
as well as an important admixture of a microphyllous (partly ericoid) shrub element (Athanasia, Elytropappus, Oedera, Stoebe)
and with a prominent (locally also dominant) succulent, rosulate tree, Aloe ferox. The low shrub layer contains a high proportion of succulent shrubs (Aloe, Crassula, Euphorbia, Ruschia).
Grasses are abundant in some favoured grazing areas.
Geology & Soils Shallow, loamy-clayey soils (mostly Glenrosa
and Mispah) derived from siltstone and shales of the Bokkeveld
Group in the western part of the area, and Jurassic Enon conglomerates and other clastic sediments of the Uitenhage Group
in the eastern part of the area. Where on hard Ordovician Table
Mountain sandstone, only on the Aasvogelberg range—on rocky
south-facing slopes with organic-rich soils (Rebelo et al. 1991).
Fc land type predominates, while Ia is of lesser importance.
Climate Nonseasonal rainfall with several slight optima (in
March, May, August, October), and with driest summer months
December to February. MAP 400 mm, which ranges from about
340 mm in the west (Swellendam) to about 940 mm in the east
(Wilderness). Frost is infrequent. MAT falls within warm-temperate range (17°C). Mean monthly maximum and minimum temperatures for the nearby Riversdale weather station are 37.5°C
and 0.2°C for February and July, respectively and corresponding
values on the coast for Mossel Bay (Cape St Blaize) are 29.6°C
and 7.4°C for April and August, respectively. Also see climate
diagram for AT 1 Southern Cape Valley Thicket (Figure 10.4).
Important Taxa Succulent Tree: Aloe ferox (d). Small
Trees: Acacia natalitia, Schotia afra var. afra. Tall Shrubs:
Chrysanthemoides monilifera (d), Elytropappus rhinocerotis
(d), Olea europaea subsp. africana (d), Carissa bispinosa subsp.
bispinosa, Clausena anisata, Euclea undulata, Grewia occidentalis, Gymnosporia buxifolia, Putterlickia pyracantha, Rhus
glauca, R. laevigata, R. longispina, R. lucida, Tarchonanthus
camphoratus. Low Shrubs: Pteronia incana (d), Anthospermum
aethiopicum, A. prostratum, Aspalathus globulosa, Asparagus
capensis var. capensis, A. striatus, Athanasia pectinata, Felicia
filifolia, Freylinia undulata, Galenia pubescens, Garuleum latifolium, Gnidia squarrosa, Lauridia tetragona, Leonotis leonurus,
Oedera genistifolia, Otholobium hirtum, Pentzia incana, Polygala
myrtifolia, P. scabra, Stoebe muirii, Sutera caerulea. Succulent
Shrubs: Adromischus triflorus, Aloe maculata, Aptenia cordifolia, Cotyledon orbiculata var. orbiculata, C. papillaris, Crassula
cultrata, Euphorbia burmannii, E. mauritanica, Lampranthus
prominulus, Zygophyllum foetidum. Woody Succulent Climbers:
Crassula perforata (d), Sarcostemma viminale. Woody Climbers:
Asparagus africanus, A. racemosus. Graminoids: Ehrharta
erecta (d), Cynodon dactylon, Ehrharta calycina, Festuca scabra,
Karroochloa curva, Merxmuellera stricta, Panicum maximum,
Stipa dregeana. Herbaceous Climber: Cynanchum obtusifolium.
Succulent Herbs: Anacampseros telephiastrum, Carpobrotus
edulis, C. muirii, Crassula muscosa, C. saxifraga, Senecio
ficoides. Geophytic Herbs: Bulbine praemorsa, Cheilanthes hirta,
C. multifida, Cyanella lutea, Hesperantha acuta, Mohria caffrorum, Nerine humilis, Oxalis bifurca var. angustiloba, O. obtusa,
O. pes-caprae. Herbs: Arctotheca calendula, Berkheya heterophylla, Cineraria lobata, Cotula sororia, Erucastrum austroafricanum, Hypoestes aristata, Lepidium africanum, Lotononis
calycina, Nemesia fruticans, Sebaea ramosissima, Sisymbrium
capense, Stachys aethiopica.
Biogeographically Important Taxa ( E Eastern limit,
Southeastern limit, W Western limit) Succulent Tree: Aloe
speciosaW. Succulent Shrubs: Aloe arborescensW, Euphorbia
mammillarisW, Portulacaria afraW. Tall Shrubs: Azima tetracanthaW, Diospyros pallensSE. Low Shrub: Lyperia antirrhinoidesE.
Succulent Climber: Crassula lacteaW. Succulent Herb: Gasteria
carinataSE. Herb: Senecio muirii (shared with AT 2 Gamka
Thicket). Graminoid: Pentaschistis trisetaE.
SE
Endemic Taxa Succulent Shrub: Cotyledon eliseae. Succulent
Herbs: Haworthia chloracantha, H. turgida (all three varieties).
Conservation Vulnerable. Target 19%. Very little of unit
conserved in Pauline Bohnen Nature Reserve (statutory) and
in Langeberg-Oos Reserve (private). 35% transformed by
cultivation. Erosion is variable—from very low to high. Near
Albertinia the local Aloe ferox has become the subject of a
local industry aimed at extracting substances for medicinal and
cosmetic use.
Remark 1 This is the westernmost thicket type completely
embedded within the matrix of the Fynbos Biome (with a minor
border with the Succulent Karoo Biome in the upper Gouritz
Valley). A number of taxa reach their westernmost limits of
distribution here (see above), suggesting a (past) link to the
Albany Thicket proper. At least two species (Cotyledon papillaris
and Senecio muirii) are shared with Gamka Thicket. Not surprisingly, this thicket type contains the highest number of Fynbos
elements of the whole Albany Thicket Biome.
Remark 2 The steep, rocky slopes, geomorphology and consequently poor soil development create environmental conditions
very different from the surrounding renosterveld vegetation
(Fynbos Biome) which typically covers the coastal plateaus of
the Southern Cape. The habitats supporting this type of thicket
are usually protected from fire that occurs in the neighbouring
renosterveld. Grazing by domestic animals was (or in places still
is) common.
References Muir (1929), Grobler & Marais (1967), Taylor (1970), Acocks
(1988), Rebelo et al. (1991), Cowling & Heijnis (2001), Vlok & Euston-Brown
(2002), Vlok et al. (2003).
AT 2 Gamka Thicket
VT 25 Succulent Mountain Scrub (Spekboomveld) (58%) (Acocks 1953). LR 8
Spekboom Succulent Thicket (47%), LR 58 Little Succulent Karoo (20%) (Low
& Rebelo 1996, 1998). BHU 97 Spekboom Xeric Succulent Thicket (42%),
BHU 89 Oudtshoorn Broken Veld (18%) (Cowling & Heijnis 2001). STEP
Gamka Arid Spekboomveld (30%), STEP Kandelaars Karroid Thicket (17%),
STEP Mons Ruber Fynbos Thicket (17%) (Vlok & Euston-Brown 2002).
Distribution Western and (marginally) Eastern Cape Provinces.
Centred around Oudtshoorn in the basin of the Little Karoo
between the Groot Swartberg Mountains in the north and
the Outeniqua Mountains in the south, where it occurs on the
lower mountain slopes and in some river valleys. It extends from
the lower Gamka River Valley and the eastern lower flank of
Rooiberg and through the Groot Swartberg Mountains (including the enclosed valley of ‘The Hell’), for about 130 km eastwards on lower parts of ridges north of the Groot Swartberg
Albany Thicket Biome
551
S %
19 (2006)
L. Mucina
commutata, C. tetragona subsp. acutifolia,
Othonna carnosa, Pachypodium succulentum, Sceletium rigidum, Zygophyllum
flexuosum, Z. foetidum, Z. fulvum. Low
Shrubs: Garuleum latifolium (d), Pteronia
incana (d), P. pallens (d), Aptosimum
indivisum, Asparagus burchellii, A.
mucronatus, A. striatus, Ballota africana,
Chrysocoma ciliata, Eriocephalus africanus, Euryops brevipapposus, Felicia
filifolia, F. muricata, Galenia africana,
Gloveria integrifolia, Helichrysum zeyheri,
Limeum aethiopicum, Lycium cinereum,
L. oxycarpum, Monechma spartioides,
Oedera squarrosa, Polygala myrtifolia, P.
scabra, Tetragonia robusta var. psiloptera,
Zygophyllum microphyllum. Woody
Succulent Climbers: Pelargonium zonale,
Sarcostemma viminale. Semiparasitic
Epiphytic Shrub: Viscum rotundifolium.
Woody Climbers: Asparagus racemoFigure 10.8 AT 2 Gamka Thicket: Spekboomveld (Portulacaria afra) on steep northern slopes of
the Huisrivier Pass between Calitzdorp and Ladismith in the Little Karoo (Western Cape).
sus, Cissampelos capensis. Herbaceous
Climbers: Cynanchum ellipticum,
Kedrostis capensis. Graminoids: Cynodon dactylon (d), C. incomas far as the Droëkloofberg Mountains (including the isolated
pletus (d), Ehrharta calycina (d), Eragrostis curvula (d), Aristida
ridges to the north that include Tierberg) and to the upper
adscensionis, Cymbopogon prolixus, Digitaria argyrograpta, D.
reaches of the Olifants River Valley south of the Groot Swartberg
eriantha, Ehrharta erecta, Eragrostis obtusa, Fingerhuthia afriand north of the Kammanassie Mountains. Altitude varies from
cana, Hyparrhenia poecilotricha, Stipagrostis ciliata var. capenabout 300–1 000 m.
sis. Succulent Herbs: Crassula muscosa, Haworthia blackburVegetation & Landscape Features Undulating to steep footniae var. blackburniae. Geophytic Herbs: Oxalis pes-caprae (d),
hills and valleys dominated by a low succulent thicket, sometimes
Asplenium cordatum, Cheilanthes hirta, Chlorophytum crispum,
quite open. In its pristine condition dense stands of spekboom
Drimia intricata. Herbs: Arctotheca calendula, Chamaesyce
(Portulacaria afra) occur, often with Euclea undulata, Gloveria
inaequilatera, Cineraria platycarpa, Conyza scabrida, Emex
integrifolia, Pappea capensis and Rhus glauca. Shrubs are also
australis, Hermannia pulverata, Lepidium africanum, Pulicaria
abundant, stem- and leaf-succulents are often prominent, and
scabra, Troglophyton capillaceum.
the grass component is poorly developed, with Cenchrus ciliaris,
Endemic Taxa Succulent Shrub: Euphorbia gamkensis.
Ehrharta calycina, Eragrostis plana and Sporobolus fimbriatus
Geophytic Herbs: Eriospermum rhizomatum, Lachenalia
occasionally abundant after good rain.
haarlemensis.
Geology & Soils Mostly restricted to sites where relatively deep
(>1 m) loamy-clayey soils occur on Enon Formation conglomer- Conservation Least threatened. Target 19%. About 9% statutorily conserved mainly in Groot Swartberg, Groenefontein and
ates (Jurassic), thus often deep beds of gravelly rocky soil. In the
Gamkapoort Nature Reserves. About 4% transformed mainly
lower Gamka River Valley it occurs on Bokkeveld Group shales
by cultivation. The invasive alien, Atriplex lindleyi, is scattered in
and north of the Swartberg Mountains it is found on arenites
places. Erosion is very low to moderate. Fragmentation of the
and shales of the Witteberg, Ecca or Bokkeveld Groups. Land
Gamka Thicket has occurred due to frequent fires that sweep
types: mostly Ag (almost half of the area), followed by Ic, Ib
down from the adjacent fynbos-clad mountains.
and Fc.
Climate The driest of the thicket types, MAP ranges from about
105 mm on the plains north of the Swartberg to about 540
mm (extremes are 102–545 mm) on the south-facing mountain
foothills. The rainfall is nonseasonal with slight optima in March
and October/November and lowest rainfall in the summer
months of December to February. Frost is fairly frequent. Mean
monthly maximum and minimum temperatures for Oudtshoorn
are 39.9°C and –0.4°C for February and July, respectively. See
also climate diagram for AT 2 Gamka Thicket (Figure 10.4).
Important Taxa Succulent Trees: Aloe ferox, A. speciosa. Small
Trees: Acacia karroo, Pappea capensis, Schotia afra var. afra.
Tall Shrubs: Cadaba aphylla, Carissa bispinosa subsp. bispinosa,
Elytropappus rhinocerotis, Dodonaea viscosa var. angustifolia, Euclea undulata, Gymnosporia heterophylla, Melianthus
comosus, Nymania capensis, Olea europaea subsp. africana,
Putterlickia pyracantha, Rhigozum obovatum, Rhus glauca,
R. lancea, R. lucida. Succulent Shrubs: Crassula cultrata (d),
Euphorbia mauritanica (d), Portulacaria afra (d), Aloe microstigma, Cotyledon orbiculata var. orbiculata, C. papillaris,
Crassula lanceolata, C. nudicaulis, C. ovata, C. rupestris subsp.
552
Albany Thicket Biome
Remarks The vegetation has complex floristic and spatial links
to Nama-Karoo and Succulent Karoo as well as to the Fynbos
Biome vegetation demonstrated by the synonymy with a
number of previously described vegetation units (see above).
It is particularly in this area that Acocks (1953) characteristically positioned his Spekboomveld (thicket) in a vegetation
sequence between the lower lying karoo and higher positioned
renosterveld.
References Acocks (1953, 1988), Lloyd et al. (2002), Vlok & Euston-Brown
(2002), Vlok et al. (2003), Cleaver et al. (2005).
AT 3 Groot Thicket
VT 25 Succulent Mountain Scrub (Spekboomveld) (43%), VT 26 Karroid
Broken Veld (27%) (Acocks 1953). LR 8 Spekboom Succulent Thicket (33%),
LR 54 Central Lower Nama Karoo (29%) (Low & Rebelo 1996, 1998). BHU
98 Willowmore Xeric Succulent Thicket (23%), BHU 92 Steytlerville Broken
Veld (13%), BHU 73 Baviaanskloof Mountain Fynbos Complex (10%), BHU
99 Addo Xeric Succulent Thicket (9%) (Cowling & Heijnis 2001). STEP Groot
Arid Spekboomveld (43%), STEP Baviaans Spekboom Thicket (21%) (Vlok &
Euston-Brown 2002).
S %
19 (2006)
Distribution Eastern Cape Province: Lower slopes and
ridges from Willowmore/Perdepoort in the west to the Klein
Winterhoek/Zuurberg Mountains (northwest of Kirkwood)
in the east including some narrow northern edges of the
Baviaanskloof and Groot Winterhoek Mountains as well as the
thicket of the central and upper Baviaanskloof (also narrow
tributaries, for example, the Kouga River). Altitude ranges from
about 200–1 100 m.
Vegetation & Landscape Features Moderate to steep slopes
on the ridges of the mountain ranges dominated by a low succulent thicket, usually fairly dense and closed. Under favourable
conditions spekboom (Portulacaria afra) is abundant amongst
sometimes dense stands of other low woody shrubs. Stem- and
leaf-succulents are present and may be prominent, and the
grass component is usually poorly developed.
Geology & Soils Commonly found on steep slopes with relatively shallow, red, clayey and often rocky soils that are derived
from a variety of parent materials, usually arenites and shales.
Geological Groups include Table Mountain, Witteberg, Dwyka
and Ecca. The dominant land types are Ib and Fc, followed by
Ag and Fb.
Climate Subjected to summer droughts, but regular winter rain
may decrease the impact of these droughts. MAP is relatively
low, generally 250–450 mm; the rainfall is nonseasonal, with
slight optima in March and November. The mean coefficient
of variation in MAP is 35% for this vegetation unit; frost incidence varies from about 5 days of frost per annum in the east
to around 65 days in the western parts. Mean monthly maximum and minimum temperatures for Willowmore are 37.7°C
and –3.1°C for January and July, respectively, although there
are smaller extremes in the east than the west. See also climate
diagram for AT 3 Groot Thicket (Figure 10.4).
Important Taxa Succulent Trees: Aloe ferox, Euphorbia
tetragona. Small Trees: Acacia karroo, Boscia albitrunca, Cussonia
spicata, Encephalartos lehmannii, Ozoroa mucronata, Pappea
capensis, Schotia afra var. afra, Sideroxylon inerme. Tall Shrubs:
Euclea undulata (d), Grewia robusta (d), Carissa bispinosa subsp.
bispinosa, Dodonaea viscosa var. angustifolia, Elytropappus rhinocerotis, Gymnosporia polyacantha, Putterlickia pyracantha,
Rhigozum obovatum, Rhus longispina, R. lucida. Succulent
Shrubs: Crassula cultrata (d), C. ovata (d), C. rupestris subsp.
commutata (d), Euphorbia ledienii (d), Portulacaria afra (d),
Adromischus cristatus var. schonlandii, Cotyledon tomentosa
subsp. tomentosa, Crassula tetragona subsp. robusta, Euphorbia
mauritanica, E. polygona, Glotiphyllum oligocarpum, G. salmii,
Pachypodium succulentum, Senecio junceus, Zygophyllum foetidum. Low Shrubs: Chrysocoma ciliata (d), Felicia muricata (d),
Indigofera denudata (d), Aptosimum elongatum, Asparagus
burchellii, A. mucronatus, A. subulatus, Eriocephalus africanus,
E. capitellatus, E. ericoides, Euryops spathaceus, Felicia filifolia, Hermannia gracilis, Leucas capensis, Limeum aethiopicum
(d), Lycium oxycarpum, Monechma spartioides, Pteronia adenocarpa, P. incana, Rosenia humilis, Selago albida, S. fruticosa,
Solanum tomentosum. Semiparasitic Epiphytic Shrub: Viscum
rotundifolium. Woody Succulent Climbers: Crassula perforata
(d), Crassula pellucida subsp. marginalis, Sarcostemma viminale. Woody Climbers: Asparagus racemosus, Capparis sepiaria var. citrifolia, Cissampelos capensis, Rhoicissus digitata.
Graminoids: Aristida adscensionis (d), A. congesta (d), Cynodon
incompletus (d), Eragrostis obtusa (d), Setaria lindenbergiana
(d), Tragus berteronianus (d), Cenchrus ciliaris, Cymbopogon
pospischilii, Ehrharta calycina, Enneapogon desvauxii, Eragrostis
curvula, Merxmuellera stricta, Sporobolus fimbriatus. Succulent
Herbs: Crassula muscosa (d), C. orbicularis (d), Crassula expansa,
Psilocaulon junceum. Geophytic Herbs: Asplenium cordatum,
Boophone disticha, Moraea pallida, Sansevieria hyacinthoides.
Herbs: Aizoon glinoides (d), Troglophyton capillaceum (d),
Hermannia pulverata, Lepidium africanum, Pollichia campestris,
Stachys aethiopica.
Endemic Taxa Succulent Shrubs: Aloe pictifolia. Succulent
Herbs: Huernia brevirostris subsp. baviaana, H. echidnopsioides, Gasteria ellaphieae, G. glomerata, G. rawlinsonii,
Haworthia glauca var. herrei, H. pungens, H. zantneriana var.
minor, Stapelia kougabergensis, Tromotriche baylissii, T. longii.
Geophytic Herbs: Albuca cremnophila, Bulbine cremnophila.
Conservation Least threatened. Target 19%. About 11% statutorily conserved mainly in the Greater Addo Elephant National
Park, Guerna Wilderness Area and Baviaanskloof Conservation
Area. 3.5% conserved in addition in other reserves, for example
in the Timbili Game Reserve and Brakkefontein Game Farm.
Only about 1.5% transformed mainly through urbanisation and
cultivation. Many parts have been opened up by overgrazing
and poor management practices and fence-line contrasts along
mountain slopes are fairly common, with thicket present on
one side and absent on the other. Erosion is generally very low
to moderate.
Remarks Although there are several species endemic to the
Groot Thicket, many Albany Centre endemics are shared with
the Kowie, Gamka, Gamtoos and Sundays Thicket vegetation
units. The Thicket vegetation here thus consists of a combination of many of the thicket species that occur within the
central portion of the Albany Thicket Biome. Despite having a
common denominating content of thicket species, the Groot
Thicket units have a unique combination of species and/or have
local endemic species present in their mosaic units (Vlok &
Euston-Brown 2002). Some of the species present in this unit
(e.g. Euphorbia polygona, E. tetragona, Ozoroa mucronata and
Plumbago auriculata) indicate a close affinity to more eastern
portions of the Albany Valley Thicket.
References Acocks (1953, 1988), Lloyd et al. (2002), Vlok & Euston-Brown
(2002), Vlok et al. (2003).
AT 4 Gamtoos Thicket
VT 70 False Macchia (42%), VT 23 Valley Bushveld (35%) (Acocks 1953).
Valley Bushveld (35%), Mosaic of South Coast Renosterveld (12%), Mesic
Grassy Fynbos (11%) (Moll & Bossi 1984). LR 54 Central Lower Nama
Karoo (28%), LR 63 South and South-west Coast Renosterveld (22%) (Low
& Rebelo 1996, 1998). BHU 92 Steytlerville Broken Veld (27%), BHU 21
Humansdorp Grassy Fynbos (20%), BHU 30 Kromme Fynbos/Renosterveld
Mosaic (20%) (Cowling & Heijnis 2001). STEP Gamtoos Valley Thicket (38%),
STEP Gamtoos Arid Spekboomveld (20%) (Vlok & Euston-Brown 2002).
Distribution Eastern Cape Province: Coastal basin of the
Gamtoos River Valley, south of the Baviaanskloof Mountains
and along some smaller river valleys such as that of the Kromme
River. Also found north of the Baviaanskloof Mountains in more
xeric conditions on some low ridges south and southeast of
Steytlerville. Altitude 0–700 m.
Vegetation & Landscape Features On the low mountain
slopes in steeply sloping areas and on low ridges. Tall, dense
thicket, where both the trees and shrubs and the succulent
component are well represented. Few distinct strata can be differentiated within much of the vegetation, as the lower and
upper canopy species are intertwined, often together with a
wide variety of liana species linking the understorey species
with the canopy. Occurs mostly as a fragmented community
with large, dense stands restricted to south- and southwestfacing slopes that are protected against fires. The structure of
Albany Thicket Biome
553
L. Mucina
S %
Figure 10.9 AT 4 Gamtoos Thicket: Nonsucculent face of Gamtoos
Thicket on steep sandstone slopes of the Baviaanskloof River Valley
(near Patensie, Eastern Cape).
the dense stands of Gamtoos Thicket is similar to that of the
Sundays Thicket, but it differs in the dominant species.
Geology & Soils Mostly restricted to rocky, sandy-loamy soils
derived from shale and sandstone of the Bokkeveld Group
(Ceres and Tarka Subgroups) and Table Mountain Group
(Nardouw Subgroup) as well as the Jurassic Enon conglomerates. Also found are fairly shallow clayey soils derived from the
Gamtoos Group limestone, phyllite and arenite of the Kaan and
Klein River Formations (Namibian Erathem). Fc land type covers
half of the area, followed by Ae and Ib.
Climate Nonseasonal rainfall with slight optima in March and
November. MAP ranges from about 180 mm in the northwest
inland areas to 850 mm in the southeast coastal sites. The
coefficient of variation in MAP is 32% for the unit, but varies
from 22% at the coast to 38% inland. The mean daily maximum temperatures for January are 24°C at the coast and 31°C
inland and the mean daily minimum temperatures for July are
3°C inland and 9°C at the coast. The incidence of frost is 7 days,
but ranging widely from 3 days at the coast to more than 25
days of frost per year inland. See also climate diagram for AT 4
Gamtoos Thicket (Figure 10.4).
Important Taxa Succulent Trees: Euphorbia triangularis (d),
Aloe africana, A. speciosa, Euphorbia grandidens. Small Trees:
Apodytes dimidiata, Canthium spinosum, Cussonia spicata, C.
thyrsiflora, Maytenus undata, Pappea capensis, Ptaeroxylon
obliquum, Schotia afra var. afra, Sideroxylon inerme, Vepris lan554
Albany Thicket Biome
19 (2006)
ceolata. Tall Shrubs: Allophylus decipiens, Azima tetracantha,
Carissa bispinosa subsp. bispinosa, Crotalaria capensis, Ehretia
rigida, Elytropappus rhinocerotis, Euclea racemosa, E. undulata,
Grewia occidentalis, Gymnosporia capitata, G. heterophylla,
G. polyacantha, Hippobromus pauciflorus, Maerua cafra,
Mystroxylon aethiopicum, Nylandtia spinosa, Olea europaea
subsp. africana, Pterocelastrus tricuspidatus, Putterlickia pyracantha, Rhus glauca, R. incisa, R. longispina, R. lucida, R. pterota,
R. refracta, Scolopia zeyheri, Scutia myrtina. Low Shrubs: Felicia
muricata (d), Anthospermum aethiopicum, Asparagus striatus,
Chaetacanthus setiger, Eriocephalus africanus, E. algoensis, E.
spathaceus, Jamesbrittenia microphylla, Lauridia tetragona,
Oedera genistifolia, Phyllanthus maderaspatensis, Pteronia
incana, Senecio linifolius. Succulent Shrubs: Portulacaria afra
(d), Exomis microphylla var. axyrioides, Cotyledon campanulata,
C. orbiculata var. oblonga, C. tomentosa subsp. tomentosa,
Crassula cultrata, Delosperma ecklonis, Euphorbia mauritanica,
E. polygona, Glottiphyllum linguiforme, Senecio oxyodontus,
Tylecodon striatus, Zygophyllum debile. Semiparasitic Shrub:
Osyris compressa. Semiparasitic Epiphytic Shrub: Viscum rotundifolium. Woody Climbers: Capparis sepiaria var. citrifolia (d),
Rhoicissus digitata (d), Asparagus aethiopicus, A. racemosus, Jasminum angulare, Plumbago auriculata, Rhoiacarpos
capensis. Woody Succulent Climber: Sarcostemma viminale.
Herbaceous Climbers: Cynanchum ellipticum, Senecio deltoideus. Graminoids: Ehrharta calycina (d), E. erecta (d), Panicum
deustum (d), Setaria sphacelata (d), Aristida congesta, Cenchrus
ciliaris, Cynodon dactylon, Digitaria natalensis, Enneapogon
desvauxii, E. scoparius, Eragrostis obtusa, Eustachys paspaloides,
Ficinia indica, F. nodosa, Heteropogon contortus, Karroochloa
curva, Leptochloa fusca, Melica racemosa, Panicum maximum,
P. stapfianum, Pycreus polystachyos var. laxiflorus, Sporobolus
africanus, S. fimbriatus, Stipa dregeana, Themeda triandra,
Tribolium hispidum. Succulent Herbs: Crassula expansa, C. muscosa, C. orbicularis, Plectranthus grandidentatus, P. madagascariensis, Senecio radicans. Geophytic Herbs: Asplenium cordatum, Bonatea speciosa var. antennifera, Bulbine alooides, B.
frutescens, Chasmanthe aethiopica, Ornithogalum longibracteatum, Oxalis obtusa, Pelargonium pulverulentum, Sansevieria
hyacinthoides. Herbs: Hypoestes aristata (d), Abutilon sonneratianum, Acalypha ecklonii, Blepharis integrifolia var.
clarkei, Hibiscus pusillus, Indigastrum costatum subsp. macrum,
Indigofera hedyantha, Peristrophe cernua, Stachys aethiopica.
Endemic Taxa Small Tree: Cussonia gamtoosensis. Succulent
Herbs: Huernia bayeri, Gasteria pulchra. Geophytic Herb:
Lachenalia latimerae.
Conservation Least threatened. Target 19%. A total of 6% of
this vegetation unit is protected in statutory conservation areas:
Baviaanskloof Conservation Area, Guerna and Berg Plaatz
Wilderness Areas as well as Stinkhoutsberg, Kabeljousrivier,
Loerie Dam and Seekoeirivier Nature Reserves. Private conservation areas (Hankey Forest Reserve No. 1, Monteaux Game
Ranch, Lombardini Game Farm, Kabeljous River Natural Heritage
Site, and Kromme River Mouth, Eastcot and Loerie Dam Nature
Reserves) also protect some patches of this vegetation type.
Some 12% of Gamtoos Thicket has been altered by cultivation and 1% by urbanisation. The alien Atriplex lindleyi subsp.
inflata has invaded many degraded arid thicket areas, especially
on soils with a high clay content. Erosion is variable.
Remarks The structural characteristics and species present
within the Gamtoos Thicket are intermediate between those
of the Sundays River Thicket and Gouritz River Thicket (sensu
Vlok & Euston-Brown 2002). However, the composition of the
dominant species differs and there are several endemic species
present in the Gamtoos Thicket, especially in the matrix vegeta-
S %
19 (2006)
tion, that only occur as fragmented clumps. The flora that occur
along its boundaries is shared and has been enriched by the species typical of the adjacent units (Cowling 1983), e.g. Sundays
Thicket. To a degree this is also true for the Baviaanskloof mountain zone, especially where the Gamtoos Thicket unit abuts the
boundaries of the Groot Thicket units. Many species typical of
both these major regions may co-occur along these overlapping
areas, presenting rather diffuse patterns in species gradients
(Vlok & Euston-Brown 2002).
References Acocks (1953, 1988), Cowling & Campbell (1983), Cowling
(1984), Pierce & Cowling (1984), Everard (1987), Midgley & Cowling (1993),
Vlok & Euston-Brown (2002), Vlok et al. (2003), Kamineth (2004).
AT 5 Sundays Noorsveld
VT 24 Noorsveld (72%) (Acocks 1953). LR 6 Xeric Succulent Thicket (84%)
(Low & Rebelo 1996, 1998). STEP Sundays Noorsveld (100%) (Vlok & EustonBrown 2002).
Distribution Eastern Cape Province: Mostly north of the
Klein Winterhoek Mountains, centred around Waterford and
the Darlington Dam and a smaller area from Jansenville westwards. Also some patches south of this mountain range west of
Kirkwood in the Sundays River Valley. Altitude 100–600 m.
Vegetation & Landscape Features Flat lowlands where the
vegetation is a dense, usually 1–2 m tall succulent thicket
consisting of a mosaic of noors (Euphorbia caerulescens) and
low karoo shrub vegetation (dominated by Pentzia incana and
Rhigozum obovatum). Punctuated by solitary trees and shrub
groups with Pappea capensis, Euclea undulata, Rhus longispina
and Gymnosporia polyacantha.
Geology & Soils Shale, mudstones and sandstones of the
Beaufort and Ecca Groups of the Karoo Supergroup in the
north as well as of the Mesozoic Uitenhage Group in the south.
Often heavy, clayey soils, but may be sandy and of Quaternary
origin. The Fc land type overwhelmingly dominates.
Important Taxa Succulent Tree: Aloe
ferox (d). Small Trees: Pappea capensis (d), Acacia karroo, Boscia albitrunca,
B. oleoides, Schotia afra var. afra. Tall
Shrubs: Grewia robusta (d), Gymnosporia
polyacantha (d), Azima tetracantha,
Cadaba aphylla, Carissa bispinosa subsp.
bispinosa, Diospyros austro-africana,
Euclea undulata, Gymnosporia capitata,
Nymania capensis, Putterlickia pyracantha, Rhus longispina. Low Shrubs:
Blepharis capensis (d), Jamesbrittenia
microphylla (d), Lycium cinereum (d),
L. oxycarpum (d), Pentzia incana (d),
L. Mucina
Climate Nonseasonal rainfall with slight optima in March and
November, but primarily in late summer. MAP ranges from about
210 mm in the west to 320 mm in the east. The incidence of
frost is only 5 days, ranging from 3 to 13 days of frost per year.
Mean daily maximum and minimum
temperatures are 29–32°C and 4–6°C
for January and July, respectively, and
this is consistent across the distribution
of the vegetation type. Mean monthly
maximum and minimum temperatures
for the Mentz Dam weather station are
41.4°C and –2.2°C for January and July,
respectively. See also climate diagram for
AT 5 Sundays Noorsveld (Figure 10.4).
Rhigozum obovatum (d), Aptosimum elongatum, Asparagus
burchellii, A. crassicladus, A. striatus, A. suaveolens, A. subulatus, Barleria pungens, B. rigida, Chrysocoma ciliata, Eriocephalus
ericoides, Felicia filifolia, F. muricata, Garuleum latifolium,
Helichrysum rosum, H. zeyheri, Hermannia althaeoides, H. gracilis, Indigofera sessilifolia, Lantana rugosa, Leucas capensis,
Lepidium africanum, Limeum aethiopicum, Monechma pseudopatulum, M. spartioides, Pelargonium aridum, Phyllanthus
verrucosus, Phymaspermum parvifolium, Polygala seminuda,
Rosenia humilis, Selago albida, S. fruticosa, S. triquetra,
Solanum capense, S. tomentosum. Succulent Shrubs: Euphorbia
caerulescens (d), Adromischus cristatus var. schonlandii, Aloe
lineata, A. striata, Cotyledon orbiculata var. oblonga, C. velutina, C. woodii, Crassula corallina subsp. corallina, C. ovata,
Delosperma frutescens, Drosanthemum lique, Euphorbia esculenta, E. mauritanica, E. pentagona, Mestoklema tuberosum,
Pachypodium succulentum, Portulacaria afra, Trichodiadema
barbatum. Semiparasitic Shrub: Thesium junceum. Semiparasitic
Epiphytic Shrubs: Viscum continuum, V. obscurum, V. rotundifolium. Woody Succulent Climber: Sarcostemma viminale.
Woody Climbers: Asparagus racemosus, Cissampelos capensis, Rhoicissus digitata. Graminoids: Aristida adscensionis (d),
A. congesta (d), Cenchrus ciliaris (d), Cynodon incompletus (d),
Ehrharta erecta (d), Eragrostis obtusa (d), Tragus berteronianus
(d), Aristida barbicollis, A. diffusa, Chloris virgata, Cynodon dactylon, Digitaria argyrograpta, Ehrharta calycina, Enneapogon
desvauxii, E. scoparius, Eragrostis chloromelas, E. curvula, E.
lehmanniana, Fingerhuthia africana, Heteropogon contortus,
Oropetium capense, Panicum coloratum, P. deustum, P. maximum, Setaria verticillata, Sporobolus fimbriatus, Tragus racemosus. Herbaceous Climbers: Cynanchum ellipticum, C. gerrardii,
Cyphia sylvatica, Kedrostis capensis, K. nana. Succulent Herbs:
Mesembryanthemum aitonis (d), C. muscosa, Gasteria maculata,
Mesembryanthemum crystallinum, Senecio radicans. Geophytic
Herbs: Drimia intricata (d), D. anomala, Ledebouria undulata,
Moraea polystachya, Oxalis stellata, Sansevieria aethiopica,
Tritonia laxifolia. Herbs: Aizoon glinoides (d), Gazania krebsiana (d), Lasiopogon glomerulatus (d), Lotononis leptoloba (d),
Abutilon sonneratianum, Amaranthus thunbergii, Boerhavia
diffusa, Chamaesyce inaequilatera, Cucumis myriocarpus,
Hermannia cernua, H. comosa, H. pulverata, Hibiscus pusillus, Indigastrum costatum subsp. macrum, Indigofera disticha,
Figure 10.10 AT 5 Sundays Noorsveld: Low succulent thicket with Euphorbia caerulescens
(Euphorbiaceae) north of Wolwefontein on the road to Jansenville in the Sundays River basin
(Eastern Cape).
Albany Thicket Biome
555
S %
Isoglossa ciliata, Lactuca dregeana, L. desertorum, Lessertia
pauciflora, Leysera tenella, Lotononis calycina, Peucedanum
typicum, Tetragonia echinata, T. microptera, Tribulus terrestris.
Parasitic Herb: Hydnora africana.
Vegetation & Landscape Features Undulating plains and low
mountains and foothills covered with tall, dense thicket, where
trees, shrubs and succulents are common, with many spinescent species. The transition between lower and upper canopies
is obscured by the presence of a wide variety of lianas. The
local dominance of Portulacaria afra increases and the relative
abundance of woody species present decreases with increasing
aridity. There is considerable structural heterogeneity within this
vegetation unit.
Conservation Least threatened. Target 19%. Almost 15%
statutorily conserved in Greater Addo Elephant National Park
and some 3% in private game ranches (Kuzuko, Voetpadskloof,
Koedoeskop, Schuilpatdop Game Farm, Goodhope). About 4%
transformed with cultivation the primary factor. Erosion is moderate to very low.
Geology & Soils Mostly on deep (>1 m) red, loamy to clayey
soils derived from the Sundays River and Kirkwood Formations
(Mesozoic Uitenhage Group) in the south. In the Zuurberg
Mountains, soils are more sandy and nutrient-poor and derived
from the Bokkeveld and Witteberg Groups (Cape Supergroup). In
the inland region of the Sundays River the soils are derived from
Ecca Group shales and mudstones, and are heavy due to high
clay content. Fc land type dominates the area, followed by Ae.
References Acocks (1953, 1988), Van der Walt (1965), Hoffman (1989a,
b), Hoffman & Cowling (1990), Du Toit & Blom (1995), Vlok & Euston-Brown
(2002), Vlok et al. (2003).
AT 6 Sundays Thicket
VT 23 Valley Bushveld (42%), VT 24 Noorsveld (28%) (Acocks 1953). LR 6
Xeric Succulent Thicket (57%) (Low & Rebelo 1996, 1998). STEP Sundays
Spekboomveld (55%) (Vlok & Euston-Brown 2002).
Climate Nonseasonal rainfall with slight optima in March
and October/November. MAP ranges from about 190 mm in
the northwest to 480 mm in the southeast on the coast near
Port Elizabeth. The coefficient of variation in MAP is 29–38%,
increasing with distance inland in a northwesterly direction.
The incidence of frost is 8 days, but ranging widely from 3
days near the coast in the southeast to more than 24 days of
frost per year in the more inland sites in the northwest. Mean
monthly maximum and minimum temperatures for Jansenville
are 41.3°C and –0.8°C for January and July, respectively, and
corresponding values for Addo are 39.0°C and –0.3°C and for
Uitenhage are 36.9°C and 1.3°C, both for February and July,
respectively. See also climate diagram for AT 6 Sundays Thicket
(Figure 10.4).
L. Mucina
Distribution Eastern Cape Province: From the surrounds of
Uitenhage and the northern edge of Port Elizabeth into the
lower Sundays River Valley to east of Colchester and northwards
to the base of the Zuurberg Mountains and stretching westwards north of the Groot Winterhoek Mountains to roughly
the Kleinpoort longitude. Also an extensive area north of the
Klein Winterhoek Mountains including much of the Jansenville
District and parts of the far-southern Pearston District and farwestern Somerset East District. Altitude 0–800 m.
Figure 10.11 AT 6 Sundays Thicket: Dense thicket with Euphorbia triangularis (Euphorbiaceae) and Cussonia spicata (Araliaceae) along
road from Addo to Zuurberg Inn (Eastern Cape).
556
Albany Thicket Biome
19 (2006)
Important Taxa Succulent Trees: Aloe africana (d), A. ferox,
Euphorbia grandidens. Small Trees: Pappea capensis (d),
Schotia afra var. afra (d), Acacia natalitia, Boscia albitrunca,
Brachylaena ilicifolia, Cussonia spicata, Encephalartos lehmannii, Ptaeroxylon obliquum, Sideroxylon inerme. Tall Shrubs:
Euclea undulata (d), Olea europaea subsp. africana (d), Azima
tetracantha, Cadaba aphylla, Carissa bispinosa subsp. bispinosa,
Diospyros pallens, Ehretia rigida, Grewia occidentalis, G.
robusta, Gymnosporia buxifolia, G. capitata, G. polyacantha,
Maerua cafra, Mystroxylon aethiopicum, Nymania capensis,
Putterlickia pyracantha, Rhus incisa, R. longispina, Scutia myrtina. Low Shrubs: Pentzia globosa (d), Aptosimum elongatum,
Asparagus burchellii, A. crassicladus, A. striatus, A. subulatus,
Barleria obtusa, B. rigida, Blepharis capensis, Chascanum cuneifolium, Chrysocoma ciliata, Eriocephalus ericoides, Euryops
algoensis, E. spathaceus, Felicia muricata, Garuleum latifolium,
Hermannia althaeoides, Hibiscus aridus, Indigofera sessilifolia,
Justicia orchioides, Lantana rugosa, Leucas capensis, Limeum
aethiopicum, Lycium oxycarpum, Osteospermum imbricatum,
Pteronia paniculata, Rhigozum obovatum, Rosenia humilis, Selago fruticosa, S. geniculata, Senecio linifolius, Solanum
capense, S. tomentosum. Succulent Shrubs: Crassula ovata (d),
Euphorbia caerulescens (d), E. ledienii (d), Portulacaria afra (d),
Adromischus cristatus var. cristatus, A. sphenophyllus, Cotyledon
campanulata, C. orbiculata var. oblonga, Crassula capitella
subsp. capitella, C. capitella subsp. thyrsiflora, C. cotyledonis,
C. cultrata, C. mesembryanthoides subsp. hispida, C. rogersii,
Delosperma echinatum, D. uniflorum, Euphorbia mauritanica,
Exomis microphylla, Kalanchoe rotundifolia, Lampranthus productus, Mestoklema tuberosum, Orbea pulchella, Pachypodium
succulentum, Pelargonium carnosum, Psilocaulon articulatum,
Zygophyllum foetidum. Semiparasitic Shrub: Osyris compressa.
Semiparasitic Epiphytic Shrubs: Viscum crassulae, V. obscurum,
V. rotundifolium.
S %
19 (2006)
Woody Succulent Climbers: Pelargonium peltatum (d), Crassula
perforata, Cyphostemma quinatum, Sarcostemma viminale.
Woody Climbers: Asparagus asparagoides, A. multiflorus,
A. racemosus, A. volubilis, Behnia reticulata, Capparis sepiaria var. citrifolia, Cissampelos capensis, Plumbago auriculata,
Rhoiacarpos capensis, Rhoicissus digitata. Herbaceous Climbers:
Cynanchum ellipticum, Kedrostis capensis. Graminoids: Aristida
adscensionis (d), A. congesta (d), Cynodon dactylon (d), C.
incompletus (d), Eragrostis obtusa (d), Panicum maximum (d),
Tragus berteronianus (d), Cenchrus ciliaris, Cyperus capensis,
Digitaria argyrograpta, Ehrharta calycina, Enneapogon scoparius, Eragrostis curvula, Eustachys paspaloides, Heteropogon
contortus, Panicum deustum, Sporobolus fimbriatus, Stipa
dregeana, Themeda triandra. Succulent Herbs: Senecio radicans (d), Crassula expansa, C. spathulata, Gasteria bicolor,
Sansevieria aethiopica. Geophytic Herbs: Bulbine frutescens
(d), Drimia intricata (d), Sansevieria hyacinthoides (d), Cyanella
lutea, Cyrtanthus loddigesianus, C. spiralis, Drimia anomala,
Freesia corymbosa, Hypoxis argentea, Justicia cuneata subsp.
cuneata, Moraea stricta, Oxalis smithiana, Spiloxene trifurcillata, Trachyandra affinis, Tritonia securigera, Tritonia strictifolia, Urginea altissima. Herbs: Abutilon sonneratianum, Aizoon
glinoides, Arctotheca calendula, Chamaesyce inaequilatera,
Commelina benghalensis, Cotula heterocarpa, Cyanotis speciosa, Cypselodontia eckloniana, Emex australis, Gazania krebsiana, Hibiscus pusillus, Hypoestes aristata, Indigastrum costatum
subsp. macrum, Lepidium africanum, Lotononis glabra, Stachys
aethiopica.
Biogeographically Important Taxa (S Southern limit) Succulent
Climber: Ceropegia ampliata var. ampliata S. Herbaceous
Climber: Fockea sinuataS. Epiphytic Parasitic Herb: Cuscuta
bifurcata. Geophytic Herb: Pelargonium campestre.
Endemic Taxa Small Tree: Encephalartos horridus. Succulent
Shrubs: Aloe bowiea, A. gracilis, Bergeranthus addoensis,
Glottiphyllum grandiflorum, Orthopterum coegana, Ruschia
aristata, Trichodiadema rupicola. Succulent Climbers: Aptenia
haeckeliana, Ceropegia dubia. Succulent Herbs: Haworthia
arachnoidea var. xiphiophylla, H. aristata, Huernia longii subsp.
longii. Geophytic Herbs: Brachystelma cummingii, B. schoenlandianum, B. tabularium, Pelargonium ochroleucum, Strelitzia
juncea, Tritonia dubia. Herbs: Arctotis hispidula, Argyrolobium
crassifolium, Lessertia carnosa, Lotononis monophylla, Senecio
scaposus var. addoensis, Wahlenbergia oocarpa.
Conservation Least threatened. Target 19%. Protected
statutorily in Greater Addo Elephant National Park, Groendal
Wilderness Area as well as in Swartkops Valley and Springs
Nature Reserves. Private conservation areas, especially game
farms (Kuzuko, Koedoeskop, Schuilpatdop, Tregathlyn,
Citruslandgoed, Voetpadskloof) and a couple of nature reserves
contribute to conservation of this vegetation type as well. More
than 6% already transformed (cultivated, urban development).
Sundays Thicket has also been highly degraded through grazing by livestock (Hoffman & Cowling 1990, 1991, Lloyd et al.
2002, Lechmere-Oertel 2003). The degraded state resembles a
secondary thornveld or grassland, dominated by invasive weedy
species. In this state, most of the original thicket species are lost.
Erosion is moderate to very low.
Remarks The considerable research interest in the Sundays
Thicket unit is linked to the popular Addo National Park (now
encompassing also the former Zuurberg National Park and
a series of inland and coastal nature reserves forming the
Greater Addo Elephant National Park)—the only locality in the
Cape housing an extant population of elephant (Loxodonta
africana) and an indigenous population of Cape buffalo
(Synceros caffer).
References Archibald (1955), Pentzhorn & Olivier (1974), Pentzhorn et al.
(1974), Aucamp (1976, 1979), Cowling (1983, 1984), Aucamp & Tainton
(1984), Everard (1987), Hoffman (1989a, b), Hoffman & Cowling (1990,
1991), La Cock (1992), Stuart-Hill (1992), Midgley & Cowling (1993), StuartHill & Aucamp (1993), Johnson (1998), Johnson et al. (1999), Kerley et al.
(1999a, b), Sigwela (1999), Lombard et al. (2001), Todkill (2001), Cowling
& Kerley (2002), Lloyd et al. (2002), Vlok & Euston-Brown (2002), LechmereOertel (2003), Vlok et al. (2003), Sigwela et al. (2004).
AT 7 Coega Bontveld
VT 23 Valley Bushveld (87%) (Acocks 1953). Valley Bushveld (98%) (Moll
& Bossi 1984). LR 7 Mesic Succulent Thicket (72%) (Low & Rebelo 1996,
1998). BHU 95 Sundays Mesic Succulent Thicket (70%) (Cowling & Heijnis
2001). STEP Grass Ridge Bontveld (100%) (Vlok & Euston-Brown 2002).
Distribution Eastern Cape Province: Northeast of Port Elizabeth
just inland of Algoa Bay; mainly around Coega, but also in small
patches in Addo (Zuurkop; Pentzhorn & Olivier 1974). Altitude
0–400 m.
Vegetation & Landscape Features On moderately undulating plains, where a mosaic of low thicket (2–3 m) built mainly
of bush clumps occurs. Secondary open grassland occurs over
wide stretches. This unit is often restricted to ‘islands’ in a
matrix of typical valley thicket. The species present are a mixture
of Fynbos, Grassland and Succulent Karoo elements.
Geology & Soils Outcrops of limestone (Nanaga Formation),
and calcareous paleo-dune fields of the Cenozoic Algoa Group.
The soils are shallow clay soils that are often lime-rich. Most of
the area of this unit is primarily classified as the Fc land type,
with Ae land type of minor importance.
Climate Nonseasonal rainfall with optima in March and October.
MAP ranges from about 400 mm inland in the west to 550 mm
in the east and closer to the coast. The coefficient of variation
in MAP ranges between 30% and 32%. The incidence of frost
is only 3 days, not varying across the range of the vegetation
unit. Mean monthly maximum and minimum temperatures for
the nearby Port Elizabeth are 32.1°C and 3.4°C for February
and July, respectively. See also climate diagram for AT 7 Coega
Bontveld (Figure 10.4).
Important Taxa Succulent Trees: Aloe africana, A. ferox. Small
Trees: Schotia afra var. afra, Sideroxylon inerme. Tall Shrubs:
Euclea undulata (d), Carissa bispinosa subsp. bispinosa, Dovyalis
caffra, Ehretia rigida, Euclea crispa, Gymnosporia capitata,
Hippobromus pauciflorus, Maerua cafra, Mystroxylon aethiopicum, Pterocelastrus tricuspidatus, Putterlickia pyracantha, Rhus
longispina, R. lucida, R. pyroides var. gracilis, Scutia myrtina.
Low Shrubs: Helichrysum anomalum (d), Jamesbrittenia microphylla (d), Tephrosia capensis var. acutifolia (d), Acmadenia
obtusata, Agathosma capensis, Asparagus falcatus, A. multiflorus, A. striatus, Blepharis capensis, Chaetacanthus setiger, Chascanum cuneifolium, Clutia daphnoides, Disparago
ericoides, Felicia muricata, Hermannia althaeoides, H. flammea, H. holosericea, Lantana rugosa, Limeum aethiopicum,
Lobostemon trigonus, Muraltia squarrosa, Osteospermum
imbricatum, O. polygaloides, Passerina rubra, Wahlenbergia
tenella. Succulent Shrubs: Crassula expansa (d), Ruschia
hamata (d), Aloe arborescens, Carpobrotus edulis, Crassula
capitella subsp. capitella, C. ericoides, C. perfoliata, C. perforata, C. tetragona subsp. robusta. Semiparasitic Shrub: Osyris
compressa. Woody Succulent Climbers: Pelargonium peltatum,
Sarcostemma viminale. Woody Climbers: Asparagus racemosus,
Jasminum angulare, Rhoiacarpos capensis, Rhoicissus digitata.
Herbaceous Climber: Kedrostis capensis. Graminoids: Aristida
diffusa (d), Cynodon dactylon (d), C. incompletus (d), Eustachys
paspaloides (d), Heteropogon contortus (d), Merxmuellera disticha (d), Panicum maximum (d), Setaria sphacelata (d), Stipa
Albany Thicket Biome
557
S %
dregeana (d), Themeda triandra (d), Cymbopogon marginatus,
C. pospischilii, Digitaria argyrograpta, D. natalensis, Ehrharta
calycina, E. erecta, Eragrostis capensis, E. curvula, E. obtusa,
Helictotrichon capense, Melica racemosa, Panicum deustum,
Pentaschistis pallida, Sporobolus ioclados. Succulent Herbs:
Mesembryanthemum aitonis (d), C. muscosa, Geophytic Herbs:
Sansevieria hyacinthoides (d), Bulbine favosa, B. inamarxiae.
Moraea pallida, Oxalis smithiana. Herbs: Aizoon rigidum (d),
Gazania krebsiana (d), Hypoestes aristata (d), Indigastrum costatum subsp. macrum (d), Senecio burchellii (d), Sutera campanulata (d), Arctotheca calendula, Berkheya heterophylla, Gazania
jurineifolia, Hibiscus pusillus, Lotononis glabra, Monsonia emarginata, Scabiosa albanensis.
Biogeographically Important Taxa (E Eastern limit, W Western
limit) Graminoids: Ficinia truncataE, Tribolium uniolaeW (d). Herb:
Gibbaria scabraE.
Endemic Taxa Succulent Shrubs: Euphorbia globosa,
Rhombophyllum rhomboideum. Low Shrub: Anginon rugosum. Geophytic Herb: Ledebouria sp. nov. (‘coriacea’ S. Venter
ined.).
Conservation Target 19%. A total of 10% of this vegetation
unit is protected in the Greater Addo Elephant National Park
and almost 4% in the private Grassridge Nature Reserve. Some
4% of Coega Bontveld has been altered by cultivation and 2%
by urbanisation. The recent building of the traffic infrastructure
around the new harbour near Port Elizabeth has encroached
heavily into the area of the Coega Bontveld and the construction of an Industrial Development Zone in the area constitutes
a serious threat to this vegetation type. Erosion is moderate
to low.
Remarks There are areas in the Eastern Cape north and east of
Grahamstown where calcrete resists weathering to form relatively flat landscapes surrounded by eroded valleys. The calcrete
in these areas breaks down to form white clay that has been
commercially harvested in the past for the production of crockery and pottery. The vegetation in all these areas is structurally
and floristically similar to Coega Bontveld
and they contain a number of taxa with
Cape links, e.g. Agathosma ovata. There
are also floristic links of Coega Bontveld
to the local dune thicket vegetation.
19 (2006)
Vegetation & Landscape Features On mainly steep and
north-facing (dry) slopes. Tall thickets dominated by succulent
euphorbias and aloes with a thick understorey composed of
thorny shrubs, woody lianas (Capparis, Secamone, Rhoicissus,
Aloe), and shrubby succulents (Crassulaceae, Asphodelaceae).
Moister south-facing slopes support thorny thickets dominated
by low evergreen trees (Cussonia, Euclea, Hippobromus, Pappea,
Ptaeroxylon, Schotia) and shrubs (Azima, Carissa, Gymnosporia,
Putterlickia) with fewer succulent shrubs and trees. The herbaceous layer is poorly developed.
Geology & Soils Clayey soils over Weltevrede and Lake Mentz
(Darlington Dam) Formation sandstone and shale (Witteberg
Group) and on Dwyka tillite (early Karoo) as well as Algoa
Group calcareous sandstone in the south. Occurs on a wide
variety of land types including Fc, Fa, Ae and Fb.
Climate Nonseasonal rainfall with optima in March and
October/November. MAP ranges from around 340 mm in the
west (north of the Zuurberg) to 650 mm in the east (at the
coast near Port Alfred). The coefficient of variation in MAP is
30%, but varies from 27% at the coast to 34% inland. The
incidence of frost is only 3 days, but ranges from 0 days at
the coast to more than 17 days of frost per year inland. Mean
monthly maximum and minimum temperatures for Bathurst are
35.0°C and 5.6°C for February and July, respectively. See also
climate diagram for AT 8 Kowie Thicket (Figure 10.4).
Important Taxa Succulent Trees: Euphorbia grandidens
(d), E. tetragona (d), E. triangularis (d), Aloe africana, A. speciosa. Small Trees: Schotia afra var. afra (d), Acacia natalitia,
Brachylaena ilicifolia, Commiphora harveyi, Cussonia spicata,
Elaeodendron croceum, Encephalartos altensteinii, E. latifrons,
E. trispinosus, Maytenus undata, Pappea capensis, Ptaeroxylon
obliquum, Schotia latifolia, Sideroxylon inerme. Tall Shrubs:
Azima tetracantha (d), Croton rivularis (d), Gymnosporia
polyacantha (d), Scutia myrtina (d), Acokanthera oppositifolia, Allophylus decipiens, Calpurnia aurea, Carissa bispinosa
subsp. bispinosa, Clausena anisata, Coddia rudis, Ehretia rigida,
References Acocks (1953, 1988), Pentzhorn &
Olivier (1974), Vlok & Euston-Brown (2002), Vlok
et al. (2003).
AT 8 Kowie Thicket
Distribution Eastern Cape Province: In
the river valleys of the Bushmans, Kariega,
Kowie, Kleinemonde and Kap Rivers
from near the Great Fish River Mouth
to Kenton-on-Sea, extending inland up
these valleys past Grahamstown to just
past Riebeeck East and Alicedale to north
of the Zuurberg. Altitude 0–700 m.
558
Albany Thicket Biome
L. Mucina
VT 23 Valley Bushveld (44%), VT 7 Eastern
Province Thornveld (29%) (Acocks 1953). Valley
Bushveld (93%) (Moll & Bossi 1984). LR 6 Xeric
Succulent Thicket (25%), LR 16 Eastern Thorn
Bushveld (24%), LR 5 Valley Thicket (21%)
(Low & Rebelo 1996, 1998). STEP Albany Valley
Thicket (38%), STEP Albany Thicket (31%) (Vlok
& Euston-Brown 2002).
Figure 10.12 AT 8 Kowie Thicket: Dense Euphorbia triangularis-dominated thicket on slopes facing the Settlers Dam in the Thomas Baines Nature Reserve (near Grahamstown, Eastern Cape).
S %
19 (2006)
Euclea undulata, Flueggea verrucosa, Grewia occidentalis,
Gymnosporia capitata, G. heterophylla, Hippobromus pauciflorus, Maerua cafra, Mystroxylon aethiopicum, Olea europaea subsp. africana, Putterlickia pyracantha, Rhus longispina,
R. lucida, R. pyroides var. gracilis, R. refracta, Scolopia zeyheri.
Low Shrubs: Asparagus striatus, A. subulatus, Chrysocoma ciliata, Galenia secunda, Hermannia althaeoides, Leonotis ocymifolia, Limeum aethiopicum, Pavonia praemorsa, Pelargonium
odoratissimum, Polygala myrtifolia, Pteronia incana, Selago
fruticosa, Senecio linifolius, Solanum rigescens. Succulent
Shrubs: Aloe arborescens (d), Crassula cultrata (d), Portulacaria
afra (d), Aptenia cordifolia, Bergeranthus scapiger, Cotyledon
orbiculata var. oblonga, C. velutina, Crassula muscosa,
C. tetragona subsp. acutifolia, Delosperma ecklonis, Euphorbia
kraussiana, Exomis microphylla var. axyrioides, Kalanchoe
rotundifolia, Mestoklema tuberosum, Senecio oxyodontus.
Semiparasitic Epiphytic Shrubs: Viscum obscurum, V. rotundifolium. Woody Succulent Climbers: Pelargonium peltatum
(d), Sarcostemma viminale (d), Aloe ciliaris, Crassula perforata,
Senecio macroglossus. Woody Climbers: Capparis sepiaria var.
citrifolia (d), Plumbago auriculata (d), Asparagus aethiopicus, A.
multiflorus, A. racemosus, Dalechampia capensis, Ficus burttdavyi, Jasminum angulare, Rhoiacarpos capensis, Rhoicissus
digitata, Secamone filiformis. Herbaceous Climbers: Acharia
tragodes, Cynanchum ellipticum, Cyphia sylvatica, Didymodoxa
caffra, Senecio deltoideus. Graminoids: Cynodon dactylon (d),
C. incompletus (d), Cyperus albostriatus (d), Ehrharta erecta (d),
Eragrostis curvula (d), Karroochloa curva (d), Panicum deustum
(d), Setaria sphacelata (d), Sporobolus fimbriatus (d), Themeda
triandra (d), Cyperus textilis, Eragrostis obtusa, Melica racemosa, Panicum maximum. Megaherb: Dracaena aletriformis.
Succulent Herbs: Plectranthus grandidentatus (d), Crassula
expansa, Gasteria bicolor, Plectranthus madagascariensis, P. verticillatus, Senecio radicans. Geophytic Herbs: Sansevieria aethiopica (d), S. hyacinthoides (d), Asplenium cordatum, Bulbine
frutescens, Cheilanthes hirta, Strelitzia reginae, Veltheimia bracteata. Herbs: Achyranthes aspera (d), Commelina benghalensis
(d), Hypoestes aristata (d), Leidesia procumbens (d), Abutilon
sonneratianum, Centella asiatica, Commelina africana, Conyza
scabrida, Ecbolium flanaganii, Emex australis, Lepidium africanum, Phyllopodium cuneifolium, Senecio burchellii, Sida ternata, Tetragonia microptera, Troglophyton capillaceum.
Endemic Taxa Succulent Herb: Faucaria nemorosa. Geophytic
Herb: Albuca crudenii. Herb: Wahlenbergia kowiensis.
Conservation Least threatened. Target 19%. A total of 5% of
this vegetation unit is protected in various statutory reserves,
including the Water’s Meeting, Kowie, Cycad, Blaauwkrantz,
Kap River Nature Reserves. A further 14% is conserved in
private conservation areas such as game ranches (Shamwari,
Emlanjeni, Amakhala, Fourie Safaris, Hunters Lodge, Elephant
Park and Schotia Safaris) and in the Aylesbury Nature Reserve.
Transformation 7%, mainly by cultivation. Erosion is moderate
to very low.
Remarks This is bioclimatically the core of the Albany Thicket
Biome and the major floristic node of the Albany Centre of
Endemism. It is located adjacent to a wide variety of other vegetation types, including Zuurberg Quartzite Fynbos, Zuurberg
Shale Fynbos, Southern Coastal Forest, Albany Coastal Belt,
Albany Broken Veld, Great Fish Noorsveld and Eastern Cape
Thornveld. This indicates the varying floristic influences on this
vegetation and many species from different vegetation types
may co-occur along these overlapping areas.
References Dyer (1937), Acocks (1953, 1988), Vlok & Euston-Brown (2002),
Vlok et al. (2003), Kamineth (2004).
AT 9 Albany Coastal Belt
VT 1 Coastal Forest and Thornveld (29%), VT 2 Alexandria Forest (29%)
(Acocks 1953). Valley Bushveld (73%) (Moll & Bossi 1984). LR 16 Eastern
Thorn Bushveld (33%), LR 48 Coastal Grassland (21%) (Low & Rebelo 1996,
1998). STEP Berlin Savanna Thicket (22%), STEP Grahamstown Grassland
Thicket (14%), STEP Hamburg Dune Thicket (11%), STEP Paterson Savanna
Thicket (7%) (Vlok & Euston-Brown 2002).
Distribution Eastern Cape Province: Within 15 km (sometimes
up to 30 km) of the Indian Ocean coastline, from Kei Mouth
to the Sundays River, interrupted by many valleys. Altitude
10–400 m.
Vegetation & Landscape Features On the gently to moderately undulating landscapes and dissected hilltop slopes close to
the coast, dominated by short grasslands punctuated by scattered bush clumps or solitary Acacia natalitia trees.
Geology & Soils The area covered by this unit is geologically
complex and includes Beaufort Group mudstone and sandstone
in the northeast, Nanaga Formation arenite and sand in the
west and Bokkeveld, Witteberg and Ecca sandstone and shale
in between, and a thin strip of Quaternary sand along the coast.
The pure grasslands are limited to the Nanaga and Quaternary
sands, whereas thornveld is prominent on the more finely textured soils derived from the Beaufort and Bokkeveld mudstone,
arenite and shale. The most important land types include Db,
Fa and Ae.
Climate In general the climate is ameliorated by the proximity
to the coast. MAP ranges from 450 mm inland in the southwest
to 900 mm in the northeast, and decreases slightly from the
coast inland. The rainfall is nonseasonal with optima in March
and October/November, but summer rainfall increases with distance northeastwards. The coefficient of variation in rainfall is
31% in the southwest inland areas, decreasing to 21% in the
extreme northeasterly parts. There is a strong rainfall gradient
across this unit, with higher rainfall further northeast, which
influences species composition, with more subtropical elements
up the coast and more drought-tolerant elements farther west.
There is little variation in temperature from season to season
and frost occurs on average for only 3 days a year in the inland
sites and never at the coast. Mean monthly maximum and minimum temperatures for East London are 32.3°C and 5.3°C for
March and July, respectively. See also climate diagram for AT 9
Albany Coastal Belt (Figure 10.4).
Important Taxa Tall Tree: Erythrina caffra. Succulent Tree:
Euphorbia triangularis. Small Trees: Acacia natalitia (d),
Brachylaena elliptica, Canthium spinosum, Cussonia spicata,
Ficus sur, Ochna arborea, Sideroxylon inerme, Zanthoxylum
capense. Tall Shrubs: Clausena anisata, Clerodendrum glabrum,
Coddia rudis, Croton rivularis, Diospyros villosa var. parvifolia,
Grewia occidentalis, Gymnosporia heterophylla, Hippobromus
pauciflorus, Mystroxylon aethiopicum, Pavetta lanceolata,
Psydrax obovata, Pterocelastrus tricuspidatus, Rhus lucida,
Scutia myrtina, Tarchonanthus camphoratus, Turraea obtusifolia. Low Shrubs: Rhynchosia ciliata (d), Carissa bispinosa subsp.
bispinosa, Chaetacanthus setiger, Helichrysum asperum var. albidulum, Pelargonium alchemilloides, Phyllanthus maderaspatensis, Selago corymbosa, Senecio pterophorus, Tephrosia capensis
var. acutifolia. Semiparasitic Epiphytic Shrub: Viscum obscurum.
Woody Succulent Climbers: Crassula pellucida subsp. marginalis, Sarcostemma viminale. Woody Climbers: Asparagus aethiopicus, A. racemosus, Capparis sepiaria var. citrifolia, Clematis
brachiata, Rhoiacarpos capensis, Rhoicissus digitata, R. tridentata, Secamone alpini, Tecoma capensis. Herbaceous Climbers:
Rhynchosia caribaea, R. totta, Thunbergia capensis, Zehneria
Albany Thicket Biome
559
S %
scabra. Graminoids: Brachiaria serrata (d), Cynodon dactylon (d),
Dactyloctenium australe (d), Digitaria natalensis (d), Ehrharta
calycina (d), Eragrostis capensis (d), E. curvula (d), E. plana (d),
Heteropogon contortus (d), Panicum deustum (d), P. maximum
(d), Setaria sphacelata (d), Sporobolus africanus (d), Themeda
triandra (d), Tristachya leucothrix (d), Cymbopogon marginatus,
Ehrharta erecta, Elionurus muticus, Melica racemosa, Setaria
megaphylla, Trachypogon spicatus. Succulent Herb: Plectranthus
verticillatus (d). Geophytic Herbs: Cheilanthes hirta, Moraea
pallida, Oxalis smithiana, Sansevieria hyacinthoides, Strelitzia
reginae. Herbs: Chamaecrista mimosoides (d), Abutilon sonneratianum, Acalypha ecklonii, Centella asiatica, Commelina
africana, C. benghalensis, Cynoglossum hispidum, Eriosema
squarrosum, Lactuca inermis, Lobelia erinus, Monsonia emarginata, Phyllopodium cuneifolium, Senecio burchellii, Sonchus
dregeanus.
Endemic Taxa Succulent Shrub: Bergeranthus concavus. Succulent Herbs: Brachystelma franksiae var. grandiflorum, Bulbine frutescens var. nov. (‘chalumnensis’ Baijnath
ined.), Faucaria subintegra, Haworthia coarctata var. tenuis, H.
cooperi var. venusta, H. reinwardtii var. reinwardtii f. chalumnensis, Stapelia praetermissa var. luteola, S. praetermissa var.
praetermissa. Geophytic Herbs: Bobartia gracilis, Apodolirion
amyanum, Aspidoglossum flanaganii, Drimia chalumnensis.
Low Shrub: Acmadenia kiwanensis. Herb: Monsonia galpinii.
Conservation Least threatened. Target 19%. Only 1% of this
vegetation unit is protected in 20 local-authority and provincial nature reserves as well as in the Greater Addo Elephant
National Park (including Alexandria Coast Reserve West) as well
as in number of private conservation areas. About 12% of the
Albany Coastal Belt has recently been altered by cultivation, 1%
by plantation forestry and 4% by urbanisation. According to
land-cover data, at least 7% consists of degraded vegetation. It
is difficult, however, to determine the proportion of the vegetation that is in a secondary state, since land-cover data do not
distinguish between primary and secondary vegetation. Erosion
is very low to moderate.
19 (2006)
Committees Drift in the east, as well as unmapped patches in
the Ecca Pass and its surroundings. Altitude 100–500 m.
Vegetation & Landscape Features Prevalent on plateaus
and mildly sloping flanks of ridges supporting succulent thicket
of low to medium height dominated by the local endemic
Euphorbia bothae (a hybrid crowd) as well as other Euphorbia
species intermixed with sclerophyllous bush clumps (Euclea,
Grewia, Gymnosporia, Putterlickia, Schotia), groups of succulent shrubs (Crassula, Cotyledon, Pelargonium), patches of rhizomatous herbs (Sansevieria hyacinthoides, Strelitzia reginae)
and accompanied by species-rich grass flora. Portulacaria afra is
dominant on rocky outcrops.
Geology & Soil Mostly finely laminated clastic sediments of
the Ecca Group (particularly the Fort Brown Formation) supporting skeletal shallow soils (Glenrosa and Mispah). Fc is the overwhelmingly dominant land type, Fb only of minor importance.
Climate Nonseasonal rainfall with optima in March and
October/November. MAP ranges from about 360 mm to 500
mm, with the higher rainfall generally in the central parts. The
incidence of frost is 3 days per annum, varying little across the
range of the unit, except in the extreme eastern part where
no frost occurs. Mean monthly maximum and minimum temperatures for Tyefu weather station are 39.6°C and 2.1°C for
January and July, respectively. See also climate diagram for AT
10 Great Fish Noorsveld (Figure 10.4).
Important Taxa Succulent Trees: Aloe africana, A. ferox. Small
Trees: Schotia afra var. afra (d), Acacia natalitia, Boscia albitrunca,
Remarks The seaboard region that contains this unit is a mosaic
of a wide variety of structural vegetation types, ranging from
grassland to forest. This variation reflects post-disturbance succession gradients as well as natural variation in geology, soil
patterns and distribution of water in the landscape. The forests
of the region have been mapped as different vegetation units
(see Chapter on Forests in this book). Admittedly, this vegetation unit exemplifies a deviation from our mapping philosophy
by featuring current-state rather than potential vegetation. We
assume that the current vegetation mosaic so typical of the
Albany Coastal Belt is a creation of man and the original (presettlement) vegetation was dominated by nonseasonal, dense
thicket. The area of this unit was prime agricultural land which
attracted early settlers who, presumably, cleared the dense
thicket cloak for pastures.
References Acocks (1953, 1988), Judd (2001), Vlok & Euston-Brown (2002),
Vlok et al. (2003).
VT 23 Valley Bushveld (100%) (Acocks 1953). Valley Bushveld (94%) (Moll &
Bossi 1984). LR 6 Xeric Succulent Thicket (84%) (Low & Rebelo 1996, 1998).
STEP Fish Noorsveld (100%) (Vlok & Euston-Brown 2002).
Distribution Eastern Cape Province: One large patch surrounded mainly by Great Fish Thicket in the valley of the Great
Fish River (north of Grahamstown) and spans a broad band
from around Pigott’s (Carlisle) Bridge in the west to around
560
Albany Thicket Biome
L. Mucina
AT 10 Great Fish Noorsveld
Figure 10.13 AT 10 Great Fish Noorsveld: Stand of Strelitzia reginae
(Strelitziaceae) in Noorsveld near Ecca Pass (north of Grahamstown,
Eastern Cape). The low succulent is Euphorbia x bothae, an endemic
taxon to this vegetation unit.
S %
19 (2006)
Cussonia spicata, Pappea capensis, Ptaeroxylon obliquum. Tall
Shrubs: Azima tetracantha (d), Grewia robusta (d), Brachylaena
ilicifolia, Cadaba aphylla, Ehretia rigida, Euclea undulata,
Gymnosporia capitata, Lantana rugosa, Rhigozum obovatum.
Low Shrubs: Asparagus striatus, A. subulatus, Ballota africana,
Becium burchellianum, Chrysocoma ciliata, Garuleum latifolium, Hermannia althaeoides, Indigofera sessilifolia, Jatropha
capensis, Leucas capensis, Limeum aethiopicum, Phyllanthus
maderaspatensis, Pteronia incana, Selago fruticosa, Senecio
linifolius, S. pterophorus, Solanum tomentosum. Succulent
Shrubs: Cotyledon orbiculata var. oblonga (d), Mestoklema
tuberosum (d), Portulacaria afra (d), Crassula nudicaulis, C.
tetragona subsp. acutifolia, Euphorbia mauritanica, E. pentagona, E. rectirama, Kalanchoe rotundifolia, Orthopterum waltoniae, Pachypodium succulentum. Semiparasitic Shrub: Thesium
lineatum. Semiparasitic Epiphytic Shrub: Viscum rotundifolium.
Woody Succulent Climbers: Crassula perforata, Cyphostemma
quinatum. Woody Climbers: Asparagus racemosus (d), A. multiflorus, Rhoicissus digitata. Graminoids: Aristida congesta (d),
Cynodon dactylon (d), Cyperus bellus (d), Digitaria argyrograpta
(d), Panicum deustum (d), Paspalum distichum (d), Sporobolus
fimbriatus (d), S. nitens (d), Tragus koelerioides (d), Chloris virgata, Cymbopogon pospischilii, Cynodon incompletus, Ehrharta
erecta, Eragrostis chloromelas, E. curvula, E. lehmanniana, E.
obtusa, Karroochloa curva, Leptochloa fusca, Microchloa caffra, Oropetium capense, Panicum coloratum, P. gilvum, P.
maximum, P. stapfianum, Themeda triandra. Succulent Herb:
Crassula expansa (d), C. muscosa, Mesembryanthemum aitonis,
Senecio radicans. Geophytic Herbs: Sansevieria hyacinthoides
(d), Strelitzia reginae (d), Bulbine asphodeloides, B. narcissifolia,
Cyrtanthus smithiae. Herbs: Aizoon glinoides, Amellus strigosus
subsp. pseudoscabridus, Atriplex suberecta, Commelina africana, Dolichos hastaeformis, Lepidium africanum, Pharnaceum
dichotomum, Salvia stenophylla.
Biogeographically Important Taxon Geophytic Herb: Drimia
acarophylla (shared with Great Fish Thicket).
Endemic Taxon Succulent Shrub: Euphorbia x bothae (d).
Conservation Least threatened. Target 19%. Good examples
of the Great Fish Noorsveld are conserved in a series of statutory
nature reserves around and north of the Ecca Pass. A total of
about 3% of the vegetation is in the Great Fish River Complex
Nature Reserve, which includes the Andries Vosloo Nature
Reserve. An additional 31% is conserved in several large-scale
private reserves and game farms, mainly the Kwande Private
Game Reserve. Great Fish Noorsveld has been relatively little
transformed: only about 3% by cultivation. Erosion is moderate
to high. This vegetation type contains the largest wild populations of the famous Strelitzia reginae—a flagship plant of South
Africa.
References Palmer (1981), Palmer et al. (1988), Vlok & Euston-Brown
(2002), Brink & Dold (2003), Vlok et al. (2003).
AT 11 Great Fish Thicket
VT 23 Valley Bushveld (38%), VT 37 False Karroid Broken Veld (30%) (Acocks
1953). LR 52 Eastern Mixed Nama Karoo (26%), LR 6 Xeric Succulent Thicket
(19%), LR 16 Eastern Thorn Bushveld (17%) (Low & Rebelo 1996, 1998).
STEP Fish Spekboom Thicket (42%), STEP Hartebeest Karroid Thicket (24%)
(Vlok & Euston-Brown 2002).
Distribution Eastern Cape Province: Mainly in the lower Great
Fish River and Keiskamma River Valleys (including the smaller
intervening river valleys nearer the coast) extending up the
Great Fish River Valley northwards to Cookhouse and into the
southernmost part of the Cradock District. Extending up the
Keiskamma River Valley as far as its confluence with the Tyume
River. Also includes the lower reaches of the Koonap River and
part of its upper reaches immediately north of Adelaide, as well
as parts of the Kat River and Little Fish River Valleys. Altitude
0–1 000 m.
Vegetation & Landscape Features Steep slopes of deeply
dissected rivers supporting short, medium and tall thicket types
(Palmer 1981, Palmer et al. 1988, Evans et al. 1997), where
both the woody trees and shrubs and the succulent component
are well developed, with many spinescent shrubs. Portulacaria
afra is locally dominant, decreasing in relative abundance and
is replaced by Euphorbia bothae with increasing aridity. With
increasing moisture status on southern aspects and in the
riparian zone, P. afra is replaced by woody elements and tall
emergent Euphorbia tetragona and E. triangularis. There is distinct clumping of the vegetation, which is linked to zoogenic
mounds, formed principally by termites (Microhodotermes viator), earthworms (Microchaetus), mole rats (Cryptomus hottentotus) and aardvarks (Orycteropus afer)—these islands of
concentrated nutrients and moisture have richer, deep soils and
are often occupied by long-lived woody shrubs and trees such
as Pappea capensis and Boscia oleoides and provide deep soils
for endemic geophytes. The closed canopy of the Portulacaria
afra-dominated thicket is another distinctive feature of parts
of the Great Fish Thicket. There is high heterogeneity within
this vegetation unit, which has been divided into nine distinct
subtypes (Vlok & Euston-Brown 2002).
Geology & Soils Mostly on shallow (<1 m) clay soils (Glenrosa
and Mispah) derived from the Adelaide and Estcourt Formations
(Beaufort Group, Karoo Supergroup) mudstone and arenite.
Half of the area falls within the Fc land type, with Fb the only
other one of some importance.
Climate Nonseasonal rainfall with slight optima in March and
October/November. MAP ranges from about 300 mm in the
western inland areas to 600 mm in the eastern coastal areas.
The coefficient of variation in MAP is 32%, but varies from 29%
at the coast to 36% inland. The mean daily maximum temperatures for January are 26°C at the coast and 30°C inland and the
mean daily minimum temperatures for July are 0°C inland and
9°C at the coast. The incidence of frost is 3 days, but ranging
widely from 0 days at the coast to more than 60 days in the
upper reaches of the river valley. See also climate diagram for
AT 11 Great Fish Thicket (Figure 10.4).
Important Taxa Succulent Trees: Euphorbia triangularis (d),
Aloe ferox, Euphorbia tetragona. Small Trees: Pappea capensis (d), Acacia natalitia, Boscia albitrunca, Brachylaena ilicifolia,
Cussonia spicata, Ozoroa mucronata, Ptaeroxylon obliquum,
Schotia afra var. afra, Zanthoxylum capense. Tall Shrubs: Euclea
undulata (d), Allophylus decipiens, Azima tetracantha, Carissa
bispinosa subsp. bispinosa, Coddia rudis, Diospyros scabrida
var. cordata, Ehretia rigida, Flueggea verrucosa, Grewia occidentalis, G. robusta, Gymnosporia capitata, G. heterophylla,
Hippobromus pauciflorus, Mystroxylon aethiopicum, Olea
europaea subsp. africana, Putterlickia pyracantha, Rhus incisa,
R. refracta, Scolopia zeyheri, Scutia myrtina. Low Shrubs:
Asparagus striatus (d), Chaetacanthus setiger (d), Chrysocoma
ciliata (d), Asparagus subulatus, Felicia muricata, Hermannia
althaeoides, Indigofera sessilifolia, Leucas capensis, Limeum
aethiopicum, Lycium cinereum, Phyllanthus maderaspatensis, Selago fruticosa. Succulent Shrubs: Crassula cordata (d),
C. ovata (d), Portulacaria afra (d), Aloe tenuior, Delosperma
ecklonis, Kalanchoe rotundifolia, Mestoklema tuberosum,
Tetradenia barberae. Semiparasitic Epiphytic Shrub: Viscum
rotundifolium. Woody Succulent Climbers: Crassula perforata,
Albany Thicket Biome
561
S %
19 (2006)
& Aucamp (1993), Evans et al. (1997), Lloyd et al.
(2002), Vlok & Euston-Brown (2002), Vlok et al.
(2003), Kamineth (2004).
AT 12 Buffels Thicket
A.I. Kamineth
VT 1 Coastal Forest and Thornveld (40%), VT
23 Valley Bushveld (39%) (Acocks 1953). LR 48
Coastal Grassland (31%), LR 5 Valley Thicket
(30%) (Low & Rebelo 1996). STEP Mountcoke
Grassland Thicket (45%), STEP Buffels Thicket
(32%) (Vlok & Euston-Brown 2002).
Figure 10.14 AT 11 Great Fish Thicket: Valley slopes clad in dense succulent thicket in the Sam
Knott Nature Reserve (near Grahamstown, Eastern Cape).
Cyphostemma quinatum, Pelargonium peltatum, Sarcostemma
viminale. Woody Climbers: Asparagus multiflorus, A. racemosus, Capparis sepiaria var. citrifolia, Jasminum angulare,
Plumbago auriculata, Rhoicissus digitata. Graminoids: Aristida
congesta (d), Cynodon incompletus (d), Digitaria eriantha (d),
Ehrharta erecta (d), Eragrostis obtusa (d), Panicum deustum
(d), P. maximum (d), P. stapfianum (d), Setaria sphacelata (d),
Sporobolus fimbriatus (d), S. nitens (d), Themeda triandra (d),
Tragus berteronianus (d), T. koelerioides (d), Cymbopogon pospischilii, Eragrostis chloromelas, E. curvula, Eustachys paspaloides. Herbs: Cyanotis speciosa (d), Hypoestes aristata (d),
Salvia scabra (d), Abutilon sonneratianum, Aizoon glinoides,
Hibiscus pusillus, Lepidium africanum, Sida ternata. Succulent
Herbs: Crassula expansa (d), Senecio radicans. Geophytic Herb:
Sansevieria hyacinthoides (d).
Endemic Taxa Succulent Shrub: Euphorbia cumulata. Low
Shrub: Euryops gracilipes. Succulent Herbs: Haworthia angustifolia var. paucifolia, H. cummingii, H. cymbiformis var. incurvula,
H. cymbiformis var. ramosa. Herb: Zaluzianskya vallispiscis.
Conservation Least threatened. Target 19%. A total of 6%
of this vegetation unit is protected in seven statutory reserves,
especially in the Great Fish River Complex Nature Reserve and
4.5% in addition in at least nine private conservation areas.
Great Fish Thicket has not been radically altered, only 3% by
cultivation and 1% by urbanisation. Erosion is very variable,
from high to low.
Remarks This is the easternmost vegetation unit assigned to
the Albany Thicket Biome, except for Buffels Thicket that only
occurs near the coast. The climate in these deep, wide river
valleys is hotter and dryer than the surrounding countryside
and the area covered by this vegetation unit may constitute an
effective physical barrier to species migration in an east-west
direction through this region. The vegetation unit also marks
the transition between more concentrated summer rainfall and
nonseasonal rainfall. The northeastern side of this vegetation
unit is marked by the east-west-running Amathole-Winterberg
mountain ranges (with its band of Eastern Cape Escarpment
Thicket), further enhancing the barrier nature of this area.
References Acocks (1953, 1988), Palmer (1981), Cowling (1984), Everard
(1987), Palmer et al. (1988), La Cock (1992), Stuart-Hill (1992), Stuart-Hill
562
Albany Thicket Biome
Distribution Eastern Cape Province: In
river valleys centred around East London,
including the Tyolomnqa River, Buffalo
River, Nahoon River, Gqunube River,
Kwelera River and stretching between 40
and 50 km inland (including some areas
around King William’s Town and Komga),
and a small area in the Great Kei River
Valley between about 10 and 20 km
from the coast. It also occurs in the valley bottom in Keiskammahoek north of
Dimbaza. Altitude 0–700 m.
Vegetation & Landscape Features Steep slopes of river valleys in highly dissected hills and moderately undulating plains,
where short, dense and tangled thicket stands reach up to 10
m. The dense thicket grades into more open, shorter thornveld
at the edges of the valley slopes.
Geology & Soils Mudstones and sandstones derived from the
Beaufort Group of the Karoo Supergroup as well as Jurassic
Dolerite Suite intrusions. The shallow soils (Glenrosa and
Mispah) derived from these rocks are fine-grained, nutrientpoor silts, but the presence of forests leads to the development
of humus-rich, deep soils. Half of the area is classified as Fa land
type, while Fb and Bd are of subordinate importance.
Climate Mild climate with few extremes, ameliorated by the
close proximity of the Indian Ocean. Rainfall is 500–840 mm per
year, and has a coefficient of variation of 22–29%, the higher
coefficients occurring in the more inland, less steep sites. The
rainfall occurs in spring and early to midsummer, but typically
of the Eastern Cape it may occur at any time of the year. Mean
monthly maximum and minimum temperatures for East London
are 32.3°C and 5.3°C for March and July, respectively, with very
little chance of frost. See also climate diagram for AT 12 Buffels
Thicket (Figure 10.4).
Important Taxa Succulent Trees: Euphorbia triangularis (d),
Aloe ferox, Euphorbia grandidens. Small Trees: Acacia natalitia, Apodytes dimidiata, Brachylaena ilicifolia, Calodendrum
capense, Canthium ciliatum, C. mundianum, Cussonia spicata, C.
thyrsiflora, Dombeya tiliacea, Elaeodendron croceum, Eugenia
zeyheri, Harpephyllum caffrum, Heteromorpha arborescens,
Ochna arborea, Pappea capensis, Ptaeroxylon obliquum, Schotia
afra var. afra, S. latifolia, Sideroxylon inerme, Trimeria trinervis,
Vepris lanceolata, Zanthoxylum capense, Ziziphus mucronata.
Tall Shrubs: Allophylus decipiens (d), Azima tetracantha (d),
Scutia myrtina (d), Suregada africana (d), Acalypha glabrata,
Acokanthera oppositifolia, Allophylus melanocarpus, Buddleja
dysophylla, Carissa bispinosa subsp. bispinosa, Chaetacme
aristata, Chrysanthemoides monilifera, Clerodendrum glabrum,
Coddia rudis, Croton rivularis, Diospyros scabrida var. cordata, D. simii, D. villosa var. parvifolia, Ehretia rigida, Euclea
natalensis, E. undulata, Grewia occidentalis, Gymnosporia
buxifolia, G. heterophylla, G. nemorosa, Hippobromus pauciflorus, Maytenus acuminata, Mystroxylon aethiopicum, Olea
S %
19 (2006)
europaea subsp. africana, Pavetta lanceolata, Putterlickia pyracantha, P. verrucosa, Rhus gueinzii, R. lucida, Scolopia zeyheri.
Low Shrubs: Pavonia praemorsa (d), Senecio pterophorus
(d), Euphorbia kraussiana, Lauridia tetragona, Lippia javanica,
Lycium cinereum, Rubus rigidus, Solanum rigescens. Succulent
Shrubs: Aptenia cordifolia (d), Exomis microphylla var. axyrioides,
Senecio oxyodontus. Woody Succulent Climbers: Cyphostemma
quinatum, Sarcostemma viminale. Woody Climbers: Rhoicissus
digitata (d), Asparagus aethiopicus, A. racemosus, Capparis
sepiaria var. citrifolia, Dalbergia obovata, Jasminum angulare,
Plumbago auriculata, Rhoicissus tomentosa, R. tridentata,
Secamone alpini, Tecoma capensis, Uvaria caffra. Graminoids:
Cynodon dactylon (d), Cyperus albostriatus (d), C. textilis (d),
Digitaria argyrograpta (d), D. natalensis (d), Ehrharta erecta (d),
Microchloa caffra (d), Panicum deustum (d), P. maximum (d),
Schoenoxiphium sparteum (d), Setaria megaphylla (d), S. sphacelata (d), Paspalum dilatatum. Herbaceous Climbers: Senecio
deltoideus (d), Coccinia quinqueloba, Cynanchum ellipticum,
Helinus integrifolius. Succulent Herbs: Sansevieria hyacinthoides
(d), Plectranthus grandidentatus. Geophytic Herbs: Moraea pallida, Ornithogalum longibracteatum, Cheilanthes hirta. Herbs:
Commelina benghalensis (d), Conyza scabrida (d), Galopina circaeoides (d), Hypoestes aristata (d), Abutilon sonneratianum,
Sida ternata.
Endemic Taxon Woody Succulent Climber: Ceropegia radicans
subsp. smithii.
Conservation Vulnerable. Target 19%. About 1% is protected
in statutory reserves (Umtiza, Bridle Drift, Fort Pato, Nahoon,
Bluebend, King William’s Town Nature Reserves) and in addition 0.7% in private nature conservation areas. Transformation
21%, mainly by cultivation, urban and built up areas, and plantations. At least 15% consists of vegetation in a degraded state.
Erosion very low to moderate.
References Acocks (1953, 1988), Low & Rebelo (1996), Vlok & EustonBrown (2002), Vlok et al. (2003), Kamineth (2004).
AT 13 Eastern Cape Escarpment Thicket
VT 21 False Thornveld of Eastern Province (34%), VT 23 Valley Bushveld
(20%) (Acocks 1953). LR 52 Eastern Mixed Nama Karoo (26%), LR 15
Subarid Thorn Bushveld (23%), LR 5 Valley Thicket (20%) (Low & Rebelo
1996, 1998). STEP Escarpment Thicket (74%) (Vlok & Euston-Brown 2002).
Distribution Eastern Cape Province: At the southern foot of
the steep escarpment slopes of the Amathole, Winterberg
and Swaershoek Mountains from the western flank of the
Keiskammahoek District to just west of Somerset East as well
as on the foothills of mountains and on hills in the mountainous
regions centred within a radius of 25–35 km south and west of
Cradock. Altitude 450–1 250 m.
Vegetation & Landscape Features Steeply sloping escarpment and mountain slopes, hills and lowlands of the region
where it forms a medium high, semi-open to closed thicket
dominated by Olea europaea subsp. africana and Acacia natalitia 3–7 m tall, grading into thornveld lower down and often
into escarpment forest higher up the slopes.
Geology & Soils Mudstones and arenite of the Adelaide
Subgroup of the Karoo Supergroup as well as Jurassic dolerite
intrusions. The soils derived from these rocks are fine-grained,
nutrient-poor silts or more nutrient-rich red clays. Soils are often
shallow, on moderate to steep slopes and the surface rock cover
is high. The major land types are Fc as well as Ib and Fb.
Climate Nonseasonal rainfall with optima in March and
November, with February and March being the maximum
months. MAP ranges from about 400–700 mm per annum on
the southern side of the escarpment and from 310–400 mm
per annum on the northern side around Cradock, increasing
with elevation. The coefficient of variation in MAP is 25–35%,
increasing with decreasing amounts of rainfall. The incidence
of frost is 16 days, but ranging widely from fewer than 5 days
to more than 35 days of frost per year, the areas with more
frost occurring higher up the escarpment slopes where snow
may occur in winter. Mean monthly maximum and minimum
temperatures for Somerset East are 38.6°C and –1.0°C for
January and July, respectively. See also climate diagram for AT
13 Eastern Cape Escarpment Thicket (Figure 10.4).
Important Taxa Succulent Trees: Aloe ferox, Euphorbia
tetragona. Small Trees: Acacia karroo (d), Cussonia spicata. Tall
Shrubs: Olea europaea subsp. africana (d), Scutia myrtina (d),
Buddleja auriculata, Euclea crispa, E. undulata, Grewia occidentalis, Gymnosporia heterophylla, Hippobromus pauciflorus,
Leucosidea sericea, Myrsine africana, Rhus dentata, R. lucida,
R. tomentosa, Scolopia zeyheri. Low Shrubs: Anthospermum
rigidum subsp. pumilum, Argyrolobium collinum, Asparagus
striatus, Chaetacanthus setiger, Felicia filifolia, F. muricata, Hermannia althaeoides, Lantana rugosa, Pelargonium
alchemilloides, Phyllanthus maderaspatensis, Polygala fruticosa, Selago corymbosa, Solanum rigescens. Succulent
Shrubs: Bergeranthus artus, Crassula obovata. Semiparasitic
Epiphytic Shrub: Viscum rotundifolium. Woody Climbers:
Asparagus aethiopicus, Plumbago auriculata. Herbaceous
Climber: Senecio deltoideus (d). Graminoids: Aristida congesta
(d), Cynodon incompletus (d), Ehrharta calycina (d), E. erecta
(d), Eragrostis chloromelas (d), E. curvula (d), Panicum maximum (d), Sporobolus fimbriatus (d), Tragus berteronianus (d),
Aristida diffusa, A. junciformis subsp. junciformis, Cymbopogon
marginatus, C. pospischilii, Cynodon dactylon, Eragrostis obtusa,
Heteropogon contortus, Melica decumbens, Panicum deustum,
P. stapfianum, Sporobolus africanus. Succulent Herbs: Stapelia
glabricaulis. Geophytic Herbs: Drimia uniflora (d), Bulbine
asphodeloides, B. narcissifolia, Drimia intricata. Herbs: Cyanotis
speciosa (d), Amaranthus praetermissus, Blepharis integrifolia
var. clarkei, Commelina africana, Dianthus caespitosus, Gerbera
piloselloides, Hibiscus aethiopicus, H. pusillus, Hypoestes
aristata, Senecio retrorsus, Sida ternata.
Conservation Target 19%. Eastern Cape Escarpment Thicket
has been permanently altered, with 3% through cultivation
and 1% through urbanisation. A total of 5% of this vegetation
unit is statutorily conserved in local-authority nature reserves
(Bosberg), provincial nature reserves (primarily the Mpofu Game
Reserve and Bush Nek Outspan) and in the Mountain Zebra
National Park. A further about 2% is protected in private conservation areas. Erosion is very variable, from very low to high.
Remarks Close floristic relationship and similar structure to
AT 14 Camdebo Escarpment Thicket to the west and Gs 17
Tarkastad Montane Shrubland to the north, and also grades
into the more mesic Buffels Thicket to the east.
References Acocks (1953, 1988), Vlok & Euston-Brown (2002), Vlok et
al. (2003), Brown & Bezuidenhout (2005).
AT 14 Camdebo Escarpment Thicket
VT 37 False Karroid Broken Veld (41%), VT 25 Succulent Mountain Scrub
(Spekboomveld) (33%) (Acocks 1953). LR 54 Central Lower Nama Karoo
(41%), LR 5 Valley Thicket (40%) (Low & Rebelo 1996, 1998). STEP
Escarpment Spekboomveld (41%), STEP Escarpment Valley Thicket (22%)
(Vlok & Euston-Brown 2002).
Albany Thicket Biome
563
L. Mucina
S %
Figure 10.15 AT 14 Camdebo Escarpment Thicket: Crassula arborescens (Crassulaceae) in succulent thicket in the Rooiberg east of Aberdeen (Eastern Cape).
Distribution Eastern Cape Province: South-sloping face of the
Great Escarpment, forming an arc from Bruintjieshoogte in the
east via the Coetzeeberg Mountains and Graaff-Reinet (including Spandaukop and the isolated Rooiberg) to Kamdebooberg
and Aberdeen in the west. Altitude varies from 570–1 600 m,
with most of the area between 700–1 200 m.
Vegetation & Landscape Features Occurs on the rugged,
broken and steeply sloping escarpment and mountain slopes
of the region where it forms a 2–3 m tall, largely succulent
thicket of Portulacaria afra-dominated clumps. Heavy browsing
by goats reduces or eliminates P. afra and low trees (Pappea
capensis and Boscia oleoides) remain.
19 (2006)
Important Taxa Succulent Tree: Aloe ferox. Small Trees: Acacia
karroo (d), Pappea capensis (d), Boscia albitrunca, B. oleoides,
Cussonia paniculata, C. spicata, Maytenus undata, Schotia
afra var. afra. Tall Shrubs: Euclea undulata (d), Gymnosporia
polyacantha (d), Buddleja glomerata, Cadaba aphylla, Carissa
bispinosa subsp. bispinosa, Diospyros lycioides, D. pallens,
Ehretia rigida, Grewia robusta, Gymnosporia capitata, G. heterophylla, Olea europaea subsp. africana, Rhus longispina, R.
lucida. Low Shrubs: Blepharis mitrata (d), Chrysocoma ciliata (d),
Lycium schizocalyx (d), Pentzia incana (d), Rhigozum obovatum
(d), Aptosimum elongatum, Asparagus burchellii, A. mucronatus, A. striatus, A. suaveolens, Blepharis capensis, B. villosa,
Eriocephalus ericoides, Felicia filifolia, F. muricata, Garuleum
latifolium, Helichrysum dregeanum, H. zeyheri, Hermannia filifolia, Indigofera sessilifolia, Lantana rugosa, Lycium oxycarpum,
Macledium spinosum, Monechma spartioides, Pegolettia retrofracta, Peliostomum origanoides, Rosenia humilis, Solanum
capense, Sutera halimifolia. Succulent Shrubs: Portulacaria afra
(d), Crassula ovata, C. rogersii, Euphorbia mauritanica, E. obesa,
Kleinia longiflora, Mestoklema tuberosum, Pachypodium succulentum, Trichodiadema barbatum. Semiparasitic Epiphytic Shrub:
Viscum rotundifolium. Woody Succulent Climber: Sarcostemma
viminale. Woody Climbers: Asparagus racemosus, Cissampelos
capensis, Dioscorea elephantipes, Rhoicissus digitata, R. tridentata. Graminoids: Aristida adscensionis (d), A. congesta (d),
Cenchrus ciliaris (d), Digitaria eriantha (d), Enneapogon desvauxii
(d), Eragrostis lehmanniana (d), E. obtusa (d), Heteropogon contortus (d), Aristida diffusa, Cynodon incompletus, Enneapogon
scoparius, Eragrostis chloromelas, E. curvula, Eustachys paspaloides, Fingerhuthia africana, Panicum maximum, Sporobolus fimbriatus, Themeda triandra, Tragus berteronianus, T. koelerioides.
Succulent Herb: Mesembryanthemum aitonis. Geophytic Herbs:
Boophone disticha, Drimia anomala, D. intricata, Moraea polystachya. Herbs: Abutilon sonneratianum, Aizoon glinoides, A.
rigidum, Asplenium cordatum, Cheilanthes deltoidea, Gazania
krebsiana, Hermannia coccocarpa, H. comosa, H. pulverata,
Hibiscus pusillus, Lepidium africanum, Pollichia campestris,
Troglophyton capillaceum.
Endemic Taxa Succulent Shrubs: Astroloba corrugata,
Bergeranthus sp. nov. (‘nanus’ A.P. Dold ined.), Delosperma karrooicum, Trichodiadema olivaceum. Succulent Herb: Haworthia
marumiana var. batesiana, Huernia kennedyana. Geophytic
Herbs: Apodolirion bolusii, Dierama grandiflorum.
Geology & Soil Sandstone and mudstone of the Permian
Adelaide Subgroup (Beaufort Group), interrupted in places by
dykes of Jurassic Karoo dolerites. Shallow skeletal soils (varying
in depth from 20–30 cm) of Mispah form, with organically rich
orthic A-horizon, moderately acidic. Land types are Ib and Fc on
shallow substrates and Da duplex soils on dolerite dykes.
Conservation Least threatened. Target 19%. About 5% of
this vegetation unit is statutorily protected in the Karoo Nature
Reserve and a further 15% in private conservation areas (Samara
Private Game Reserve, Asanta Sana Game Reserve, Rupert
Game Farm, Buchanon Game Farm, Hoeksfontein Game Farm
and Glen Harry Game Reserve). Camdebo Escarpment Thicket
has been transformed by only about 1%, through cultivation,
but this vegetation has been subjected to degradation through
grazing by domestic goats in many places. It is likely that it
extended further down the slopes in recent history. Clear fenceline contrasts can be recognised both by satellite imagery and in
the field (Lloyd et al. 2002). Erosion is moderate to high.
Climate Nonseasonal rainfall with optima in March and
November and with February and March being the maximum
months. MAP ranges from about 270–550 mm, increasing with
elevation. The incidence of frost is 25 days, but ranging widely
from fewer than 8 days to more than 40 days of frost per year,
the areas with more frost occurring higher up the escarpment
slopes where snow may occur in winter. Mean monthly maximum and minimum temperatures for Graaff-Reinet are 38.6°C
and –0.3°C for January and July, respectively. See also climate
diagram for AT 14 Camdebo Escarpment Thicket (Figure 10.4).
Remarks The dominance of Portulacaria afra is the main link
of this unit with the Albany Thicket Biome, as earlier classified (Palmer 1988, 1991a, b). The overall floristic composition
suggests rather that this is a marginal Nama-Karoo unit whose
thicket structure can be ascribed to special regional habitat conditions, in particular geomorphology and associated microclimate. P. afra is a facultative C3 /CAM plant, and its distribution
may be linked to CAM being activated following the extreme
daily variation in temperature and moisture (Guralnick & Ting
1987) as often experienced on these south-facing slopes. The
564
Albany Thicket Biome
S %
19 (2006)
distribution of P. afra, an important indicator of this thicket,
has been modelled using a correlative modelling approach
(Robertson & Palmer 2002).
References Acocks (1953, 1988), Palmer (1988, 1989, 1991a, b), Lloyd et
al. (2002), Robertson & Palmer (2002), Vlok & Euston-Brown (2002), Vlok
et al. (2003).
9.
Credits
The Albany Thicket region was mapped using original sources,
including contributions of D.B. Hoare (eastern and western
parts) and A.R. Palmer (portion of western part); much of the
latter was replaced by a detailed unpublished STEP map (Vlok
& Euston-Brown 2002). The STEP source (counting more than
100 mapping units) was simplified by M.C. Rutherford and
L. Mucina (for the main key see Table 10.1) and many of the
more marginal (edge) STEP units were reconciled with other
sources. The delimitation of the AT units was also influenced
by the delimitation of AZa 6, Gs 18, Gs 16, SVs 6 and SVs 7 (all
D.B. Hoare) as well as by placement of the forest patches (socalled Forest Biome forest map; see also Credits in the chapter
on Forests). A.P. Dold contributed considerably to the species
lists, Albany endemic species in particular. A.R. Palmer contributed to descriptions of units AT 2, 3, 11 and 14. D.B. Hoare
contributed to the text of all mapping units except for AT 1. L.
Mucina wrote AT 1 and contributed to the text of all other AT
units. R.G. Lechmere-Oertel contributed to the text of AT 4 and
6; J.H.J. Vlok and D.I.W. Euston-Brown contributed to the text
(list of species in particular) of AT 2 and 3.
The introductory text is the result of a joint effort by (in order of
the volume of the contribution) D.B. Hoare (all major sections),
A.R. Palmer (Sections 1, 2 and 3), R.G. Lechmere-Oertel (Sections
5 and 6), L. Mucina (sections 4.3 and 7) and Ş.M. Procheş (Section
4.1). The section 3.2 of the introductory text was shaped by A.R.
Palmer and R.A. Ward. M.C. Rutherford considerably improved
section 3.3. L.W. Powrie and M.C. Rutherford provided physicogeographical information extracted from various GIS sources for
the descriptions and constructed the climate diagrams. The references were compiled and collated by L. Mucina. M. Rouget,
and others within the Directorate of Biodiversity Programmes,
Policy & Planning of SANBI, provided quantitative information
for each vegetation unit on conservation status and targets,
areas currently conserved and areas transformed.
The STEP map and accompanying reports were kindly provided
by the Terrestrial Ecology Unit, now of the Nelson Mandela
Metropolitan University, Port Elizabeth (available at the website
www.zoo.upe.ac.za/step). R.A. Ward corrected the geological
terminology in the descriptions. Photographs were contributed
by L. Mucina, D.B. Hoare, A.R. Palmer, Ş.M. Procheş and A.I.
Kamineth.
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11
Indian Ocean Coastal Belt
Ladislav Mucina, C. Robert Scott-Shaw, Michael C.
Rutherford, Kelson G.T. Camp, Wayne S. Matthews,
Leslie W. Powrie and David B. Hoare
Table of Contents
1 Introduction
1.1 Position and Landscape Complexity
1.2 Biome Identity
2 Ecology: Climate, Geology, Soils and Hydrology
2.1 Climate
2.2 Geology and Soils
2.3 Hydrology
3 Biogeographical Patterns: Past and Present
3.1 Palaeo-ecological Patterns
3.2 Current Biogeographical Patterns
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5
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10
Present Status
Threats to Natural Vegetation
Action: Conservation and Management of Resources
Further Research Challenges
Descriptions of Vegetation Units
Credits
References
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List of Vegetation Units
CB 1 Maputaland Coastal Belt
CB 2 Maputaland Wooded Grassland
CB 3 KwaZulu-Natal Coastal Belt
CB 4 Pondoland-Ugu Sandstone Coastal Sourveld
CB 5 Transkei Coastal Belt
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Figure 11.1 Black Rock north of Sodwana Bay on the Maputaland coast (KwaZulu-Natal)
with coastal thicket, subtropical dune forest and fragments of coastal grassland.
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1.
Introduction
1.1
Position and Landscape Complexity
The region covers the seaboard in two provinces of South
Africa—KwaZulu-Natal and the northern half of the Eastern
Cape (in the latter part also known as the Wild Coast). This
coastal belt in its subtropical facies extends also beyond the
national borders into Mozambique as far as the Limpopo River
mouth. It continues in strongly tropical facies further northwards into Tanzania, Kenya and southern Somalia (for approximate delimitation, consult Moll & White 1978: Figures 1 and 2).
In South Africa it has been known as Coastal Belt (Bews 1920)
or as Indian Ocean Coastal Belt (Moll & White 1978). It is the
region, both for a biologist and a layman, where South Africa
feels the breath of the Tropics the most.
The Indian Ocean Coastal Belt (IOCB) occurs as an almost
800 km long coastal strip between the South African border
with Mozambique as far south as the mouth of the Great Kei
River (near East London). It spans altitudes from 0–450 m (and
higher up to 600 m in the Pondoland-Ugu Sandstone Coastal
Sourveld). The landscapes of the IOCB are flat (Maputaland)
or characterised by alternating rolling hills and deeply incised
valleys (coastal stretch between Richards Bay and Port Edward
in KwaZulu-Natal and then more markedly further south to Port
St Johns as far as the Great Kei River mouth). Elevated plateaus
and deep gorges are characteristic of the Pondoland coast and
other regions with underlying sandstone geology. The belt is
about 35 km wide at some places in the north (somewhat wider
in the valley of the Thukela River), narrowing irregularly southwards to <20 km in parts of Pondoland to <10 km in several
parts of the Wild Coast.
The region is very densely populated, with towns such as
KwaNgwanase (Manguzi), St Lucia, Mtubatuba, KwaMbonami,
Empangeni, Richards Bay, Stanger, Tongaat, Durban
Metropolitan Area (Ethekwini), Umkomaas, Port Shepstone,
Margate and Port Edward (all KwaZulu-Natal). Further south, in
the Eastern Cape, densely populated rural areas are also found,
for example in the Xhora District. Much of the KwaZulu-Natal
coast (roughly between Stanger and Port Edward) has been
turned into a ‘South African Riviera’—an almost continuous
chain of holiday settlements frequented by millions of tourists
every year.
1.2
Biome Identity
Bews (1920: 383), in his classical paper on The plant ecology of
the coast belt of Natal established that
‘... both from the purely ecological and from the floristic standpoints... there are good reasons why the coast belt of Natal
should be considered as part of a distinct subtropical region...’.
Later, some researchers would honour this proposition and
would recognise the peculiarity of the KwaZulu-Natal (and to
an extent also the Wild Coast) immediate seaboards as deserving special status in both ecological (Moll & White 1978; to
an extent also Huntley 1984) and biogeographical (Van Wyk
& Smith 2001, Heijnis 2004, Kirkwood 2004) terms. The overwhelmingly large extent of transformation of the coastal belt
outside the existing strips and patches of embedded forest represents significant loss of evidence of its prior condition. This
has led to a diversity of opinions on the broad-level classification of the vegetation of this coastal belt or its components (see
Rutherford & Westfall 1986: Table 1 and Figure 4). Although
the present work broadly follows Bews (1920) and Moll &
White (1978) who assume a dominant forest cover interrupted
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by edaphically or hydrologically controlled areas of grassland,
some others have assumed that at least a significant part of
the belt had been an open to dense savanna vegetation, interspersed with many areas of forest and grassland. For example,
Huntley (1984) mapped most of the IOCB as his Moist Savanna
Biome type in which was embedded smaller but significant
areas of his Lowland Forest unit. Rutherford & Westfall (1986)
mapped the IOCB as part of their Savanna Biome explicitly on
nonfloristic (only structural and climatic) criteria and followed
a defined criterion at biome scale level which precluded the
mapping of the small or narrow ‘lowland forests’. They showed
the rainfall seasonality of the IOCB as essentially summer rainfall tending towards even year rainfall near the northern coast.
Despite the overriding floristic affinities of forest floras within
the IOCB with the African East Coast to the north, the IOCB
(the Pondoland-Ugu Sandstone Coastal Sourveld aside) also
has some floristic links with savannas toward the northwest
interior. Examples of elements straddling both Savanna and
IOCB biomes include Acacia ataxacantha, A. caffra, A. nilotica,
A. robusta, Combretum molle, Erythrina lysistemon, Gardenia
volkensii, Gymnosporia maranguensis, Heteropyxis natalensis, Ozoroa paniculosa, Sclerocarya birrea, Turraea obtusifolia
and Vangueria infausta. Acocks (1953) supported the notion
that the whole IOCB (except the Pondoland Coastal Plateau
Sourveld) ‘was naturally some form of forest’, but acknowledged that the ‘veld today is a more or less open thornveld with
numerous and extensive patches of forest’.
We argue that the reasons for considering the IOCB a biome
in its own right lie in the combination of vegetation structure
and combination of climatic characters which are different
from the Savanna Biome. The ‘tropical appearance of vegetation’ (to cite the words of Bews 1920) is a result of a mixture of
growth forms such as trees, lianas and epiphytes that dominate
the zonal (forest) vegetation of the region, while grasses play
only a subordinate role in the zonal vegetation itself. Grasses
are, naturally, the structure-shaping growth form in azonal (or
intrazonal) vegetation types such as hygrophilic grasslands and
shallow-soil sourvelds, also found within IOCB. The presence of
these azonal grasslands as well as extensive secondary grasslands led Low & Rebelo (1996, 1998) to classify a large portion
of the IOCB as part of the Grassland Biome. The absence of
an entirely rain-free dry period (so typically characterising the
winter months in the Savanna Biome) and implied increased
probability of winter rainfall is another feature distinguishing
the IOCB from the Savanna. Although the rainfall of the IOCB
is clearly higher in summer than in winter (Figure 1), along the
Maputaland coast the winter half-year rainfall makes up as
much as 40% of the total yearly precipitation. The overall high
air-moisture saturation throughout the year gives the climate of
the IOCB its strikingly tropical character, especially in summer.
Burgess et al. (2004) classify this region as part of the global
‘Tropical Broadleaved Moist Forest’ biome—a concept still much
too broad as it would encompass not only the most (sub)tropical
forests of the Indian Ocean seaboards (spanning East London
and southern Somalia), but also afrotropical rainforests of
Central and West Africa.
The biogeographical peculiarity of the IOCB (links to inland
tropical regions of Central Africa) and regional concentration of
endemic species, initiated an evolution of ideas spanning nearly
100 years (from Marloth 1907 to Van Wyk & Smith 2001).
Marloth (1907) suggested ‘South Eastern Coast Belt’, which
would incorporate not only the immediate coastal rims of the
present KwaZulu-Natal and Transkei coast of the Eastern Cape,
but also the deep hinterland. The ‘Coast Belt’ of Bews (1920)
is a more conservative concept. In fact its extent is very close to
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19 (2006)
the mapped extent of the IOCB in this chapter. Acocks’s (1953;
see Acocks Map No. 4 in Acocks 1988) ‘Forest and Scrubforest’
basically copies the extent of the IOCB as it is depicted in our
map. Acocks (1988) recognises the identity of the Coastal Belt
in his Veld Type 1 called ‘Coastal Forest and Thornveld’—a unit
reaching beyond East London westwards as far as Keiskamma
and incorporating most of the Maputaland coastal plains. The
combination of Low & Rebelo’s (1996, 1998) Vegetation Type
23 (Coastal Bushveld/Grassland, largely corresponding to the
Acocks’s Veld Type 1) and Vegetation Type 48 Coastal Grassland
(incorporating the Acocks’s Veld Type 3: Pondoland Coastal
Plateau Sourveld) roughly corresponds to the IOCB as featured
in this chapter. To date, Camp (1999a, b) has undertaken the
most detailed climatic, geological and pedological delimitation
of the Coastal Belt and classified it as his BRG 1 Moist Coast
Forest, Thorn and Palm Veld. We follow (within the borders of
the KwaZulu-Natal Province) this delimitation.
to intensive human influence dating since the Iron Age, but
it demonstrates (under the climatic conditions of the current
Holocene Interglacial) its clear tropical affinity.
The IOCB (or Subtropical Coastal Forest Biome) encompasses
subtropical forest (Table 11.1) as zonal vegetation, accompanied by a series of intrazonal (edaphic grasslands) and azonal
vegetation types. Within the latter, we count the azonal
forest types (Northern Coastal Forest, Mangrove Forest, Swamp
Forest, Lowveld Riverine Forest) and azonal nonforest vegetation units such as Subtropical Freshwater Wetland, Subtropical
Dune Thicket and Subtropical Coastal Vegetation. For practical purposes we have singled out the forest vegetation (both
zonal and azonal) of the IOCB and feature it, alongside other
forest types, within Chapter 12. The nonforest vegetation is
the subject of Chapters 13 and 14. The vegetation units in
this particular chapter include the edaphic grassland units
(Maputaland Wooded Grasslands, Pondoland-Ugu Sandstone
Coastal Sourveld) as well as a series of ‘Coastal Belts’ (CB 1, 3,
5) which feature, similar to AT 9 Albany Coastal Belt (but unlike
the rest of the units of the National Vegetation Map), current
rather than potential vegetation patterns. We presume that
most of the CB 1, 3 and 5 were formed by subtropical forests
The World Wildlife Fund recognises five ‘ecoregions’ (Goldberg
& Frank 2004, Heijnis 2004, Kirkwood 2004, Schipper & Burgess
2004a, b) within so-called ‘Tropical and Subtropical Moist
Broadleaf Forests’ which straddle the Indian Ocean seaboards
from the Jubba River in southern Somalia as far south as Port
Elizabeth in South Africa. The southern
part of the WWF ecoregion Maputaland
Coastal Forest Mosaic (Kirkwood 2004)
Table 11.1 Indian Ocean Coastal Belt (corresponding to Subtropical Coastal Forest Biome)
and KwaZulu-Natal-Cape Coastal
as a composite of zonal, intrazonal and azonal vegetation units. For the discussion on the
Forest Mosaic (Heijnis 2004) overlap
concepts related to zonality, see Chapter 13 on 'Inland Azonal Vegetation'.
with the IOCB as defined in this chapter. The former unit is identical with our
Vegetation Unit
Extent (km2) Zonality status
Maputaland Coastal Belt (with all imbedFOz 7 Northern Coastal Forest 1,F
467
zonal
ded intrazonal and azonal vegetation
units), while the latter extends westFOz 8 Scarp Forest 4,F
435
intrazonal (endemic)6
wards beyond the limits of the southernFOa 1 Lowveld Riverine Forest F
5
intrazonal/azonal5
most vegetation unit within the IOCB (CB
FOa 2 Swamp Forest F
38
intrazonal/azonal5
5 Transkei Coastal Belt) and incorporates
F
FOa 3 Mangrove Forest
33
intrazonal/azonal5
also the coastal belt between the Buffels
River (East London) and Port Elizabeth.
CB 4 Pondoland-Ugu Sandstone Coastal Sourveld
1297
intrazonal (endemic)7
We consider the classification of the
CB 2 Maputaland Wooded Grassland
991
intrazonal (endemic)7
coastal belt of the Albany Thicket Biome
CB 1Maputaland Coastal Belt
4015
zonal2
into the KwaZulu-Natal-Cape Coastal
CB 3 KwaZulu-Natal Coastal Belt
6293
zonal2
Forest Mosaic as not justified. The latter
CB 5 Transkei Coastal Belt
1628
zonal2
portion of the coast has a warm-temperC
AZe 3 Subtropical Estuarine Salt Marshes
3
intrazonal/azonal5
ate character, carries climax vegetation
C
(Albany Thickets), various coastal vegAZs 3 Subtropical Dune Thicket
20
intrazonal/azonal5
C
etation types on the adjacent seashore,
AZd 4 Subtropical Seashore Vegetation
42
intrazonal/azonal5
strandveld (Vlok & Euston-Brown 2002,
AZf 6 Subtropical Freshwater Wetlands A
501
intrazonal/azonal5
Vlok et al. 2003) as well as forest vegetaAZa 7 Subtropical Alluvial Vegetation A
08
intrazonal/azonal5
tion (Von Maltitz et al. 2003).
3
Freshwater Lakes
91
not applicable
The IOCB is a climatically, ecologically
465
not applicable
Coastal Lagoons3
and biogeographically peculiar region
1
that deserves standing on its own at
incl. KwaZulu-Natal Coastal Forest and KwaZulu-Natal Dune Forest (Forest Types according
the level of biome within the scope of
to Von Maltitz et al. 2003)
2
the South African vegetation. It is the
mapped as mosaic of primary (mainly edaphic) grassland, secondary grassland and sucsouthernmost, hence marginal, outlier of
cession thickets seral to the subtropical coastal forests (still found in patches and mapped as
the East African Tropical Coastal Forest
Northern Coastal Forest)
3
(Burgess et al. 1996, 1998, Burgess &
not recognised as vegetation units (nonvegetated water bodies)
4
Clarke 2000)—a member of the global
incl. Pondoland Scarp Forest and Eastern Scarp Forest (Forest Types according to Von
Tropical and Subtropical Moist Forest
Maltitz et al. 2003)
5
Biome. As such it can be classified as the
intrazonal on regional scale; azonal on continental scale
6
‘Subtropical Coastal Forest Biome’—an
endemism of this vegetation type relates to southern Africa (Scarp Forest occurs in Eastern
interesting geographical analogue of the
Cape, KwaZulu-Natal and Mpumalanga, Swaziland, and possibly also in Mozambique)
7
‘Mata Atlântica’, the subtropical coastal
endemic to the Indian Ocean Coastal Belt
forest of the Atlantic seaboards of east- 8 none mapped in Indian Ocean Coastal Belt
A
ern Brazil (Hueck 1966), experiencing a
discussed in Chapter 13: Inland Azonal Vegetation
fate very similar to the IOCB (Por 1992). C discussed in Chapter 14: Coastal Vegetation
F
The IOCB lost its natural ‘forest face’ due
discussed in Chapter 12: Afrotemperate, Subtropical and Azonal Forests
Indian Ocean Coastal Belt
571
S %
20.4°C at Mount Edgecombe (near Durban) to 19.9°C at Cape
Hermes (Port St Johns) and to 19.1°C at the Bashee Lighthouse
(near the mouth of the Mbhashe River). Summers are hot to
very hot, while winters are mild, with hardly any frost (higher in
the southernmost parts and then only mild).
(see also the modelling study by Eeley et al. 1999), and possibly
also by some more natural grassland. However, today these forests and natural grasslands have been replaced by a mosaic of
secondary grasslands, seral thickets and bushveld or obliterated
by agriculture and human settlements.
2.
Ecology: Climate, Geology, Soils and
Hydrology
2.1
Climate
The northern regions of the IOCB, close to the coast, have marginally nonseasonal (even) rainfall, with precipitation concentrated in summer. Richards Bay and St Lucia both have 41.6%
of their annual mean rainfall in winter. There are approximately
14 rain days in June and July (Camp 1999b). The winter rains
are associated with frontal systems from the south. Further
south, the rainfall seasonality of the belt, also close to the sea,
becomes clearly summer (Bailey 1979) in most places. The winterrainfall proportion is 35.6% for Empangeni, 30.9% for Mount
Edgecombe, 27.6% for Pinetown, 31.8% for Port Shepstone,
28.8% for Paddock, 32.7% for Cape Hermes Lighthouse (at
Port St Johns) and 36.6% at Bashee Lighthouse (near the
mouth of the Mbhashe River). The rainfall seasonality increases
gradually inland towards neighbouring savanna vegetation
types, for instance from about 33.6% on the border between
Maputaland Coastal Belt and Zululand Thornveld (Riverview)
and 26.7% on the border between KwaZulu-Natal Coastal Belt
and Ngongoni Veld (Eshowe) to 28.0% (Mkuze) and 25.1%
(Makatini Agr) well within savanna vegetation types. Strong
summer-rainfall seasonality (<20% Bailey 1979) is only found
in savanna types much further inland (e.g. in Thukela Valley
Bushveld: Muden 19.3%). On the Transkei coast Cawe (1994)
found that the proportion of winter rainfall is highest along the
coastal belt closest to the sea; he refers to this as rainfall type D
‘High rainfall with high winter rainfall’ and he found this climate
type to be confined to Acocks Veld Type 1.
In the KwaZulu-Natal part of the IOCB the mean annual rainfall ranges between 1 272 and 819 mm (Camp 1999b), while
on the Eastern Cape coast the mean annual rainfall reaches
1 120 mm at Cape Hermes (Port St Johns) and 1 128 mm at
Bashee Lighthouse (near the mouth of the Mbhashe River). The
east-west gradient of annual precipitation is remarkably steep,
especially in Maputaland, with around 1 200 mm on the coast,
while about 60 km inland (Ndumo in the Savanna Biome) only
about 60% of this amount occurs.
Evaporation is roughly between 1 490 mm per annum on the
South Coast (KwaZulu-Natal) and as high as 1 833 mm near
Empangeni. Air humidity is high, especially along the coast in
summer and may reach saturation point. Mean monthly relative
humidity at 14:00 at Richards Bay varies from 72% in November
to 59% in August. Moist summer heat may be a cause of discomfort, but it helps to maintain the temperature-sensitive and
moisture-demanding tropical vegetation of the region—both
indigenous as well as alien (crops and ornamental flora).
The region is under the combined influence of several wind
systems (Bews 1920): rain-bearing southern and southwestern
winds, eastern afternoon sea-breezes, and autumn anticyclonic
föhns. The wind run was measured to be about 160 km per
day in Empangeni. Cyclones originating over the Indian Ocean
occasionally hit the region from the northeast, causing major
climatic and hydrological havoc, for example the 1984 cyclone
called Domoina.
The pronounced hot and damp tropical character of the climate
of the IOCB in summer and its mild and slightly drier subtropical character in winter can be ascribed to several global and
macroregional factors. Firstly, it is the unusual southbound shift
of the Intertropical Convergence Zone in summer (Tyson 1986,
Stokes et al. 1997). Secondly, it is the ameliorating influence of
the warm Agulhas Current flowing close to the eastern coasts
of South Africa. These factors control the deep intrusion of
typical tropical biota on terra firma (terrestrial flora and fauna
and associated biotic communities) on shore (global southernmost occurrence of mangroves) and offshore (global southernmost occurrence of corals: Ramsey 1994, Riegl 2003). Relative
humidity of at least parts of the IOCB is remarkably similar to
that in regions much further up the east coast of Africa within
the tropics. For example, mean annual relative humidity for
Durban is 79% (max. in February: 82% and min. in July: 73%)
compared to 73% (max. in April: 82% and min. in October:
67%) for Dar-es-Salaam (Tanzania) and to 74% (max. in May:
79% and min. in February: 70%) for Mombasa (Kenya) (Müller
1982). Corresponding figures for relative humidity in Beira and
especially Maputo (both in Mozambique) are considerably lower
than for Durban.
The mean annual temperature ranges relatively narrowly from
about 22°C (in the north, near the Mozambique border) to
CB 1 Maputaland Coastal Belt
mm
120
933 ^^
>2A
30 2A4G
21
21.1 4
20 >2E
0U
>75
10
>2A6 1904 ^^
0 >2D>D
68
90
60
30
0
mm
120
°C
1075 ^^
>2A
30 2A4G
18
18.4 4
20 >2E
1U
>75
10
>2A6 1549 ^^
0 >2D>D
63
60
30
0
; 7>2> ; ; 2 D@?5
572
°C
964 ^^
>2A
30 2A4G
20
21.0 4
20 >2E
0U
>75
10
>2A6 1902 ^^
0 >2D>D
68
60
30
0
; 7>2> ; ; 2 D@?5
CB 4 Pondoland-Ugu Sandstone Coastal Sourveld
90
Geology and Soils
The IOCB is geologically very heterogeneous, including Mokolianage granites and gneisses that form the basement rocks for
90
; 7>2> ; ; 2 D@?5
mm
120
2.2
CB 2 Maputaland W ooded Grassland
°C
Indian Ocean Coastal Belt
19 (2006)
CB 3 KwaZulu-Natal Coastal Belt
mm
120
°C
989 ^^
>2A
30 2A4G
20
19.6 4
20 >2E
0U
>75
10
>2A6 1659 ^^
0 >2D>D
65
90
60
30
0
; 7>2> ; ; 2 D@?5
CB 5 Transkei Coastal Belt
mm
120
°C
1015 ^^
>2A
30 2A4G
19
18.4 4
20 >2E
0U
>75
10
>2A6 1594 ^^
0 >2D>D
65
90
60
30
0
; 7>2> ; ; 2 D@?5
Figure 11.2 Climate diagrams of Indian Ocean
Coastal Belt units. MAP: Mean Annual Precipitation;
APCV: Annual Precipitation Coefficient of Variation;
MAT: Mean Annual Temperature; MFD: Mean Frost
Days (days when screen temperature was below 0°C);
MAPE: Mean Annual Potential Evaporation; MASMS:
Mean Annual Soil Moisture Stress (% of days when
evaporative demand was more than double the soil
moisture supply).
S %
19 (2006)
sedimentary deposits spanning almost the entire Phanerozoic,
from Ordovician to Recent times, and representing all levels of
softness and the large variety of physical and chemical traits.
The most striking, and for the region most characteristic, rocks
are sandstones of the Msikaba Formation and those of the Natal
Group (Thomas et al. 1992) which support endemic vegetation
types such as Pondoland Scarp Forests (sensu Von Maltitz et al.
2003)—part of FOz 5 Scarp Forest (see Chapter 12) and CB 4
Pondoland-Ugu Sandstone Coastal Sourveld. On the Pondoland
Wild Coast these sandstones descend to sea level, where they
form dramatic coastal cliffs ornamented by numerous spectacular waterfalls. In KwaZulu-Natal, most of this belt turns
inland and continues in the form of geological islands at variable distance from the coast. The Msikaba Sandstones have a
high quartz content (70%–96%), with potassium feldspar and
small amounts of mica occurring as well (Hobday & Mathew
1974). They are stratigraphically linked to the Witteberg Group
of the Cape Supergroup (both are of Devonian age). The Natal
Group is, like the Peninsula Formation sandstones of the Table
Mountain Group, Ordovician. Like the sandstones building the
core of the Cape Fold Belt mountains, the soils developing over
both Msikaba and Natal Sandstones are sandy, highly leached,
acidic and mostly very shallow. Rock outcrops are very frequent
and dramatic scarps, krantzes and deep canyons are the typical accompanying geomorphological feature of this geological
landscape.
The sandstone belt (spanning Port St Johns and Port Edward)
divides the remainder of the IOCB into two distinct parts. The
northernmost region (Maputaland) is a broad coastal plain consisting of a variety of Cenozoic to Recent marine sediments,
mainly of Berea and Muzi Formations. A system of dune cordons
can be traced on this plain, marking past sea-level stillstands of
various ages. The oldest dune cordon (Ndumo) is more than 25
my old and occurs outside the IOCB proper. The coastal plain
itself is of Plio-Pleistocene age (3 mya to 10 000 yrs ago; Davis
1976, Botha 1997) and is covered by sandy deposits, forming
a high dune cordon all along the coast. Between Richards Bay
and Umlalazi these dunes cover the interesting Port Dunford
Formation (Oschadleus et al. 1996), 70 000 years old. Dystric
regosols (formed by well-drained and acidic sands) are formed
on elevated slopes and crests of the dune cordons. Humic gleysols
(wet, acidic sands with abnormal accumulation of organic matter) are found in depressions—habitats with a high water table
(Matthews et al. 1999). The rest of the KwaZulu-Natal coastal
belt is a geologically complicated mosaic of Karoo Supergroup
clastic sediments, metamorphic rocks of the Namibian Erathem
and Cenozoic to Recent sediments.
Most of the Transkei Coastal Belt is built of Karoo sediments,
including sandstone and mudstone of the Adelaide Subgroup,
shale, mudstone and sandstone of the Ecca Group as well as
tillites of the Dwyka Group; Jurassic dolerite intrusions occur
in places.
Right at the coast, sand dune cordons have been formed or are
being formed—these are calcareous young Quaternary sands
derived from rocks of Cretaceous and Cenozoic origin. The sand
dunes are massive and very high, especially in Maputaland as
well as on the Zululand coast. They become rare in the southern
part of the IOBC, where they are concentrated into small pockets
at river mouths cutting though the steep coasts of Transkei.
2.3
Hydrology
The vegetation patterns of the IOCB are the result of intricate
palaeofloral history, climate, geology, and last, but not least,
hydrology. There are a number of azonal (or intrazonal) vegeta-
tion types controlled by temporal or semipermanent flooding
embedded within the IOCB (Table 1). These include freshwater wetlands, estuaries, coastal lakes, mangroves, riverine and
swamp forests, described in separate chapters on Inland Azonal
Vegetation, Coastal Vegetation and Forests.
Maputaland is a particularly water-rich environment with, for
example, spectacular coastal lagoons such as Kosi Bay and St
Lucia, big lakes (Lake Sibaya is the largest freshwater lake in
South Africa; Wright et al. 2000) and extensive swamps (Muzi
Swamp, swamps of the Mkuze floodplain north of the St Lucia
lagoon). In many places the ground-water table is very high. It
feeds the marshes and pans and is regularly replenished by rain.
Sandy substrates result in considerable fluctuations in groundwater level (Matthews et al. 1999). The existence of some of the
grassland types, including the enigmatic Maputaland Wooded
Grasslands and other ‘edaphic’ grasslands embedded within
the Maputaland Coastal Belt and KwaZulu-Natal Coastal Belt,
is linked to dynamics of the ground-water table and temporary
surface flooding (e.g. Matthews et al. 1999).
3.
Biogeographical Patterns: Past and
Present
3.1
Palaeo-ecological Patterns
According to Maud (in Tinley 1985: 43), at least the Maputaland
region must have been submerged approximately 10 mya as
witnessed by Miocene and Pliocene sediments reaching up
to 300 m above present sea level. Mid- and Upper Pliocene
were characterised by uplift and tilting of the southern African
subcontinent, resulting in formerly submerged areas (or some
parts of them) becoming dry land. However, the areas that we
define as parts of the current IOCB were formed only much
later—through a series of Pleistocene marine regressions.
It is clear that the climate in southern Africa underwent dramatic changes during the Pliocene and Pleistocene (past
5 my) marked by about 21 climatic cycles (each approximately
100 000 yrs long) of alternation of dry/cold and wet/warm
climates (Deacon 1983, Tyson 1986, Deacon & Lancaster 1988).
Undoubtedly these changes shaped the face of South African
vegetation and are supposed to have had major impacts on
the vegetation, especially on the extremes of macroclimatic
gradients. There is only scanty palaeo-ecological (palynological) information on the vegetation of the IOCB during the Last
Interglacial (approximately 130 000–40 000 BP). Studies of a
lignite layer embedded in the Port Dunford Formation between
Umlalazi Lagoon near Mtunzini and Richards Bay (Scott et al.
1992, Oschadleus et al. 1996) suggest existence of a complex
of palustrine vegetation probably surrounded by coastal freshwater lakes, and forest vegetation in which Podocarpus (most
likely Afrocarpus falcatus) might have been dominant. These
papers hypothesised that the yellowwood forest developed
here after formation of the peat (turning lignite) layer, coinciding with the deposition of sand with lower organic content.
An abundance of Podocarpus pollen was found also in the
sediments of the Lake Teza (near Mtubatuba)—around 3 400
yrs BP. Podocarpus contributed up to 20% of pollen found in
the studied profile (Scott & Steenkamp 1996) deposited since
the early Holocene. Scott & Steenkamp (1996) further imply
that the Podocarpus pollen came from an ‘original coastal
woodland environment’. Unlike Port Dunford, in the surroundings of Lake Teza, Podocarpus was replaced by local swampy
elements. Whatever the direction of the replacement, both
studied localities suggest a spatial and temporal link between
swamp vegetation and (presumably) Podocarpus-dominated
Indian Ocean Coastal Belt
573
S %
vegetation. Incidentally, it is the Swamp Forest, which supports
(probably relictual) populations of afrotemperate tree elements
such as Apodytes dimidiata, Ilex mitis, Rapanea melanophloeos,
Peddiea africana, Afrocarpus falcatus, Psychotria capensis and
Scutia myrtina (Wessels 1991). Afrocarpus falcatus occurs in
the IOCB not only in the Scarp Forest (which shows a number
of transitional traits between coastal and afrotemperate forests;
see Chapter 12), but also in subtropical Coastal Forest (Lubbe
1997, Van Wyk & Smith 2001). Mazus (2000) added some more
palynological data from the KwaZulu-Natal coastal peatlands
and confirmed that Podocarpus has been abundant, especially
in times when the regional climate during the Last Glacial was
presumably wetter (70 000–34 000 BP and 14 000–5 000 BP).
Botha et al. (1992) found Podocarpus pollen to be abundant
in buried paleosols from cooler and wetter periods of the Late
Pleistocene Hypothermal, but their locality is situated almost
1 000 m higher than the coastal peat deposits. Does the abundant occurrence (and dominance at the Port Dunford site) of
Podocarpus in the pollen spectra mean (as argued for instance
by Mazus 2000) that the coastal belt between Richards Bay and
Umlalazi (and even further north as far as the Muzi Swamp)
supported forests of afrotemperate nature? Not necessarily, as
the tree species known today as ‘afrotemperate’ (including both
genera Podocarpus and Afrocarpus) might rather be relicts of
temporary migrations (or dispersal) from afromontane localities
during wetter periods to palustrine coastal forests. The afrotemperate elements found within the IOCB today are exclusive
to the Swamp Forests (Venter 1972, Lubbe 1997). These, as we
know them today, ‘(sub)tropical’ Swamp Forests might have
acquired a more ‘afrotemperate’ face due to the increase of
cover of Podocarpus/Afrocarpus in these habitats during cooler
(but sufficiently wet) periods.
The vegetation landscapes of the IOCB, in concert with other
biomes of southern Africa, underwent major changes as a
response to a drop in temperature, reaching its minimum at
about 18 000 yrs BP, at Late Glacial Maximum (LGM). This
period is known to be not only cold (on average 5–6°C lower
than today, Botha et al. 1992), but also drier—with precipitation
as low as 40–70% of the present mean. The Indian Ocean seaboards of South Africa were much cooler and drier than today,
owing also to the lower sea-surface temperatures (Van Zinderen
Bakker 1982) and weaker and shallower Agulhas Current (Prell
et al. 1980). Low precipitation and concentration of water in ice
shields can cause a decrease of sea level by about 120 m. At
the Indian Ocean seaboards, this resulted in reworking of the
coastal dune cordons.
Following the LGM, climate ameliorated rather rapidly and wetter conditions re-established in the IOCB, sometimes between
17 000–15 000 BP (Tyson 1986). Along the time axis towards
the present time, the temperature kept rising and around 7 000
BP it reached its alti-thermal (Tyson 1986, Deacon & Lancaster
1988, Partridge et al. 1990).
A new dune cordon was built and formed a corridor allowing (sub)tropical flora to migrate southwards together with the
southward shift of the Intertropical Convergence Zone. It was
supposedly during this period (between 15 000 to 7 000 BP)
when the subtropical woody vegetation of the IOCB (as we
know it today) staged its come-back or re-established here. In
the process, the IOCB—the youngest biome in South Africa—
was born.
3.2 Current Biogeographical Patterns
Biogeographically the IOCB region (and, unfortunately, also
much of its deep hinterland) has been classified as Tongaland574
Indian Ocean Coastal Belt
19 (2006)
Pondoland Regional Mosaic, spanning the coastal regions
between Port Elizabeth and Xai Xai at the Limpopo River mouth
in Mozambique and including regions such as the former
Albany District, coastal hinterland as deep as Pietermaritzburg
and Nongoma, most of Swaziland and the southern Lowveld
(Moll & White 1978, White 1983). In a decisively altered version
this region was redefined by Van Wyk (1994; see also Van Wyk
& Smith 2001), setting the southernmost border at the Buffels
River (albeit with reservations) and by including coastal plains of
the Eastern Cape as far as Queenstown and piedmonts of the
Southern Berg and further north all regions as far as the Low
Drakensberg. Van Wyk (1994) renamed this unit to become the
‘Maputaland-Pondoland Region’, which is claimed to encompass two Centres of Endemism (CE), namely the Pondoland CE
and Maputaland CE. Clarke (1998) reclassified the Maputaland
CE by incorporating it into his Swahili-Maputaland Regional
Transition Zone.
The extent of the Pondoland CE corresponds well with the core
of our vegetation unit CB 4 Pondoland-Ugu Sandstone Coastal
Sourveld. The Maputaland CE is heterogeneous in terms of
vegetation (as well as in terms of age of incorporated vegetation units). It incorporates the CB 1 Maputaland Coastal Belt,
CB 2 Maputaland Wooded Grasslands as well as part of the
accompanying forest types (see Chapter 12) and azonal wetland and coastal vegetation. Unlike Van Wyk & Smith (2001),
we do not recognise the Lebombo Mountains as part of the
Maputaland CE.
The IOCB appears to be the youngest biome in our region
and still two regional centres of endemism (Pondoland and
Maputaland) coincide with the extent of the IOCB. How does
this fit with the relatively ‘recent’ dramatic climatic (and palaeoecological) scenarios that led to formation of this new biome?
We suggest that the explanation lies in the azonality (or intrazonality) of the habitats supporting endemic flora. The endemicrich coastal sourveld is limited to special geology (sandstones
of Msikaba Formation) supporting nutrient-stressed soils, and
in a way simulating the geological and pedological conditions
typical of the Fynbos (Van Wyk 1989, 1990a, 1994, Van Wyk &
Smith 2001). The evolutionary old endemics of the Pondoland
are concentrated either to scarp (and deep-gorge) forests,
which undoubtedly must have undergone major shrinkage during the LGM (as well as during the much earlier Pleistocene
glacials), but were able to recover from local, well-sheltered
refugia. These forests, too, are confined largely to the same
types of sandstones and to a lesser extent also to granites
(Ongoye Forest near Empangeni). The endemics of Maputaland
are largely neo-endemics—the infraspecific status of many of
them suggests a very recent origin (Van Wyk & Smith 2001).
Within the IOCB proper, they are almost exclusively found in
azonal vegetation types, such as CB 2 Maputaland Wooded
Grassland. The occurrence of palaeo-endemics in the region
(such as Helichrysopsis septentrionale in wooded grasslands,
Encephalartos ferox in coastal thicket and coastal forest, and
palustrine palm Raphia australis) demonstrates the ability of
these taxa to resist dramatic climate changes. Resilience of habitats such as wooded grasslands and swamps might have also
played a role in preserving these old relics.
The nature of regional endemism in the IOCB and the major
phytogeographic links are discussed in detail by Moll & White
(1978). These authors have established that the flora of the IOCB
contains Zanzibar-Inhambane, Zambezi, Afromontane, Upland,
Cape/Afromontane, Karoo-Namib and Guineo-Congolian linking elements as well as a separate category of ‘chorological and
ecological transgressors’ occurring in a wide range of vegetation types in southern Africa.
S %
4.
19 (2006)
Present Status
Land use is primarily sugarcane farming (over 88% of the cultivated area; Camp 1999b) in the KwaZulu-Natal area of the
biome and subsistence farming in the Eastern Cape. Subsistence
farming areas from Port Shepstone in southern KwaZulu-Natal
to the KwaZulu-Natal/Mozambique border are undergoing
rapid development to small-scale sugarcane farming and smallscale commercial tree farming. This is resulting in the loss of
vast areas of natural vegetation.
The coastline of KwaZulu-Natal south of St Lucia Estuary is highly
developed, with only small isolated occurrences of natural vegetation. A considerable area of the Forest Biome is embedded
within this geographical area. In contrast, the coastline of the
Transkei is little transformed and there are many natural grassland patches outside formal nature reserves. The IOCB supports
the highest human population concentrations on the eastern
seaboard.
About 39% of the IOCB's geographical area has been transformed. However, there is a considerable range in the levels
of transformation within and between vegetation types, with
corresponding implications for meeting conservation targets for
biodiversity. South of the KwaZulu-Natal/Eastern Cape border
there remain extensive areas of natural vegetation and consequently conservation targets are likely to be attainable, but
throughout the KwaZulu-Natal portion of the biome critically
high levels of transformation make it very difficult to meet conservation targets.
Approximately 7% of the IOCB is formally protected in statutory
reserves. However, this is disproportionately spread between the
five vegetation units, one of them with less than 1% protected.
5.
Threats to Natural Vegetation
Cultivation and afforestation are the greatest threats. Extensive
areas, in many cases previously grazed on a subsistence basis,
are undergoing rapid development to small-scale sugarcane
farming and small-scale commercial tree farming. Outgrow
projects of large companies coupled with large-scale government water supply schemes and other agricultural incentive
schemes are promoting small-scale commercial farming in areas
hitherto not available for these land uses.
Alien invasive plants are a major and growing threat.
Replacement of natural plant communities to ones dominated
by alien plants is prevalent throughout the geographical area
of the biome and the vegetation units. Chromolaena odorata is
the main problem plant. Severe loss of browsing and grazing for
both domestic livestock and wildlife is commonplace. Where
landowners can afford it, large amounts of money are often
allocated to control of invasive plants. However, in poor areas
infestation is usually so severe that little indigenous vegetation
survives.
Extensive areas of subsistence farming often occur in underdeveloped areas between commercial agriculture. Grasslands
are often burnt indiscriminately to the disadvantage of many
natural plant communities and consequently of wildlife in general. This also tends to affect the ecological functioning of bushclump and forest margins. Traditional hunting is sometimes the
cause of such fires.
Urbanisation is rapidly expanding into the few natural areas
remaining near the many development nodes. Some of the
most prolific examples are to be seen at Richards Bay, Durban,
Scottburgh, Port Shepstone and Margate.
The Pondoland coastal area faces the threat of dune mining and
the construction of a new N2 toll road.
6.
Action: Conservation and
Management of Resources
In terms of the conditions of a World Heritage Site, the Greater
St Lucia Wetland Park is run by a Wetlands Authority. The management of the wildlife has been delegated to the provincial
nature conservation agency Ezemvelo KZN Wildlife. In addition,
many natural areas of Maputaland are benefiting from the
Lubombo Spatial Development Initiative. This applies mainly to
the Savanna Biome west of the IOCB and is discussed in that
chapter. It places much of the northern part of the IOCB in the
fortunate position of being under well-developed, secure management structures.
Ezemvelo KZN Wildlife is mandated to attend to nature conservation needs throughout the KwaZulu-Natal part of the
IOCB. The southern half of the coastal belt is, however, poorly
provided for in terms of well-integrated land use planning. To
this end, Ezemvelo KZN Wildlife has developed detailed conservation planning protocols based on systematic conservation
planning approaches. This includes the modelling of irreplaceable areas. These are then embedded in the Municipal Spatial
Development Frameworks. Other land use planning controls
that are important for the conservation of natural vegetation include the Durban Metro Municipal Open Space System
(D-MOSS).
In the Eastern Cape a project integrating conservation and
development on the Wild Coast (most of the Transkei coastline and incorporating most of Pondoland), has been launched
by the Eastern Cape Department of Economic, Environmental
Affairs and Tourism and the Wilderness Foundation (The Herald
News 29/7/2004). The project will build on the 1997 Spatial
Development Initiative and is being modelled on the STEP
Programme for the Thicket vegetation type. The Wild Coast
Conservation and Development Project has initiated actions
that include conservation assessment, strategic environmental
assessment, an integrated land use plan that nests biodiversity
conservation objectives into the regional sustainable development framework, a conservation strategy and action plan, participation in the Global Environmental Facility (GEF) funding
proposals, and implementation programme for the Wild Coast
in conjunction with the national Department of Environmental
Affairs and Tourism. The long-term goal of the GEF project is:
Representative system of protected areas in priority bioregions
is established effectively, managed and contributes to sustainable development. The GEF project objective is: An effective
network of protected areas is established on the Wild Coast
and provides tested co-management models for replication.
The possible creation of a Pondoland Park will form part of this
planning.
7.
Further Research Challenges
Maputaland became a focus of interest of geologists (Botha
1997, Maud & Botha 2000, Wright et al. 2000) as a prime
example of evolution of coastal plains, of vegetation ecologists
owing to interesting sources of palaeo-ecological data (Scott et
al. 1992, Scott & Steenkamp 1996, Mazus 2000), of biogeographers because of the key importance of the Belt for southbound plant and animal migrations (White 1983, Lawes 1990)
and of vegetation ecologists for the diversity of vegetation
types reflecting intricate soil and hydrological patterns as well
Indian Ocean Coastal Belt
575
S %
as regional climatic gradients (Moll & White 1978, Moll 1978,
1980, Lubbe 1997). The Maputaland coast, and to some extent
also southern stretches of the KwaZulu-Natal coast, with its
mosaic of grasslands, thickets and coastal forests, faces human
pressures ranging from over-development due to increasing
tourism, urban sprawl to coastal mining. These pressures have
generated considerable interest in biological research (Weisser
1978, 1987, Weisser & Marques 1979, Ward 1980). Our knowledge of floristic treasures of Pondoland is increasing (Van Wyk
1990b, Van Wyk & Smith 2001), and the region continues to
yield new surprises, such as the discovery of a spectacular new
Clivia species (Murray et al. 2004). There is still no comprehensive vegetation monograph for either the Pondoland coastal
sourveld or of the famous Pondoland subtropical forests. Within
the IOCB, the biota of the remainder of the Transkei coast is
poorly known. More research in all aspects of ecology should
be initiated here, especially in the light of the increased interest
of developers targeting this coastal stretch.
8.
Descriptions of Vegetation Units
CB 1 Maputaland Coastal Belt
VT 1 Coastal Forest and Thornveld (97%) (Acocks 1953). LR 23 Coastal
Bushveld-Grassland (86%) (Low & Rebelo 1996). BRG 1 Moist Coast Forest
Thorn & Palm Veld (59%) (Camp 1999a, b). Coast Grassveld p.p. & Palm
Veld p.p. (Moll 1978, 1980).
Distribution KwaZulu-Natal Province (and continuing also in
southern Mozambique): Up to 35 km broad strip along the
coast of the Indian Ocean stretching from the Mozambique
border in the north to Mtunzini in the south. Altitude varies
from about 20–120 m.
secondary grasslands, extensive timber plantations and cane
fields. The belt of the IOCB immediately inland (only a few
kilometres wide) and parallel to the line of Northern Coastal
Forest has a characteristic appearance of very irregular dunes
with generally open vegetation and Syzygium cordatum dotted prominently on the dunes, with many irregular dune slacks
interspersed. There is little to suggest that this part of the vegetation, e.g. between Lake Sibaya and Kosi Lake, is secondary.
The peculiar CB 2 Maputaland Wooded Grassland—still another
vegetation unit embedded within the geographical extent of
the Maputaland Coastal Belt—is treated as a separate vegetation unit (see below).
Geology & Soils Up to about 18 000 yrs old Quaternary sediments of marine origin—mainly yellowish and argillaceous redistributed sands (Berea and Muzi Formations of the Maputaland
Group, respectively). Soils nutritionally very poor and well
leached, except in the interdune depressions where organic-rich
soils are sometimes found. The dominant land types include Hb
and Ha, with some contribution of Db land type.
Climate Weak rainfall seasonality near the coast tending toward
summer rainfall towards the interior. Relatively high precipitation attaining annual values up to 1 200 mm in coastal localities,
decreasing rapidly to the interior. High humidity and temperature. Mean maximum and minimum monthly temperature for
Lake St Lucia Research Centre are 35.3°C and 5.5°C (for January
and June, respectively). No incidence of frost. See also climate
diagram for CB 1 Maputaland Coastal Belt (Figure 11.2).
Important Taxa Low Shrubs: Agathisanthemum bojeri (d),
Helichrysum kraussii (d), Tephrosia longipes. Small Trees & Tall
Shrubs: Syzygium cordatum (d), Acacia natalitia, Annona senegalensis, Apodytes dimidiata, Bridelia cathartica, Canthium
inerme, Chrysanthemoides monilifera subsp. rotundata, Euclea
natalensis subsp. natalensis, Ficus burtt-davyi, Kraussia floribunda, Phoenix reclinata, Rhus natalensis, Sclerocroton integerrimum, Strychnos spinosa. Woody Climbers: Abrus precatorius subsp. africanus, Smilax anceps. Herbs: Achyranthes aspera,
Centella asiatica, Chamaecrista plumosa, Hermbstaedtia odorata var. aurantiaca, Vernonia centaureoides, V. oligocephala.
Graminoids: Diheteropogon amplectens (d), Eragrostis sclerantha (d), Ischaemum fasciculatum (d), Themeda triandra
(d), Urelytrum agropyroides (d), Aristida stipitata subsp. graciliflora, Cymbopogon pospischilii, Elionurus muticus, Eragrostis
inamoena, E. lappula, Sporobolus subulatus, Trachypogon spicatus, Trichoneura
grandiglumis, Tristachya leucothrix.
L. Mucina
Vegetation & Landscape Features Flat coastal plain originally probably densely forested in places with a wide range of
interspersed nonforest plant communities including dry grasslands (which include palm veld where special conditions prevail),
hygrophilous grasslands and thicket groups. Today the vegetation landscape is composed of pockets of various forest types
(separated into different vegetation units), thickets, primary and
Figure 11.3 CB 1 Maputaland Coastal Belt: Seasonally wet grasslands of the Palm Veld (with
Hyphaene coriacea) near KaNgwanase in Maputaland, northern KwaZulu-Natal.
576
Indian Ocean Coastal Belt
19 (2006)
Biogeographically Important Taxa
(CCoastal belt element, FGeneric fynbos
element, ILPIsolated lowland populations,
M
Maputaland endemic, NNorthern distribution limit, SSouthern distribution limit)
Geoxylic Suffrutex: Diospyros galpiniiS.
Low Shrubs: Indigofera williamsoniiC, Rhus
kwazuluanaM, Stylosanthes fruticosaS.
Small Trees & Tall Shrubs: Hyphaene coriaceaS (d), Ozoroa obovataS, Rhus nebulosaC,
Synaptolepis kirkiiM. Woody Climber:
Dalbergia obovataC. Herbs: Helichrysopsis
septentrionaleM, Helichrysum tongenseC,
H. cymosum subsp. cymosumN, Nidorella
tongensisM, Senecio ngoyanusC, Vernonia
natalensisILP. Megaherb: Strelitzia nicolaiC (d). Succulent Herb: Orbea longidens M . Semiparasitic Herb: Striga
junodii S. Graminoid: Monocymbium
ceresiiformeILP.
S %
19 (2006)
Endemic Taxa (FGeneric fynbos element) Herbs: Helichrysum
adenocarpum subsp. ammophilum, Vahlia capensis subsp. vulgaris var. longifolia. Geophytic Herbs: Asclepias gordon-grayae,
Kniphofia leucocephala, Raphionacme lucens. Graminoid:
Restio zuluensisF (d).
Conservation Vulnerable. Target 25%. 15% statutorily
conserved in the Greater St Lucia Wetland Park as well as
in Sileza, Enseleni and Amathikulu Nature Reserves. More
than 30% transformed for plantations and cultivation and
by urban sprawl. Aliens include scattered populations of
Chromolaena odorata and Lantana camara. Erosion is mostly
very low. This vegetation type has a relatively high number
of plant taxa at the southernmost and northernmost limits
of their distribution range—the occurrence of widely disjunct
or outlier populations increases the conservation value of this
vegetation type.
Remark 1 The primary grasslands of interdune depressions
and seasonally waterlogged bottomlands of the Maputaland
were classified by Matthews et al. (1999) as the Eragrostis
lappula–Helichrysopsis septentrionalis and Ischaemum fasciculatum–Eragrostis inamoena hygrophilous grasslands, and
by Lubbe (1997) as Ischaemum fasciculatum–Centella asiatica hygrophilous grassland. Like the Maputaland Wooded
Grasslands, these primary grasslands are home to a number of
Maputaland endemics such as the enigmatic Restio zuluensis
and Helichrysopsis septentrionale.
Remark 2 Most of the Maputaland Coastal Belt is agricultural
land and very little of this unit remains in a natural state in the
South African part of Maputaland. A much larger area of wellpreserved coastal belt is found in Mozambique.
References Venter (1972), Moll (1972, 1978, 1980), Moll & White (1978),
Weisser (1978, 1987), Weisser & Marques (1979), Lubbe (1997), Camp
(1999a, b), Matthews et al. (1999), Smith (2001), Van Wyk & Smith (2001).
CB 2 Maputaland Wooded Grassland
VT 1 Coastal Forest and Thornveld (100%) (Acocks 1953). LR 23 Coastal
Bushveld–Grassland (98%) (Low & Rebelo 1996). BRG 1 Moist Coast Forest
Thorn & Palm Veld (61%) (Camp 1999a, b). Incl. Themedo–Salacietum Myre
(1964).
relatively high-lying level plains. Water table found at depth 1.6–
2.0 m below surface (and slightly deeper) in average rainfall years.
Ha is the overwhelmingly dominant land type, followed by Hb
land type.
Climate Approximately the same as for the CB 1 Maputaland
Coastal Belt (both units form an intricate regional mosaic). See
also climate diagram for CB 2 Maputaland Wooded Grassland
(Figure 11.2).
Important Taxa (#Suffrutex form) Geoxylic Suffrutices: Parinari
curatellifolia (d), Salacia kraussii (d), Ancylobotrys petersiana,
Diospyros galpinii, Eugenia capensis#, Syzygium cordatum#.
Graminoids: Diheteropogon amplectens (d), Themeda triandra (d), Aristida stipitata subsp. graciliflora, Bewsia biflora,
Cyperus obtusiflorus, C. tenax, Digitaria natalensis, Eustachya
paspaloides, Setaria sphacelata, Sporobolus fimbriatus, S. subulatus, Urelytrum agropyroides. Herb: Chamaecrista plumosa.
Geophytic Herb: Cyrtanthus galpinii. Low Shrubs: Helichrysum
kraussii (d), Agathisanthemum bojeri, Crotalaria monteiroi var.
monteiroi. Small Trees & Tall Shrubs: Acridocarpus natalitius var.
linearifolius, Dichrostachys cinerea subsp. nyassana, Diospyros
lycioides subsp. sericea, Hyphaene coriacea, Terminalia sericea.
Biogeographically Important Taxa (CCoastal belt element,
M
Maputaland endemic, SSouthern distribution limit) Geoxylic
Suffrutices: Eugenia albanensisC, Gymnosporia markwardiiM;
Graminoids: Abildgaardia hygrophilaC, Cyperus natalensisC.
Herbs: Helichrysopsis septentrionaleM; Oxygonum robustumM,
Tricliceras mossambicenseM. Tall Shrub: Grewia microthyrsaS.
Woody Climbers: Albertisia delagoensisS, Cissampelos hirtaS.
Endemic Taxa (#Suffrutex form) Geoxylic Suffrutices: Ochna sp.
nov., Syzygium cordatum#. Succulent Herb: Aloe sp. nov. (Strey
5100 PRE). Geophytic Herb: Brachystelma vahrmeijeri.
Conservation Endangered. Target 25%. About 17% statutorily
conserved mainly in the Greater St Lucia Wetland Park. Some
46% transformed mostly for plantations and partly for cultivated land. The southern half of the area is not protected and
it is here that over 90% of the extent of the vegetation type
has been transformed—mostly to pulpwood timber plantations,
cane fields and informal settlements. Aliens include scattered
populations of Chromolaena odorata and Lantana camara.
Vegetation & Landscape Features
Generally flat landscape of the
Maputaland coastal plain supporting
coastal sandy grasslands rich in geoxylic suffrutices, dwarf shrubs, small trees
and very rich herbaceous flora. Excluded
from this unit are the many interdune
depression wetlands and hygrophilous
grasslands neighbouring the wooded
grasslands.
Geology & Soils Quaternary redistributed sand supporting yellowish redistributed sands of the Berea Formation
(Maputaland Group). These are dystric
regosols building dune crests, slopes and
W.S. Matthews
Distribution KwaZulu-Natal Province
and southern Mozambique: In South
Africa from the Mozambique border near
KwaNgwanase southwards to Sileza,
Sibaya, Mseleni, Mbazwana, Sodwana
Bay, Ozabeni, eastern and western shores
of Lake St Lucia, KwaMbonambi and as
far south as near Richards Bay. Altitude
varies from about 20–120 m.
Figure 11.4 CB 2 Maputaland Wooded Grassland: Wooded grassland in Maputaland (northern KwaZulu-Natal) with prominent (silvery leaves) undescribed species of geoxylic suffrutex
(Ozoroa sp. nov.).
Indian Ocean Coastal Belt
577
S %
Remarks This type is an example of the famous ‘underground
forests of Africa’ (White 1976) characterised by plants with
sometimes enormous underground woody parts connecting apparently separate dwarf shrubs or even with only tufts
of leaves above ground. This growth form is called a geoxylic
suffrutex (dwarf woody plant with annual or short-lived
above-ground woody shoots sprouting from massive underground ‘stem’) (White 1976, Matthews et al. 1999, Van Wyk &
Smith 2001). Some of the taxa occur naturally only as geoxylic
suffrutices, while in some, generally more widely distributed
taxa (incl. Eugenia capensis, Syzygium cordatum) suffrutex
forms occur in these habitats. Several hypotheses have been
suggested to explain the existence of this enigmatic vegetation
type as well as the peculiar concentration of the geoxylic suffrutices. Fire-resistance and adaptation to high groundwater tables
have been proposed most often (see White 1976, Matthews
et al. 1999), but none of these (and other) explanations have
been accompanied by conclusive evidence. Species with the
geoxylic suffrutex form are also found within many open and
well-wooded savanna types including some with sandy substrate where there is commonly a higher investment in belowground organs.
References Myre (1964, 1971), White (1976, 1983), Moll (1978, 1980),
Moll & White (1978), Van Wyk (1994, 1996), Lubbe (1997), Mathews et al.
(1999), Smith (2001), Van Wyk & Smith (2001), Felton (2002).
CB 3 KwaZulu-Natal Coastal Belt
VT 1 Coastal Forest and Thornveld (81%) (Acocks 1953). LR 23 Coastal
Bushveld–Grassland (62%) (Low & Rebelo 1996). BRG 1 Moist Coast Forest
Thorn & Palm Veld (89%) (Camp 1999a, b).
Distribution KwaZulu-Natal Province: Long and in places broad
coastal strip along the KwaZulu-Natal coast, from near Mtunzini
in the north, via Durban to Margate and just short of Port
Edward in the south. Altitude ranges from about 20–450 m.
Geology & Soils Ordovician Natal Group
sandstone, Dwyka tillite, Ecca shale and
Mapumulo gneiss (Mokolian) dominate
the landscapes of the KwaZulu-Natal
Coastal Belt. Weathering of old dunes
has produced the red sand, called the
Berea Red Sand, in places. The soils supported by the above-mentioned rocks are
shallow over hard sandstones and deeper
over younger, softer rocks. Fa land type
dominates the area, while Ab land type
is only of minor importance.
Climate Summer rainfall, but with some
rainfall also in winter. High air humidity.
No incidence of frost. Mean maximum
578
Indian Ocean Coastal Belt
and minimum monthly temperatures for Durban (airport) are
32.6°C and 5.8C and for Port Shepstone 30.6°C and 8.8°C
(both for January and July, respectively). See also climate diagram for CB 3 KwaZulu-Natal Coastal Belt (Figure 11.2).
Important Taxa Graminoids: Aristida junciformis subsp. galpinii
(d), Digitaria eriantha (d), Panicum maximum (d), Themeda triandra (d), Alloteropsis semialata subsp. eckloniana, Cymbopogon
caesius, C. nardus, Eragrostis curvula, Eulalia villosa, Hyparrhenia
filipendula, Melinis repens. Herbs: Berkheya speciosa subsp.
speciosa (d), Cyanotis speciosa (d), Senecio glaberrimus (d),
Alepidea longifolia, Centella glabrata, Cephalaria oblongifolia,
Chamaecrista mimosoides, Conostomium natalense, Crotalaria
lanceolata, Dissotis canescens, Eriosema squarrosum, Gerbera
ambigua, Hebenstretia comosa, Helichrysum cymosum subsp.
cymosum, H. pallidum, Hibiscus pedunculatus, Hybanthus
capensis, Indigofera hilaris, Pentanisia prunelloides subsp.
latifolia, Senecio albanensis, S. bupleuroides, S. coronatus, S.
rhyncholaenus, Sisyranthus imberbis, Stachys aethiopica, S.
nigricans, Vernonia galpinii, V. oligocephala. Geophytic Herbs:
Bulbine asphodeloides, Disa polygonoides, Hypoxis filiformis,
Ledebouria floribunda, Pachycarpus asperifolius, Schizocarphus
nervosus, Tritonia disticha. Low Shrubs: Clutia pulchella, Gnidia
kraussiana, Phyllanthus glaucophyllus, Tephrosia polystachya.
Woody Climbers: Abrus laevigatus, Asparagus racemosus,
Smilax anceps. Small Trees & Tall Shrubs: Bridelia micrantha (d),
Phoenix reclinata (d), Syzygium cordatum (d), Acacia natalitia,
Albizia adianthifolia, Antidesma venosum.
Biogeographically Important Taxa (CCoastal belt element,
Southern distribution limit) Graminoids: Cyperus natalensisC, Eragrostis lappulaS. Herbs: Helichrysum longifoliumC,
Selago tarachodesC, Senecio dregeanusC, Sphenostylis angustifoliaS. Geophytic Herbs: Kniphofia gracilisC, K. littoralisC,
K. rooperiC, Pachystigma venosumS, Zeuxine africanaS. Low
Shrubs: Helichrysum kraussiiS (d), Agathisanthemum bojeriS,
Desmodium dregeanumC. Megaherb: Strelitzia nicolaiC (d).
Geoxylic Suffrutices: Ancylobotrys petersianaS, Eugenia albanensisC, Salacia kraussiiS. Small Trees & Tall Shrubs: Anastrabe
integerrimaC (d), Acacia nilotica subsp. kraussianaS.
S
Endemic Taxa Herb: Vernonia africana (extinct). Geophytic Herb:
Kniphofia pauciflora. Low Shrub: Barleria natalensis (extinct).
Conservation Endangered. Target 25%. Only very small part
statutorily conserved in Ngoye, Mbumbazi and Vernon Crookes
L. Mucina
Vegetation & Landscape Features Highly dissected undulating coastal plains which presumably used to be covered to
a great extent with various types of subtropical coastal forest
(the remnants of one of which are described in Chapter 12 as
Northern Coastal Forest). Some primary grassland dominated by
Themeda triandra still occurs in hilly, high-rainfall areas where
pressure from natural fire and grazing regimes prevailed. At
present the KwaZulu-Natal Coastal Belt
is affected by an intricate mosaic of very
extensive sugarcane fields, timber plantations and coastal holiday resorts, with
interspersed secondary Aristida grasslands, thickets and patches of coastal
thornveld.
19 (2006)
Figure 11.5 CB 3 KwaZulu-Natal Coastal Belt: Complex of primary species-rich grasslands and
subtropical forests in Vernon Crookes Nature Reserve near Umzinto, KwaZulu-Natal.
S %
19 (2006)
Nature Reserves. About 50% transformed for cultivation, by
urban sprawl and for road-building. Aliens include Chromolaena
odorata, Lantana camara, Melia azedarach and Solanum mauritianum. Erosion is low and moderate.
References Edwards (1967), Moll & White (1978), Ward (1980), Roberts
(1993), Camp (1999a, b), Heijnis (2004), Van der Linden et al. (2005).
CB 4 Pondoland-Ugu Sandstone Coastal
Sourveld
VT 1 Coastal Forest and Thornveld (53%) (Acocks 1953). LR 48 Coastal
Grassland (38%), LR 42 Moist Upland Grassland (28%) (Low & Rebelo 1996).
BRG 1 Moist Coast Forest Thorn & Palm Veld p.p. Camp (1999a, b).
Distribution Eastern Cape and KwaZulu-Natal Provinces:
Elevated coastal sandstone plateaus from Port St Johns on the
Pondoland coast (Eastern Cape) to the vicinity of Port Shepstone
(Ugu District, KwaZulu-Natal), incl. the sourveld of the wellknown Oribi Gorge. Altitude ranges from about 0–600 m.
Vegetation & Landscape Features Coastal peneplains and
partly undulating hills with flat table-lands and very steep
slopes of river gorges. These sites support natural, species-rich
grassland punctuated with scattered low shrubs or small trees
(sometimes with bush clumps, especially in small gullies). Rocky
outcrops and krantzes are common and dramatic sea-cliffs
occur. Proteaceous trees (Protea, Faurea) can be locally common where conditions allow. Although less important here, the
geoxylic suffrutex growth form (so typical of CB 2 Maputaland
Wooded Grassland), is also represented in this sourveld.
Geology & Soils This unit is strictly delimited by its geology—it
is built of hard, white, coarse-grained, siliceous quartz arenites
(sandstones) of the Msikaba Formation of the Devonian Period
(Thomas et al. 1992) giving rise to shallow, nutrient-poor (highly
leached), skeletal, acidic sandy soils. Almost 80% of the area is
classified as Fa land type, followed by Aa land type (10%).
Important
Ta x a
Graminoids:
Alloteropsis semialata subsp. eckloniana
(d), Aristida junciformis subsp. galpinii (d),
Cymbopogon nardus (d), Themeda triandra (d), Tristachya leucothrix (d), Cyperus
rupestris, Diheteropogon amplectens,
Elionurus muticus, Eragrostis capensis, E.
plana, Eulalia villosa, Heteropogon contortus, Panicum natalense, Trachypogon
spicatus. Herbs: Chaetacanthus burchellii
(d), Cyanotis speciosa (d), Helichrysum
allioides (d), H. appendiculatum (d), H.
krebsianum (d), H. spiralepis (d), Pentanisia
angustifolia (d), Rhynchosia totta (d),
Tephrosia macropoda (d), Berkheya
speciosa subsp. speciosa, Cephalaria
oblongifolia, Chamaecrista mimosoides,
Eriosema salignum, Euphorbia ericoides, Helichrysum adenocarpum
Biogeographically Important Taxa ( CCoastal belt element, EEastern isolated occurrence, FGeneric fynbos element, NNorthern distribution limit, SSouthern distribution
limit) Geoxylic Suffutex: Gymnosporia vanwykiiC. Graminoids:
Loudetia simplexS (d), Calopsis paniculataF, Tetraria robustaEF.
Herbs: Helichrysum auricepsS, H. natalitiumS, H. pannosumS,
Senecio dregeanusS, S. rhyncholaenusS, Berkheya insignisS,
Eriosema acuminatumC, Helichrysum acutatumS, H. longifoliumC, Peucedanum natalenseC, Roella glomerataF,C. Geophytic
Herbs: Stenoglottis woodiiS, Asclepias patensC, Disperis woodiiC, Kniphofia rooperiC. Low Shrubs: Senecio medley-woodiiS,
Gnidia woodiiS (d), Agathosma ovataF, Erica aspalathifoliaC,
Gnidia coriaceaN, Muraltia lancifoliaF, Pseudarthria hookeri F,S,
Relhania pungensF, Stangeria eriopusC, Syncolostemon rotundifoliusC. Geoxylic Suffutex: Eriosemopsis subanisophyllaS. Small
Trees & Tall Shrubs: Faurea salignaS (d), Protea roupelliae subsp.
roupelliaeF (d), Encephalartos cafferN, Loxostylis alataF, Polygala
gazensis (isolated populations; also Inyanga), Protea caffra
subsp. caffraF, P. simplexF, Sclerocroton integerrimumS.
Endemic Taxa (FGeneric fynbos element) Graminoid: Fimbristylis
variegata. Herbs: Eriosema umtamvunense, Geranium sparsiflorum, Lotononis bachmanniana, Selago peduncularis, Senecio
erubescens var. incisus, Geophytic Herbs: Brachystelma australe, B. kerzneri, Watsonia inclinataF, W. mtamvunaeF. Geoxylic
Suffrutex: Rhus acocksii. Low Shrubs: Leucadendron spissifolium subsp. natalenseF (d), L. spissifolium subsp. oribinumF (d),
Acalypha sp. nov. (Scott-Shaw 636 NU), Anthospermum streyi,
Erica abbottii, E. cubica var. natalensisF, Eriosema dregei, E. latifolium, E. luteopetalum, Euryops leiocarpus, Gnidia triplinervis,
Leucadendron pondoenseF, Leucospermum innovansF, Raspalia
trigynaF, Struthiola pondoensisF, Syncolostemon ramulosus,
Tephrosia bachmannii. Tall Shrub: Tephrosia pondoensis.
L. Mucina
Climate Summer rainfall with some rain in winter. No or very
infrequent incidence of frost. Mean maximum and minimum
monthly temperatures at Paddock (near Oribi Gorge in the
north) are 32.2°C and 5.8°C (for January and July, respectively).
The corresponding values for Cape Hermes Lighthouse (Port
St Johns, in the south) are 29.5°C and
9.6°C for the same months. See also
climate diagram for CB 4 PondolandUgu Sandstone Coastal Sourveld (Figure
11.2).
subsp. adenocarpum, H. aureum var. monocephalum, H. herbaceum, H. nudifolium var. pilosellum, H. pallidum, Indigofera
hilaris, Pentanisia prunelloides subsp. latifolia, Pimpinella caffra, Vernonia capensis. Geophytic Herbs: Brachystelma tenellum, Eriospermum mackenii. Low Shrubs: Athrixia phylicoides,
E. natalensis, E. natalitia, Gnidia anthylloides, G. kraussiana,
G. nodiflora, Leonotis intermedia, Polygala hottentotta. Small
Trees & Tall Shrubs: Euryops brevipapposus, Syzygium cordatum.
Semiparasitic Shrubs: Thesium acutissimum, T. cupressoides.
Figure 11.6 CB 4 Pondoland-Ugu Sandstone Coastal Sourveld: Pondoland sourveld on the
edge of the Umtamvuna Gorge (near Port Edward, KwaZulu-Natal) with scattered trees of
Protea roupelliae subsp. roupelliae. The dominant grasses are Aristida junciformis and
Loudetia simplex.
Indian Ocean Coastal Belt
579
S %
19 (2006)
Conservation Vulnerable (one of the
top six vegetation units with the highest level of overall vulnerability in South
Africa). Target 25%. Only about 7%
statutorily conserved in the Mkambati
Wildlife Reserve & Marine Sanctuary, and
Umtamvuna, Mbumbazi and Oribi Gorge
Nature Reserves. About 29% transformed for cultivation and plantations or
by urban sprawl. In the Eastern Cape the
land use is mostly subsistence farming.
Erosion is very low and low.
L. Mucina
Remark 1 The sandstone geology
links Pondoland to other ‘sourvelds’
of South Africa. Pondoland forms the
lowest step along a staircase of nutrient-poor geologies, comprising further
the early Palaeozoic Natal Sandstones
of the KwaZulu-Natal Midlands and the
Late Triassic Clarens Sandstones of the
Drakensberg (see also Van Wyk 1994).
The occurrence of Protea roupelliae, P. Figure 11.7 CB 5 Transkei Coastal Belt: Coastal grasslands and subtropical dune thickets near
simplex, P. welwitschii, Erica natalitia, Umgazi River Mouth on the Transkei Coast (Eastern Cape Province).
Helichrysum herbaceum, H. krebsianum,
H. pannosum, Senecio rhyncholaenus and Schizoglossum atro- slopes of low-reach river valleys and coastal ridges, sometimes
broad enough to form small plains. A mosaic of grassland vegpurpureum subsp. virens is indicative of this link. Pondoland
etation on the higher lying areas and characteristically on hill
is a crossroads of old migration routes and perhaps also a
tops and upper hill slopes, alternating with bush clumps and
migration cul-de-sac (Van Wyk 1990a) of some of them. It
shows not only a clear Drakensberg link, but also clear bio- small forests (considered as part of the vegetation unit FOz 5
Scarp Forest) is the major vegetation feature of the region. Most
geographical (and geological) relationships to the Capensis
through the occurrence of genera such as Agathosma, Aristea, of the grasslands are undoubtedly secondary (result of forest
Athrixia, Calopsis, Cliffortia, Erica, Euryops, Leucadendron, clearing for cattle grazing). At the seaward border this vegetaLeucospermum, Loxostylis, Muraltia, Phylica, Podalyria, tion mosaic is fringed by an interrupted belt of coastal dune
Prionium, Protea, Pseudoscolopia, Raspalia (the only repre- thicket (considered as part of AZs 3 Subtropical Dune Thicket)
sentative of the family Bruniaceae outside Capensis), Restio, and vegetation of young coastal habitats (dunes and beaches).
Relhania, Roella, Struthiola, Tetraria and Watsonia. Some of
Geology & Soils Most of the area is built of Karoo Supergroup
these disjunctions occur at the species level (!): Calopsis panicusediments including sandstone and mudstone of the Adelaide
lata, Cliffortia odorata, Helichrysum diffusum, Loxostylis alata,
Subgroup, shale, mudstone and sandstone of the Ecca Group
Prionium serratum, Pseudoscolopia polyantha and Restio tritas well as tillite of the Dwyka group. Intrusions of Jurassic Karoo
iceus (Midgley 1986, Carbutt & Edward 2001).
Dolerite Suite occur in places. The dominating soil forms are
Glenrosa and Mispah. Fa land type dominates the area.
Remark 2 Slight depressions on the coastal plateau and rock
pools on rocky outcrops support another suite of local endemClimate Summer rainfall with some rain in winter (with up to
ics or biogeographically important taxa linked to hygromor36.6% rainfall in winter at Bashee Lighthouse). No incidence of
phic soils. These include Kniphofia rooperi, Podalyria velutina,
frost. Bashee Lighthouse recording a mean minimum temperaPsoralea abbottii, Utricularia sandersonii, Watsonia bachmannii
ture of 7.7°C in July. See also climate diagram for CB 5 Transkei
and W. pondoensis.
Coastal Belt (Figure 11.2).
References Moll & White (1978), Midgley (1986), Shackleton (1989, 1992),
Shackleton (1990), Van Wyk (1990a, b), Shackleton et al. (1991), Abbott
(1993), Shackleton & Shackleton (1994), Le Roux (1995), Glen (1996), Camp
(1999a, b), Scott-Shaw (1999), Abbott et al. (2000), Carbutt & Edwards
(2001), Van Wyk & Smith (2001).
CB 5 Transkei Coastal Belt
VT 1 Coastal Forest and Thornveld (84%) (Acocks 1953). LR 48 Coastal
Grassland (37%), LR 23 Coastal Bushveld–Grassland (21%) (Low & Rebelo
1996).
Distribution Eastern Cape Province: Narrow coastal strip along
the Wild Coast of Transkei and the Indian Ocean seaboards
between Port St Johns (Egossa Interval) as far as the vicinity of
the Great Kei River in the south. Altitude ranges from about
20–450 m.
Vegetation & Landscape Features The Transkei Coastal Belt
is highly dissected, hilly coastal country with alternating steep
580
Indian Ocean Coastal Belt
Important Taxa Graminoids: Aristida junciformis subsp. galpinii (d), Stenotaphrum secundatum (d), Abildgaardia ovata,
Cynodon dactylon, Dactyloctenium aegyptium, Ehrharta erecta
var. erecta, Setaria plicatilis, S. sphacelata, Sporobolus africanus.
Herb: Ipomoea cairica. Geophytic Herb: Bonatea speciosa var.
antennifera. Low Shrubs: Anisodontea scabrosa, Passerina rigida.
Succulent Herb: Crassula multicava subsp. multicava. Small Trees
& Tall Shrubs: Acacia natalitia, Cestrum laevigatum, Grewia occidentalis var. occidentalis. Succulent Tree: Aloe ferox.
Biogeographically Important Taxa (all coastal belt elements)
Herb: Stachys comosa. Geophytic Herbs: Asclepias patens,
Strelitzia reginae. Geoxylic Suffrutex: Gymnosporia vanwykii.
Low Shrub: Pavetta revoluta.
Conservation Vulnerable. Target 25%. Only about 1% statutorily conserved, for example in Dwesa-Cwebe Wildlife Reserve
& Marine Sanctuary, Silaka Wildlife Reserve and Hluleka Wildlife
Reserve & Marine Sanctuary. About 20% transformed mainly
for cultivation. Erosion is low and moderate.
S %
19 (2006)
Remarks The nonforest vegetation of the Transkei Coastal Belt is
one of the most poorly studied vegetation types in the country.
References Acocks (1953, 1988), Moll & White (1978), Hoffman (1983).
9.
Credits
The delimitation of the IOCB is based on K.G.T. Camp’s map of
Bioresource Groups for KwaZulu-Natal (Camp 1999a) within
the borders of KwaZulu-Natal and on analysis based on interpretation of satellite-image data by D.B. Hoare in the Eastern
Cape Province. The borders between CB 1 and CB 3 follow,
to a great extent, the Camp’s (1999a) map, but have been
modified by C.R. Scott-Shaw and L. Mucina. The concept of
CB 2 was jointly defined by W.S. Matthews, C.R. Scott-Shaw
and L. Mucina, partly using the sources by Smith (2001) and
Felton (2002). The concept of CB 3 resulted from fusion, as
suggested by L. Mucina, and C.R. Scott-Shaw, of several units
defined by Camp (1999a). The extent of CB 1 and CB 2 was
partly defined also by mapping of the wetlands in Maputaland
by M.C. Rutherford and L.W. Powrie. The extent of all IOCB
vegetation units was also modified by the extent of the forest
patches (see Chapter 12 for Credits).
The descriptions of CB 1 to CB 4 were a joint effort by L. Mucina
and C.R. Scott Shaw; W.S. Matthews contributed to descriptions of CB 1 and CB 2; L. Mucina wrote the description of CB
5. The species lists were created by L. Mucina, C.R. Scott-Shaw
and W.S. Matthews (the last-named for the Maputaland units).
The introductory text was written by L. Mucina (sections 1 to
3), while C.R. Scott-Shaw contributed sections 4 to 7 of the
introductory text. M.C. Rutherford contributed to sections 1
and 2 of the introductory text as well as to the climate and
conservation sections of the vegetation unit descriptions. Table
11.1 was created jointly by L. Mucina, M.C. Rutherford and
L.W. Powrie. The last-mentioned two authors also provided all
climate diagrams. L. Mucina (with help of C.R. Scott-Shaw) collated the list of references. The photographs were contributed
by W.S. Matthews and L. Mucina. M. Rouget, and others within
the Directorate of Biodiversity Programmes, Policy & Planning
of SANBI, provided quantitative information for each vegetation unit on conservation status and targets, areas currently
conserved and areas transformed.
Ezemvelo KZN Wildlife kindly provided data on the extent of CB
2 as well as forest patches imbedded within the IOCB (Ezemvelo
KZN Wildlife 2004. Metadatabase file: KwaZulu-Natal Forest
Types, Dataset ID 550. Ezemvelo KZN Wildlife Scientific Services
Branch, Pietermaritzburg). The wetlands were mapped using
selected data from the National Land Cover 2000 project as
well as digitising by L.W. Powrie from topographic maps of a
number of wetlands in the Maputaland region. P.S. Goodman
contributed valuable comments and C. Oellerman assisted
C.R. Scott-Shaw with GIS work. R.A. Ward kindly corrected the
geological terminology.
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Indian Ocean Coastal Belt
583
‘Die dag as die Bos tot niet is, is julle soos miere waarvan die nes uitmekaargeskop is. Al verskil
is dat miere weer kan nes maak, maar julle kan nie weer die Bos maak nie. Het jy al gaan sit en
uitreken hoeveel byle in hierdie bos kap? Hoeveel hande aan die grootword is om nóg te kap?’
from D. Matthee, 1984. Kringe in ’n bos. Tafelberg, Cape Town. p. 140
S %
19 (2006)
Afrotemperate, Subtropical
and Azonal Forests
12
Ladislav Mucina and Coert J. Geldenhuys
with contributions by
Michael C. Rutherford, Leslie W. Powrie, Mervyn C. Lötter,
Graham P. von Maltitz, Doug I.W. Euston-Brown, Wayne S.
Matthews, Linda Dobson and Bruce McKenzie
Table of Contents
1 Introduction
2 Current Biogeographic Patterns
3 Diversity Patterns
4 Palaeo-ecological Patterns: Role of Climate and Fire
5 Ecology
5.1 Climate
5.2 Geology and Soils
6 Forest Dynamics
6.1 Gap Dynamics
6.2 Litter Fall and Nutrient Cycling
6.3 Dispersal Syndromes and Animal-plant Interactions
7
8
9
10
11
12
13
Status of Indigenous Forests of South Africa
Threats to Indigenous Forests of South Africa
Action: Conservation and Utilisation
Further Research
Descriptions of Vegetation Units
Credits
References
586
588
589
589
592
592
593
593
593
594
594
594
595
596
597
597
609
610
List of Vegetation Units
Zonal & Intrazonal Units
FOz 1 Southern Afrotemperate Forest
FOz 2 Northern Afrotemperate Forest
FOz 3 Southern Mistbelt Forest
FOz 4 Northern Mistbelt Forest
FOz 5 Scarp Forest
FOz 6 Southern Coastal Forest
FOz 7 Northern Coastal Forest
FOz 8 Sand Forest
FOz 9 Ironwood Dry Forest
597
597
599
600
601
602
603
604
605
606
Azonal Units
FOa 1 Lowveld Riverine Forest
FOa 2 Swamp Forest
FOa 3 Mangrove Forest
607
607
607
608
L. Mucina
Figure 12.1 Typical moist form of indigenous warm-temperate forest (FOz 1 Southern Afrotemperate Forest) with tree fern Cyathea capensis (Diepwalle, Knysna, Western Cape).
585
S %
1.
Introduction
Indigenous forest in South Africa is defined as ‘a generally multilayered vegetation unit dominated by trees (largely evergreen
or semi-deciduous), whose combined strata have overlapping
crowns (i.e. the crown cover is 75% or more), and where
graminoids in the herbaceous stratum (if present) are generally
rare’ (Bailey et al. 1999, Shackleton et al. 1999). Stand height
ranges from high forest over 30 m to scrub forest with a height
of just over 3 m. All indigenous forest of southern Africa is evergreen. Besides the obviously distinctive structure, the forests
differ from the surrounding vegetation (fynbos, succulent
thicket, grassland, savanna) by a large specific set of flora.
Forests occur scattered along the eastern and southern margins (Great Escarpment, mountain ranges and coastal lowlands)
of South Africa, from the Soutpansberg in the north (inland,
22° 40’ S) and Maputaland in the east (coast, 27° S) to the
Cape Peninsula in the west (34° S) (Figures 12.2 and 12.3).
Typically they occur as a series of scattered small to very small
patches (<10 ha), and most forests are smaller than 100 ha in
size (Cooper 1985, Geldenhuys 1991, Midgley et al. 1997). In
Mpumalanga the average forest patch size is 29 ha (Lötter et
al. 2002). Most of the forest realm is an archipelago of forest
islands imbedded within large-scale patches of biomes such as
Fynbos, Albany Thicket, Grassland and Savanna. Today these
patches form scarce, but typical elements of the Subtropical
Coastal Forest Biome along the subtropical seaboards of the
Indian Ocean. Only few larger forest complexes can be recog-
FOz 1
FOz 2
FOz 3
FOz 4
FOz 5
FOz 6
FOz 7
FOz 8
FOz 9
FOa 1
FOa 2
FOa 3
nised in South Africa, and these are widely separated. The largest single forest (25 706 ha) is found in the surrounds of Knysna
in the south; it forms part of a still larger complex of 60 560 ha
at about 34° S, spanning 22° to 24° 30’ E (Geldenhuys 1991).
The Amathole forest complex (Eastern Cape) covers 40 550 ha
between latitudes 32° S and 33° S, and longitudes 26° E and
27° 30’ E (Thompson 1991). In the Pirie-Isidenge-Kubusie area
there is a single patch larger than 8 000 ha (Phillipson 1987). In
KwaZulu-Natal the Dukuduku Forest is the largest one (3 500 ha)
(Cooper 1985). The Woodbush-De Hoek Forest (6 626 ha) is the
largest forest patch along the Northern Escarpment (Scheepers
1978, Cooper 1985). Smaller and isolated, still significant forests occur in the regions between the larger forest complexes
around Knysna, in the Amathole Mountains, in KwaZulu-Natal
(both coastal and montane forests), and along the Northern
Escarpment in Mpumalanga and Limpopo Provinces (Cooper
1985, Anonymous 1987, Von Breitenbach 1990, Geldenhuys
1991, Cooper & Swart 1992, Everard & Hardy 1993, Geldenhuys
& Venter 2002).
The recent floristic-biogeographic classification of the indigenous forests of South Africa (Von Maltitz et al. 2003; further developed by L. Mucina, unpublished data) recognises
26 Forest Types grouped into 8 zonal groups and 1 azonal
group. Table 12.1 features the correspondence between this
detailed classification scheme and the system of vegetation
units adopted here (see below). The vegetation units (as well as
underlying Forest Types) were derived on the basis of real quadrate data, whereby the floristic composition, biogeographic
relationship as well as climate, substrate and water dynamics
Southern Afrotemperate Forest
Northern Afrotemperate Forest
Southern Mistbelt Forest
Northern Mistbelt Forest
Scarp Forest
Southern Coastal Forest
Northern Coastal Forest
Sand Forest
Ironwood Dry Forest
Lowveld Riverine Forest
Swamp Forest
Mangrove Forest
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586
Afrotemperate, Subtropical and Azonal Forests
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19 (2006)
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19 (2006)
Table 12.1 Crosswalk between the vegetation units adopted in this study and the National Forest Type Classification (modified
after Von Maltitz et al. 2003; *not in the latter source). Zonality, intrazonality and azonality status is given for each forest type.
The notion ‘Savanna/Grassland’ indicates that the particular forest type straddles the ecotone of both biomes.
Vegetation Units
FOz 1 Southern Afrotemperate Forest
FOz 2 Northern Afrotemperate Forest
FOz 3 Southern Mistbelt Forest
FOz 4 Northern Mistbelt Forest
FOz 5 Scarp Forest
FOz 6 Southern Coastal Forest
FOz 7 Northern Coastal Forest
FOz 8 Sand Forest
FOz 9 Ironwood Dry Forest
FOa 1 Lowveld Riverine Forest
FOa 2 Swamp Forest
FOa 3 Mangrove Forest
National Forest Classification
I
I1
I2
I3
II
II1
II2
II3
II4
III
III1
III2
III3
IV
IV1
IV2
V
V1
V2
V3
VI
VI1
VI2
VI3
VII
VII1
VII2
VIII
VIII1
VIII2
VIII3
A1
A2
A3
Southern Afrotemperate Forest Group
Western Cape Talus Forest
Western Cape Afrotemperate Forest
Southern Cape Afrotemperate Forest
Northern Afrotemperate Forest Group
Marekele Afromontane Forest
Northern Highveld Forest
Drakensberg Montane Forest
Low Escarpment Mistbelt Forest
Southern Mistbelt Forest Group
Eastern Mistbelt Forest
Transkei Mistbelt Forest
Amathole Mistbelt Forest
Northern Mistbelt Forest Group
Northern Mistbelt Forest
Mpumalanga Mistbelt Forest
Scarp Forest Group
Eastern Scarp Forest
Pondoland Scarp Forest
Transkei Coastal Scarp Forest
Northern Coastal Forest Group
Eastern Cape Dune Forest
Albany Coastal Forest
Western Cape Milkwood Forest
Southern Coastal Forest Group
KwaZulu-Natal Coastal Forest
KwaZulu-Natal Dune Forest
Tropical Dry Forest Group*
Licuati Sand Forest
Nwambyia Sand Forest*
Ironwood Dry Forest*
Lowveld Riverine Forest
Swamp Forest
Mangrove Forest
were taken into consideration. Details on the procedures of the
classification of the indigenous forests into Forest Types, which
led to the conceptualisation of the vegetation units in this study,
are given by Mucina & Geldenhuys (2002).
Owing to the fragmented distribution of forests, the concept
of zonality (as defined by Walter 1976) can be applied to forests only to a limited extent. The notion of a ‘zone’ relates (by
definition) to biome (see Mucina 2000 for a definition). In the
past the indigenous forests of South Africa were classified
broadly into either two biomes, such as Afromontane forests
and Coastal Belt forests (e.g. Huntley 1984) or just as a single
biome (Forest Biome) as in Rutherford & Westfall (1986) and
later in Low & Rebelo (1996). The latter notion was apparently
motivated by purely structural rather than climatic-structural or
floristic-biogeographic criteria.
In the case of the afromontane (White 1978) or more appropriately ‘afrotemperate’ (see Meadows & Linder 1989, 1993)
forests, only one Forest Type would qualify as a part of a
biome in its own right. It is the Forest Type I3: Southern Cape
Afrotemperate Forests, which comprises the only forest area
(the Knysna-Tsitsikamma Forest complex) of a biome dimension (Rutherford & Westfall 1986). Here these forests descend
to sea level at 34º S latitude, providing a mirror image to the
Biome
Zonality
Fynbos
Fynbos
Afrotemperate Forest Biome
intrazonal
intrazonal
zonal
Savanna/Grassland
Savanna/Grassland
Grassland
Grassland
intrazonal
intrazonal
intrazonal
intrazonal
Grassland
Grassland
Grassland
intrazonal
intrazonal
intrazonal
Savanna/Grassland
Savanna/Grassland
intrazonal
intrazonal
Savanna
Indian Ocean Coastal Belt
Indian Ocean Coastal Belt
intrazonal
zonal
zonal
Albany Thicket Biome
Albany Thicket Biome
Fynbos
intrazonal
intrazonal
intrazonal
Indian Ocean Coastal Belt
Indian Ocean Coastal Belt
zonal
zonal
Savanna
Savanna
Savanna
Savanna
Indian Ocean Coastal Belt
Indian Ocean Coastal Belt
intrazonal
intrazonal
intrazonal
azonal
azonal
azonal
distribution pattern of warm-temperate forests of the northern
hemisphere (Klötzli 1988) to such forests in Eastern Asia (e.g.
Ohsawa 1993) and southwestern United States (Christensen
1988, Fujiwara & Box 1994, Haeupler 1994). The rest of the
afrotemperate ‘forest archipelago’ in southern Africa should
be seen as ‘wreckage’ of a warm-temperate biome occupying
a narrow but probably formerly continuous belt along the steps
of the Escarpment. These forests are imbedded (surrounded)
by various temperate biomes such as Fynbos and Grassland or
straddle ecotones between the Grassland and Savanna Biomes.
The evolutionary young Coastal Subtropical Forest Biome,
known also as Indian Ocean Coastal Belt (Bews 1920, Moll &
White 1978 and Huntley 1984) was probably dominated by a
subtropical forest, of which only fragments classified as Forest
Type VII1 KwaZulu-Natal Coastal Forests and VII2 KwaZulu-Natal
Dune Forests remain. The other forest types rich in subtropical
elements (the remainder of the Forest Group VI; Von Maltitz
et al. 2003) are intrazonal—hence forming specific vegetation
units embedded within (and unique to) well-defined vegetation zones (Table 12.1). Within South Africa the azonal Swamp
Forests and Mangrove Forests (both of pronouncedly tropical
character and distribution) are limited to the zone of the Indian
Ocean Coastal Belt.
Afrotemperate, Subtropical and Azonal Forests
587
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19 (2006)
Forest
Figure 12.3 Distribution of the mapped vegetation units of the indigenous forests in KwaZulu-Natal.
The marginal (albeit very interesting owing to high concentration of tropical elements and endemic species) group of dry
forests (represented by two vegetation units: Sand Forest and
Ironwood Dry Forest) occur imbedded within seasonally dry
and hot types of Lowveld (Maputaland and northern Kruger
National Park).
There are three clearly hydrologic-edaphic azonal forest types
typical of habitats controlled by specific hydrological regimes:
LowveldRiverine Forest (gallery forest that fringes rivers in
subtropical regions of South Africa and neighbouring
countries).
Swamp Forest (forest showing evolutionary and ecological
links to tropical swamp forests of central Africa).
Mangrove Forest (specific intertidal forests of subtropical
and tropical coasts, reaching the southernmost distribution
along the Indian Ocean coast of South Africa).
At least 7% of the country is a potential habitat owing to
the favourable combination of climate and substrate suitable
for forest growth. Still, forests cover just more than 3 000
km2 or 0.1% of the land surface of South Africa (Huntley
1984, Cooper 1985, Rutherford & Westfall 1986, Anonymous
1987, Geldenhuys 2000a). This estimate varies depending on
the criteria (minimum forest size mapped of 50 ha, 30 ha or
1 ha) and mapping method (use of satellite imagery or aerial
photographs).
588
Afrotemperate, Subtropical and Azonal Forests
2.
Current Biogeographic Patterns
In very general terms, the zonal forests in South Africa show
floristic and palaeo-biogeographic links to two main African forest zones (Chapman & White 1970, White 1983, Timberlake &
Shaw 1994), namely the afrotemperate forests and the coastal
forests. The former is part of the Afromontane Region which
also occurs outside South Africa further north in Zimbabwe,
Malawi and along the East African mountain ranges, reaching
as far north as Ethiopia and westwards to Cameroon and northern Angola. The coastal forests form part of the TongalandPondoland Regional Mosaic with some forest elements shared
with the adjacent Zanzibar-Inhambane Regional Mosaic
(sensu White 1983). The former region has also recently been
recognised as a Centre of Endemism (Van Wyk & Smith 2001),
although one should reconsider joining Maputaland and
Pondoland into one Centre because of the different geological
and evolutionary ages of the two regions and their floras.
Taxa shared between forests show at least three patterns
(Geldenhuys 1992a). Firstly, forest patches share many more
of their species with neighbouring forest patches to their north
and east than with those occurring to their south and west. This
indicates the erosion of species diversity from the two tropical source areas—both mountains and coastal regions of East
Africa—towards the South African distribution area of afrotemperate as well as subtropical forests (McKenzie 1978, Tinley
1985, Cawe 1986, Geldenhuys 1992b). For example, 206 of
the 470 species found in the southern Cape forests (consider-
S %
19 (2006)
ing all growth forms) reach their geographical distribution limit
here (Geldenhuys 1992b). Of these, 158 species reached their
western limit and only 23 species reached their eastern limit in
the area of the southern Cape forests. Secondly, forests share
many more species with their nearest neighbouring forests
than with forests further away. Thirdly, the afrotemperate forests (including those occurring in mountains close to the coast
in the southwest of the country) share relatively fewer species
with the forests of the subtropical coastal areas (Geldenhuys
1992a). Canopy trees and ferns have the lowest proportions of
unique species, whereas these proportions are >40% for the
shrubs, geophytes and forbs.
Reconstruction of the relic temperate flora of the small, isolated
forests of the inland mountains of the southern Cape showed
the changes in species composition that may have happened as
a result of forest contraction and expansion due to landscape
and climatic changes (Geldenhuys 1997a). The less isolated
forests had been enriched from the large forest complex on
the coast along specific migration routes and during specific
waves of forest expansion. The distribution ranges of taxa of
the southern Cape forests were used to establish generalised
tracks of the flora in order to test hypotheses about the speciation and development of the forest floras (Geldenhuys 1994a).
The results indicated that the ecological characteristics of species of each geographical species group reflected the environmental conditions and disturbance regimes that prevailed in
each source area. The southern Cape forest flora was therefore
considered to be composed of the following elements:
Species adapted to a narrow, cool, humid afromontane
area.
Species of a transition zone between the montane zone
and the humid, warm, subtropical coastal areas.
Species adapted to more frequent and extreme droughts
and drier conditions of the lowlands between the coast
and mountains.
Species adapted to the southern temperate cool, moist
mountain areas.
Species adapted to frequent grassland and shrubland fires
on the forest margin.
Local endemic species.
The present patterns of composition of the different forests
(within either afrotemperate or coastal regions) suggest that
their high degree of similarity may have been established before
major fragmentation of the forests since the late Miocene—the
time period which experienced increasing aridity (Geldenhuys
1992a). During this period of fragmentation, forests and forest
biota survived in areas now considered as dispersal corridors.
The number of dispersal corridors (mountain chains, escarpments, river valleys, coastal dune systems) meeting in a particular forest is probably one of the strongest variables determining the number of woody plants in a forest (Geldenhuys
1992a, 1997a).
3.
Diversity Patterns
Geldenhuys (1992a) listed 1 438 plant species that had been
recorded for 14 forests or forest complexes representing the
geographical range of the mixed evergreen forests in South
Africa. These included 155 families and 661 genera. The forests
covered only 0.08% of the area and 7.1% of the vascular species, but had a relatively rich 0.58 species per km2. Gibbs Russell
(1987) indicated a ratio of 0.0079 plant species per km2 overall
for southern Africa, with 20 227 indigenous vascular taxa. Only
fynbos exceeded the forest value with 1.36 species per km2 (7
316 species). The third richest biome was grassland with 0.25
species per km2 (3 788 species).
Plant species richness remains relatively constant along the tropical-temperate gradient of southern Africa, except for the southwestern extreme (Geldenhuys & MacDevette 1989, Geldenhuys
1992a). KwaZulu-Natal Coastal Forests and Pondoland Scarp
Forests with a large proportion of endemic plants (Van Wyk &
Smith 2001) have the highest number of woody species (254
and 338 species respectively). The Western Cape Afrotemperate
Forests (from the Cape Peninsula to Swellendam) and the
Drakensberg Montane Forests have the lowest number (48 and
78 species respectively). The number of both woody and herbaceous species of isolated forests and forest complexes increases
with area of the forest (Geldenhuys 1992a). However, woody
species richness is more strongly correlated with the proximity
to other forests and the number of available dispersal corridors
(mountain range, escarpment, river, coastal dune system).
The ratio of woody to herbaceous plant species varies greatly
between individual forests (Geldenhuys 1992a). In general,
coastal forests have a ratio in excess of 60%, whereas in montane forests the ratio varies between 39% and 53%.
Species richness varies more within a forest than between forests (Geldenhuys & MacDevette 1989). Montane forests, in general, have fewer species than lowland, coastal and dune forests,
both in KwaZulu-Natal and the southern Cape. Furthermore,
drier (or warmer?) forests are richer in species than wetter (or
cooler?) forests. The different growth forms also show clear
patterns amongst the different forest types. Species turnover
of woody plants from montane to lowland forests increases
more sharply than for herbaceous plants. Fern species richness
experiences decline, and richness of vines, graminoids, geophytes and forbs increases from the montane to the coastal
forests. The species richness of epiphytes is the highest in less
disturbed and mature forests, especially in the mistbelt and subtropical forests.
4.
Palaeo-ecological Patterns: Role of
Climate and Fire
The remarkable variability of extant forests in southern Africa
and their generally patchy (archipelago-like) dispersal over landscapes of several biomes are indicative of their relictual character. We discuss the role of two major probable agents that
shaped the current and past forest patterns—climate and fire.
Geldenhuys (1994b) suggested that not only environmental
factors (rainfall and substrate) determine the potential limits
of forest distribution but that actual pattern of forests and
their boundary shapes are to a large extent (particularly in hilly
and mountainous areas) determined by the fire pattern. This
pattern, in turn, is determined by the interaction between the
prevailing winds during dry periods and terrain physiography.
Gusty, hot, desiccating northwesterly föhn-like berg winds are
common during autumn and winter (Tyson 1964, 1986). Berg
wind direction is locally changed by barriers, such as the mountain ridges to the windward (northern) side of the forests. The
wind direction is channelled through valleys running from the
mountains, and its flow direction is determined by the position and form of the barriers (see Figure 12.4). Lightning and
human-induced fires (Deacon et al. 1983) are exacerbated by
the berg winds. The fires burn with higher frequency in zones in
the landscape where forest is absent (fire pathway), fragmenting the forests along the fire pathways. Forest persists in the
Afrotemperate, Subtropical and Azonal Forests
589
S %
topographic or wind shadow areas (also
called fire refugia).
a. Typical forest location pattern on the Tsitsikamma coastal platform
Main West-East
Tsitsikamma Mountain Range
North-South Ridge
N
Coastal East-West Ridge
Coastal Platform
River
The borders between forests and surrounding fire-prone ecosystems (FPE;
sensu Bond et al. 2003b), including
Fynbos, Grassland and Savanna, are characteristically sharp. Geldenhuys’ (1994b)
hypothesis addresses this phenomenon
convincingly in regions of frequent berg
winds and under current climatic conditions (Figure 12.4 and 12.5). Persistence
of the large number of forest patches
scattered over vast areas of southern
Africa and the existence of sharp forest
limits outside the regions of berg-wind
influence demand additional, alternative
explanations. Increased inflamability due
to long-lasting (unusual) droughts and
unnatural high-frequency of man-made
fires in coastal grasslands may alter forest limits (Figure 12.6). Sharp change in
substrate properties, such as observed
on the border between boulder screes
on steep slopes in deep kloofs (supporting afrotemperate forest) and the surrounding fire-driven fynbos (Figure 12.7),
may be seen as another important factor for survival of forest patches in a FPE
landscape.
19 (2006)
Bergwind-driven fire
Indian Ocean Coastline
b. Landscape profiles with
remnant forest
c. Forest in upper
catchment or valley
No Forest
C. J. Geldenhuys
Fire does not normally play a role in
Figure 12.4 Schematic view of hypothetical airflow across and around topographic barriers to
ecosystem dynamics of forest patches,
show the persistence of forest in wind-shadow areas in relation to wind-driven fires (adapted from
except at the fringes (Bailey et al. 1999).
Geldenhuys 1994a; courtesy of Blackwell Science Publishing).
However, Geldenhuys (1993e) collected
charcoal from the litter and feeding root
zone of many seemingly mature forest stands throughout the
of and response of forests and species to fire inside forests, we
southern Cape. The charcoal resulted from fires caused by light- refer to papers by Edwards (1984), Granger (1984), Pammenter
et al. (1985), Lübbe (1990a) and Geldenhuys et al. (2002).
ning (Geldenhuys et al. 1994), spotting during berg winds or
by honey collectors. In principle, the South African forests (in
particular the afrotemperate ones) as we know them today are
From a palaeo-ecological perspective, fire must have played a
non-flamable by nature. A study by Van Wilgen et al. (1990)
major role in shaping the extent of forests in our region since
has shown that the reasons for fire-resistance of forests can
the formation of the fire-prone ecosystems (late Miocenealso be found in vegetation structure (spatial compartmenting
Pliocene; see chapters on Grassland and Savanna in this book).
of fuel) and physico-chemical properties of the fuel with high
Subtropical and warm-temperate evergreen forests covered the
moisture and low fat content in the leaves. For various causes
largest part of Africa until the Great Escarpment was formed and
separated the moist coastal belt from the
arid interior (Deacon 1983, Deacon et al.
1983). Increasing aridity (combined with
prolonged dry seasons) developed, and
increased fire frequency contributed to
the expansion of fire-adapted woodlands,
shrublands and grasslands. The relictual
nature of the forests within the grasslands and woodlands has been attributed to the destructive activities of man
during the relatively recent past, i.e. over
the last 100 to 300 years (e.g. Acocks
1953, White 1983). However, as argued
by Deacon et al. (1983) and Meadows &
Linder (1989, 1993), patterns of forest
distribution were to a far greater extent
determined by climatic (see Eeley et al.
1999) and landscape changes.
Figure 12.5 Patches of Drakensberg montane forests (FOz 2 Northern Afrotemperate Forest) in
fire-protected kloofs in the Cathedral Peak area (uKhahlamba-Drakensberg Park, KwaZulu-Natal).
The fire-exposed ridges are devoid of forest (see also Figure 12.4).
590
Afrotemperate, Subtropical and Azonal Forests
Scholtz (1986) demonstrated from palynological and charcoal studies that large
climatic changes occurred in the south-
S %
19 (2006)
lend this idea strong support. Rebelo
et al. (see Chapter on Fynbos in this
book: FFg 3 Peninsula Granite Fynbos)
argue that changes in fire-management
allowed forest to take over much of the
area formerly covered with granite fynbos over a short period of only several
decades. In the Soutpansberg, and along
the Northern Escarpment, the exclusion
of fire changed some grasslands to forests through woodlands serving as an
intermediary step (Geldenhuys & Venter
2002).
Hypotheses addressing the past and present distribution of forests (in particular the age of forests and their persistence on a
site) must consider the origins and dynamics of the surrounding FPEs. A study of West et al. (2000), using oil-carbon isotope methods, revealed that C4 plants (hence grasslands) earlier
dominated the site that is today covered by Hluhluwe Forest—a
member of the endemic-rich vegetation unit FOz 5 Scarp Forest.
Incidentally, the Hluhluwe Forest itself houses Albizia suluensis,
a very restricted local endemic. West et al.’s study concluded
that grasslands were precursors to the forest vegetation in the
region because of the observed shift from a also C3- to C4-dominated ecosystem with increasing soil depth. This fact, however,
does not preclude a possibility of existence of this forest on
the site in pre-Pliocene times. Its extent might have undergone
reduction (or even obliteration in the study site). The Hluhluwe
Forest could have regenerated from close-by patches, still leaving a C3–C4 transition signal behind. Simulation studies (Bond et
al. 2003a, b) predicted a shift from C4- to C3-ecosystems, due to
increase of woody biomass, under exclusion of fire. Considering
the long-term dynamics of forests (and FPEs surrounding them),
a new element of ecological thinking appears —the interaction of CO2 ambient concentration and fire (Bond et al. 2003a).
Paleoclimatology presumes that during LGM (21 000 to 18 000
ya) and implicitly during all glacial maxima of the other 20+ glaciation cycles during the Pleistocene (and possibly beyond into
Pliocene), the forest cover was sparse. During the LGM low CO2
levels (180 ppm) have promoted C4-dominated grasslands. A
simulation study by Bond et al. (2003b) argues, that by current
(human-forced) levels of CO2 of 360 ppm, the grassland ecosystems with precipitation above 650 mm would develop towards
fire-sensitive forest, if fire was excluded. Also the mesic fynbos
would then turn into forest under the simulated conditions.
Experiments addressing success of establishment of forest precursors in fynbos (Manders 1990, Manders & Richardson 1992)
L. Mucina
W.S. Matthews
Despite mounting evidence for the role
of climate and fire in shaping the current
patterns of forest cover, the influence
of man cannot be denied. Climatically
favourable Holocene and humanenforced increases of temperature result
in expansion of the forest cover. Still
some potentially forest-rich regions (see
Figure 12.6 Scorched edges of a dune forest (FOz 7 Northern Coastal Forest) neighbouring
onto coastal grassland in Maputaland (northeastern KwaZulu-Natal).
Chapter on Indian Ocean Coastal Belt in
this book) show only very fragmented
ern Cape over the last 60 000 years. Since the cold and dry Last
and scanty forest cover. We argue that these regions, comprisGlacial Maximum, the most mesic period (with forest expan- ing mainly the coastal belts of KwaZulu-Natal and the northsion) was between 14 000 and 12 000 BP. This was followed
eastern Eastern Cape have experienced heavy forest clearing in
by a hot, dry period (with forest regression) until the climatic the past. The Iron Age farmers migrating southwards along the
optimum period fostered forest spread during the period 4 000
to 2 500 BP. Another period of warm, dry summers followed,
accompanied by forest regression. However, the climate since
about 1 400 BP is considered to have been similar to the present
and supported another boost of the forest spread.
Figure 12.7 Patch of afrotemperate forests on scree (Table Mountain
Group sandstone) in Leopard’s Kloof in the Harold Porter National
Botanical Garden (Betty’s Bay, Western Cape).
Afrotemperate, Subtropical and Azonal Forests
591
S %
broad coastal belt settled in high density
in preferred sites at least over the last
1400 years. Forest and scrub forest have
been continuously cleared for pastures
and exploited for timber, plant foods
and medicines during this period (Feely
1980, 1987), but also recovered in many
places in the same areas (Von Maltitz et
al. 1996).
FOz 1 Southern Afrotemperate Forest
mm
200
150
100
50
>2A
30 2A4G
20 >2E
>2A6
10
100
50
Forest persists in areas with mean annual
rainfall >525 mm with strong winter
rainfall and >725 mm with strong summer rainfall (Rutherford & Westfall 1986,
Geldenhuys 1991). Rutherford & Westfall
(1986) have suggested that a summer
aridity index may be a better predictor
of forest distribution than rainfall per se.
They have shown that forests grow under
lower rainfall conditions in winter-rainfall
areas than in summer-rainfall areas. The
basic climatic characteristics of the forest
vegetation units are depicted in the climate diagrams featured in Figure 12.8.
988
20
15.7
1674
^^
4
^^
0
100
50
150
100
50
1030
19
19.0
1710
^^
4
^^
0
0
100
50
^^
4
^^
100
50
679
26
21.5
2005
^^
4
^^
561
29
22.0
2035
^^
4
^^
1298
16
20.8
1757
^^
4
^^
0
FOz 8 Sand Forest
>2A
30 2A4G
20 >2E
>2A6
10
150
100
50
1044
20
21.0
1853
^^
4
^^
0
0
mm
200
°C
>2A
30 2A4G
20 >2E
>2A6
10
150
100
50
0
0
; 7>2> ; ; 2 D@?5
; 7>2> ; ; 2 D@?5
FOz 9 Ironwood Dry Forest
FOa 1 Lowveld Riverine Forest
°C
>2A
30 2A4G
20 >2E
>2A6
10
150
100
50
532
30
21.8
2115
^^
4
^^
0
0
mm
200
°C
>2A
30 2A4G
20 >2E
>2A6
10
150
100
50
0
0
; 7>2> ; ; 2 D@?5
; 7>2> ; ; 2 D@?5
FOa 2 Swamp Forest
FOa 3 Mangrove Forest
°C
>2A
30 2A4G
20 >2E
>2A6
10
0
; 7>2> ; ; 2 D@?5
>2A
30 2A4G
20 >2E
>2A6
10
150
; 7>2> ; ; 2 D@?5
°C
0
730
25
17.2
1785
°C
0
FOz 7 Northern Coastal Forest
50
^^
4
^^
0
mm
200
; 7>2> ; ; 2 D@?5
100
1084
19
16.7
1946
FOz 6 Southern Coastal Forest
>2A
30 2A4G
20 >2E
>2A6
10
150
>2A
30 2A4G
20 >2E
>2A6
10
150
; 7>2> ; ; 2 D@?5
°C
mm
200
^^
4
^^
°C
0
FOz 5 Scarp Forest
mm
200
1042
19
14.8
1799
0
mm
200
; 7>2> ; ; 2 D@?5
mm
200
>2A
30 2A4G
20 >2E
>2A6
10
150
FOz 4 Northern Mistbelt Forest
°C
mm
200
°C
0
FOz 3 Southern Mistbelt Forest
Climate
Forest is limited to regions with high
water availability. This is mostly determined by high rainfall, though riverine
and kloof forests exist outside the normal rainfall envelopes associated with
forests—here the groundwater, flood
water and shelter phenomenon (deep
gorges with low solar irradiation, hence
lower evaporation and evapo-transpiration) play a role. Hence, the water availability to forest vegetation is a function
of amount of precipitation (rainfall and
mist), evapo-transpiration, availability of
groundwater and, in addition, soil structure and seasonality of precipitation.
mm
200
; 7>2> ; ; 2 D@?5
0
5.1
^^
4
^^
; 7>2> ; ; 2 D@?5
150
Ecology
863
22
16.7
1647
0
0
mm
200
5.
FOz 2 Northern Afrotemperate Forest
°C
>2A
30 2A4G
20 >2E
>2A6
10
19 (2006)
934
21
21.1
1953
^^
4
^^
mm
200
°C
>2A
30 2A4G
20 >2E
>2A6
10
150
100
50
0
0
; 7>2> ; ; 2 D@?5
Mist precipitation along the Great
Escarpment and some exposed mountain
ranges supplements the rainfall consid- Figure 12.8 Climate diagrams of afrotemperate, subtropical and azonal forest units. Blue bars
erably. Forests are, however, also found
show the median monthly precipitation. The upper and lower red lines show the mean daily maximum and minimum temperature respectively. MAP: Mean Annual Precipitation; APCV: Annual
along rivers and in protected kloofs
Precipitation Coefficient of Variation; MAT: Mean Annual Temperature; MAPE: Mean Annual
(gorges) in areas of lower rainfall (Von
Potential Evaporation.
Maltitz et al. 2003). In the drier inland
areas, mountains provide important
sites for development of forest, e.g. the southern slopes of the
Azonal types, and especially riverine forest, occur in areas
Soutpansberg (Geldenhuys & Murray 1993) and sheltered valof lower rainfall than are typical for forests.
leys in the southwestern Cape (McKenzie 1978, Masson 1990,
The areas of highest rainfall are found in the Mpumalanga
Geldenhuys 1997a).
and Soutpansberg areas.
Most areas covered in forest are linked to orographic precipitaThe Alexandria (Albany) forests have lower rainfall than
tion. These mountainous areas show steep gradients in premost forest types.
cipitation and localised rain shadows. Spatial patterns of total
precipitation do not show a clear correlation with forest type
The southern Cape forests have a mix of rainfall, with some
distribution. Most afforested areas of the country show local
areas receiving low rainfall (Geldenhuys 1991 indicated a
gradients in rainfall. The following conclusions were drawn from
range from 500 mm near Great Brak River to 1 200 mm in
an analysis of rainfall envelopes for the indigenous forests:
Jonkersberg, Diepwalle and Storms River).
592
Afrotemperate, Subtropical and Azonal Forests
S %
19 (2006)
Two discernible gradients exist in seasonality of precipitation.
There is a trend from west to east following the coastline from
the Western Cape coast with winter rainfall to all-year rainfall in
the Knysna region. Most of the remaining coast to the east has
predominantly summer rainfall, though the northern KwaZuluNatal coast also receives rainfall all year. From Port Elizabeth
eastwards there is a gradient from the coast inland of increasingly greater summer dominance of rainfall.
A number of factors influence temperature within forests.
Temperature decreases with both latitude and altitude. Proximity
to the coast has a moderating influence on temperature and
tends to reduce the range in temperature extremes. Maximum
temperature is most extreme on the KwaZulu-Natal north coast
where mean maximums for the hottest month are in the region
of 30°C and mean annual temperature is 22°C. Temperature
decreases southwestwards along the coast to a mean maximum
of 25°C for the hottest month in the afrotemperate forests of
the Knysna area. Inland areas tend to be cooler, especially in
the mistbelt and high mountains of KwaZulu-Natal. The inland
Eastern Cape region has higher maximum temperatures than
other inland forests.
The coastal influence moderates minimum temperature in the
coastal region. Along the coast there is a decrease in temperature from the northern Zululand coast through to the GeorgeKnysna area. Inland minimum temperatures decline rapidly from
the coast towards the mountains as altitude increases. There is
also a discernible decrease in temperature with latitude.
Persistence and recovery of forests are also linked to microclimate created by the forest patches themselves. A mixed evergreen forest is a layered community and always has a continuous tree layer, with or without shrub and/or herbaceous layers
(Geldenhuys et al. 1988a). The layering and the closed forest
canopy buffer the outer macroclimate to create a more equable
internal microclimate (Geldenhuys 1993a). In relation to conditions above the canopy, the temperature in the shrub layer is
lower, the humidity is higher and the wind speed is considerably
lower to almost nonexistent, even during berg wind conditions.
Large gaps created in the canopy during road construction or
careless timber harvesting have two major effects on the plants
growing in and around such gaps. Below-canopy plants are
exposed to the more extreme conditions prevailing outside the
canopy. Many of them cannot adapt to the changed conditions,
and die. Wind blowing over the relatively smooth, undulating
forest canopy becomes turbulent within the gap and uproots
the trees on the side of the gap from which the wind blows
(Geldenhuys et al. 1988b).
Vegetation of a natural forest edge has an effect on the microclimate of the forest interior similar to that of the closed forest canopy. A natural forest edge consists of plants of various
growth forms and sizes that close the gaps between the mature
trees. It usually forms what is known as a soft edge, which
gradually decreases in height and increases in foliage density
away from the mature forest. This transitional area, or ecotone,
also has a higher biodiversity than either the forest or the outside vegetation, because it includes elements of both. Creation
of a hard forest edge, such as during removal of the forest edge
vegetation or cutting of a clearing in the forest, exposes the
forest interior to penetration by the hot, dry and gusty winds,
and even fires, to the detriment of the less hardy plant species
that grow there.
5.2
Geology and Soils
The substrates supporting forests include a wide range of
geological formations: quartzitic sandstone, mudstone, shale,
schist, Enon conglomerate, dolerites, dolomite, granite-gneiss
and aeolian sands (Geldenhuys 2000a). The derived soils vary in
depth, water-holding capacity and nutrient status.
The high rainfall in areas supporting forests has major effects on
forest soils. It causes waterlogged conditions in clayey soils and
leaches the soluble nutrients deeper into the soil. The result is
that the trees develop very shallow root systems. In the southern Cape forests, in general, the root system of a tree has a
maximum depth immediately beneath the bole and decreases
further away from the tree where the roots are confined to
the top 30 cm of the soil (Kotze & Geldenhuys 1992). Large
individual trees of Afrocarpus falcatus have roots of more than
20 cm in diameter appearing above the soil surface and extending horizontally for distances in excess of 40 m away from the
bole. A dense mat of fine, feeder roots concentrates in the
upper 10 cm of the soil. The waterlogged conditions inhibit
penetration of roots deeper into the soil, where they would
suffocate from lack of oxygen. The main function of the feeder
roots is to absorb nutrients from decomposing litter in the
upper part of the soil profile. Disturbance of the root and litter
layers will have significant negative effects on forest nutrition,
and this will, in turn, adversely affect forest regeneration and
recovery. The trees are also particularly sensitive to poor soil
aeration caused by standing water resulting from disturbance
of the natural drainage patterns and from soil compaction
(Geldenhuys et al. 1988b, Lübbe & Mostert 1991). Naturally,
the trees, shrubs and many herbs of the riverine, swamp and
mangrove forests have developed a number of adaptations to
cope with anaerobic conditions in waterlogged soils.
6.
Forest Dynamics
Forest stand dynamics are determined by a number of important processes inside the forests, such as natural disturbance
and gap dynamics, litter fall and a closed nutrient cycling,
characteristic fruit and seed types and associated regeneration
processes, and plant-animal interactions.
6.1
Gap Dynamics
The forest interior is subject to regular small-scale disturbances
causing gaps of 0.005 to 0.5 ha (Geldenhuys & Maliepaard
1983, Midgley et al. 1995). Lightning may cause a fire or merely
kill a small group of trees (Geldenhuys et al. 1994). Some trees,
such as Ocotea bullata, can recover from such strikes by resprouting, whereas others (e.g. Rapanea melanophloeos) can
be easily killed. Hail events occur very infrequently, but still they
can cause major damage by defoliation of whole stands. Winds
cause the breakage of large branches or occasionally uproot a
single tree, or at the most a small group of trees. Large windfalls occur very infrequently in the southern Cape and other
forests along the escarpment. In northern KwaZulu-Natal tropical cyclones occasionally flatten large parts of the coastal and
riverine forests. However, most trees die standing and singly
from old age or some form of disease or stress (Geldenhuys &
Maliepaard 1983, Midgley et al. 1995). Van Daalen & Shugart
(1989) applied an individual-tree gap model aimed at simulating succession dynamics on a site in the Outeniqua Forest
(near Knysna) using demographic parameters for 28 woody
plant species.
Severe droughts affect the forests from time to time. In 1983
the leaves of most evergreen trees in some Eastern Cape forests died on the trees (Geldenhuys 1993b). The leaves of the
evergreen Buxus macowanii remained green throughout the
Afrotemperate, Subtropical and Azonal Forests
593
S %
drought, but many plants died shortly afterwards when they
were totally defoliated by larvae of a moth species, which
appeared in large numbers after the first rains.
6.2
Litter Fall and Nutrient Cycling
The high nutrient content in the surface layers of the soil is maintained through the fall of litter—leaves, twigs, bark, flowers
and fruit—as well as through the death of forest microbes and
animals (Geldenhuys & Theron 1994). Contrary to the general
(perhaps eurocentric) perception that leaves fall in autumn, leaf
fall in the South African indigenous forests occurs throughout
the year, but with a definite peak in midsummer (December
and January). During this time the rainfall is high (except in the
west), but the trees experience a physiological drought because
of the high temperatures and associated high loss of water due
to transpiration. The total litter fall in forests in the southern
Cape amounts to 3 000–4 500 kg. ha-1.yr-1 (Geldenhuys &
Theron 1994), but it may reach values up to 10 000 kg.ha-1.yr -1
in the high-rainfall areas of the Limpopo Province (Geldenhuys
et al. 1984). The total amount of litter increases with increasing
total mass of living material (biomass) of the forest, which is
well correlated with rainfall. The litter, with the leaf component
forming about 80%, decomposes relatively quickly. However,
the decomposition in the warm-temperate forests proceeds
at a much slower pace than in warm, moist tropical rainforests. The rate of decomposition of the litter is about two years
for a moist forest, and four years for a dry forest, resulting in
a gradual build-up of litter on the forest floor (Geldenhuys &
Theron 1994).
Forests can also grow on nutrient-poor or shallow soils, provided
that the moisture is sufficient and disturbance is minimised, so
that the nutrient cycle can develop. It is a slow process and one
that requires the recovery and increase of the nutrient status in
the upper layers of the soil.
6.3
Dispersal Syndromes and Animal-plant
Interactions
The suite of dispersal syndromes in the southern Cape indigenous forests are considered (Geldenhuys 1993c) to be similar to those of the closed, mixed tropical-subtropical forest as
described by Hall & Swaine (1981). They include:
34% Species with small, dry seeds dispersed by gravity or ballistic mechanisms.
24% Species with small seeds either from fleshy fruits or with
a fleshy aril from drier fruits, dispersed by frugivores.
18% Species with spores or dust-like seed for dispersal by
wind.
8% Species with fleshy fruits with large seeds, dispersed by
larger frugivores.
8% Species with small seed with a pappus or wool for wind
dispersal.
4% Species with larger dry seeds from capsules, cones or
nuts, dispersed by mechanical means.
3% Species with seed with attachments for accidental dispersal by mammals.
The representation of propagule type also varies across growth
forms (Phillips 1931, Geldenhuys 1993c). Fleshy propagules,
especially of small size, predominate in tree species. Large fleshy
propagules are more important in canopy than in sub-canopy
594
Afrotemperate, Subtropical and Azonal Forests
19 (2006)
trees. Large dry propagules are more common than small dry
ones in both canopy and sub-canopy trees. Very few tree species have true wind-dispersed seeds. A few trees have very small
seeds that can drift in the wind over short distances. Woody
shrubs usually have small, fleshy propagules and soft shrubs
mostly small, dry ones. Lianas have either fleshy (64%) or winddispersed (36%) propagules, whereas vines have dry (64%),
mostly wind-dispersed (53%) propagules. The other categories
occur in the geophytes, graminoids, epiphytes, ferns and other
forbs. Fruit type and seed dispersal agent are important in the
seedling germination and population demography of many forest species (Geldenhuys 1996a).
Forests are home to many animal species—they use them for
shelter, breeding and forage. Animals act both as disturbance
and regeneration agents. Most of the mammals and a large
proportion of the birds found in South African forests are not
confined to the forest habitat and have wide distribution ranges
(Geldenhuys & MacDevette 1989). Many of the forest-dependent birds migrate to forests at lower altitudes during winter.
Bird species richness is relatively low in forest areas and shows a
decline from north to south like plant species do (Koen & Crowe
1987). For example, moving southwards from the Eastern Cape,
54 species have been recorded in Dwesa Forest, 43 in Alexandria
Forest, 35 in Diepwalle Forest near Knysna, and only 15 in forest patches of the Cape Peninsula (Cody 1983).
Forest mammals generally occur solitarily or in small groups, are
shy and many are nocturnal. Mammals are particularly important in forest dynamics in browsing of young plants and coppice re-growth (Lübbe 1990b), in seed predation (Geldenhuys
1993d, Koen 1991) and seed dispersal (Koen 1983, Geldenhuys
1993d, 1996a). Birds are important in pollination and seed dispersal (Koen 1988, 1992, Geldenhuys 1996a).
7.
Status of Indigenous Forests of South
Africa
Ownership determines the type and quality of forest management and possible impacts on the vegetation (Phillips 1963,
Cooper 1985, Cawe 1986, McKenzie 1988, Geldenhuys 1991,
Cooper & Swart 1992). Most of the forests are surrounded by
areas of high population density (Geldenhuys 1999a). Some
forests occur in areas surrounded by developed affluent societies. In such areas, the people strive to satisfy higher-order
needs, such as high-quality furniture and crafts, recreation and
ecotourism, and biodiversity conservation. In general the forests
expand, with a small impact from development (roads, power
lines, dams, housing complexes). Other forests occur in areas
surrounded by poor developing rural communities. In such
areas, traditional subsistence practices are used to satisfy the
livelihood needs, such as building material, fuel wood, food
and medicine, and other household goods. The actions are
poverty-driven because people lack alternative income-generating activities. Such activities often lead to forest degradation.
The challenge is to move the living standards of the rural poor
towards higher income-generating levels of society.
The national and provincial governments and statutory bodies manage and control a very large proportion of the forests
(and the largest forests), and only a small portion is privately
owned or on communal land (Cooper 1985, Geldenhuys &
MacDevette 1989, Geldenhuys 1991). Conserved forests in
South Africa range from forests in private and tribal ownership that are in good condition, to forests in conservancies and
natural heritage sites, through to forests in nature reserves and
S %
19 (2006)
wilderness areas proclaimed under the Forest Act. There are
many forests outside the proclaimed areas that are well conserved but with insecure conservation status. Geldenhuys &
MacDevette (1989) defined conserved forests as those in the
custody of government authorities, including the National Parks
Board (currently South African National Parks) and city councils.
The forest types and forest complexes in southern Africa are
generally well conserved (Geldenhuys & MacDevette 1989, Von
Maltitz et al. 2003). However, various sources still exert pressure
on these forests (McKenzie 1988, Geldenhuys & MacDevette
1989, Von Maltitz et al. 2003):
Growing human needs in rural tribal areas (uncontrolled
use of forest resources for construction, crafts and traditional medicine, and forest clearing).
High-intensity farming interests (causing the clearing of
scrub forest and riverine forest for agriculture).
Economic pressures (causing uncontrolled exploitation,
grazing and burning of forests on farms).
Mining of forested dunes along the coast.
Development of infrastructure (roads, power lines, dams),
township and resort developments.
8.
Threats to Indigenous Forests of
South Africa
With the settlement of the Europeans in southern Africa since
1652, large-diameter trees of selected species were harvested
for building and furniture timber and for railway sleepers (King
1938, 1941, Phillips 1963, McKenzie et al. 1977, Scheepers
1978, Cawe 1986). However, the forests of South Africa have
played a role over a much longer period in the welfare of society that is disproportionately greater than their small extent and
low potential for commercial exploitation. McKenzie (1988)
recognised many direct uses and indirect values of the South
African forests. A review showed that 365 of the 568 tree and
shrub species recorded from 14 forest complexes throughout
South Africa (Geldenhuys 1992a) were utilised for a wide range
of direct uses (Table 12.2; Geldenhuys 1999a). A recent survey
of 21 villages for forest resource accounting in the Eastern Cape
Province (with many forests in poor rural areas) showed much
informal commercial and subsistence use of the forests (Hassan
& Haveman 1997). A total of 140 tree and shrub species were
recorded, some more widely and generally used than others,
but not all were indigenous species. The uses include a variety
of poles (mainly for construction), firewood, crafts (from timber
and non-timber species), binding and weaving, food sources
(vegetables, fruits and bush meat), and traditional medicine
(bark, roots and other sources). Poverty of rural people and their
inability to afford alternative commodities cause a continuous
use of products from the forests and increased forest clearing
to grow crops to support their families.
Fuel wood represents the highest volume of forest products
used by rural people (Basson 1987) and the resulting pressure
is particularly severe where the forests are not surrounded
by woodland, plantations or woodlots of introduced species
(McKenzie 1988). Acacia natalitia (formerly included in A.
karroo: see Coates Palgrave 2002), a pioneer species in many
forest areas along the coast, is an important firewood species (Hassan & Haveman 1997, Van Eck et al. 1997). Climbers,
leaves, leaf petioles and tree bark are sources of binding materials (Cunningham & Gwala 1986). Use of wood for building
varies with building style and availability of materials, and a
variety of species have been recorded (Johnson 1982, 1983,
Cunningham 1985, McKenzie 1988, Van Eck et al. 1997, Obiri
2002, Obiri et al. 2002). Traditional medicines are important to
rural communities for medical, psychosomatic and economic
reasons (McKenzie 1988). Urbanisation of rural people has
generated a local and countrywide multimillion Rand annual
trade between rural source areas and urban markets and shops
(Cunningham 1986, Williams et al. 1997, Mander 1998). This
trade has increased the pressure on the forests in the rural areas
and on specific species such as Rapanea melanophloeos, Curtisia
dentata, Prunus africana and Ocotea bullata in the Umzimkhulu
District in the Eastern Cape (Geldenhuys 2002, 2004).
Coastal Forests and Dune Forests experience significant current utilisation pressures with the potential to increase. These
forests have more species bearing fleshy fruits (a primary source
of vitamin C), whereas Sand Forest has the highest diversity of
fruit-bearing species (Cunningham 1985, McKenzie 1988, Van
Eck et al. 1997). Several home crafts are based on sources from
the forest (McKenzie 1988). Various palms, reeds and climbers
are used, mainly for baskets and mats, for example Flagellaria
guineensis (Cawe & Ntloko 1997), and the pioneer tree Millettia
grandis is used in woodcarving (Obiri & Lawes 1997). Around
Port St Johns (Eastern Cape coast) people directly employed in
craftwork earn an annual income of over US$0.2 million (Obiri &
Lawes 1997). Fronds (leaves) of the fern Rumohra adiantiformis
are used extensively in the florist trade, both locally and abroad.
Since 1981 the development of the export market for the fern
has developed into a lucrative local industry (Milton 1987a, b,
Table 12.2 Number of tree and shrub species in the South African
forests that have been or are still used traditionally and/or commercially (Geldenhuys 1999a). C: Canopy trees; SC: Sub-canopy trees;
S: Shrubs.
Category
Timber
Traditional medicine
(by plant part used)
Food
(by plant part used)
Crafts
(from other than
timber)
Other uses
Use
C
SC
S
Furniture
43
13
-
Construction
40
26
6
Poles
15
22
6
Fuelwood
18
25
4
Ornamental
45
42
18
Leaves
10
22
15
Fruit
2
5
2
Bark
34
34
4
Roots
10
17
13
Other
18
16
13
Leaves
-
3
3
Fruit
29
38
29
Roots
2
-
2
Other
2
2
-
Basket
-
2
3
Weaving
1
-
-
Binding
2
7
6
Other (including dyes)
6
12
2
Horticulture
83 100 93
Floristic
Other
-
2
-
15
10
12
Total in forests
109 185 274
Total used
102 143 120
Afrotemperate, Subtropical and Azonal Forests
595
S %
Geldenhuys & Van der Merwe 1988, 1994, Geldenhuys 1994c).
During 1994/1995, 2.2 million fronds were harvested from the
forest over a total area of 15 000 ha and sold for a value of
almost US$125 000.
9.
Action: Conservation and Utilisation
The initial colonial timber exploitation and destruction of forests
was followed by forest protection since 1939 and the development of sustainable forest management systems (King 1938,
Phillips 1963, Geldenhuys 1980). Today timber and other minor
but important forest products are utilised conservatively from
ecologically suitable but small areas of State Forest. Two large
forest complexes, the southern Cape and Amathole forests, are
mainly state-controlled and managed under a formal multipleuse system, with close monitoring to ensure sustainable use
(Phillips 1931, Laughton 1937, McKenzie 1988, Seydack et al.
1990, Geldenhuys 1994c, 1996b, Seydack 1995, Vermeulen
2000). Scientific and multiple-use management principles were
developed in the southern Cape forests and are applied through
five management classes (production 19.8%; protection 55.8%,
nature reserves 23%, recreation 0.4% and research 1.1%) in
order to sustain utilisation of forest products, recreation and
conservation. Furniture timber is currently provided mainly from
the relatively large southern Cape forests where this industry
has an annual turnover of >15 million Rand and employs about
650 people, and from the Amathole forests. Today commercial plantations of pines, eucalypts and wattles, covering >1.4
million ha, provide in the structural timber needs of the region.
Commercial forestry plantations of pines, eucalypts, acacias
and other species have been established in the grasslands and
shrublands surrounding the forests, but rarely in areas cleared
of evergreen forest. Interestingly enough, besides the obvious
negative effect of establishment of forest plantations on biodiversity of grasslands and fynbos (see Chapter on Grassland in
this book), there are also positive sides to such silviculture practices: the plantations aid the rehabilitation of the forests, and
expansion in places, reduce pressure on the forests for timber,
fibre and firewood needs, and protect forest margins against
frequent fires (Geldenhuys et al. 1986). Commercial timber
plantations currently cover an area of about 1 487 million ha,
comprising 53.2% pines of various species, 39.2% eucalypts of
various species and 7.6% acacias (mainly Acacia mearnsii) and
other species (Forestry SA 2002). Several good indigenous timber species can grow fast outside the forest if planted in suitable
sites and managed appropriately (Lübbe & Geldenhuys 1991,
Geldenhuys & Von dem Bussche 1997), and several of these
species establish naturally under nurse stands of, for example,
pines, eucalypts and acacias (Van Wyk et al. 1995, Geldenhuys
1996c, 1997b, Geldenhuys & Delvaux 2002).
The establishment of pure stands of indigenous tree species
through planting was practised for many years, but this proved
to be a very expensive process. A more acceptable and costeffective approach was developed. Recent studies show that
tree plantings catalyse or nurse the establishment of natural
forest species to restore forest biodiversity and productivity
(Geldenhuys et al. 1986, Parrotta 1995, Geldenhuys 1996c,
1997b, Parrotta et al. 1997). It is based on the concept that
if fire is controlled in the landscape (urban development, crop
production, commercial plantations), the areas in the former
fire pathways (Figure 12.4) grow back to trees: firstly by alien
invader species. They are intolerant of shade, cannot establish under their own canopy, but shade-tolerant forest species
become established in the understorey (Geldenhuys 1994d,
1996c, 1997b, Geldenhuys & Delvaux 2002).
596
Afrotemperate, Subtropical and Azonal Forests
19 (2006)
Careful manipulation of the invader stand through selective thinning where forest species start to establish, facilitates stronger
growth of the established indigenous species and establishment of more species (Geldenhuys et al. 1986). Eventually
the invader plant stand can be converted to re-growth forest.
Similarly, plantation stands can be converted to forest (Van Wyk
et al. 1995). This can also be done with natural stands of indigenous forest pioneer species such as Acacia karroo (as well as
Acacia kosiensis and A. natalitia, formerly included within A.
karroo; see Coates Palgrave 2002), Trema orientalis, Virgilia
divaricata and other useful, fast-growing indigenous tree species such as Afrocarpus falcatus, Millettia grandis, Ptaeroxylon
obliquum, Prunus africana, Rapanea melanophloeos etc. (Van
Wyk et al. 1995, Geldenhuys & Delvaux 2002). Nurse stands of
indigenous species can also be planted to develop useful, mixed
forest stands in degraded forest gaps or forest margins (but
outside the fire zones) to restore forest (Geldenhuys & Von dem
Bussche 1997, Geldenhuys & Delvaux 2002).
Facilitation of forest re-establishment and recovery, using stands
of planted trees, provides the basis for combining forest rehabilitation and production of the plants used by rural communities for their daily livelihood (Geldenhuys 1999b). Selected,
traditionally used forest species grow faster in mixed-species
stands, add value to products harvested from the planted
stands through small businesses, reduce the pressure on forests
through socio-economic upliftment of poor rural communities,
and restore forest. Restoration actions are successful only if they
are economically viable or if they provide in the daily needs of
rural communities. In particular (1) they need to resolve the
conflicts between resource users and resource managers and
(2) there must be an improved, diversified and productive commercial use of the natural resources.
The actions must contribute to improved productivity of
degraded land (such as through growth of leguminous trees
and agrobiological improvement of degraded soil). They must
ensure sustainable resource management.
In some areas, deforestation is continuing at an alarming rate,
primarily for maize cultivation, to provide in the daily food needs
of the very poor people. Cutting trees for construction poles
and firewood is a secondary cause of forest degradation, but
considered essential as the rural people have no money to buy
such products. This degradation of the forest causes the loss
of other sources of income such as woodcrafts and the basket
industry. The Eastern Cape Resource Accounting Survey (Hassan
& Haveman 1997) indicated a number of wrong perceptions on
both sides that relate partly to the real meaning of sustainability
and partly to the true dependence of the poor rural communities on the forests for their daily livelihood. This accentuates the
need for implementation of joint resource management strategies in the rural areas to resolve the conflicts and to ensure
sustainable resource use and socio-economic development.
Development of sustainable resource use from forest involves a
process within which the resource managers (often the authorities) and the resource users must (Geldenhuys 2000b):
Define the products to be used.
Make an inventory of resource availability and match this
with the resource needs.
Determine the rate of production.
Make assumptions on aspects not known.
Set management objectives and guidelines.
Implement management.
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Monitor.
Re-evaluate and adapt management.
Resource use should be approached from a business development perspective to focus the attention on critical issues related
to market demand, whether it is other rural communities,
sophisticated industries (furniture, florist greenery, medicine)
or conservation.
Development of small businesses in rural areas, based on sustainable use of forests, is a new approach in South Africa to
deal with illegal resource use practices. It was developed with
implementation of the harvesting of Rumohra fern for the
florist industry in a commercial forestry and farming environment (Geldenhuys 1994c). The approach was further advanced
with the harvesting of bark for traditional medicine in a rural
environment (Geldenhuys 2002, 2004), but also in other areas
such as vine harvesting for basket-making (Venter 2000).
Businesses in rural areas, based on the use of forest species,
could be developed as an approach to improve management of
forests for the benefit of rural communities.
Forests play an increasingly important role in providing for the
recreation and aesthetics of the growing urban and industrial
societies of southern Africa. Many picnic sites, viewpoints,
camping sites, forest walks and hiking trails in forests offer
unique experiences (Levy 1987, Van Dijk 1987). The care taken
with the management of recreation sites has contributed to
forest recovery in several areas.
Forests also have cultural importance as burial sites (Netshiungani
et al. 1981, McKenzie 1988). Undisturbed forest and wooded
copses persist around major grave sites in many parts of South
Africa because of the acknowledged importance of the role
that ancestral spirits play in daily life and the value of ensuring
them peace.
10. Further Research
The recently completed National Forest Type Classification (Von
Maltitz et al. 2003) has brought together most of the existing information and knowledge of the natural forests in the
different parts of South Africa. Forest inventory data exist for
many areas (see Von Maltitz et al. 2003), but the data are not
always in a form that would facilitate sustainable resource use,
or provide knowledge of the conservation status of important
species. What is needed are data on the population demography of the key ecological and economic species, i.e. data
on the numbers of a species in all age or size categories. This
would indicate what the important species would require for
recruitment, establishment and for growth to maturity. There is
a considerable amount of data on the recruitment, growth and
mortality of forest stands and species (Geldenhuys 1997c, 1998,
2000c), which, after detailed analysis and interpretation, would
shed light on the problems of forest dynamics. Prediction of
forest dynamics will also require much improved understanding
of competitive relationships of forest plants, mutualisms and
ecosystem-level functions, including nutrient cycling.
Traditionally, trees and shrubs were the subject of forest
research, grossly neglecting the non-woody component. It is
becoming increasingly clear (Mucina & Geldenhuys 2002) that
this situation is untenable, especially in the light of conservation
needs and sustainable use of non-woody forest components.
Biodiversity studies in forests are also hampered by our ignorance (or negligence) of epiphytes, herbs and grasses in forest
environments. There are many taxonomic and biogeographic
surprises out there.
The small and fragmented forests are unlikely to support longterm resource removal, in areas subject to frequent harvesting,
that is sustainable (Adie & Goodman 2000). Appropriate utilisation guidelines have to be researched and compiled to enable
the long-term utilisation of forest products, such as bark, that is
not destructive and would also not change the species composition of the forest or impact on forest integrity.
Management of natural forest has to integrate the knowledge
of forest types, the relationship between forest composition
and site conditions, the development stage of the vegetation
(stand dynamics), the rates of recruitment, growth and mortality, disturbance and recovery processes. For some areas, knowledge and understanding of the forest is advanced (Seydack et al.
1990, Geldenhuys 1996b), but for others it is seriously lacking.
11. Descriptions of Vegetation Units
Zonal & Intrazonal Units
FOz 1 Southern Afrotemperate Forest
Knysna Forests (Acocks 1988). Southern Cape Forests (Phillipson & Russell
1988, Geldenhuys 1993e). Afrotemperate Forests p.p. (Low & Rebelo 1996).
Knysna-Tsitsikamma Forests, Swellendam Area Forests, Cape Peninsula
Forests and South-western Cape Forests (Bailey et al. 1999). Western
Cape Talus Forest, Western Cape Afrotemperate Forest and Southern Cape
Afrotemperate Forest (Von Maltitz et al. 2003).
Distribution Western Cape, Eastern Cape and also (only few
patches) in Northern Cape Provinces: The largest complex is
found in the southern Cape along the narrow coastal strip
(250 km long) between Humansdorp in the east and Mossel
Bay (Knysna-Tsitsikamma forest region)—here occurring on
sheltered seaward slopes, plateaux and coastal scarps. The
easternmost outlier forest patches occur near Port Elizabeth,
while westwards floristically impoverished forms of these forests occur along the feet of south- and east-facing slopes and
in deep kloofs and ravines of the Cape Fold Belt mountains
as far as the Cape Peninsula in the west. The northernmost
localities are near Vanrhynsdorp Pass and in the Matsikamma
Mountains. At altitudes ranging from about 10 m (Tsitsikamma
region) to 600 m (most of patches), with notable outliers occurring as high as 1 060 m.
Vegetation & Landscape Features Tall, multilayered afrotemperate forests dominated by yellowwoods (Afrocarpus falcatus
and Podocarpus latifolius), Ocotea bullata, Olea capensis subsp.
macrocarpa, Pterocelastrus tricuspidatus, Platylophus trifoliatus
etc. In scree and deep-gorge habitats Cunonia capensis, Heeria
argentea, Metrosideros angustifolia, Podocarpus elongatus and
Rapanea melanophloeos predominate. The shrub understorey
and herb layers are well developed, especially in mesic and
wet habitats.
Geology & Soils Soils varying from shallow (and skeletal)
Mispah, Glenrosa and Houwhoek forms to sandy humic
Fernwood form, derived from Table Mountain Group sandstones and shales of the Cape Supergroup and partly also from
Cape Granite.
Important Taxa Tall Trees: Afrocarpus falcatus (d), Cunonia
capensis (d), Curtisia dentata (d), Nuxia floribunda (d), Ocotea
bullata (d), Olinia ventosa (d), Podocarpus elongatus (d), P.
latifolius (d), Pterocelastrus tricuspidatus (d), Rapanea melanophloeos (d), Ilex mitis, Olea capensis subsp. macrocarpa. Small
Trees. Canthium inerme (d), Cassine peragua (d), Diospyros
Afrotemperate, Subtropical and Azonal Forests
597
L. Mucina
19 (2006)
L. Mucina
S %
Figure 12.9 FOz 1 Southern Afrotemperate Forest: Riparian forest
with prominent Cunonia capensis, Olinia ventosa and Platylophus trifoliatus in the Disa Kloof, Harold Porter National Botanical Garden near
Betty’s Bay (Western Cape).
Figure 12.10 FOz 1 Southern Afrotemperate Forest: Dense warm-temperate forests near Nature’s Valley (Western Cape) featuring a dense
population of endemic Strelitzia alba (Strelitziaceae).
whyteana. Tree Fern: Cyathea capensis (d). Herbaceous Climber:
Cissampelos torulosa. Epithytic Herb: Angraecum pusillum.
Tall Shrubs: Burchellia bubalina (d), Trichocladus crinitus (d),
Sparrmannia africana.Geophytic Herbs: Blechnum capense (d),
B. tabulare (d), Dietes iridioides (d), Rumohra adiantiformis (d),
Todea barbara (d), Oxalis incarnata. Graminoid: Oplismenus
hirtellus (d).
and Wilderness National Parks, several nature reserves and a
number of otherwise protected forests formerly under DWAF
jurisdiction), Table Mountain National Park, and many nature
reserves managed by CapeNature in the Western Cape Province
(including Cederberg Wilderness Area, Kogelberg Biosphere
Reserve, Boosmansbos Wilderness Area, nature reserves of
Jonkershoek, Assegaaibos, Limietberg, Hottentots Holland,
Riviersonderend, Marloth, Outeniqua, Swartberg etc.); small
portions are also protected in the Oorlogskloof Nature Reserve
(Northern Cape) and in the Groendal Wilderness Area and
Loerie Nature Reserve (Eastern Cape). Number of privately
owned nature reserves in both Western and Eastern Cape also
protect some patches of this forest. Unknown portion of the
original area (only about 300 ha in the southern Cape; see
Geldenhuys 1991) has been transformed for plantations.
Biogeographically Important Taxa (CEndemic of Capensis,
W
Western distribution limit) Tall Trees: Brabejum stellatifoliumC,
Ochna arborea var. arboreaW. Small Trees: Gonioma kamassi W (d),
Heeria argenteaC (d), Metrosideros angustifoliaC (d), Allophylus
decipiensW, Brachylaena neriifoliaC, Cassine schinoidesC, Lachnostylis
hirtaC, Virgilia divaricataC. Woody Climber: Asparagus scandens C.
Epiphytic Herb: Mystacidium capenseW. Tall Shrub: Laurophyllus
capensisC. Herb: Gerbera cordataW, Streptocarpus rexii W. Geophytic
Herbs: Liparis capensis C. Graminoids: Ischyrolepis subverticillataC,
Schoenoxiphium lanceumC.
Endemic Taxa Tall Tree: Platylophus trifoliatus (d). Small
Trees: Apodytes geldenhuysii, Cryptocarya angustifolia, Virgilia
oroboides subsp. ferruginea, V. oroboides subsp. oroboides.
Megaherb: Strelitzia alba (d). Geophytic Herbs: Amauropelta
knysnaensis, Clivia mirabilis, Freesia sparrmannii, Polystichum
incongruum.Graminoid: Schoenoxiphium altum.
Conservation Least threatened. Target 34%. More than half of
the extent of these forests enjoy statutory conservation in the
proposed Garden Route National Park (including Tsitsikamma
598
Afrotemperate, Subtropical and Azonal Forests
Remarks Southern Afrotemperate Forests are species-poorer
than those of the mistbelt, but they still support some
woody (palaeo)endemic elements such as Cunonia capensis, Cryptocarya angustifolia, Heeria argentea, Metrosideros
angustifolia, Platylophus trifoliatus, Podocarpus latifolius and
Afrocarpus falcatus.
References Phillips (1931), Laughton (1937), Taylor (1955, 1996), Von
Breitenbach (1974), Campbell & Moll (1977), McKenzie et al. (1977),
McKenzie (1978), Geldenhuys (1982, 1987, 1992a, 1993c, e, 1994b,
1997a), Hanekom et al. (1989), Masson & McKenzie (1989), Masson
(1990), McKenzie et al. (1990), Vermeulen (1995), Von Maltitz et al. (2003),
Geldenhuys & Mucina (2006).
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Reserves, Marekele National Park and Pilanesberg Game Reserve.
Some private nature reserves (e.g. Mooibron, Mhlongamvula,
Tafelkop, Oudehoutdraai, Oshoek and Ossewakop) protect
some patches too. Occasional hot fires encroaching from the
surrounding savanna woodlands, uncontrolled timber extraction, medicinal-plant harvesting, and grazing in forest can be
viewed as the current major threats (Von Maltitz et al. 2003).
FOz 2 Northern Afrotemperate Forest
Mountain Podocarpus Forest (Edwards 1967). Kloof Forest (Coetzee 1974).
Afromontane Podocarpus Forest (Cooper 1985). Highland Sourveld p.p.
(Acocks 1988). Montane Podocarpus Forests (Everard 1992). Marekele
Afromontane Forest, Northern Highveld Forest, Drakensberg Montane Forest
and Low Escarpment Mistbelt Forest (Von Maltitz et al. 2003).
Distribution Free State, KwaZulu-Natal, Mpumalanga, NorthWest, Gauteng and Limpopo Provinces (as well as Lesotho):
Restricted to mountain kloofs and low ridges (Strydpoortberg,
Waterberg, Pilanesberg, Witwatersrand, Magaliesberg,
Suikerbosrand, Sekhukhuneland) interrupting the relatively
flat northern highveld. This group also comprises forests
found in kloofs along the northern and eastern flanks of the
Drakensberg and those found on the slopes and scarps of the
Low Escarpment between Van Reenen’s Pass and Pongola Bush
near Piet Retief. The westernmost localities of these forests are
found in the Koranaberg (close to Thaba ‘Nchu). The remnants
of forests rich in afrotemperate elements in Lesotho might also
be classified within this vegetation unit. Most patches occur at
altitudes between 1 450 and 1 900 m, with outliers as low as 1
100 m and around 2 000 m.
Remarks In the northern highveld, these forest patches are
either imbedded within Savanna Biome or straddle an ecotone
between sourveld grassland and subtropical savanna of the
Central Bushveld. This group of forests is a ‘high-altitude’ analogue to ‘high-latitude’ afrotemperate forests of the southern
and western Cape. The major unifying trait of the two groups
of forests mentioned above is impoverished floristic composition when compared to Northern Mistbelt Forest and Southern
Mistbelt Forest (both also of afrotemperate character).
References Roberts (1961), Van Vuuren (1961), Killick (1963), Van Vuuren
& Van der Schijff (1970), Van Zinderen Bakker (1971, 1973), Coetzee (1974,
1975), Van der Meulen (1978, 1979), Bredenkamp & Theron (1978, 1980),
Westfall (1981), Cooper (1985), Westfall et al. (1985), Everard (1986), Behr &
Bredenkamp (1988), Du Preez & Bredenkamp (1991), Du Preez et al. (1991),
Smit et al. (1993), Hill (1996), Eckhardt et al. (1997), Ellery et al. (2001), Siebert
(2001), Van Staden (2002), Siebert et al. (2003), Von Maltitz et al. (2003), Van
Staden & Bredenkamp (2005, 2006), Geldenhuys & Mucina (2006).
Vegetation & Landscape Features Low (in the Low
Escarpment region with canopy reaching up to 20 m), relatively species-poor forests of afromontane origin and some
of them still showing clear afromontane character. Found as
small patches in kloofs and on sub-ridge scarps at high altitudes
(1 500–1 900 m). Canopy dominated usually by Podocarpus
latifolius, Olinia emarginata, Halleria lucida, Scolopia mundii
and rarely also by Widdringtonia nodiflora, in drier facies also
by Pittosporum viridiflorum, Celtis africana, Mimusops zeyheri,
Nuxia congesta and Combretum erythrophyllum. Xymalos monospora sometimes dominate patches of species-poor mistbelt
forests of northern KwaZulu-Natal.
Geology & Soils Shallow acidic soils over sandstones of the
Karoo Supergroup, quartzites and rarely also volcanic rocks
of Ventersdorp Supergroup and intrusive diabases of Pretoria
Igneous Complex.
Endemic Taxa Tall Tree: Scolopia oreophila. Small Tree:
Maytenus albata. Tall Shrub: Sparrmannia ricinocarpa. Herb:
Streptocarpus polyanthus subsp. dracomontanus.
Conservation Least threatened. Target 31%. About 30% statutorily conserved in uKhahlamba Drakensberg Park, Phongola
Bush, Vryheid Mountain, Poccolan/Robinson’s Bush, Ngome
and Ncandu Nature Reserves, Magaliesberg Nature Area,
Merville Ridge, Paardeplaats, Rustenburg, Suikerbosrand Nature
L. Mucina
Important Taxa Tall Trees: Celtis africana (d), Halleria lucida (d),
Olinia emarginata (d), Pittosporum viridiflorum (d), Podocarpus
latifolius (d), Rothmannia capensis (d), Scolopia mundii (d),
Afrocarpus falcatus, Buddleja saligna, Dais cotinifolia, Ilex
mitis. Small Trees: Acalypha glabrata (d), Buddleja salviifolia (d),
Calpurnia aurea (d), Combretum erythrophyllum (d), Diospyros
lycioides subsp. guerkei (d), D. whyteana (d), Euclea crispa
subsp. crispa (d), Widdringtonia nodiflora (d), Bowkeria verticillata, Canthium ciliatum, Leucosidea sericea, Scolopia flanaganii.
Woody Climber: Cassinopsis ilicifolia (d). Tall Shrubs: Myrsine
africana (d), Cliffortia nitidula. Soft Shrubs: Isoglossa grantii (d),
Hypoestes aristata, Plectranthus fruticosus. Herbs: Plectranthus
grallatus (d), P. hereroensis (d), Peperomia retusa, Streptocarpus
haygarthii, S. pusillus. Geophytic Herbs: Blechnum attenuatum (d), Asplenium aethiopicum, Polystichum luctuosum.
Graminoids: Carex spicato-paniculata (d), Oplismenus hirtellus (d), Cyperus albostriatus, Schoenoxiphium lehmannii,
Thamnocalamus tessellatus.
Figure 12.11 FOz 2 Northern Afrotemperate Forest: Kloof forests with
Podocarpus latifolius above Thendele Camp in uKhahlamba-Drakensberg Park near Bergville, KwaZulu-Natal.
Afrotemperate, Subtropical and Azonal Forests
599
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tude scarps are low (in places having the character of a scrub
forest), and although less structured into different tree layers, they are still species-rich. The tall forests show a mix of
coarse-grained, canopy gap/disturbance-driven dynamics and
fine-grained, regeneration characteristics. The Amathole mistbelt forests are dominated by emergent trees of Afrocarpus
falcatus and a range of deciduous and semi-deciduous species
such as Celtis africana, Calodendrum capense, Vepris lanceolata and Zanthoxylum davyi. Further east (Transkei, KwaZuluNatal Midlands) Podocarpus henkelii becomes prominent in the
canopy layer. Deciduous elements play an important role.
FOz 3 Southern Mistbelt Forest
Mist Belt Mixed Podocarpus Forests (Edwards 1967). Transkei and Natal
Montane Forests p.p. & Eastern Cape Montane Forests (Phillipson & Russell
1988). High Altitude Afrotemperate Forests, Middle Altitude Afrotemperate
Forests, Mistbelt Afrotemperate Forests, Moist Afrotemperate Forests (Cawe
1996, Cawe & McKenzie 1989). Afromontane Forests p.p. (Low & Rebelo
1996). Amathole Forest Complex (Bailey et al. 1999). Eastern Mistbelt Forest,
Transkei Mistbelt Forest and Amatole Mistbelt Forest (Von Maltitz et al.
2003).
Distribution KwaZulu-Natal and Eastern Cape Provinces:
Forest patches varying in size, occurring in fire-shadow habitats
on south- and southeast-facing slopes and located along the
Great Escarpment, spanning a large area from Somerset East,
the Amathole Mountains, scarps of Transkei to the KwaZuluNatal Midlands as far east as Ulundi. In KwaZulu-Natal these
forests are found in a wide band sandwiched between the
Drakensberg Montane Forests and Northern KwaZulu-Natal
Mistbelt Forests at higher altitudes and Eastern Scarp Forests
at lower altitudes. Belts of forest patches belonging to this vegetation unit occur in the Baviaanskloof Mountains, Zuurberg
Mountains and in the region spanning Grahamstown and King
William’s Town. Found at altitudes spanning 850–1 600 m (most
patches between 1 000 and 1 400 m).
Geology & Soils Some of the soils are deep, loamy and with
high nutrient status, developed on weathered dolerite intrusions
or mudstones, shales and sandstones of the Karoo Supergroup
(on Great Escarpment). The soils supporting forests of low-lying
scarps are shallower as they developed on quartzitic Witteberg
Sandstones or sandstones of the Karoo Supergroup.
Important Taxa Tall Trees: Afrocarpus falcatus (d), Apodytes
dimidiata subsp. dimidiata (d), Celtis africana (d), Chionanthus
foveolatus subsp. foveolatus (d), C. peglerae (d), Cunonia capensis (d), Curtisia dentata (d), Kiggelaria africana (d), Olea capensis
subsp. macrocarpa (d), Podocarpus henkelii (d), P. latifolius (d),
Protorhus longifolia (d), Ptaeroxylon obliquum (d), Rapanea
melanophloeos (d), Rhus chirindensis (d), Scolopia mundii
(d), S. zeyheri (d), Vepris lanceolata (d), Xymalos monospora
(d), Combretum kraussii, Elaeodendron croceum, E. zeyheri,
Halleria lucida, Mimusops obovata, Ochna arborea var. arborea,
Ocotea bullata, Pleurostylia capensis, Psydrax obovata subsp.
elliptica, Zanthoxylum davyi. Small Trees: Canthium ciliatum (d),
C. inerme (d), Cassipourea flanaganii (d), Clausena anisata (d),
Eugenia capensis (d), Gymnosporia buxifolia (d), Maerua racemulosa (d), Ochna serrulata (d), Scutia myrtina (d), Trichocladus
ellipticus (d), Trimeria grandifolia (d), Allophylus dregeanus,
Diospyros whyteana, Mystroxylon aethiopicum, Rinorea angustifolia. Tall Shrubs: Burchellia bubalina (d), Carissa bispinosa
subsp. zambesiensis (d), Grewia occidentalis (d), Calodendrum
capense, Diospyros scabrida var. cordata, Hyperacanthus
amoenus, Maesa alnifolia. Low Shrub: Azima tetracantha (d).
Soft Shrubs: Hypoestes aristata (d), Isoglossa woodii (d). Herbs:
Streptocarpus daviesii, S. haygarthii, S. pentherianus, S. polyanthus subsp. comptonii, S. polyanthus subsp. polyanthus.
Geophytic Herbs: Dietes iridioides (d), Dryopteris inaequalis (d),
Polystichum pungens (d). Graminoid: Oplismenus hirtellus (d).
Vegetation & Landscape Features On the Great Escarpment
(Amathole, Transkei Escarpment) and in the KwaZulu-Natal
Midlands these forests are tall (15–20 m tall) and multilayered
(having two layers of trees, a dense shrubby understorey and
a well-developed herb layer). The forests found on low-alti-
L. Mucina
Endemic Taxa Tall Shrub: Eugenia zuluensis (d). Herbs:
Plectranthus elegantulus, P. rehmannii, Pyrrosia africana,
Streptocarpus bolusii, S. candidus, S. fanniniae, S. silvaticus.
Figure 12.12 FOz 3 Southern Mistbelt Forest: Patch of Amathole Mistbelt Forest in the Zuurberg (Eastern Cape).
600
Afrotemperate, Subtropical and Azonal Forests
Conservation Least threatened. Target 30%. Some 8% statutorily conserved (including forests under DWAF jurisdiction) in
the Eastern Cape encompassing the Bosberg Nature Reserve,
Greater Addo Elephant National Park as well as Hogsback,
Kologha, Isidenge, Kubusi, Katberg and Nabakyu State Forests.
In KwaZulu-Natal these forests are statutorily protected in
Impendle, Igxalingenwa, Karkloof and Qudeni Nature Reserves.
Several private reserves protect smaller patches. About 5%
has been transformed for plantations. Invasive aliens include
Solanum mauritianum, Rubus species and several Acacia and
Eucalyptus species. Uncontrolled harvesting of timber, poles
and firewood, overexploitation of non-timber forest products
and mismanagement of fire and burning regimes in surrounding grasslands are considered as current major threats (Von
Maltitz et al. 2003).
Remarks All mistbelt forests are species-rich afrotemperate forests containing an important share of subtropical floral elements.
S %
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Podocarpus henkelii is a near-endemic species for this vegetation unit, as it marginally occurs in the Northern Afrotemperate
Forests as well.
capensis (d), Canthium kuntzeanum, Carissa bispinosa subsp.
zambesiensis, Pavetta kotzei, Sclerochiton harveyanus. Soft
Shrubs: Galopina circaeoides, Hypoestes triflora. Herbs:
Begonia sonderiana, Plectranthus rubropunctatus, P. tetragonus,
Streptocarpus meyeri, S. pentherianus. Geophytic Herbs: Dietes
iridioides (d), Asplenium aethiopicum, A. boltonii, A. splendens,
Crocosmia aurea, Dryopteris inaequalis, Elaphoglossum acrostichoides, Polypodium polypodioides subsp. ecklonii, Polystichum
macleae, Pteris catoptera. Graminoids: Carex spicato-paniculata
(d), Cyperus albostriatus (d), Oplismenus hirtellus (d).
References Story (1952), Edwards (1967), Moll (1976), Cooper (1985),
Cawe (1986, 1996), Phillipson (1987), Cawe & McKenzie (1989), Everard
(1992), Geldenhuys (1992a), Everard & Hardy (1993), Everard et al. (1995),
Geldenhuys & Rathogwa (1997), Von Maltitz et al. (2003), Geldenhuys &
Mucina (2006).
FOz 4 Northern Mistbelt Forest
Biogeographically Important Taxa (SSouthern distribution
limit, BEndemic of Barberton Centre) Tall Tree: Anthocleista
grandifloraS, Faurea galpinii. Tall Shrubs: Psychotria zombamontanaS (d), Coptosperma rhodesiacumS. Soft Shrub: Duvernoia
adhatodoides B. Megaherbs: Ensete ventricosumS, Strelitzia
caudataS. Herbs: Plectranthus swynnertonii S, Sphaerocionium
capillare S.
Soutpansberg Forests & Transvaal Drakensberg Escarpment Forests (Cooper
1985). Transvaal Forests (Phillipson & Russell 1988). Afromontane Forest p.p.
(Low & Rebelo 1996). Northern Mistbelt Forest and Mpumalanga Mistbelt
Forest (Von Maltitz et al. 2003). Limpopo Mistbelt Forests (Geldenhuys &
Mucina 2005).
Distribution Limpopo and Mpumalanga Provinces as well as in
Swaziland: Occurring along the Soutpansberg from Blouberg in
the northwest to the Samandou Plateau in the northeast and
further southwards (along the Northern Escarpment) from Abel
Erasmus Pass (Olifants River) to the surroundings of Badplaas
and Barberton. In northern Swaziland in fire refugia and cooler
sheltered areas along a north-south trending lowveld/highveld
transition. Most of the patches occur in an altitudinal belt spanning 1 050 to1 650 m.
Endemic Taxa Tall Trees: Cryptocarya transvaalensis (d), Ochna
gamostigmata. Small Trees: Dombeya pulchra, Heteropyxis
canescens. Epiphytic Herb: Mystacidium brayboniae. Tall
Shrub: Pavetta barbertonensis (d). Herbs: Streptocarpus davyi,
S. fenestra-dei, S. micranthus, S. parviflorus, S. roseo-albus, S.
wilmsii. Geophytic Herb: Clivia caulescens (d).
Conservation Least threatened. Target 30%. About 10%
statutorily conserved in Blyde River Canyon, Lekgalameetse,
Songimvelo, Makobulaan, Malalotja, Nelshoogte, Barberton,
Starvation Creek Nature Reserves. More than 25% enjoys pro-
Vegetation & Landscape Features Tall, evergreen afrotemperate mistbelt forests occurring primarily in east-facing fire
refugia such as subridge scarps and moist sheltered kloofs
where they form small, fragmented patches. The most common canopy trees include Xymalos monospora, Podocarpus
latifolius, Combretum kraussii, Cryptocarya transvaalensis
Schefflera umbellifera, Syzygium gerrardii, Olea capensis subsp.
macrocarpa, Psydrax obovata subsp. elliptica, Pterocelastrus
galpinii. In the understorey Psychotria zombamontana, Canthium
kuntzeanum, Gymnosporia harveyana, Peddiea africana,
Pavetta inandensis, Mackaya bella, Sclerochiton harveyanus
etc. are found. The herb layer supports a number of dominating Acanthaceae (Isoglossa), Lamiaceae (Plectranthus, Stachys)
and Rubiaceae (Galopina) herbs and so called ‘soft shrubs’,
geophytic herbs and ferns (Asplenium, Dryopteris, Polystichum).
Of lianas and climbers Dalbergia armata, Combretum edwardsii, Jasminum abyssinicum, Rhoicissus rhomboidea and Keetia
gueinzii are the most conspicuous vines, as is the scandent
grass Prosphytochloa prehensilis.
Important Taxa Tall Trees: Brachylaena transvaalensis (d),
Combretum kraussii (d), Curtisia dentata (d), Drypetes gerrardii
(d), Kiggelaria africana (d), Ocotea kenyensis (d), Olea capensis subsp. macrocarpa (d), Podocarpus latifolius (d), Psydrax
obovata subsp. elliptica (d), Rhus chirindensis (d), Schefflera
umbellifera (d), Syzygium gerrardii (d), Xymalos monospora
(d), Aphloia theiformis, Chionanthus battiscombei, C. foveolatus subsp. major, Maytenus acuminata, Pterocelastrus galpinii, Rapanea melanophloeos, Rothmannia capensis, Trichilia
dregeana. Small Trees: Cassipourea malosana (d), Oxyanthus
speciosus subsp. gerrardii (d), Englerophytum magalismontanum, Gymnosporia harveyana, Mackaya bella, Ochna arborea
var. oconnorii, Peddiea africana, Rinorea angustifolia. Woody
Climbers: Acacia ataxacantha (d), Keetia gueinzii (d), Rhoicissus
rhomboidea (d), Bauhinia galpinii, Dalbergia armata. Climbing
Graminoid: Prosphytochloa prehensilis (d). Tall Shrubs: Psychotria
L. Mucina
Geology & Soils Highly weathered, clayey soils mainly of Avalon
and Hutton soil forms, derived from shales (Pretoria Group),
quartzite (Black Reef Formation), dolomite (Chuniespoort
Group), granite (Nelspruit Basement) and diabase (Mokolian
intrusives).
Figure 12.13 FOz 4 Northern Mistbelt Forest: Stand of tree fern Cyathea capensis on the edge of mistbelt forest in a shady gully below the
escarpment near Graskop (Mpumalanga).
Afrotemperate, Subtropical and Azonal Forests
601
S %
19 (2006)
tection in privately owned nature reserves, including for instance
Wolkberg Wilderness Area, In-De-Diepte, Sudwala, Mac Mac,
Buffelskloof, Mount Sheba etc. Aliens such as Solanum mauritianum, Caesalpinia decapetala, Acacia mearnsii and Lantana
camara can be locally of concern. Encroaching subsistence agriculture, firewood collection in communal areas, and selective
harvesting of bark are viewed as serious threats (Von Maltitz
et al. 2003). Below the escarpment between Mariepskop and
Graskop, the natural forest has expanded into former grassland
areas due to the protection of the timber plantations against
fire (when comparing the current forest areas with aerial
photographs of the 1930s, before the establishment of the
plantations) (Grossman 2005).
Remarks These forests border on sourveld grasslands on their
upper boundary, whereas they often border on bushveld on
their lower boundary. The Northern Mistbelt Forests are typically
species rich, containing a mixture of afrotemperate elements
and species of subtropical provenience, indicating a floristic (and
possibly also biogeographic-evolutionary) link of these forests
to the Scarp Forests. This phenomenon is clearly observed along
the Northern Escarpment below God’s Window and Marieskop,
and in the Barberton region (Morgenthal & Cilliers 1999).
References Van der Schijff & Schoonraad (1971), Scheepers (1978), Deall
et al. (1989), Von Breitenbach (1990), Matthews et al. (1992), Geldenhuys
& Murray (1993), Geldenhuys & Pieterse (1993), Masson (1994), Morgenthal
& Cilliers (1999), Stalmans et al. (1999), Geldenhuys & Venter (2002), Von
Maltitz et al. (2003), Lötter & Beck (2004), Geldenhuys & Mucina (2006).
Semi-Coast Forest (Edwards 1967). Tongaland-Pondoland Undifferentiated
Forest p.p. (White 1983). Coast Scarp Forest (Cooper 1985). Pondoland
Coastal Plateau Sourveld p.p. & Transitional Coastal Forest (Acocks 1988).
Natal and Transkei Coastal Forests p.p. (Phillipson & Russell 1988). Ngoye
Group Forests p.p. (MacDevette et al. 1989). Pondoland Coast Forest &
South Coast Forest (Cooper & Swart 1992). Moist Subtropical Forest (Cawe
1996). Coastal Forest p.p. (Low & Rebelo 1996). Eastern Scarp Forest,
Pondoland Scarp Forest and Transkei Coastal Scarp Forest (Von Maltitz et
al. 2003).
Distribution Eastern Cape, KwaZulu-Natal and Mpumalanga
Provinces as well as in Swaziland (and possibly also in
Mozambique): An archipelago of scattered patches (some of
them large, such as Ongoye) spanning southern Mpumalanga
(Crocodile River Gorge), the southern part of Lebombo
Mountains (KwaZulu-Natal) and reaching nearly as far as Kei
River Mouth on the Transkei coast. Patches of this forest lie as far
as 140 km inland (Mpumalanga), but extend increasingly closer
to the sea in a southward direction—in Pondoland, and southern Transkei they occur at the coast or in deep gorges, often
associated with krantzes, scarps and coastal platforms. Most of
the patches occur at low altitudes between 50 and 600 m.
Vegetation & Landscape Features Tall (15–25 m), species-rich
and structurally diverse, multilayered forests, with well-developed canopy and understorey tree layers, but a poorly developed
herb layer. Buttressed stems are common in the Scarp Forest.
The most conspicuous trees are Buxus macowanii, B. natalensis,
Drypetes gerrardii, Englerophytum natalense, Harpephyllum
caffrum, Heywoodia lucens, Memecylon natalense, Millettia
grandis, Oricia bachmannii, Philenoptera sutherlandii, Rinorea
angustifolia, Rothmannia globosa and Umtiza listeriana.
Geology & Soils Natal Sandstone outcrops (Msikaba Group
Sandstones in Pondoland) as well as syenitic granite, rhyolite of
the Jozini Formation of the Lebombo Group (Karoo Supergroup)
and other Karoo sedimentary rocks; supporting nutrient poor,
leached and shallow soils.
602
Afrotemperate, Subtropical and Azonal Forests
L. Mucina
FOz 5 Scarp Forest
Figure 12.14 FOz 5 Scarp Forest: Endemic-rich subtropical scarp
forests on Msikaba sandstones in the gorge of the Umtamvuna River
near Port Edward (southern KwaZulu-Natal).
Important Taxa Tall Trees: Buxus natalensis (d), Drypetes gerrardii (d), Englerophytum natalense (d), Harpephyllum caffrum (d), Heywoodia lucens (d), Rothmannia globosa (d),
Commiphora harveyi, C. woodii, Drypetes arguta, Manilkara
discolor, Nectaropetalum capense, Nuxia congesta, Olinia
emarginata, Ptaeroxylon obliquum, Pterocelastrus tricuspidatus, Vitellariopsis marginata. Small Trees: Buxus macowanii
(d), Rinorea angustifolia (d), Dombeya cymosa, Encephalartos
natalensis, E. villosus, Ochna natalitia, Strychnos henningsii, S.
mitis. Herbaceous Climbers: Flagellaria guineensis, Thunbergia
alata. Tall Shrubs: Memecylon natalense (d), Eugenia natalitia.
Low Shrub: Stangeria eriopus. Soft Shrub: Piper capense. Herbs:
Begonia dregei, B. homonyma, Streptocarpus grandis, S. johannis. Geophytic Herb: Clivia miniata.
Biogeographically Important Taxon Tall Shrub: Pseudoscolopia
polyantha (disjunct populations also in Capensis in AZa 1 Fynbos
Riparian Vegetation).
Endemic Taxa Tall Trees: Millettia grandis (d), Oricia bachmannii (d), Philenoptera sutherlandii (d), Umtiza listeriana (d),
Celtis mildbraedii, Colubrina nicholsonii, Cryptocarya myrtifolia, C. wyliei, Dahlgrenodendron natalense, Jubaeopsis caffra,
Manilkara nicholsonii, Maytenus oleosa, Pseudosalacia streyi,
Rinorea domatiosa. Small Trees: Alberta magna, Albizia suluensis, Apodytes abbottii, Canthium vanwykii, Encephalartos woodii
(extinct in the wild), Gerrardanthus tomentosus, Rhynchocalyx
lawsonioides, Tarchonanthus trilobus var. trilobus. Woody
Climber: Podranea ricasoliana (d). Epiphytic Herb: Bolusiella
S %
19 (2006)
maudiae. Epiphytic Shrub: Dermatobotrys saundersii. Epiphytic
Parasitic Shrubs: Actinanthella wyliei, Helixanthera woodii. Tall
Shrubs: Eugenia simii, E. verdoorniae, Gymnosporia bachmannii,
Justicia bolusii, J. petiolaris subsp. bowiei, Oxyanthus pyriformis,
Putterlickia retrospinosa. Soft Shrubs: Heterosamara galpinii,
Metarungia galpinii. Herbs: Impatiens flanaganiae, Plectranthus
oribiensis, P. praetermissus, Streptocarpus fasciatus, S. kentaniensis, S. lupatanus, S. porphyrostachys, S. primulifolius subsp.
formosus. Geophytic Herbs: Clivia robusta (d), C. gardenii.
Succulent Herbs: Plectranthus ernstii, P. hilliardiae subsp. australis, P. hilliardiae subsp. hilliardiae, P. oertendahlii, P. saccatus
var. longitubus.
Conservation Least threatened in protected areas, but exposed
to over-exploitation elsewhere. Target 40%. More than 20%
statutorily conserved in Umtiza and Manubi Nature Reserves,
Dwesa-Cwebe Wildlife Reserve & Marine Sanctuary, Hluleka,
Mount Thesiger, Umkambati, Umtamvuna, Oribi Gorge, Vernon
Crookes, Krantzkloof, Nkandla, Ongoye, Dlinza, Entumeni,
Ghost Mountain and Hlatikulu (Gwalinweni) Nature Reserves as
well as in Hluhluwe-iMfolozi Park. Still most of the approximately
70 smaller scarp forests between Durban and Umtamvuna are
not protected. Proclamation of the planned Pondoland National
Park is expected to improve the conservation status of these
unique forests along the Wild Coast. Smaller patches of the
northern scarp forests are protected in the Barberton area, in
southern Kruger National Park and in some Swaziland nature
reserves. Almost 5% has been transformed for cultivation or
plantations. Aliens such as Chromolaena odorata, Solanum
mauritianum, Melia azedarach, Lantana camara and Litsea sebifera are of concern locally. Collapse of traditional authorities
in both Eastern Cape (especially in Transkei and in KwaZulu)
has led to uncontrolled use of forests formerly protected under
the authority of headmen and chiefs. Bark stripping, muthi
collection, deadwood extraction, and land-claims may become
other major sources of threat to the existence of some
forest patches (Von Maltitz et al. 2003). Dahlgrenodendron
natalense and Metarungia galpinii are listed as endangered.
Encephalartos ngoyanus, Eugenia simii, Jubaeopsis caffra
and Rhynchocalyx lawsonioides are vulnerable. Encephalartos
woodii (formerly found only in the Ongoye Forest) is extinct in
the wild, and survives in about five individuals in various living
botanical collections.
FOz 6 Southern Coastal Forest
Coastal Forest (Taylor 1961, Knight 1989). Coastal Dune Bush (Comins 1962).
Alexandria Forest (Phillipson & Russell 1978). Alexandria Forest p.p. (Acocks
1988). Mature Dune Forests (Burns 1986, Burns & Raal 1993). Coastal Forest
p.p. (Low & Rebelo 1996). Eastern Cape Dune Forest, Albany Coastal Forest
and Western Cape Milkwood Forest (Von Maltitz et al. 2003).
Distribution Eastern Cape and Western Cape Provinces:
Coastal plains between Alexandria and Van Stadens River canyon (west of Port Elizabeth) and on coastal dunes of the Eastern
Cape. Also found at low altitudes (close to the sea) in deeply
incised river valleys in the Albany District surrounded by subtropical succulent thickets. The westernmost forest type of this
group is the Western Cape Milkwood Forest found as an interrupted belt of patches stretching along the southern seaboard
between Nature’s Valley (Plettenberg Bay) and Llandudno (Cape
Town). At low altitudes between 20 and 340 m (most patches).
Vegetation & Landscape Features Generally low forests
dominated by Celtis africana, Sideroxylon inerme, Mimusops
caffra and Dovyalis rotundifolia. In the eastern regions of the
distribution area, having well-developed low-tree and shrub
(Brachylaena discolor, Strychnos decussata, Euclea natalensis,
Dracaena aletriformis etc.) as well as herb (Isoglossa woodii,
Hypoestes aristata, Laportea grossa, Oxalis pes-caprae) layers,
becoming increasingly floristically and structurally impoverished
in a westward direction.
Geology & Soils Well-drained sandy soils of coastal (dune)
origin over sedimentary rocks of Alexandria and Nanaga
Formations of the Algoa Group. Loamy skeletal soils are supported by the Bokkeveld Group sediments, while deep, nutrient-rich sandy soils over aeolinite or limestone of Bredasdorp
Group. The patches situated deeper inland (such as those in
Albany region) are found at colluvial valley-bottom sediments
derived from Karoo Supergroup shales.
Important Taxa Tall Trees: Celtis africana (d), Ficus burkei (d),
Mimusops caffra (d), Nuxia congesta (d), Rhus chirindensis (d),
Schotia latifolia (d), Sideroxylon inerme (d), Vepris lanceolata
(d), Afrocarpus falcatus. Small Trees: Allophylus natalensis (d),
Brachylaena discolor subsp. discolor (d), Diospyros natalensis (d),
Euclea natalensis (d), E. racemosa (d), Gymnosporia buxifolia (d),
References Huntley (1965), Van Wyk (1981, 1989),
Nicholson (1982), Whateley & Porter (1983),
Cooper (1985), Acocks (1988), MacDevette et
al. (1989), Cawe (1990, 1996), Cooper & Swart
(1992), Van Wyk & Everard (1993a, b), Everard
et al. (1995), Glen (1996), Jacobs (1996), Van
Wyk & Smith (2001), Von Maltitz et al. (2003),
Geldenhuys & Mucina (2006).
L. Mucina
Remarks Biogeographically (and from
the point of view of biodiversity) this
is probably the most valuable forest in
South Africa housing many endemic species, six endemic genera and one endemic
family (Rhynchocalycaceae) of trees and
relict occurrences of small populations of
Encephalartos, suggesting that this vegetation unit is biogeographically ancient.
The endemism in the herbaceous understorey is also high, particularly in the
genera Plectranthus and Streptocarpus.
The Pondoland Scarp Forest is a core
vegetation unit of the Pondoland Centre
of Endemism as defined by Van Wyk &
Smith (2001).
Figure 12.15 FOz 6 Southern Coastal Forest: Remnants of milkwood (Sideroxylon inerme) dune
forests in Gordon’s Bay (Western Cape).
Afrotemperate, Subtropical and Azonal Forests
603
S %
19 (2006)
Maytenus undata (d), Mystroxylon aethiopicum (d), Strychnos
decussata (d), Trichocladus ellipticus (d), Atalaya capensis,
Brachylaena ilicifolia, Encephalartos altensteinii. Succulent Tree:
Euphorbia grandidens. Woody Climbers: Behnia reticulata (d),
Rhoicissus tomentosa (d), Tecoma capensis. Succulent Woody
Climber: Aloe ciliaris. Herbaceous Climbers: Cissampelos
torulosa, Cynanchum obtusifolium. Tall Shrubs: Carissa
bispinosa subsp. bispinosa (d), Hyperacanthus amoenus (d),
Maytenus lucida, Olea exasperata, Rhus glauca. Low Shrub:
Phyllanthus heterophyllus. Soft Shrubs: Euphorbia kraussiana
(d), Hypoestes aristata (d), Isoglossa woodii (d). Megaherbs:
Dracaena aletriformis (d). Herb: Laportea grossa (d). Geophytic
Herb: Oxalis pes-caprae (d). Succulent Herbs: Sansevieria hyacinthoides (d). Graminoids: Cyperus albostriatus (d), Ehrharta
erecta (d), Oplismenus hirtellus (d).
Biogeographically Important Taxa (Southern distribution
limit) Tall Tree: Erythrina caffra (d). Small Trees: Dovyalis rotundifolia (d), Deinbollia oblongifolia.
Conservation Least threatened. Target: 40%. More than half
of the area of these forests is under statutory conservation
since the frontal dune cordons along the Eastern Cape coast
fall largely on state-owned land. The Eastern Cape Dune Forests
(sensu Von Maltitz et al. 2003) are relatively well-preserved
by Eastern Cape government authorities in Cape Morgan,
Bosbokstrand, Cape Henderson, Kwelera, Three Sisters, Joan
Muirhead and Woody Cape Nature Reserves; the latter is now
part of the Greater Addo Elephant National Park. The Albany
Coastal Forests are protected in the Greater Addo Elephant
National Park (including the extensive Alexandria Forest),
Waters Meeting, Kap River, Thomas Baines, Peddlar’s Bush, The
Island and Maitland River Nature Reserves. The Western Cape
Milkwood Forests (sensu Von Maltitz et al. 2003) are well preserved in Goukamma Nature Reserve and Wilderness National
Park (now incorporated into the Garden Route National Park),
De Hoop, De Mond and Walker Bay Nature Reserves. A number
of private reserves protect patches of the Southern Coastal
Forests both in the Eastern Cape and Western Cape. About
6% has been transformed mainly for cultivation or by urbanisation. Invasion by woody aliens such as Acacia cyclops, A. saligna
and Casuarina equisetifolia are a serious concern especially on
the dunes. The most serious threat to these forests is posed by
coastal development, accidental fires, and in the Eastern Cape
also by mining of heavy minerals from the coastal dunes (Von
Maltitz et al. 2003). Encephalartos altensteinii, occurring in the
Eastern Cape, is listed as vulnerable.
Remarks Southern Coastal Forests can be viewed as an impoverished form of Northern Coastal Forests. They show features
of interesting biogeographic and floristic transitions between
forests of subtropical and afrotemperate provenience and character (see also Phillipson & Russell 1978).
References Taylor (1961), Phillipson & Russell (1978), Burns (1986), Acocks
(1988), Cowling et al. (1988), Lubke & Strong (1988), Knight (1989),
McKenzie et al. (1990), Cooper & Swart (1992), Von Maltitz et al. (2003),
Geldenhuys & Mucina (2006).
FOz 7 Northern Coastal Forest
Coast Forest & Psammophilous Bush (Bews 1920). Coastal Dune Forest
& Coast Lowland Forest (Edwards 1967). Dune Forest & Undifferentiated
Lowland Forest (Moll & White 1978). Tongaland-Pondoland Undifferentiated
Forest p.p. (White 1983). Typical Coastal-belt Forest (Acocks 1988). Typical
Coast Lowland Forest (Bartholomew 1989). Mozambique Coastal Plain Forest
(MacDevette et al. 1989). Dune Forest (Cooper & Swart 1992). KwaZulu-Natal
Coastal Forest and KwaZulu-Natal Dune Forest (Von Maltitz et al. 2003).
604
Afrotemperate, Subtropical and Azonal Forests
L. Mucina
Endemic Taxon Small Tree: Sterculia alexandri.
Figure 12.16 FOz 7 Northern Coastal Forest: Interior of a scarp
forest with Strelitzia nicolai in the Vernon Crookes Nature Reserve near
Scottburgh (KwaZulu-Natal).
Distribution KwaZulu-Natal and (to a very small extent) Eastern
Cape Province: Especially along the seaboards of Indian Ocean
of KwaZulu-Natal Province and particularly well-developed in
Maputaland. Few patches of the dune forest also occur on the
Wild Coast of Transkei (Eastern Cape Province). Beyond South
Africa these forests occur throughout the Mozambican seaboard as far as southern Tanzania. At low altitudes, from about
10 to 150 m.
Vegetation & Landscape Features Species-rich, tall/mediumheight subtropical coastal forests occur on coastal (rolling) plains
and stabilised coastal dunes. Forests of the coastal plains are
dominated by Drypetes natalensis, Englerophytum natalense,
Albizia adianthifolia, Diospyros inhacaensis etc. The low-tree
and shrubby understoreys are species-rich and comprise many
taxa of (sub)tropical provenience. On dunes, these forests have
well-developed tree, shrub and herb layers. Mimusops caffra, Sideroxylon inerme, Dovyalis longispina, Acacia kosiensis
and Psydrax obovata subsp. obovata are the most common
constituents of the tree layer. Brachylaena discolor var. discolor, Chrysanthemoides monilifera subsp. rotundata, Carissa
bispinosa subsp. bispinosa, Euclea natalensis, E. racemosa,
Eugenia capensis, Gymnosporia nemorosa, Kraussia floribunda,
Peddiea africana, Strelitzia nicolai and Dracaena aletriformis are
frequent in the understorey. The herb layer usually contains by
Asystasia gangetica, Isoglossa woodii, Microsorum scolopendria,
Zamioculcas zamiifolia and Oplismenus hirtellus. Herbaceous
S %
19 (2006)
vines and woody climbers (Acacia kraussiana, Artabotrys monteiroae, Dalbergia armata, Landolphia kirkii, Monanthotaxis
caffra, Rhoicissus tomentosa, Rhus nebulosa, Scutia myrtina,
Uvaria caffra, Gloriosa superba etc.) are important structural
determinants in these forests.
Geology & Soils Well-developed sandy-loamy soils on sedimentary rocks of the Karoo Supergroup and Jurassic intrusive
dolerites (in places) as well as on Holocene marine sediments.
Forming stabilised sandy dune systems, mostly younger than
10 000 years and still in the process of sedimentation.
Important Taxa Tall Trees: Albizia adianthifolia (d), Drypetes
reticulata (d), Mimusops caffra (d), Psydrax obovata subsp.
obovata (d), Sideroxylon inerme (d), Trichilia emetica, Vepris
lanceolata. Small Trees: Brachylaena discolor subsp. discolor
(d), Buxus natalensis (d), Cavacoa aurea (d), Englerophytum
natalense (d), Erythroxylum emarginatum (d), Eugenia capensis (d), Gymnosporia nemorosa (d), Kraussia floribunda (d),
Peddiea africana (d), Rhus nebulosa (d), Strychnos henningsii
(d), Acokanthera oblongifolia, Callichilia orientalis, Deinbollia
oblongifolia, Dovyalis rhamnoides, Euclea natalensis, E. racemosa, Scutia myrtina, Strychnos decussata, Tapura fischeri,
Teclea gerrardii, Turraea floribunda, Xylotheca kraussiana.
Woody Climbers: Acacia kraussiana (d), Rhoicissus tomentosa (d), Dalbergia armata, Monanthotaxis caffra, Uvaria
caffra. Herbaceous Climber: Gloriosa superba. Tall Shrubs:
Carissa bispinosa subsp. bispinosa, Hyperacanthus amoenus, Putterlickia verrucosa. Low Shrub: Chrysanthemoides
monilifera subsp. rotundata. Soft Shrub: Isoglossa woodii (d).
Megaherbs: Dracaena aletriformis (d), Strelitzia nicolai (d).
Herbs: Achyranthes aspera (d), Asystasia gangetica (d), Laportea
peduncularis (d). Geophytic Herb: Microsorum scolopendria (d).
Graminoids: Cyperus albostriatus (d), Oplismenus hirtellus (d).
Biogeographically Important Taxa (MMaputaland endemic,
Southern distribution limit) Tall Trees: Celtis gomphophyllaS
(d), Chrysophyllum viridifoliumS (d), Diospyros inhacaensisS (d),
Drypetes natalensisS (d), Cola natalensisS, Inhambanella henriquesii S, Manilkara concolor S. Small Trees: Coffea racemosaS (d),
Dovyalis longispinaS (d), Artabotrys monteiroaeS, Encephalartos
ferox M, Erythrococca berberideaS, Pancovia golungensis S.
Tall Shrubs: Haplocoelum foliolosum subsp. mombasenseS,
Landolphia kirkii S.
S
(Von Maltitz et al. 2003). Coastal dunes are being prospected
and exploited for heavy metals—some companies are, however,
actively engaged in dune forest regeneration programmes (Van
Aarde & Wassenaar 1999). These subtropical forests are sensitive
to alien plant invasion, and invaders such as Chromolaena odorata, species of Pereskia and Acacia are posing serious threats.
Maputaland endemic Encephalartos ferox is listed as vulnerable.
Remarks However, many tropical species reach their southern
distribution here. Von Maltitz et al. (2003) classified these forests into two Forest Types, namely the KwaZulu-Natal Coastal
Forests (plains) and KwaZulu-Natal Dune Forests. The Manguzi
Forest (near KaNgwanase in Maputaland) and some forest in
the False Bay area of St Lucia show transitional features towards
Sand Forest (Kirkwood & Midgley 1999).
References Bews (1920), Breen (1971), Venter (1976), Wager (1976),
Weisser (1978, 1980, 1987), Ward (1980), MacDevette (1987, 1989, 1993),
MacDevette & Gordon (1989a, b), MacDevette & MacDevette (1989),
MacDevette et al. (1989), Cooper & Swart (1992), Weisser et al. (1992), Van
Wyk & Everard (1992), Van Wyk et al. (1996), Von Maltitz et al. (1996, 2003),
Lubbe (1997), Kirkwood & Midgley (1999), Van Aarde & Wassenaar (1999),
Geldenhuys & Mucina (2006).
FOz 8 Sand Forest
Licuati Forest (Myre 1964). Baphia massaiensis–Guibourtia conjugata thicket
(Van Rooyen et al. 1981). Tropical Dry Forests (MacDevette et al. 1989). Sand
Forest (Low & Rebelo 1996). Licuati Sand Forest (Von Maltitz et al. 2003).
Distribution KwaZulu-Natal Province and Mozambique:
Occurring in a broad and highly fragmented belt in South Africa
from False Bay Park (Greater St Lucia Wetland Park) in the south
to the national border with Mozambique (Tembe Elephant Park
and Ndumo Game Reserve). The main distribution of this forest
is in Maputaland, where still reasonably extensive patches of
this forest can be encountered. Special thicket communities,
floristically very close to the Maputaland sand forest, are found
in the northern part of the Kruger National Park—here imbedded within Nwambyia and Pumbe sandvelds. At low altitudes
between 20 and 160 m, with about half of the area between
100 and 120 m.
Vegetation & Landscape Features Dense thickets of 5–6
m (‘short forest’ of Matthews et al. 2001) up to tall forests
Conservation Least threatened in general, but still under threat on coastal
dunes of KwaZulu-Natal (due to mining). Target 43%. About 68% statutorily
conserved in Manguzi, Greater St Lucia
Wetland Park, Maphelana, Dukuduku,
Sodwana Bay, Richards Bay, Umlalazi,
Enseleni, Amathigulu, Harold Johnson,
Hawaan, Umhlanga Lagoon, Kenneth
Stainbank, Impisini, Skyline, Frederika,
Mpenjati Nature Reserves, mostly under
Ezemvelo KZN Wildlife magement. The
original extent of these forests has been
diminished by agriculture (mainly sugar
cane and fruit gardens), timber plantations, urban sprawl and tourism-oriented
development on the KwaZulu-Natal coast.
The current threats count (besides the
ongoing coastal development pressures)
also illegal clearing of the forest and turning it into lots for small-scale agriculture
W.S. Matthews
Endemic Taxon Small Tree: Acacia
kosiensis (d).
Figure 12.17 FOz 8 Sand Forest: Aerial view of patches of sand forest in Maputaland (KwaZuluNatal) surrounded by short savanna grasslands.
Afrotemperate, Subtropical and Azonal Forests
605
S %
with the canopy reaching 15 m (‘tall forest’ of Matthews et
al. 2001), with well-developed shrub layer and very poorly
developed ground layer. The dominant trees are Cleistanthus
schlechteri, Dialium schlechteri and emergent Newtonia hildebrandtii in Maputaland, whereas Baphia massaiensis subsp.
obovata, Cleistanthus schlechteri and Guibourtia conjugata are
most conspicuous in the tree layer in the Nwambyia and Pumbe
regions. The shrub layer is dominated by Croton pseudopulchellus, Cola greenwayi, Pteleopsis myrtifolia, Psydrax locuples,
Drypetes arguta and the woody climber Uvaria lucida. The most
conspicuous graminoid in the herb layer is Eragrostis moggii.
Epiphytic orchids and lichens festoon the tall trees.
Geology & Soils Grey to orange-brown (Maputaland), and dull
brown/red-brown (Kruger National Park), deep arenosols and
dystric (strongly leached) regosols; soils contain very little clay
and are acidic. In Maputaland these soils develop on ancient (up
to 3 myr old; Ndumo Hill cordon is up 5 myr old) mega-dune
systems (crests, slopes and rarely also inter-dune depressions) of
the Maputaland and Zululand Groups.
Important Taxa (MIn South Africa only in Maputaland, KOnly in
northern Kruger National Park) Tall Trees: Balanites maughamii
(d), Cleistanthus schlechteri (d), Cola greenwayi M (d), Dialium
schlechteri M (d), Drypetes argutaM (d), Guibourtia conjugataK (d), Newtonia hildebrandtii (d), Pteleopsis myrtifolia (d),
Drypetes mossambicensis K, D. natalensis M, Lagynias lasiantha,
Lannea antiscorbutica M, Pterocarpus lucens subsp. antunesii K,
Suregada zanzibariensis M, Xeroderris stuhlmannii K. Small
Trees: Baphia massaiensis subsp. obovataK (d), Hymenocardia
ulmoides (d), Wrightia natalensis (d), Alchornea laxifloraK,
Brachylaena huillensis, Callichilia orientalis M, Cassipourea mossambicensis M, Cavacoa aureaM, Coffea racemosaM, Dalbergia
nitidulaK, Heinsia crinitaK, Hexalobus monopetalus K, Hugonia
orientalis K, Markhamia zanzibaricaK, Monodora junodii var.
junodii, Strychnos madagascariensis, Toddaliopsis bremekampii, Xylotheca kraussiana. Woody Climbers: Uvaria lucida
(d), Prionostemma delagoensis var. delagoensis M, Sclerochiton
apiculatus M, Uvaria gracilipes K. Tall Shrubs: Croton pseudopulchellus (d), C. steenkampianus (d), Canthium setiflorum subsp.
setiflorum, Coptosperma zygoonK, Erythrococca menyharthii K,
Haplocoelum foliolosum subsp. mombasense M, Pavetta catophylla. Low Shrubs: Tricalysia junodii var. junodii, Warneckea
sousae. Herb: Aneilema arenicolaM. Succulent Herb: Crassula
maputensis M. Graminoids: Eragrostis moggii M (d), Panicum
laticomum.
Endemic Taxa (MIn South Africa only in Maputaland, KOnly
in northern Kruger National Park) Tall Tree: Erythrophleum
lasianthumM. Small Trees: Monodora junodii var. macranthaK,
Oxyanthus latifolius M. Woody Climbers: Combretum celastroides subsp. orientale, Schlechterina mitostemmatoides M,
Strophanthus luteolus M. Tall Shrubs: Gymnosporia oxycarpaK,
G. pubescens, Psydrax fragrantissimaM, Tricalysia delagoensis M. Low Shrubs: Leptactina delagoensis subsp. delagoensis,
Salacia leptocladaM. Geophytic Herb: Bonatea lamprophyllaM.
Graminoid: Brachychloa schiemannianaM.
Conservation Critically endangered due to its vulverability and
economic pressure. Target 100%. Some 42% statutorily conserved in Tembe Elephant Park, Sileza Nature Reserve, Ndumo
and Mkhuze Game Reserves, Greater St Lucia Wetland Park,
Kruger National Park and in private Phinda Resource Reserve.
An unknown portion was lost through clearing for subsistence
agriculture and grazing. Uncontrolled extraction of wood for
fuel and woodcraft is a problem as is the high density of elephants in Tembe Elephant Park—the best preserved portion of
the sand forest in South Africa.
606
Afrotemperate, Subtropical and Azonal Forests
19 (2006)
Remarks This forest houses a large number of local Maputaland
endemics (Matthews et al. 1999, 2001) and forms the core
of the Maputaland Regional Centre of Endemism (Van Wyk &
Smith 2001). Many other tropical elements have their southernmost distribution here and/or are found in South Africa exclusively here (Van Wyk & Smith 2001, Schmidt et al. 2002).
References Myre (1964), De Moor et al. (1977), Moll (1978), Van Rooyen
(1978), Van Rooyen et al. (1981), Gertenbach (1983), Kirkwood & Midgley
(1999), Matthews et al. (1999, 2001), Van Wyk & Smith (2001), Schmidt
et al. (2002), Von Maltitz et al. (2003), Gaugris et al. (2004), Geldenhuys &
Mucina (2006).
FOz 9 Ironwood Dry Forest
Androstachys johnsonii–Croton pseudopulchellus dry forest (Van Rooyen et
al. 1981).
Distribution Limpopo Province: Northern part of the Kruger
National Park in the Lebombo Mountains as well as in the
surroundings of Punda Maria. Possibly also found in the
Soutpansberg. Found at most mapped patches at altitudes
between 280 and 580 m.
Vegetation & Landscape Features On moderate to steep
mountain slopes (up to 22°), forming dense forests (sometimes
called ‘thicket’) dominated by Lebombo Ironwood (Androstachys
johnsonii), which may build a closed canopy reaching up to 10
m. Croton pseudopulchellus attains high densities in the understorey. The adjacent bushveld communities are often sharply
demarcated from the forest (Van Rooyen et al. 1981).
Geology & Soil fine to medium-textured (dark red-brown to
brown-red) sand to sandy- loamy soil derived from Soutpansberg
Group sandstone and quartzite, Karoo Supergroup sandstone as
well as Lebombo Group rhyolites and the Cretaceous Malvernia
Formation sandstones. Rocks cover 60% of the surface and soil
depth ranges from 100–250 mm. pH of soil spans 4.8–8.3 and
there is a moderate concentration of soluble salts or the soil is
strongly leached in places (Van Rooyen et al. 1981).
Important Taxa (*Also occurring in FOz 8 Sand Forest) Tall
Trees: Androstachys johnsonii (d), Entandrophragma caudatum*. Small Trees: Alchornea laxiflora*, Boscia albitrunca,
Cassia abbreviata subsp. beareana, Commiphora tenuipetiolata, Croton gratissimus, Euphorbia espinosa, Hymenodictyon
parvifolium, Monodora junodii var. junodii*, Pouzolzia mixta,
Vitex ferruginea*. Succulent Tree: Euphorbia confinalis. Woody
Climbers: Combretum paniculatum, Strophanthus kombe*.
Herbaceous Climber: Ipomoea magnusiana. Tall Shrubs:
Croton pseudopulchellus* (d), C. madandensis, Dombeya
kirkii, Phyllanthus reticulatus. Low Shrubs: Asparagus setaceus,
Hibiscus micranthus, Phyllanthus pinnatus. Herbs: Achyranthes
aspera (d), Commelina benghalensis (d), Selaginella dregei (d),
Blainvillea gayana, Blepharis maderaspatensis, Celosia trigyna,
Cleome monophylla, Corchorus longipedunculatus, Monechma
debile, Pupalia lappacea, Spermacoce senensis, Triumfetta
pentandra, Xerophyta equisetoides, X. humilis. Geophytic
Herbs: Cheilanthes viridis, Pellaea calomelanos. Graminoids:
Aristida congesta (d), Panicum maximum (d), Brachiaria deflexa,
Danthoniopsis pruinosa, Digitaria eriantha, Enteropogon macrostachyus, Leptocarydion vulpiastrum, Setaria pumila, S. sagittifolia, Sporobolus panicoides.
Endemic Taxon Tall Shrub: Pavetta tshikondeni.
Conservation Target 100%. About 78% (of the mapped
patches) statutorily conserved in Kruger National Park and
Mlawula Nature Reserve. Only a very small portion has been
transformed.
S %
19 (2006)
Remarks Despite early recognition of this vegetation as ‘dry forest’ (Van Rooyen 1978, Van Rooyen et al. 1981), forest managers have, surprisingly, persisted in considering it a ‘thicket’ form
of savanna. The Punda Maria ironwood forests are more mesic
than those of the Lebombo (Gertenbach 1983). More extensive and still taller forest stands of this vegetation type can be
found in neighbouring Mozambique and southern Zimbabwe.
Due to lack of data we have not mapped this forest type in the
Soutpansberg range.
References Van Wyk (1973), Van Rooyen (1978), Van Rooyen et al. (1981),
Coetzee (1983), Gertenbach (1983), Von Maltitz et al. (2003), Geldenhuys
& Mucina (2006).
Azonal Units
FOa 1 Lowveld Riverine Forest
Gallery Forest (sensu auct.). Fringing Forest (Moll & White 1978). Riverine
Forest (Cooper 1985). Lowveld Riverine Forest (Von Maltitz et al. 2003).
Distribution KwaZulu-Natal, Mpumalanga and Limpopo
Provinces (as well as in Swaziland and other countries neighbouring on South Africa): Broad river alluvia of Zululand
(Hluhluwe, middle reaches of Phongolo), Maputaland (Mkuze,
lower reaches of Phongolo, Usutu) and numerous rivers draining the northern provinces of South Africa (Limpopo, Luvuvhu,
Phongolo, Shingwedzi, Letaba, Olifants, Timbavati, Sabie,
Crocodile). At low altitudes, from about 20 to 320 m.
Vegetation & Landscape Features Tall forests fringing larger
rivers (gallery forests) and water pans. When dominated by Ficus
sycomorus or Diospyros mespiliformis (alluvial sediments along
major rivers), these forests are dense and tall, structured into
several tree layers and with a well-developed dense shrub layer.
Geology, Soils & Hydrology Recent alluvial deposits with
deep, fine-textured soils (e.g. Dundee soil form). Subject to frequent flooding and occasionally to very heavy flood spells.
Conservation Critically endangered. Target 100%. Half statutorily conserved in Kruger and Mapungubwe National Parks,
Greater St Lucia Wetland Park, Ndumo and Mkhuze Game
Reserves (here the Fig Forest is one of the prime examples),
Mlawula and Blyde River Canyon National Park in South Africa,
Royal Hlane Game Sanctuary in Swaziland as well as in a
number of private game and nature reserves east and south of
the Kruger National Park, Selati Game Reserve, Limpopo Valley
Wildlife Utilisation Area etc. Unknown portion has been irreversibly transformed by clearing for cultivation. Aliens such as Melia
azedarach, Lantana camara, Psidium guajava, Chromolaena
odorata, Caesalpinia decapetala are serious invaders in places.
Agricultural malpractices upstream, building of dams and excessive water extraction for agriculture and mining as well as local
exploitation for timber and non-timber forest products are serious threats to this vegetation (Von Maltitz et al. 2003).
Remarks Low (as compared to forests) riparian thickets found
along rivers in Lowveld and Central Bushveld feature as part of
the AZa 7 Subtropical Alluvial Vegetation.
References De Moor et al. (1977), Moll (1978), Van Rooyen (1978), Van
Rooyen et al. (1981), Gertenbach (1983), Whateley & Porter (1983), Cooper
(1985), Bredenkamp & Deutschländer (1995), Von Maltitz et al. (2003),
Geldenhuys & Mucina (2006).
FOa 2 Swamp Forest
Hygrophilous Bush, Waterboom Associes & Barringtonia Associes (Bews
1920). Hygrophilous Forest (Weisser 1978). Swamp Forest (Von Maltitz et
al. 2003).
Distribution KwaZulu-Natal and Eastern Cape Provinces: In
pockets and narrow ribbons extending in a narrow belt along
the Indian Ocean coast from Maputaland
as far south as Port Grosvenor in
Pondoland. Swamp Forests reach lower
latitudes than Mangrove Forests, which
suggests that they are climatically more
limited than the mangroves. At low altitude, mainly between 20 and 60 m.
L. Mucina
Important Taxa Tall Trees: Acacia robusta subsp. clavigera (d),
Breonadia salicina (d), Diospyros mespiliformis (d), Faidherbia
albida (d), Ficus sycomorus (d), Kigelia africana (d), Berchemia
discolor, Combretum erythrophyllum, C. imberbe, Ekebergia
capensis, Philenoptera violacea, Rauvolfia caffra, Spirostachys
africana, Syzygium guineense, Trichilia emetica, Xanthocercis
zambesiaca. Small Trees: Combretum hereroense, Croton megalobotrys, Hyphaene coriacea, Nuxia oppositifolia, Phoenix reclinata, Vernonia colorata. Tall Shrubs: Abutilon angulatum, Acacia
schweinfurthii, Ficus capreifolia. Soft Shrub: Hypoestes aristata.
Herb: Achyranthes aspera (d). Graminoids: Digitaria eriantha
(d), Panicum maximum (d), Echinochloa pyramidalis, Eriochloa
meyeriana, Panicum coloratum, Phragmites mauritianus, Setaria
incrassata, S. sphacelata, Sporobolus consimilis.
Figure 12.18 FOa 1 Lowveld Riverine Forest: Riparian forests with Acacia gerrardii on the
Crocodile River near Lephalale (Limpopo Province).
Vegetation & Landscape Features
12–15 m tall forests with two main
strata (canopy and shrub layers). The
dominating trees include Ficus trichopoda, Barringtonia racemosa, Casearia
gladiiformis, Cassipourea gummiflua,
Syzygium cordatum, Phoenix reclinata
and Raphia australis. Understorey is
poorly developed. Some ferns such as
Microsorum punctatum and Nephrolepis
biserrata are of importance and orchids
(Eulophia horsfallii) occur frequently.
Geology, Soils & Hydrology Very fine,
muddy, waterlogged soil, with organic
humus, a peat-like layer and anoxic conditions. The St Lucia swamp forests are
Afrotemperate, Subtropical and Azonal Forests
607
S %
19 (2006)
found on sand, sandy loam or loamy
sand with a moderate to high status
(7–17%) of organic matter. The soil is
acidic, pH range 2.5–6 (mean 3–4.5),
and calcium and magnesium concentrations can be high. Impeded drainage and poor aeration characterise soil
forms such as Sterkspruit, Valsrivier and
Katspruit (Nyalazi area) or Fernwood
and Champagne (Eastern Shores State
Forest in the St Lucia area). Water is
acidic to alkaline and mineral-rich with
high calcium, magnesium and conductivity values. Water tables were found to
fluctuate from the surface to a depth of
600 mm (Wessels 1991b).
J.C. Manning
Important Taxa Tall Trees: Barringtonia
racemosa (d), Ficus trichopoda (d),
Macaranga capensis (d), Rauvolfia
caffra (d), Schefflera umbellifera (d),
Shirakiopsis elliptica (d), Syzygium cordatum (d), Ficus lutea. Small Trees:
Figure 12.19 FOa 2 Swamp Forest: Scadoxus multiflorus subsp. katherinae (Amaryllidaceae)
Allophylus dregeanus (d), Bridelia
flowering in the understorey of swamp forest near Munster on the KwaZulu-Natal south coast.
micrantha (d), Cassipourea gummiflua
(d), Morella serrata (d), Phoenix reclinata (d), Sclerocroton inte- Geophytic Herbs: Eulophia horsfallii (d), Microsorum punctatum
gerrimum. Woody Climber: Adenopodia spicata. Herbaceous
(d), Nephrolepis biserrata (d). Graminoid: Scleria angusta (d).
Climbers: Stenochlaena tenuifolia (d), Ipomoea indica, I. mauriBiogeographically Important Taxa (all at southern distributiana. Tall Shrubs: Burchellia bubalina (d), Psychotria capensis (d),
tion limit) Tall Trees: Voacanga thouarsii (d), Scolopia stolzii. Tall
Tarenna pavettoides subsp. pavettoides (d), Hibiscus tiliaceus (d).
Shrub: Ficus verruculosa. Megaherb: Dracaena mannii.
Endemic Taxon Tall Tree: Raphia australis (d).
Conservation Critically endangered. Target 100%. Some
66% statutorily conserved in Greater St Lucia Wetland Park,
Maphelana, Dududuku, Raphia Palms and Umlalazi Nature
Reserves. Unknown portion has been already transformed
either for plantations or by illegal clearing for making fruit and
vegetable gardens. Especially the swamp forests in the Kosi Bay
area are disappearing with alarming speed. Chromolaena odorata, Lantana camara and Pereskia species are common invaders
in disturbed swamp forests. Change in local hydro-geological
conditions poses another serious threat to this fragile forest
ecosystem (Von Maltitz et al. 2003).
Remarks Swamp Forests have a strong tropical link and reach
their southernmost distribution limit in South Africa. The
endemic Raphia australis is limited to Maputaland and forms
an intriguing forest in the Kosi Bay lagoon system. It also forms
a planted grove in Mtunzini (KwaZulu-Natal).
References Bews (1920), Moll (1972), Venter (1972, 1976), Moll & White
(1978), Weisser (1978, 1987), Ward (1980), Weisser & Ward (1982), Wessels
(1991a, b), Weisser et al. (1992), Lubbe (1997), Von Maltitz et al. (2003),
Geldenhuys & Mucina (2006).
L. Mucina
FOa 3 Mangrove Forest
Figure 12.20 FOa 2 Swamp Forest: Interior of a swamp forest with
Ficus trichopoda near Mtunzini (KwaZulu-Natal).
608
Afrotemperate, Subtropical and Azonal Forests
Distribution KwaZulu-Natal and Eastern Cape Provinces:
Coastal lagoons and estuaries of Transkei as far south as
Kobonqaba Estuary—the highest latitude with extant mangroves in the world (Moll & Werger 1978, Ward & Bunyard
1992) as far north as KwaZulu-Natal/Mozambique border (Kosi
Bay estuary) and beyond to Mozambique and further northwards to tropical East Africa. At very low altitudes around sea
level.
Vegetation & Landscape Features Species-poor and often
monospecific, low and dense forests of mangroves (and fring-
19 (2006)
L. Mucina
L. Mucina
S %
Figure 12.21 FOa 3 Mangrove Forest: Interior of Avicennia marina
mangrove in St Lucia Estuary with tracks of a hippo (Hippopotamus
amphibius).
Figure 12.22 FOa 3 Mangrove Forest: Avicennia marina shrub on the
edge of a mangrove forest in Umlalazi Nature Reserve near Mtunzini
(KwaZulu-Natal).
ing thickets of Hibiscus tiliaceus and Acrostichum aureum) in
tidal zones of coastal lagoons and estuaries.
South African mangroves belong to the group of ‘East Coast
Mangroves’ (referring to eastern coasts of Africa).
Geology, Soils & Hydrology Mangroves occur between mean
sea level and mean high-water spring tide level in sheltered
estuaries on tidal flats built by recent sediments caused by
accretion of river-borne sediments, to which material brought
in from the sea with the rising tide is added; the soils are poorly
drained, saline, anoxic, fine-grained and rich in organic content
(coming from decomposing plant debris).
References Berjak et al. (1995), Moll & Werger (1978), Ward (1980), Ward
& Steinke (1982), Ward et al. (1986), Weisser (1987), MacDevette et al.
(1989), Cooper & Swart (1992), Ward & Bunyard (1992), Roberts (1993),
Steinke (1995), Colloty et al. (2002), Von Maltitz et al. (2003), Geldenhuys
& Mucina (2006).
Important Taxa Small Trees: Avicennia marina (d), Bruguiera
gymnorrhiza (d), Ceriops tagal, Lumnitzera racemosa,
Rhizophora mucronata, Xylocarpus granatum. Tall Shrub:
Hibiscus tiliaceus (d). Geophytic Herb: Acrostichum aureum (d).
Conservation Critically endangered. Target 100%. About 72%
statutorily conserved in Greater St Lucia Wetland Park, Richards
Bay, Beachwood Mangroves and Umlalazi Nature Reserves.
Much of the original extent of mangrove was lost in South Africa
through harbour development (Richards Bay and Durban), clearing for development (Durban) or they became degraded through
unfavourable agricultural practices upstream of the rivers feeding into the estuaries.
Remarks Mangrove Forests are imbedded within the Indian
Ocean Coastal Belt (see also Chapter 11) where they are
found to form a vegetation complex with AZe 3 Subtropical
Estuarine Salt Marshes. According to Moll & Werger (1978), the
12. Credits
The text of descriptions of all units was provided by L. Mucina.
The species lists were compiled by L. Mucina and C.J. Geldenhuys
(extracted from so far unpublished report by Von Maltitz et al.
2003, wherein the species lists were also created by the senior
authors of this chapter). C.J. Geldenhuys wrote the extensive
introductory text to the chapter (sections 1 to 10) to which L.
Mucina contributed several additions (especially to section 4).
L. Mucina has further contributed to the delimitation of several
forest patches in the Western Cape, Eastern Cape, KwaZuluNatal and Free State Provinces. C.J. Geldenhuys selected the
quotation on the opening page. G.P. von Maltitz contributed to
this chapter by providing unpublished material, leading to formulation of the sections on Conservation in the descriptions of
vegetation units. M.C. Lötter and L. Dobson have contributed
to improvement of the mapped forest coverage in Mpumalanga
and in Swaziland, respectively. M.C. Lötter and W.S. Matthews
Afrotemperate, Subtropical and Azonal Forests
609
S %
have contributed to the descriptions of FOz 4 and FOz 8, respectively, and provided further valuable comments on other parts of
the text and the mapped forest coverage. D.I.W. Euston-Brown
contributed an unpublished coverage of milkwood forests in
the Overberg region (FOz 6) and B. McKenzie helped mapping
forest patches in the Western Cape (FOz 1). M.C. Rutherford
and L.W. Powrie have provided environmental data used in the
descriptions of the vegetation units. M.C. Rutherford was also
instrumental in conceptual issues concerning units FOz 1, FOz 2
and FOa 1 as well as shaping the final appearance of the forest
patches on the map. L.W. Powrie and L. Mucina jointly produced Figures 12.2 and 12.3. M.C Rutherford and L.W. Powrie
supplied climate diagrams (Figure 12.8). M. Rouget and others
within the Directorate of Biodiversity Programmes, Policy and
Planning of SANBI provided the quantitative information for
each vegetation unit on various conservation issues.
The original Forest Biome Project Map (Anonymous 1987)
was provided by the CSIR, Pretoria through the project on
classification of indigenous forests (see Von Maltitz et al. 2003
for a public-domain report). In KwaZulu-Natal this coverage
was replaced by new data which resulted from a forest mapping project steered by Ezemvelo KZN Wildlife. In Mpumalanga
a part of the original Forest Biome Project Map was replaced
by coverage featured in an unpublished report by Emery et al.
(2002). We express our gratitude to DWAF, CSIR, Ezemvelo
KZN Wildlife and Mpumalanga Parks Board for providing these
sources. J.E. Burrows kindly commented on FOz 4 and suggested corrections to the species list. W.S. Matthews and J.C.
Manning contributed some photographs. R.A. Ward kindly collated the geological terminology. J. Gilliatt redrew Figure 12.4.
13. References
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Anonymous 1987. Map of South African indigenous evergreen forest. FRD,
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Bailey, C.L., Shackleton, C.M., Geldenhuys, C.J., Moshe, D., Flemming, G.,
Vink, E.R., Rathogwa, N.R. & Cawe, S.G. 1999. Guide to and summary of
the meta-database pertaining to selected attributes of South African indigenous forests and woodlands. Report ENV-P-C 99027, Division of Water,
Environment and Forestry Technology, CSIR, Pretoria.
Bartholomew, R.L.C. 1989. A quantitative assessment of Henderson forest,
Sunwich Port, Natal. In: Gordon, I.G. (ed.), Natal indigenous forests. A preliminary collection of reports on indigenous forests in Natal, pp. 119–133.
Natal Parks Board, Pietermaritzburg.
Basson, J.A. 1987. Energy implications of accelerated urbanization. S. Afr.
J. Sci. 83: 294–298.
Behr, C.M. & Bredenkamp, G.J. 1988. A phytosociological classification of
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13
Inland Azonal Vegetation
Ladislav Mucina, Michael C. Rutherford and Leslie
W. Powrie
with contributions by
Jacques Gerber, Hugo Bezuidenhout, Erwin J.J. Sieben,
Sarel S. Cilliers, P. Johann du Preez, John C. Manning, David
B. Hoare, Charles Boucher, Anthony G. Rebelo, George J.
Bredenkamp and Frances Siebert
Table of Contents
1
2
3
Introduction: Concepts Related to Zonality of Vegetation
Typology of Inland Azonal Vegetation in South Africa
Freshwater Wetlands, Alluvial and Inland Saline Vegetation
3.1 Freshwater Wetlands
3.2 Alluvial Vegetation
3.3 Inland Saline Vegetation
4
5
Caveats: Neglected Azonal Vegetation
Conservation Challenges: Status, Threats and Action
5.1 Value of Wetlands
5.2 Threats to Wetlands
5.3 Sustainable Use and Restoration of Wetlands
6
7
8
9
Research Challenges
Descriptions of Vegetation Units
Credits
References
618
619
621
621
622
624
626
627
627
627
629
629
630
652
652
List of Vegetation Units
Freshwater Wetlands
AZf 1 Cape Lowland Freshwater Wetlands
AZf 2 Cape Vernal Pools
AZf 3 Eastern Temperate Freshwater Wetlands
AZf 4 Drakensberg Wetlands
AZf 5 Lesotho Mires
AZf 6 Subtropical Freshwater Wetlands
630
630
631
632
633
634
635
Alluvial Vegetation
Aza 1 Fynbos Riparian Vegetation
AZa 2 Cape Lowland Alluvial Vegetation
AZa 3 Lower Gariep Alluvial Vegetation
AZa 4 Upper Gariep Alluvial Vegetation
AZa 5 Highveld Alluvial Vegetation
AZa 6 Albany Alluvial Vegetation
AZa 7 Subtropical Alluvial Vegetation
636
636
637
638
639
640
640
641
Continued on next page
L. Mucina
Figure 13.1 AZf 1 Cape Lowland Freshwater Wetlands: Dense cover of waterblommetjie
(Aponogeton distachyos) in a temporary pool near Elim (Agulhas Plain, Western Cape).
617
S %
Inland Saline Vegetation
AZi 1 Namaqualand Riviere
AZi 2 Namaqualand Salt Pans
AZi 3 Southern Kalahari Mekgacha
AZi 4 Southern Kalahari Salt Pans
AZi 5 Bushmanland Vloere
AZi 6 Southern Karoo Riviere
AZi 7 Tanqua Wash Riviere
AZi 8 Muscadel Riviere
AZi 9 Cape Inland Salt Pans
AZi 10 Highveld Salt Pans
AZi 11 Subtropical Salt Pans
1.
642
642
643
644
645
645
646
647
648
649
650
651
Introduction: Concepts Related to
Zonality of Vegetation
Water, salt and processes linked to concentration of both are
the major controls of the creation, maintenance and development of peculiar habitats. Habitats, formed in and around
flowing and stagnant freshwater bodies experience waterlogging (seasonal or permanent) and flooding (regular, irregular
or catastrophic), leading to formation of special soil forms.
Habitats with high levels of salt concentration form a highly
stressed environment for most plants and often markedly affect
the composition of plant communities. Invariably, both waterlogged and salt-laden habitats appear as ‘special’, deviating
strongly from the typical surrounding zonal vegetation. They
are considered to be of azonal character.
Azonal vegetation has long been an orphan of vegetation mapping in South Africa and overseas. Its enormous complexity is
usually little known, and its limited extent (small size of patches)
poses a challenge to mapping at scales smaller than 1:50 000.
In countries such as South Africa, where broad-scale vegetation
complexes (or in other words vegetation on supra-habitat level)
have always been the major focus, the concept of azonality
remained largely unknown, denied or at best recognised but
unexplored. A notable exception is the study of Campbell (1985)
on classification of mountain fynbos of the Cape. He used the
term ‘azonality’ explicitly to recognise various groups of communities within his ‘Restioid Fynbos’. Azonal Restioid Fynbos
according to Campbell (1985) is limited owing to waterlogging
or to excessive drainage or as a consequence of a combination
of these two habitat conditions. In his ground-breaking monograph on vegetation of the upper Orange (Gariep) River Valley,
Werger (1980), who was instrumental in importing European
ways of doing vegetation science to South Africa, speaks about
‘minor communities’, obviously referring to those of azonal
nature. Mention of only these two sources does not necessarily imply that other students of South African vegetation did
not sample azonal vegetation. However, they came short of
defining the relationship of such vegetation to zonal vegetation patterns, neglected the question of intrazonality and, most
importantly, failed to feature azonal (and intrazonal) vegetation
on vegetation maps of the country. Admittedly, this was also
due to the physical limitation imposed by the small scale of the
maps (1:1 500 000 in Acocks 1953 and 1:1 850 000 in Low
& Rebelo 1996) concomitant with the then more limited state
of knowledge of the spatial variation of vegetation in South
Africa. There was an attempt at continued adherence to the
practice of not mixing different spatial scales on the same map.
It is one of the major purposes of the National Vegetation Map
to give the azonal vegetation of the region (with its 23 inland
and 11 coastal azonal vegetation units) desired coverage for the
first time.
618
Inland Azonal Vegetation
19 (2006)
All concepts related to zonality of vegetation go back to the
fundamental work of Heinrich Walter. In simple terms, he used
the term zonal to refer to the vegetation typical of climatic
zones. Such vegetation forms an integrated part of biomes (for
recent definitions see Mucina 2000 and the Chapter on Biomes
and Bioregions in this book) or, more precisely, of ‘zonobiomes’
in Walter’s terminology (Walter 1964, 1973, Walter & Box 1976,
Walter & Breckle 1991). Hence, it is a complex of macroclimate
characteristics, which exert control over structure and dynamics
of the zonal vegetation. The typical soils occurring within such
(climate-defined) zones are also considered zonal. The zonal
vegetation can occur as extrazonal in specialised habitats outside the climatic zones (where this kind of vegetation is considered to be of zonal nature).
In azonal vegetation sensu lato, on the other hand, special
substrate (special soil types or bedrocks) and/or hydrogeological conditions (waterlogging, flooding, tidal influence) exert
an overriding influence on floristic composition, structure and
dynamics over macroclimate. (Vegetation of heavily disturbed
and man-made habitats, termed anthropogenic, synanthropic,
ruderal or agrestal, falls within this broadly conceived concept
of azonality as well.) If such vegetation occurs exclusively within
a climatic (and vegetation or biome) zone, then it is considered
to be intrazonal. Where such vegetation occurs irrespective of
climatic and vegetation zones, we use the term azonal vegetation sensu stricto.
An example of typical zonal vegetation would be proteoid sandstone fynbos, granite asteraceous renosterveld etc. occurring
within the zone called the Fynbos Biome. Hence vegetation
units such as FFs 9 Peninsula Sandstone Fynbos, FFg 2 Boland
Granite Fynbos, FRs 9 Swartland Shale Renosterveld and the
like are considered as zonal. The vegetation units such as AZf
2 Cape Vernal Pools or AZi 9 Cape Inland Salt Pans are typical
intrazonal units. Structure and dynamics of both are determined
by either waterlogging or accumulation of salt (hence by special
hydrogeological or pedological conditions), and equally importantly—both embedded within the zone of the Fynbos Biome
and experiencing similar climatic traits of that particular climaticvegetation zone. AZf 6 Subtropical Freshwater Wetlands, on
the other hand, occur across the zones of the Savanna Biome,
Indian Ocean Coastal Belt and Albany Thicket Biome, and hence
qualify as an azonal unit in the narrow sense (Table 13.1). The
climate diagrams of the particular regions where the azonal
vegetation units have been mapped (Figure 13.2) reflect the
patterns of intrazonality (where the form of the climate diagram follows the basic patterns of the surrounding zone) as
well as azonality (characterised by a lack of distinct pattern due
to a pooling effect).
Although the concept of azonality did receive some marginal attention in South African vegetation-ecological literature in the past, the concept of intrazonality is entirely new
to it. Undeniably, it is also a rather controversial issue as it is
scale dependent, requiring definition of the system of zones.
Therefore, for practical reasons we refrain from an attempt
to distinguish clearly between intrazonal and azonal (sensu
stricto) units. Because the concepts of azonal (sensu lato) units
as defined in our map and in this chapter are narrowly defined
both in habitat and regional terms, most of those units are
actually intrazonal (Table 13.1).
We are well aware of the fact that the same concepts (azonality
and intrazonality) can be applied to the forest vegetation. We
have decided to feature both zonal and azonal forest vegetation
within one chapter for conventional and practical purposes.
S %
19 (2006)
Table 13.1 Spatial link between the inland azonal vegetation units and surrounding biome, with reference to the zonality status of the units. IOCB: Indian Ocean
Coastal Belt.
Vegetation Unit
Biome
Zonality
AZf 1 Cape Lowland Freshwater Wetlands
Fynbos
intrazonal
AZf 2 Cape Vernal Pools
Fynbos
intrazonal
Freshwater Wetlands
AZf 3 Eastern Temperate Freshwater Wetlands Grassland
intrazonal
AZf 4 Drakensberg Wetlands
Grassland
intrazonal
AZf 5 Lesotho Mires
Grassland
intrazonal
AZf 6 Subtropical Freshwater Wetlands
Savanna; Albany Thicket; IOCB
azonal
Alluvial Vegetation
AZa 1 Fynbos Riparian Vegetation
Fynbos
intrazonal
AZa 2 Cape Lowland Alluvial Vegetation
Fynbos
intrazonal
AZa 3 Lower Gariep Alluvial Vegetation
Succulent Karoo
intrazonal
AZa 4 Upper Gariep Alluvial Vegetation
Grassland
intrazonal
AZa 5 Highveld Alluvial Vegetation
Grassland
intrazonal
AZa 6 Albany Alluvial Vegetation
Albany Thicket
intrazonal
AZa 7 Subtropical Alluvial Vegetation
Savanna; IOCB
azonal
AZi 1 Namaqualand Riviere
Succulent Karoo
intrazonal
AZi 2 Namaqualand Salt Pans
Succulent Karoo
intrazonal
AZi 3 Southern Kalahari Mekgacha
Savanna
intrazonal
AZi 4 Southern Kalahari Salt Pans
Savanna
intrazonal
AZi 5 Bushmanland Vloere
Nama-Karoo
intrazonal
AZi 6 Southern Karoo Riviere
Nama-Karoo
intrazonal
AZi 7 Tanqua Wash Riviere
Succulent Karoo
intrazonal
AZi 8 Muscadel Riviere
Succulent Karoo
intrazonal
Inland Saline Vegetation
but does not yet enjoy broad general
acceptance in South Africa.
On (sub)continental level there were
several attempts to classify the surface
of South(ern) Africa into wetland zones.
Harrison (1959) attempted to subdivide
the territory of South Africa, Lesotho
and Swaziland into 13 ‘hydrobiological regions’ based on types of rivers.
Allanson et al. (1990) introduced a limnological system comprising five categories,
such as Subtropical Coastal Peneplain,
Southeastern Coastal Plain and Elevated
Plateau, Australomontane, Temperate
Acid Waters of the Western Cape and
finally Arid West. Rogers (1995) suggested a system based on several ‘determinants’ such as topography (prevailing
criterion), hydrology and nutrient regime
to arrive at four broad groups, based on
the ‘broad morphology of the country’
further subdivided into 26 regions. The
latest attempt was made within a panAfrican background when Thieme et al.
(2005) suggested the subdivision of the
region comprising South Africa, Lesotho
and Swaziland into seven ‘ecoregions’
(representing four bioregions), such
as 37-Drakensberg-Maloti Highlands,
36-Amatolo-Winterberg Highlands,
73-Southern Temperate Highveld, 77Zambezian Lowland, 33-Cape Fold,
91-Southern Kalahari and 93-Western
Orange. The classification and delineation into bioregions and ecoregions primarily followed fish distribution data.
Our classification approach follows multilayered criteria, the macro-ecological
AZi 9 Cape Inland Salt Pans
Fynbos
intrazonal
one (character of azonality and combiAZi 10 Highveld Salt Pans
Grassland; Nama-Karoo
azonal
nation of azonality-driving ecological
factors such as water and salt content)
AZi 11 Subtropical Salt Pans
Savanna
intrazonal
being the most important. According
to this criterion, we distinguish, firstly,
freshwater wetlands (along stagnant or
2. Typology of Inland Azonal Vegetation
slow-flowing waters) as different from,
in South Africa
secondly, alluvial vegetation fringing
water courses and undergoing dynamic
Water, in conjunction with geology, soil, topography and cli- change due to a periodic flood regime. The third class—the
mate, is responsible for the creation of remarkably many types ‘inland azonal vegetation’—comprises vegetation accompanying salt-laden intermittent rivers and salt pans. High concentraof habitats. Water chemistry, temperature (and temporary
tion of salt in the environment (either soil or water or both) is
changes in both) together with the amount of water (depth of
the major ecological determinant of this vegetation complex.
water column), timing of occurrence (regular tides or irregular
floods) and speed of its movement (discharge, flow and stagna- Further subdivision within these three categories follows biotion) are the major factors shaping the ecology of biotic com- geographical (hence floristic and floral-evolutionary) criteria
and reflects the link between the azonal vegetation unit and
munities occupying such habitats.
its corresponding ‘matrix’ zonal vegetation (Table 13.1). A comparison of the spatial extent of the zonal and azonal vegetation
Noble & Hemens (1978) coined the first habitat-level system
identified only four units as truly azonal, hence occurring within
for southern African wetlands. Their original scheme has been
modified (adding new categories and hierarchies to the sys- more than one biome—three subtropical units and Highveld
Salt Pans. The other vegetation units are intrazonal. The vegetatem) in later publications (Breen & Begg 1989, Rogers 1995 and
recently also Sieben et al. 2004; see Rogers 1997 for a compre- tion units recognised in this chapter can be classified with high
certainty into four Rogers’s (1995) regions (Table 13.2), with the
hensive account). A simple vegetation/habitat system (from a
pan-African point of view) was also suggested by Denny (1993). notable exception of our subtropical units (AZf 6, AZa 7 and AZi
The habitat-level system adopted by the Ramsar Convention in 11) shared by three of the four broad groups; the subtropical
wetland units naturally do not occur in the fourth group—the
Recommendation C.4.7 (Rev) of 199 (see also Cowan 1995c) is
comprehensive and also includes categories of coastal wetlands, ‘Mountain Wetlands’.
Inland Azonal Vegetation
619
S %
AZf 1 Cape Lowland Freshwater W etlands
mm
°C
128
32 >2A
2A4G
96
24
>2E
64
16 >75
32
8 >2A6
0
0
-32 ; 7 > 2 > ; ; 2 D @ ? 5
-8
AZf 2 Cape Vernal Pools
566
29
16.5
3
1862
^^
4
U
^^
AZf 4 Drakensberg W etlands
mm
°C
32 >2A
128
2A4G
24
96
>2E
16 >75
64
8 >2A6
32
0
0
-8
-32 ; 7 > 2 > ; ; 2 D @ ? 5
739
25
9.7
103
1468
^^
4
U
^^
379
33
16.8
4
2345
^^
4
U
^^
325
34
17.0
34
2566
^^
4
U
^^
419
32
21.6
4
2303
^^
4
U
^^
239
36
19.0
21
2945
^^
4
U
^^
769
25
4.4
183
1269
^^
4
U
^^
mm
°C
128
32 >2A
2A4G
96
24
>2E
64
16 >75
32
8 >2A6
0
0
-32 ; 7 > 2 > ; ; 2 D @ ? 5
-8
mm
°C
128
32 >2A
2A4G
96
24
>2E
64
16 >75
32
8 >2A6
0
0
-32 ; 7 > 2 > ; ; 2 D @ ? 5
-8
mm
°C
32 >2A
128
2A4G
24
96
>2E
16 >75
64
8 >2A6
32
0
0
-8
-32 ; 7 > 2 > ; ; 2 D @ ? 5
243
36
16.3
27
2398
^^
4
U
^^
mm
°C
32 >2A
128
2A4G
24
96
>2E
16 >75
64
8 >2A6
32
0
0
-8
-32 ; 7 > 2 > ; ; 2 D @ ? 5
380
33
16.9
3
1987
^^
4
U
^^
447
31
16.2
3
1848
^^
4
U
^^
^^
4
U
^^
mm
°C
32 >2A
128
2A4G
24
96
>2E
16 >75
64
8 >2A6
32
0
0
-8
-32 ; 7 > 2 > ; ; 2 D @ ? 5
856
23
20.6
3
1992
^^
4
U
^^
mm
°C
128
32 >2A
2A4G
96
24
>2E
64
16 >75
32
8 >2A6
0
0
-32 ; 7 > 2 > ; ; 2 D @ ? 5
-8
131
39
19.2
14
2888
^^
4
U
^^
354
34
18.1
4
2011
^^
4
U
^^
100
40
17.6
1
2562
^^
4
U
^^
141
39
16.8
30
2692
^^
4
U
^^
210
37
17.9
4
2416
^^
4
U
^^
734
25
21.1
2
2071
^^
4
U
^^
AZa 6 Albany Alluvial Vegetation
495
31
16.6
36
2507
^^
4
U
^^
mm
°C
128
32 >2A
2A4G
96
24
>2E
64
16 >75
32
8 >2A6
0
0
-32 ; 7 > 2 > ; ; 2 D @ ? 5
-8
AZi 2 Namaqualand Salt Pans
147
39
18.1
6
2647
^^
4
U
^^
mm
°C
128
32 >2A
2A4G
96
24
>2E
64
16 >75
32
8 >2A6
0
0
-32 ; 7 > 2 > ; ; 2 D @ ? 5
-8
AZi 5 Bushmanland Vloere
194
38
18.6
20
2908
^^
4
U
^^
mm
°C
32 >2A
128
2A4G
24
96
>2E
16 >75
64
8 >2A6
32
0
0
-8
-32 ; 7 > 2 > ; ; 2 D @ ? 5
AZi 8 Muscadel Riviere
162
38
17.3
20
2581
^^
4
U
^^
AZi 10 Highveld Salt Pans
mm
°C
32 >2A
128
2A4G
24
96
>2E
16 >75
64
8 >2A6
32
0
0
-8
-32 ; 7 > 2 > ; ; 2 D @ ? 5
704
26
14.9
38
1953
AZa 3 Lower Gariep Alluvial Vegetation
AZi 7 Tanqua W ash Riviere
AZi 9 Cape Inland Salt Pans
mm
°C
32 >2A
128
2A4G
24
96
>2E
16 >75
64
8 >2A6
32
0
0
-8
-32 ; 7 > 2 > ; ; 2 D @ ? 5
mm
°C
128
32 >2A
2A4G
96
24
>2E
64
16 >75
32
8 >2A6
0
0
-32 ; 7 > 2 > ; ; 2 D @ ? 5
-8
mm
°C
128
32 >2A
2A4G
96
24
>2E
64
16 >75
32
8 >2A6
0
0
-32 ; 7 > 2 > ; ; 2 D @ ? 5
-8
AZf 6 Subtropical Freshwater W etlands
AZi 4 Southern Kalahari Salt Pans
AZi 6 Southern Karoo Riviere
mm
°C
32 >2A
128
2A4G
24
96
>2E
16 >75
64
8 >2A6
32
0
0
-8
-32 ; 7 > 2 > ; ; 2 D @ ? 5
mm
°C
32 >2A
128
2A4G
24
96
>2E
16 >75
64
8 >2A6
32
0
0
-8
-32 ; 7 > 2 > ; ; 2 D @ ? 5
AZi 1 Namaqualand Riviere
AZi 3 Southern Kalahari Mekgacha
mm
°C
32 >2A
128
2A4G
24
96
>2E
16 >75
64
8 >2A6
32
0
0
-8
-32 ; 7 > 2 > ; ; 2 D @ ? 5
^^
4
U
^^
AZa 5 Highveld Alluvial Vegetation
AZa 7 Subtropical Alluvial Vegetation
mm
°C
128
32 >2A
2A4G
96
24
>2E
64
16 >75
32
8 >2A6
0
0
-32 ; 7 > 2 > ; ; 2 D @ ? 5
-8
342
34
17.3
7
2384
AZa 2 Cape Lowland Alluvial Vegetation
AZa 4 Upper Gariep Alluvial Vegetation
mm
°C
128
32 >2A
2A4G
96
24
>2E
64
16 >75
32
8 >2A6
0
0
-32 ; 7 > 2 > ; ; 2 D @ ? 5
-8
AZf 3 Eastern Temperate Freshwater W etlands
AZf 5 Lesotho Mires
AZa 1 Fynbos Riparian Vegetation
mm
°C
128
32 >2A
2A4G
96
24
>2E
64
16 >75
32
8 >2A6
0
0
-32 ; 7 > 2 > ; ; 2 D @ ? 5
-8
mm
°C
128
32 >2A
2A4G
96
24
>2E
64
16 >75
32
8 >2A6
0
0
-32 ; 7 > 2 > ; ; 2 D @ ? 5
-8
19 (2006)
mm
°C
32 >2A
128
2A4G
24
96
>2E
16 >75
64
8 >2A6
32
0
0
-8
-32 ; 7 > 2 > ; ; 2 D @ ? 5
AZi 11 Subtropical Salt Pans
399
33
16.7
36
2551
^^
4
U
^^
mm
°C
32 >2A
128
2A4G
24
96
>2E
16 >75
64
8 >2A6
32
0
0
-8
-32 ; 7 > 2 > ; ; 2 D @ ? 5
Figure 13.2 Climate diagrams of Inland Azonal Vegetation units. Blue bars show the median monthly precipitation. The upper and lower red lines
show the mean daily maximum and minimum temperature respectively. MAP: Mean Annual Precipitation; APCV: Annual Precipitation Coefficient of
Variation; MAT: Mean Annual Temperature; MFD: Mean Frost Days (days when screen temperature was below 0°C); MAPE: Mean Annual Potential
Evaporation.
620
Inland Azonal Vegetation
S %
19 (2006)
Table 13.2 Correspondence between the Wetland Regions of
Cowan (1995c) coded as C, S, M and P and the vegetation
units as described in this Chapter (for the codes see the List
of Vegetation Units) and combined into three groups, namely
FW (Freshwater Wetlands), AV (Alluvial Vegetation) and ISV
(Inland Saline Vegetation). The units given in bold are shared
between Wetland Regions C, S and P, while the other units show
exclusive links to a wetland region. N: data do not apply.
FW
AV
ISV
C Coastal plain wetlands
AZf 6
AZa 7
AZi 11
S
AZf 6
AZf 1
AZf 2
AZa 7
AZa 2
AZa 3
AZa 6
AZi 11
AZi 1
AZi 2
AZi 9
AZi 6
Coastal slope & rimland
AZi 7
AZi 8
M Mountain wetlands
AZf 4
AZf 5
AZa 1
N
P Plateau wetlands
AZf 6
AZf 3
AZa 7
AZa 4
AZa 5
AZi 11
AZi 3
AZi 4
AZi 5
AZi 10
3.
to remain wet without being eroded by flowing water. Many of
these vleis on the highveld are peat forming, especially where
the dominant species is the reed Phragmites australis. Rietvlei
in Gauteng is a prime example of a wetland with peat deposits sufficiently large to be suitable for mining. The perimeter
around stagnant water bodies (lakes, banks of dams) as well as
the ‘Floodplain Vleis’ of Noble & Hemens (1978; see also Rogers
1995) is here classified as part of Freshwater Wetlands as well.
Many pans, especially on the precipitation-rich eastern and
northeastern highveld are also considered freshwater wetland
habitats. A very significant pan field is that of the Lake Chrissie
region in Mpumalanga where over 250 pans occur—remnants
of a fossil riverine system. The surrounding landscape is also
very uniformly flat with an underlying layer of marine-deposited sandstone that forms the bed of many of the pans. These
freshwater pans can be classified as Open Pans, Reed Pans, and
Grass Pans (according to Rogers 1997; see also Geldenhuys
1982 for the definitions of these concepts), depending on vegetation cover and its composition. The narrow alluvia of highveld
streams are also tentatively classified as part of the Freshwater
Wetland category due to notable floristic similarity to the vlei
vegetation.
The high-altitude wetlands of the Lesotho Highlands (with a
small portion belonging to South Africa) enjoy particular status within southern African wetlands. They have been called
‘bogs’ (e.g. Van Zinderen Bakker 1955, Jacot Guillarmod 1962,
Van Zinderen Bakker & Werger 1974), ‘mires’ (Backéus 1988)
or ‘flushes’ and ‘cushion bogs’ (Thompson & Hamilton 1983),
and they are characterised by the formation of peat—a phenomenon typical of precipitation-rich and cold climates (Gore
1983). These wetlands develop into depressions, and on slightly
inclined slopes they are fed by rain water as well as lateral flow of
water released from the peat layer down-slope. Hence, according to the hydrological classification (see for instance Walter
1968) they should be considered to be ombro-soligenous mires
(influenced by rain water as well as water seeping through the
soil). The water is eutrophic since the underlying basalt is rich
in calcium, potassium and phosphorus and has a pH of about
8. The mires develop, in an oligotrophic direction (Van Zinderen
Bakker & Werger 1974), under extreme precipitation conditions
Freshwater Wetlands, Alluvial and
Inland Saline Vegetation
In this chapter we address the inland segment of the wetlands
of southern Africa. Here we feature and classify (in floristic-biogeographical terms) the wetland vegetation of all freshwater
wetlands (including vleis, marshes, mires, lakes, alluvia) and vegetation of land-locked salt-laden habitats
(including salt pans and river channels of
intermittent rivers in arid and semi-arid
AZF 1 Cape Lowland Freshwater Wetlands
regions).
3.1
Freshwater Wetlands
Freshwater wetlands form a system of
archipelagos of small and highly fragmented patches, embedded within all
mainland biomes of South Africa. They
are particularly common landscape
features in regions with mean annual
precipitation exceeding 500–600 mm
(Figure 13.3). The floristic composition
in the freshwater habitats underwent a
series of ecological and evolutionary filters linking the azonal vegetation with its
background zonal vegetation. The classification of the freshwater wetlands into
vegetation units as applied in our map
reflects this link very closely (Table 13.1).
The typical freshwater wetlands are vleis,
which form in the catchment areas of
highveld streams (spruits), where a sufficiently shallow gradient permits the soils
AZf 2
Cape Vernal Pools
AZf 3
Eastern Temperate Freshwater Wetlands
#
AZf 4
Drakensberg Wetlands
AZf 5
Lesotho Mires
AZf 6
Subtropical Freshwater Wetlands
#
# #
#
# #
#
#
##
#
#
#
#
##
####
#
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#
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#
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#
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#
#
#
#
#
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#
#
#
# #
#
#
#
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#
#
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# ##
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Figure 13.3 Position of patches of vegetation units featuring freshwater wetlands (AZf group) in
South Africa, Lesotho and Swaziland.
Inland Azonal Vegetation
621
S %
leading to flushing of bases from the mineral-rich peat. Moist
or so-called head-valley ‘sponges’ should not be included in the
mire category since they do not show a marked rise in the peat
layer. Formation of thufurs (small hummocks) and tarns (small
water pools) are typical geomorphological and hydrological features of the Lesotho mires. The origin of the thufurs is still not
fully understood, but uneven freezing/snowing patterns might
be an obvious cause (see Van Zinderen Bakker & Werger 1974
for a review of the problem and Thompson & Hamilton 1983
for some comparative ideas). The high-altitude bogs and mires
of southern Africa have a long evolutionary history and as evolutionary laboratories and museums, they house a high number
of relicts of the past afromontane flora migrations and they also
became a cradle of neo-endemism.
Peat layers are also formed in wetlands on the highest summit
plateaus of the mountains in the southwestern Cape (Kruger
1979, Sieben et al. 2004). These are rain-fed and acidic and
in the Cape they also receive a considerable amount of fog
precipitation, also with some in summer (Marloth 1907). In
summer these small peatlands experience seasonal drought
(or at least considerable decrease in water content). Formation
of typical raised bogs (purely ombrogenous mires) has not yet
been observed.
All of the different freshwater wetland types as listed above
can contain permanent water bodies qualifying as natural lakes
(Allanson 1979, 1981, Hart 1995; Figure 13.4). The shallow
fringes of these lakes support a variety of so-called macrophytic
aquatic vegetation composed of various life forms adapted to
life on the lake bottom, free-floating within a water column or
floating on the surface of the water. These habitats are considered (also in accordance with the definition of a wetland of the
Ramsar Convention) as wetlands, although we have not always
mapped them.
3.2 Alluvial Vegetation
Southern Africa is a dry land, and it has been so since about
the mid-Tertiary. Still, water has long been a major landscapeshaping factor. Tributaries of major perennial river systems,
of which the Orange, Thukela and Limpopo are the most
important water courses draining South Africa, Lesotho and
Swaziland. There are many smaller ones dissecting the sloping face of the subescarpment regions of Namaqualand (e.g.
Buffels), the southwestern and southern Cape (e.g. Berg,
Breede, Gouritz) and the broad coastal slopes of the Eastern
Cape (e.g. Gamtoos, Great Fish, Kei) and KwaZulu-Natal
(e.g. Phongolo).
The systems of permanent and intermittent rivers of southern
Africa, as we know them today, represent a snapshot in history of the evolution of our landscapes. Continental uplift and
climate change events (and associated changing precipitation
and through-flow patterns) have always driven the dynamics
of formation, alteration and obliteration of riverine systems.
The development of the Orange River basin (Wellington 1958,
Dingle & Hendey 1984, De Wit 1999, Goudie 2005) has demonstrated beyond doubt that, since dryness became a dominant
feature of the climate of our planet, the changes in the major
riverine systems draining arid and semi-arid regions of southern
Africa have been extensive.
All the extant perennial as well as intermittent rivers are accompanied by systems of alluvial terraces suited to support a special
category of wetlands characterised by flooding and associated
disturbance. Alluvium is usually defined as a place where sediments carried by a river are deposited. Typically, alluvia are flat
terraces built of assorted sedimentary material, and regularly
accompany the middle (partly) and lower (prevalently) reaches of
slow-flowing rivers. Because the volume of water carried by rivers might change seasonally, the build-up of the alluvia follows
these cyclic changes. The alluvia undergo frequent rebuilding
by erosion of old or adding of new material, depending on the
mobility of the river. As a river changes its direction or might cut
deeper into the surrounding landscape, new systems of alluvial
terraces are built, older ones are eroded away or abandoned
in places where the influence of flooding has ceased. In general, typical alluvia are habitat complexes where sedimentation
(hence habitat-creating) processes prevail over erosion (destructive) processes. The riverbanks of rapidly
flowing, montane rivers, sometimes with
rapids, along the upper river reaches with
steep gradients can also develop alluvia.
This happens especially in places where
the valley carrying the river becomes
broader or where gradients become less
pronounced. There are several differences between these alluvia and those
along the middle and lower reaches of a
river. The mountain river alluvia are usually built of coarse sedimentary material
including large boulders and gravel, they
have a low nutrient status and they are
exceedingly prone to extensive damage
(and obliteration) by unpredictable catastrophic floods.
L. Mucina
The freshwater wetlands found outside the centres of regional
endemism (Van Wyk & Smith 2001), and especially at low altitudes, show certain uniformity in terms of dominants and house
a number of species of subcosmopolitan distribution. In regions
known for their high endemism (Capensis, Drakensberg), their
contribution to the scores of endemism is considerable (e.g.
Drakensberg Wetlands, Cape Vernal Pools, Fynbos Riparian
Vegetation and unmapped freshwater wetlands in the mountainous regions of the Fynbos Biome).
Figure 13.4 Island Lake (Onder-Langvlei) near Wilderness on the Garden Route (Western
Cape)—an example of a coastal freshwater lake separated from the sea by a high cordon of
dunes.
622
Inland Azonal Vegetation
19 (2006)
Alluvia support habitat complexes emerging as a result of the interplay of several
ecological factors such as temporary and
spatial sedimentation-to-erosion rates,
water sediment load, water chemistry
and nutrient content, frequency and
S %
19 (2006)
duration of flooding, soil texture and soil nutrient status, just to
mention the most important ones. It has been shown (Van Coller
1993, Van Coller et al. 1997, 2000) that vegetation populating
the alluvia is primarily structured by environmental gradients
reflecting the habitat differences in the vertical (above), lateral
(away from) and longitudinal (along) dimensions of the river
channel. The elevation above the macrochannel explains the
main variation in vegetation pattern, with processes of flooding
frequency and water availability as major determinants of the
vegetation cover on the alluvia (Van Coller et al. 2000). The latter authors further demonstrate that patchiness factors (such as
presence of well-developed alluvial bars and quality of bedrock)
also play an important role as vegetation-structuring processes.
The diversity of the alluvial habitats is considerable, which is
reflected in diversified pertinent geomorphological and hydrological terminology. Ecologists have also coined several sets of
terms describing alluvial habitats especially in relation to occurrence (and frequency) of flooding. Kopecký’s (1969) typology
of riverbank habitats is based on three criteria, namely (1) the
vertical division of the riverbanks into riparian and subriparian
zones, (2) range of the water level fluctuation, and (3) intensity of wave action or speed of flow. The amplitude of the
fluctuation in water level defines either a stenosauletic type
of riverbank (when the difference between maximum and
minimum levels does not exceed 0.6 m) or a eurysauletic type
(where water level fluctuates more than 1 m). Four ‘ecotopes’
(= habitats) can be distinguished within the stenosauletic type
of riverbanks, depending on the duration of floods: the submerse ecotope is permanently flooded, the demerse ecotope is
exposed only briefly during dry periods, the semi-emerse ecotope is usually dry as a rule, but flooded during shallow flood
periods, and finally the emerse ecotope is the zone inundated
only during high floods. An unpublished system by Boucher &
Tlale (1999a; see also Sieben 2003) is in principle very similar to
the one described above and involves three basic zones, namely
Aquatic, Wet Bank (with Lower and Upper Zones) and Dry Bank
(with Lower Dynamic, Shrub/Tree, and Back Dynamic zones).
Frequently flooded lower banks are usually populated by transient herblands made up of short-lived, nutrient-demanding
flora. Reeds occupy beds forming on banks of very slow-flowing rivers or are found in still backwaters. Patches of flooded
grasslands are usually found on both low and middle terraces,
while riparian thickets usually occur on high terraces experiencing only occasional disturbance events resulting from floods.
Permanent (or semipermanent) alluvial lakes or backwaters can
form within extensive alluvial complexes. They may diminish in
size and expose broad bands of clayey banks in regions characterised by seasonal rainfall. The actual water bodies in this
habitat complex, including the backwater (pan) lakes, oxbows
as well as slow-flowing river channels, may support macrophytic
vegetation (sensu Hejný 1960)—true aquatic vegetation built
of plants floating on the water surface or dwelling within the
water column. These patterns hold for most of the perennial
river systems and occur in modified form also on alluvial complexes accompanying intermittent rivers. The narrow mountain
alluvia can support herblands, restiolands and sedgelands consisting of disturbance-resistant clonal plants. They also support thickets such as those constituted by endemic shrubs in
Capensis and Leucosidea sericea in the Drakensberg.
The alluvial vegetation shows many common floristic and ecological features across the biomes of southern Africa (Figure 13.5),
resulting from selection of plant functional types that respond
well to high water supply, occasional (and sometimes heavy)
disturbance and extraordinarily high nutrient status (especially
in the case of lower alluvia). Disturbance, both natural and maninduced, in these habitats creates a set of conditions allow-
AZa 1 Fynbos Riparian Vegetation
AZa 2 Cape Lowland Alluvial Vegetation
AZa 3 Lower Gariep Alluvial Vegetation
AZa 4 Upper Gariep Alluvial Vegetation
AZa 5 Highveld Alluvial Vegetation
AZa 6 Albany Alluvial Vegetation
AZa 7 Subtropical Alluvial Vegetation
Figure 13.5 Position of patches of vegetation units featuring alluvial (and riparian) wetlands (AZa group) in South Africa.
Inland Azonal Vegetation
623
S %
ing and fostering the rapid spread of highly responsive native,
ruderal flora. Alluvia also serve as important corridors for linear
invasions by alien flora (e.g. Duvenhage 1993, Pyšek & Prach
1994; see also Macdonald et al. 1986).
3.3
Inland Saline Vegetation
The salt-laden habitats found inland, hence outside the immediate influence of the sea, are diverse in character and origin. Still
they do share several basic ecological features, such as a high
concentration of salt soil and water. The salinity originates either
from a salt-bearing substrate or from mineral-rich groundwater
aquifers, typically those located close to the soil surface, or from
other forms of water that seep to the surface and deposit salt
after evaporation. Inland saline habitats are found in regions
that experience a prolonged dry period.
19 (2006)
interesting natural phenomenon. The authors concluded that
there are three basic integrated mechanisms of pan initiation
involving (a) suitable substratum (easily weathering rocks such
as those of Karoo Supergroup sediments), (b) disrupted drainage (induced either by tectonic or climate-change processes),
and (c) geological structure (including the presence of dolerite
sills, fracture intersections and volcanism). Deflation and the
concentration of animals around pans (to drink and wallow)
may play an enhancing role in the formation of the pans. The
concentrated occurrence of inland salt pans coincides with
ancient (usually Tertiary) river systems, for example those of
the northern and western Free State (Grobler et al. 1988) or
the Orange (Gariep) River (Wellington 1958). Because of the
conserving properties of high salt concentrations, the pan sediments preserve pollen and other remains of organisms, which
are used as an important source of palaeoecological information (e.g. Scott & Brink 1992, Partridge & Scott 2000).
The most prominent inland saline habitats are those in and
around salt pans (Allan et al. 1995), also called ‘closed drainage
salt pans’ (Rogers 1995) and ‘vloere’ or ‘kolk’ by the local population in Bushmanland (the latter also called ‘Karoo salt flats’
by Rogers 1995). The term ‘endorheic’ is often used for these
pans and refers to the closed nature (no outlet) of the drainage
system of the pans. The size of the salt pans can range from
very small to very large (such as Grootvloer in Bushmanland).
Typically, they are filled with fine clayey sediments with a high
salt content (pH of soil regularly exceeding values of 8). Most of
them are dry for most of the year, while only some carry water
(subject to large water-column fluctuations) all year round. The
central, flat part of many pans is usually devoid of vegetation,
and typical vegetation zonation patterns may form at the edges
of the pan floor and on the banks of the pan.
The salt pans along the Atlantic seaboard of the West Coast
are of marine origin. These pans used to be coastal lagoons
and as they became fully severed from the sea, they turned
into salt pans (Rocher Pan near Velddrif, salt pans near Darling
and Cape Town). The pans of Namaqualand as well as those of
the Agulhas Plain and of the plains bordering the Indian Ocean
further east (near Albertinia in the Western Cape, Uitenhage
and Despatch in the Eastern Cape) are remnants of Pleistocene
marine transgressions.
Marshall & Harmse’s (1992) review of the knowledge on the
origin and formation of pans revealed the complexity of this
In the Overberg region (typically made up of salt-laden
Bokkeveld Shales), and to a small extent also in other regions
The most extensive salt pan systems in South Africa are found in
Bushmanland, the northeastern Free State and in the adjacent
regions of the North-West Province. The name of the region is
derived from the salt pans of the Kalahari (Figure 13.6).
AZi 2 Namaqualand Salt Pans
AZi 4 Southern Kalahari Salt Pans
AZi 5 Bushmanland Vloere
AZi 9 Cape Inland Salt Pans
AZi 10 Highveld Salt Pans
AZi 11 Subtropical Salt Pans
Figure 13.6 Position of patches of inland salt-pan vegetation units (part of AZi group) in South Africa.
624
Inland Azonal Vegetation
S %
19 (2006)
consisting of shales of different origin
(around Worcester and Malmesbury),
inland saline vegetation is limited to
erosion scars and to narrow alluvia collecting salty, clayey, shale-derived sediments. Quite extensive salt alluvia and
flats are especially found in the vicinity of
Bredasdorp, Napier and Swellendam.
L. Mucina
Salt pans in the subtropical regions of
South Africa and Swaziland are another,
special wetland category. They are well
known to both South Africans and tourists for excellent game viewing in the
parks and nature reserves of the Lowveld
and the Central Bushveld, especially in
the dry season (summer), when some of
them still carry some water or turn into
muddy pools (Figure 13.7). These natural pans are usually either remnants of
dysfunctional drainage systems or are
formed in drainage lines of intermittent
rivers. They are seldom formed in deflated
Figure 13.8 Lowveld pans are important habitat of large herbivores: young hippo (Hippopotadepressions, sealed with clayey sedi- mus amphibius) in an artificial pan filled with alien Pistia stratiotes (Araceae) near Lower Sabie
ments and perpetuated (and extended)
Rest Camp in the eastern Kruger National Park.
by animals visiting the water pools
landscapes of southern Africa. In the Kalahari they are called
emerging from them from time to time. Only one of these pans
is known to be of impact (meteorite) origin—Soutpan in the ‘mekgacha’ (plural); in Namibia, Walter (1985) adopted the
Tswaing Crater, north of Pretoria. The most extensive subtropi- Afrikaans term ‘riviere’ (plural) for them.
cal pans are those of the Ndumo Game Reserve (Nyamiti and
The mekgacha and riviere are dry most of the year. In fact, they
Banzi) and other pans of the same riverine (Phongolo) system
may stay dry for many consecutive years. They very seldom are
in Maputaland, and the pans in the Lowveld (Kruger National
in flood and then only for a short time, immediately after heavy
Park). The subtropical pans in South Africa provide habitats for
(often unexpected) rains and are usually not able to carry the
tropical hygrophytes and hydrophytes at the southern limits of
flood surges far. Water typically recedes very quickly (sometimes
their distribution (Cook 2004) and are of enormous conservawithin hours) and disappears into the sandy riverbeds, where it
tion importance for maintenance of populations of megahercan persist in the soil column (as capillary water) or form small
bivores (Figure 13.8) and water birds.
aquifers. Erosion and sedimentation cycles redistribute not
Azonal vegetation is also found on the bottom and on slopes
only water-borne soil particles, larger rock debris or dead plant
of hardpan (mainly calcrete, sometimes also ferricrete and sil- material, but also seeds and entire mats of creeping grasses.
crete) edges of dry riverbeds criss-crossing the driest parts of This natural plant propagation material provides the foundation
South Africa (Figure 13.9). The drainage channels of intermit- for a new vegetation cover on the dried bottom of the intertent rivers, called ‘waadi’ in Arabic-speaking countries or ‘river- mittent rivers after the waters have receded and soil particles
wash’ in America, are a typical feature of semidesert and desert
have settled.
The drainage lines of the intermittent rivers are often associated with outcrops of
hardpan (mainly calcrete), which supplies
(through erosion and in times of flood
surges or through seeps in the calcrete
riverbanks) high levels of calcium in the
soil. High evaporation pressure leads to
salt accumulation on the surface (also on
the dry bottom of intermittent rivers). It
is therefore not surprising that the vegetation of dry river bottoms is of halophytic character.
L. Mucina
The drainage systems of (semi)desert
intermittent rivers are probably very old
as the events leading to dramatic change
of the course are rare.
Figure 13.7 Nyamiti Pan in Ndumo Game Reserve (Maputaland, KwaZulu-Natal). Cynodon
dactylon sward covers the proximal pan bank, while Acacia xanthophloea (fever tree) dominates
the opposite upper bank of the pan.
The classification of vegetation units
related to salt-laden habitats of intermittent rivers follows the same principles as
for salt pans—the position of the respective vegetation unit in relation to the surrounding biome (Figure 13.10).
Inland Azonal Vegetation
625
S %
19 (2006)
L. Mucina
of alluvia of the Cape forelands, Highveld,
Central Bushveld, Lowveld and KwaZuluNatal and the Eastern Cape coastal belt
(and deep inland coastal forelands). The
mapping of the extent of units such
as AZf 4 Drakensberg Wetlands, AZa 1
Fynbos Riparian Vegetation and AZa 2
Cape Lowland Alluvial Vegetation is in its
infancy.
Figure 13.9 Valley-bound view of the subescarpment plains of the Knersvlakte below the Vanrhyns Pass (on the border between Northern and Western Cape) with tributaries of drainage lines
carrying intermittent water courses fringed by Acacia karroo thickets.
AZi 1 Namaqualand Riviere
AZi 3 Southern Kalahari Mekgacha
AZi 6 Southern Karoo Riviere
AZi 7 Tanqua Wash Riviere
AZi 8 Muscadel Riviere
The recognition of Freshwater Wetlands
embedded within the Fynbos Biome
(especially fynbos shrubland units—see
chapter on Fynbos in this book) is the
major challenge for future vegetation
mapping. These wetlands encompass a
plethora of habitats classified by Sieben
et al. (2004) into four major habitat complexes, namely slope seepages, valley
seepages, high-altitude fens (called ‘acid
fens’ by Rogers 1997), and restio marshlands (Figure 13.11). Apart from several
notable exceptions (such as restio marshlands near Rawsonville in the Breede
River Valley and temporary wetlands of
the Agulhas Plains), these habitats are
small and mainly mappable only at scales
below 1:50 000 (see Boucher 1978). Like
its surrounding zonal vegetation, the
Fynbos Freshwater Wetlands show high
levels of endemism and regional distinctness resulting from high beta diversity
across the coenoclines of freshwater fynbos communities. Classification of such a
highly fragmented archipelago of habitats and associated vegetation showing
high levels of distinctive species composition, remains an exciting challenge.
Despite the high diversity of azonal vegetation types featured in this chapter,
the list is far from complete. We admit
to have disregarded a number of very
specific vegetation types—potential subjects for more detailed future mapping
exercises. We believe that all these smallscale vegetation units can be mapped
at scales spanning 1:5 000 to 1:50 000.
Among those, we wish to mention:
(a)
Vegetation of inland cliff
faces and crevices, rock
ledges and sheets
Inland cliffs create a plethora of microhabitats supporting specific vegetation
reflecting geology, soil-trapping (and
Figure 13.10 Position of patches of vegetation units (part of AZi group) featuring vegetation of
erosion) processes, duration and intenintermittent rivers and associated habitats in South Africa.
sity of insulation (a function of aspects
and shading by surrounding landscape
4. Caveats: Neglected Azonal Vegetation features), presence of trickling or seeping water, disturbance
by animals and several other ecological factors. They are found
on steep slopes along the Cape Fold Mountains and Great
Much of the Freshwater Wetlands escaped mapping at this
Escarpment as well as deep gorges (Figure 13.12) cutting the
stage due to their small extent and lack of data. We admit that
table landscapes of southern Africa. Poor accessibility (hence
the major caveats are in the coverage of Freshwater Wetlands of
protection from grazing pressure), low levels of competition and
the Cape Fold Mountains, Highveld, Drakensberg (and adjacent
often relative habitat stability over millennia (and possibly even
parts of the Great Escarpment) and KwaZulu-Natal and Eastern
longer) are prerequisites for the presence of relict and endemic
Cape coastal forelands. We still lack proper data on the extent
626
Inland Azonal Vegetation
S %
19 (2006)
flora. Brief accounts of this kind of community are scattered in
reports of the Nama-Karoo Biome (Werger & Coetzee 1977, pp.
19, 20) and the Grassland Biome (e.g. Hilliard & Burtt 1987, pp.
54–56, Siebert et al. 2003). Unlike in the northern hemisphere,
in South Africa research on the flora and vegetation of rocky
habitats is in its infancy (Van Jaarsveld & Van Wyk 2000, 2003).
Given the basic geometry of plain-surface mapping, the depiction of the vegetation of near vertical cliffs on such maps might
be a challenge, even at a scale of 1:5 000.
(b)
Vegetation of ephemeral freshwater
wetlands of (semi-)arid regions
Ephemeral wetlands in semidesert and desert regions usually
form in close proximity of (temporary) springs or on banks of
temporary streams. Some of the plants are ephemeral annual
herbs, while others may survive the dry period by means of
bulbs and corms in the soil until their habitat is soaked the next
time. For instance, extensive granite-derived coarse-sand seeps
emerge in high-rainfall years in central Namaqualand, showing a rich display of bulbous flora well adapted to this habitat.
To an extent these habitats simulate synecological conditions
of AZf 2 Cape Vernal Pools. Short-lived wetland species such
as Cotula coronopifolia and C. nigellifolia, and bulbous plants
such as Androcymbium dregeanum, Bulbine latifolia var. latifolia (Figure 13.13), Oxalis namaquana and Romulea pearsonii are
floral gems typical of these ephemeral wetlands.
(d)
5.
Vegetation of rock overhangs and cave
openings
Cave openings and rock overhangs are a very special habitat
characterised by steep gradients, low moisture (due to shelter effect) and often a high nutrient-status of the soil due to
frequent visits by both humans and animals seeking shelter.
Because of the slow rates of rock weathering, these shelters
remain for tens to hundreds of thousands of years, hence
long enough to allow evolution of specific flora. Herbs such
as Crassula densa (Werger & Coetzee 1977, p. 20), C. umbraticola, Cynoglossum spelaeum, Juncus mollifolius (endemic
to the Drakensberg), Lappula squarrosa, Malva verticillata,
Nemesia rupicola, Parietaria micrantha and Troglophyton capillaceum (all cited by Hilliard & Burtt 1987, pp. 60, 61) and shadetolerant ferns (Adiantum capillus-veneris, A. poiretii, Asplenium
trichomanes, Blechnum australe, Cheilanthes hirta, Cystopteris
fragilis, Mohria caffrorum, Woodsia montevidensis var. burgessiana etc.) have been reported from the rock overhangs.
(c)
The major reason why these specific vegetation complexes
(indeed deserving status as mapping entities) are not featured
on our map is their extremely small size and patchy occurrence.
We believe that they will receive proper attention in local classifications and microscale mapping studies as in the past (Boucher
1972, 1978).
Vegetation of temporary rock pools
Temporary rock pools (Figure 13.14 and 13.15) are a quite common small-scale habitat, supporting fascinating assemblages
of plants and animals. They come alive during the rainy season and are especially encountered in depressions on the surface of rock sheets and outcrops of granite and gneiss (Cape
granite plutons, Namaqualand, Richtersveld, Augrabies Falls;
e.g. Werger & Coetzee 1977, p. 21) as well as sandstone and
quartzite (Cape Fold Mountains, the Karoo Escarpment and
Drakensberg; e.g. Hilliard & Burtt 1987, pp. 39, 40). Typical
species sharing the short-lived water pools with fairy shrimps
are Aponogeton desertorum, A. stuhlmannii, Crassula aphylla,
C. elatinoides (endemic to the top of Table Mountain), C. inanis,
C. natans, C. vaillantii, very rare Isoetes stellenbossiensis, I.
stephanseniae (both in the Cape), I. toximontana (endemic to
Gifberg), I. transvaalensis and I. welwitschii (both occurring in
the eastern part of the country), Limosella africana, L. grandiflora, L. inflata, Lindernia conferta, L. pulchella and L. wilmsii
etc. The temporary rock pools found in winter-rainfall regions
are of particular interest due to high levels of endemism.
Conservation Challenges: Status,
Threats and Action
Conservation and restoration of wetlands (including riverine
vegetation and rivers) in southern Africa have been the subject of a number of reports, proceedings, chapters and books
(e.g. Noble & Hemens 1978, Denny 1985, O’Keeffe 1986, Begg
1990, Dallas & Day 1993, Davies et al. 1993, Cowan 1995c,
Thieme et al. 2005; see also reports of the Water Research
Commission, website: http://www.wrc.org.za). In this work we
want to highlight only briefly sev eral issues directly pertinent to
conservation and the wise use of wetland vegetation.
5.1
Value of Wetlands
Water is one of the essential preconditions of life. It is a renewable resource, but the ‘renewability’ has its limits and has to
be addressed in countries experiencing water shortages. South
Africa is a dry land (at least most of the area for most of the
year) and therefore the water availability, its spatial and temporal distribution and, last but not least, its quality, are of national
strategic importance. Vegetation occupying wet (albeit often
only temporarily) areas carries important information about
parameters such as water quantity, position and status of the
groundwater table and aquifers, chemical composition of water
and sources of pollution.
Wetlands are home to many rare plant species, including ecological specialists and relicts of past migration patterns. To an
extent wetlands are both evolutionary museums and laboratories. In the light of their high biological value as a habitat
for resident and migratory waterfowl, the international conservation community has recognised the role of some wetlands
as crucial. The Convention for Conservation of Wetlands (also
known as the Ramsar Convention; see Cowan 1995a, b, 1999)
declared in 1971, has so far recognised 16 wetland areas (most
of them freshwater ones) in South Africa as members of the
Ramsar wetland network. Tourism is a major industry in South
Africa and depends largely on wildlife conservation as its major
attraction. Therefore protection of spectacular water-dwelling
wildlife such as crocodile, hippo, otter and water birds is not
only a matter of conservation in its own right or the evolutionary responsibility of mankind, but has become an important
economic factor.
5.2 Threats to Wetlands
The principle threats to wetlands include the conversion of a
wetland from one form to another (changing the status of
the wetland) and reduction in size, often resulting in the total
demise of the wetland habitat.
Conversion usually involves the erection of structures within
the wetland, typically dams. Impounding causes changes in the
functioning of the wetland by reducing the flow of water downstream while increasing the inundation period and/or depth of
inundation. These interventions initiate changes in the structure of biota populating the wetland. Excessive water pollution
results in shifts from oligotrophic (usually very diverse habitats
Inland Azonal Vegetation
627
Figure 13.13 Bulbinella latifolia subsp. latifolia (Asphodelaceae) in
a temporary vlei overgrown by alien Populus, south of Grootvlei near
Nieuwoudtville (Northern Cape).
628
Inland Azonal Vegetation
L. Mucina
Figure 13.12 Complex of steep cliffs, rock ledges, deep cracks and
fissures housing fragments of fynbos vegetation and specific chasmophytic (cremnophilous) vegetation in the Storms River gorge (west of
Humansdorp, Eastern Cape).
L. Mucina
Figure 13.11 Restio marshland (mire) below Landdroskop in the Hottentots Holland Mountains. The dominant plants are Ursinia caledonica,
various species of Elegia and Anthochortus crinalis.
L. Mucina
19 (2006)
L. Mucina
S %
Figure 13.14 Temporary mini-wetland—a rock pool in Nardouw sandstone on the Bokkeveld Plateau (near Nieuwoudtville, Northern Cape)
with Crassula aquatica.
S %
19 (2006)
of high conservation value) to eutrophic wetlands, often dominated by single ubiquitous species choked by algal blooms.
Drainage of a wetland involves both diversion of water away
from the wetland, as well as the extraction of water from the
wetland itself via drains. This results in changes in the species
composition from wetland species to a habitat dominated by
purely terrestrial species, as well as changes in the soils from
typically anaerobic to aerobic. In urban areas, housing developments are a specific problem. Occasionally this is due to ignorance, but often a developer will deliberately set out to destroy
a wetland should it be present on a development site. Urban
wetlands, especially, are subject to increased water runoff from
hard surfaces. Although the total volume may be similar, the
water flows faster into and through the wetland, resulting in
increased erosion. A common source of headcuts, where erosion gullies form in the wetland, is the construction of culverts
permitting roads to cross wetlands. The bottom of these culverts are often much lower than the surface of the wetland,
resulting in erosion.
The main pollution threats to wetlands are petrochemical spills,
unprocessed or semiprocessed sewage, fertiliser and pesticide
runoff, and dumping, both of garbage and rubble. Petrochemical
spills are toxic to most organisms, including the vegetation, of a
wetland. These are often due to indiscriminate disposal of lubrication oils into storm-water drains, as well as from runoff from
roads. The dumping of sewage is usually due to blockages and
bursts in sewage pipes discharging organic wastes into wetlands. This results in the increase in the Escherichia coli count as
well as an increase in organic matter, phosphates and nitrates in
the system. Sewage processing plants usually discharge treated
water into wetland systems. Although the dissolved organic solids may have been removed from this water, it is usually high
in phosphates and nitrates. Surplus of fertilisers and especially
pesticides used in the agricultural industry usually end up in
wetlands via surface runoff or infiltration into the water table.
Phosphates and nitrates form the bulk of agricultural fertilisers.
Wetlands are often perceived as wasted space, and as such are
used as unofficial dumpsites for household and garden refuse
as well as rubble from construction sites.
Many of the species declared as alien invasive weeds are wetland species. These species have varying effects on wetlands,
from the displacement of indigenous species to unduly high
extraction of water from wetlands and rivers. For instance,
Le Maitre et al. (2000) estimated that the total incremental
water use of invading alien plants attained 3 300 million m3
of water per year—an equivalent to about 75% of the virgin
MAR of the Vaal River system. Alien infestation is often exacerbated by nitrate and phosphate pollution. Some species such
as Eichhornia crassipes increase the evaporation from water
bodies and alter the nutrient and oxygen levels of the water.
Much attention has been devoted to controlling this species (for
extensive literature on Eichhornia crassipes see Gopal 1987 for
a global review, and Thompson et al. 1985 and O’Keeffe 1986
for references relevant to Africa). Still more research and management effort (despite the very successful Working for Water
Programme launched in 1996) is needed to understand and to
bring these invaders under control.
Some fast developing regions of South Africa sometimes
experience water shortages during dry periods, leading to
the implementation of water-saving measures. Because of
the lack of surface water, new sources are being investigated,
natural underground reservoirs in particular. Water extraction
from aquifers such as those in sandstones of the Cape Fold
Mountains is being considered. However, care must be exercised as uncontrolled and scientifically ill-funded extractions can
easily lead to the demise of fynbos seeps, which support hundreds of local endemics.
5.3 Sustainable Use and Restoration of
Wetlands
Wetlands have long been sources of vital resources for human
populations, water being the most important commodity.
Apart from supplying water, wetlands have other major roles
in a healthy functioning landscape, for instance in matter and
nutrient cycling, source of food for grazing animals, protein for
humans (wild fowl, fish) or material for building shelters. A wise
farmer knows that his springs and vleis can be used in a sustainable way only when the carrying capacity is not superseded.
Reed beds can recover easily if harvesting is done wisely according to sustainable scenarios (e.g. McKean 2001, Van Rooyen et
al. 2004).
Legal conservation of extant well-preserved wetlands is in place
in many parts of South Africa, but more extensive measures are
called for. First and foremost, development of extant wetlands
must be halted. Uses of wetlands that might lead to conversion
from one form such as a vlei, to another, such as an impoundment, should be abandoned. It is not too late for many altered
wetlands and rehabilitation is possible.
6.
Research Challenges
Obvious economic interests made water and water biota
the focus of a number of research groups and organisations
such as the Water Research Commission (established in terms
of the Water Research Act—Act 34 of 1971), South African
Institute for Aquatic Biodiversity at the Rhodes University in
Grahamstown (a national research facility of National Research
Foundation), the Freshwater Research Unit at the Department of
Zoology, University of Cape Town, the Centre for Environmental
Management of the University of KwaZulu-Natal in Durban, the
Centre for Water in the Environment at the University of the
Witwatersrand and hydrogeology and hydrochemistry research
at the Department of Earth Sciences of the University of the
Western Cape. However, our understanding of variability and
biodiversity of wetlands (and saline habitats), and the functioning of wetlands in regional and continental nutrient-energy
cycling context is calling for more research.
The long list of references at the end of this chapter (see also
Thompson et al. 1985 and Rogers 1997) may suggest that vegetation of inland wetlands as well as vegetation of salt-laden
habitats has received much attention in South Africa, Lesotho
and Swaziland. However, most of the published academic
research on wetlands in South Africa (and neighbouring countries) is fragmented by focusing on small areas or by giving the
wetlands only marginal attention in studies devoted to zonal
vegetation such as grassland and savanna. An integrated and
comprehensive picture of the distribution and variability of the
wetlands is still outstanding. Effective conservation (see above)
of the wetlands and saline habitats is very much dependent on
knowing the scale of variability (biodiversity) of these special
and vulnerable habitats. We do have some management tools,
such as regional classification systems, and now also floristicbiogeographical systems at hand (presented in this chapter),
but a comprehensive habitat classification system for wetlands
remains lacking (see also lament by Rogers 1997). Our classification is a large-scale one and intuitive, although based on
meta-analysis of available information, including extensive and
well-defined data sets. More rigorous data treatment is necesInland Azonal Vegetation
629
S %
repens (d), Chironia decumbens, Conyza pinnatifida, Epilobium
hirsutum, Persicaria decipiens, Samolus valerandi. Geophytic
Herbs: Triglochin bulbosaB complex, T. striataB. Succulent
Herb: Sarcocornia natalensis agg.B (d). Reed & sedge beds
Megagraminoids: Bolboschoenus maritimusB (d), Phragmites
australis (d), Typha capensis (d), Cladium mariscus subsp. jamaicense, Cyperus thunbergii. Graminoids: Ficinia nodosa (d),
Juncus kraussii subsp. kraussiiB (d), Carex clavata, Cyperus denudatus, C. sphaerospermus, C. textilis, Pycreus nitidus. Low Shrub:
Plecostachys serpyllifolia (d). Geophytic Herb: Zantedeschia
aethiopica (d). Water bodies Aquatic Herbs: Myriophyllum spicatum (d), Nymphaea nouchali var. caerulea (d), Aponogeton
junceus, Ceratophyllum demersum, Nymphoides indica subsp.
occidentalis, N. thunbergiana, Potamogeton pectinatus, Ruppia
cirrhosaB, R. maritimaB, Zannichellia palustris. Macroalgae: Chara
globularis, Lamprothamnium papulosumB, Nitella dregeana.
sary. Vegetation ecological research and conservation practice
in the northern hemisphere has identified the floristically based
approach as very effective in identifying patterns (classification of wetland plant communities, identification of indicators
of environmental change). A classification system of habitats
(including wetlands) adopted in the European Union Habitat
Directive (see Rodwell et al. 2002 for analysis of relations of this
document to existing habitat databases) has become a powerful tool for nature land managers and conservationists.
The relative simplicity of wetland habitat in terms of only a few
dominating environmental gradients, relatively easily predictable pattern formation and low species diversity, but high plantfunctional group diversity make wetlands an ideal model for
testing theories of community assembly at a small scale.
7.
19 (2006)
Descriptions of Vegetation Units
Endemic Taxa Marshes Low Shrubs: Passerina paludosa.
Water bodies Aquatic Herbs: Aponogeton angustifolius (d), A.
distachyos (d), Cotula myriophylloides.
Freshwater Wetlands
Conservation Target 24%. Some 14% statutorily conserved in
the Cape Peninsula and Agulhas National Parks as well as in the
proposed Garden Route National Park, Rondevlei and Zandvlei
Bird Sanctuaries as well as in Botrivier, De Hoop, Doringrivier,
Salmonsdam, Verlorenvlei and Walker Bay Nature Reserves. De
Hoop Vlei, Verlorenvlei and Wilderness Lakes (formerly within
AZf 1 Cape Lowland Freshwater Wetlands
Including Phragmites, Scirpus or Typha Reed Beds (Boucher 1978).
Aponogeton–Sporobolus Community & Potamogeton–Aponogeton Vlei
Community (Campbell et al. 1980). Submerged Aquatic Communities,
Emergent and Wetland Communities & Tetragonia decumbens–Senecio
halimifolius Moist Dune Community (O’Callaghan 1990a).
Distribution Western Cape Province: Freshwater inland vleis,
edges of water bodies, such as Verlorenvlei (West Coast), De
Hoop Vlei, Cape Flats vleis, Papenkuils Wetland, some vleis
of the Agulhas Plains and Wilderness Lake System (between
George and Knysna). This azonal unit is embedded within various types of renosterveld (especially those on shale) and the
alluvial fynbos of the Fynbos Biome. Altitude ranges from close
to sea level to mainly 400 m.
Vegetation & Landscape Features Flats and landscape
depressions with extensive tall reeds of Phragmites australis and
Typha capensis, temporarily or permanently flooded restiolands,
sedgelands and rush-beds as well as macrophytic vegetation
embedded in permanent water bodies.
Climate Seasonal winter rainfall (West Coast) to nonseasonal
(South Coast) climate regime, but still characterised by general
prevalence of winter rainfall. MAP ranges between 175 and
845 mm. Characterised by typical warm-temperate regime with
MAT spanning 16.0–17.6°C. Incidence of frost is infrequent.
See also climate diagram for AZf 1 Cape Lowland Freshwater
Wetlands (Figure 13.2).
Important Taxa (BBrackish habitats): Marshes Low Shrub:
Senecio halimifolius. Graminoids: Paspalum vaginatum (d),
Diplachne fusca, Juncus rigidusB, Pennisetum macrourum, P.
thunbergii, Polypogon monspeliensisB, Stenotaphrum secundatumB. Herbs: Berula erecta subsp. thunbergii (d), Falkia
630
Inland Azonal Vegetation
L. Mucina
Geology, Soil & Hydrology Substrate built of fine sandy,
silty and clayey soils over young Quaternary sediments, largely
derived from weathering Cape Supergroup shales and Cape
granites as well as Table Mountain sandstones. They fill depressions and accompany broad alluvia of lowland rivers. The major
source of water is either permanent (banks of permanent lakes)
or temporary (hence either of riverine origin or result of high
winter precipitation). In places (especially due to salt leaching
from Malmesbury Group shales), these wetlands can acquire a
brackish character.
Figure 13.15 AZf 1 Cape Lowland Freshwater Wetlands: Wachendorfia thyrsiflora (Haemodoraceae) in a Typha capensis reed bed on the
edge of a small dam in the Helderberg Nature Reserve (Somerset West,
Western Cape).
S %
19 (2006)
Important Taxa Herbs: Cotula coronopifolia (d), Arctotheca
forbesiana, Felicia tenella, Hesperantha falcata, Wimmerella
secunda. Geophytic Herbs: Onixotis stricta (d), Ornithogalum
thyrsoides (d), Geissorhiza aspera, G. juncea, Lachenalia
aloides var. aloides, L. orchioides, Micranthus alopecuroides, M.
plantagineus, Romulea rosea, R. tabularis, Sparaxis bulbifera,
Spiloxene aquatica, Triglochin bulbosa, Zantedeschia aethiopica.
Succulent Herbs: Crassula aphylla, C. decumbens, C. expansa,
C. natans, C. vaillantii. Aquatic Herb: Limosella grandiflora.
Graminoids: Diplachne fusca (d), Stenotaphrum secundatum
(d), Cyperus tenellus, Isolepis diabolica, Schoenus nigricans,
Scirpus cernuus.
the Wilderness National Park) enjoy Ramsar site status. More
than 2% is also protected in private nature reserves such as
Rietvlei, Oude Bosch, Groothagelkraal, Kleyn Kloof, Sandies
Glen and Vergaderingskop. More than 15% has been transformed to cultivated land, plantations and urban areas. The
vegetation of these wetlands is prone to invasion by alien shrubs
(Acacia saligna, A. longifolia, A. mearnsii), herbs (Apium inundatum) and grasses such as Pennisetum clandestinum (kikuyu
grass) and Paspalum dilatatum.
Remarks Unlike marshes and seeps dominated by endemic elements of the Capensis (preliminarily included within particular
vegetation units of the Fynbos Biome), this vegetation has a
(sub)cosmopolitan character indicated by the occurrence of a
number of species with worldwide distribution in analogous
habitats.
Biogeographically Important Taxon Herb: Pilularia americana (continental disjunction).
Endemic Taxa Graminoids: Isoetes capensis, I. stellenbossiensis,
I. stephansenii. Herbs: Cadiscus aquaticus (d), Arctotheca marginata, Cotula vulgaris, Marsilea schelpeana. Geophytic Herbs:
Lachenalia bachmannii, Oxalis disticha, O. natans, Romulea
aquatica, R. multisulcata.
References Marloth (1908), Adamson (1929), Stephens (1929), Phillips
(1931), Liversidge (1955), Martin (1960a, b), Middlemiss (1960), Taylor
(1969), Andrag (1970), Van der Merwe (1976), Boucher & Jarman (1977),
Van der Merwe (1977b), Linder (1978), Noble & Hemens (1978), Lamprecht
(1979), Weisser (1979), Campbell et al. (1980), Howard-Williams (1980b),
Howard-Williams & Liptrot (1980), Jacot Guillarmod (1982), Weisser &
Howard-Williams (1982), Allanson & Whitfield (1983), Hall (1985), Boucher
(1987, 1996b, 1999a, b, c), O’Callaghan (1990b), Weisser et al. (1992),
Boucher & Rode (1995), Privett (1998), http://www.ngo.grida.no/soesa/
nsoer/resource/wetland/sa_ramsar.htm.
Conservation Critically endangered through especially cultivation and none so far conserved in statutory conservation areas.
Target 24%.
Remark 1 The seasonal (vernal) pools (called ‘Smaller Cyperaceae
Zone’ by Muir 1929, p. 70) used to be a common sight on the
Cape Flats and Stellenbosch Flats in the past. Only remnants are
encountered today (e.g. Campbell et al. 1980: Edith Stephens
AZf 2 Cape Vernal Pools
Distribution Western and Northern Cape Provinces: Cape
Peninsula, Cape Flats and West Coast (especially between
Hopefield and Piketberg) as far north as the surrounds of
Vanrhynsdorp and Nieuwoudtville. This azonal unit is embedded within some shale renosterveld and sand fynbos units of
the Fynbos Biome. Altitude ranging from 50–850 m.
Geology, Soil & Hydrology Vernal pools form either on fine
clays or silts overlying some impermeable layer and are thus
largely restricted to Malmesbury Group shales (Namibian
Erathem) and sometimes on the coastal sands derived from
sandstones of the Table Mountain Group. They vary in dimension, but are mostly between 20 and 100 m in diameter. The
pools are highly seasonal, filling up from May and beginning to
dry out in October. The water level rarely exceeds 10 cm at the
deepest point and they become completely dry in summer.
Climate Found exclusively in regions characterised by winterrainfall (MAP range 163–430 mm). Climate is warm-temperate
with MAT ranging between 16.4°C and 17.2°C. See also climate diagram for AZf 2 Cape Vernal Pools (Figure 13.2).
J.C. Manning
Vegetation & Landscape Features The vegetation is distinctly
zoned, with fringing species that occupy waterlogged soils surrounding the pools plus specialised aquatics that are rooted in
the mud but often have floating stems or leaves. The zone of
fringing species which grow in water up to 2 cm deep, comprises
a band up to 2 m wide of various small annuals, typically species of Crassula (e.g. C. vaillantii, C. natans) and of Cotula (e.g.
C. coronopifolia) along with several small geophytes, such as
species of Trachyandra. The small aquatic Limosella with floating leaves is also found in this zone. Later in the season as the
margins dry out, larger bulbs such as Ornithogalum thyrsoides
predominate. The specialised aquatics grow in waters deeper
than 2 cm although seldom more than 10 cm and typically
include a combination of one or two species with floating stems,
such as Oxalis natans, O. disticha or Cadiscus aquaticus plus one
or two geophytes, especially Romulea aquatica, R. multisulcata,
Onixotis stricta and Lachenalia bachmannii.
Figure 13.16 AZf 2 Cape Vernal Pools: A flooded vernal pool near
Hopefield (West Coast) with rare and endemic Cadiscus aquaticus,
Romulea species and Onixotis stricta.
Inland Azonal Vegetation
631
L. Mucina
S %
Figure 13.17 AZf 2 Cape Vernal Pools: Temporary pools on hard Nardouw sandstones on the
top of the Bokkeveld Plateau (Farm Meulsteen near Nieuwoudtville, Northern Cape). The vegetation is dominated by annual Crassula aphylla and Cotula coronopifolia.
Flora Reserve) and apparently many endemic taxa (tiny ephemerals or bulbous ephemeroids) supported by this special habitat
are either under critical threat or have not been encountered
again for a long time. A very specialised seasonal-pool habitat
is formed on granite boulders and sheets (around Stellenbosch,
Paarl, Darling, Langebaan and Saldanha).
Remark 2 Most of the small seasonal pools are not featured
on our map due to lack of proper coverage and difficulties with
featuring this vegetation unit at large (country-wide) mapping
scales.
References Duthie (1929), Muir (1929), Taylor (1972), Noble & Hemens
(1978), Campbell et al. (1980), Boucher (1987), Cook (2004).
AZf 3 Eastern Temperate Freshwater
Wetlands
Distribution Northern Cape, Eastern Cape, Free State, NorthWest, Gauteng, Mpumalanga and KwaZulu-Natal Provinces as
well as in neighbouring Lesotho and Swaziland: Around water
bodies with stagnant water (lakes, pans, periodically flooded
vleis, edges of calmly flowing rivers) and
embedded within the Grassland Biome.
Altitude ranging from 750–2 000 m.
19 (2006)
rence of Jurassic Karoo dolerite dykes
having a profound influence on run-off.
Soils are peaty (Champagne soil form)
to vertic (Rensberg soil form). The vleis
form where flow of water is impeded
by impermeable soils and/or by erosion
resistant features, such as dolerite intrusions. Many vleis and pans of this type
of freshwater wetlands are inundated
and/or saturated only during the summer
rainfall season, and for some months
after this into the middle of the dry winter season, but they may remain saturated all year round. Surface water inundation may be present at any point while
the wetland is saturated and some plant
species will be present only under inundated conditions, or under permanently
saturated conditions. The presence of
standing water should not be taken as a
sign of permanent wet conditions.
Climate Exclusively summer-rainfall
region (MAP range 421–915 mm). Cooltemperate pattern with MAT ranging
between 12.6°C and 16.7°C. Due to high elevation, frost is a
frequent phenomenon. See also the summary climate diagram
for AZf 3 Eastern Temperate Freshwater Wetlands (Figure 13.2).
Important Taxa Marshes Megagraminoid: Cyperus congestus (d). Graminoids: Agrostis lachnantha (d), Carex acutiformis
(d), Eleocharis palustris (d), Eragrostis plana (d), E. planiculmis (d), Fuirena pubescens (d), Helictotrichon turgidulum (d),
Hemarthria altissima (d), Imperata cylindrica (d), Leersia hexandra (d), Paspalum dilatatum (d), P. urvillei (d), Pennisetum thunbergii (d), Schoenoplectus decipiens (d), Scleria dieterlenii (d),
Setaria sphacelata (d), Andropogon appendiculatus, A. eucomus, Aristida aequiglumis, Ascolepis capensis, Carex austro-africana, C. schlechteri, Cyperus cyperoides, C. distans, C. longus,
C. marginatus, Echinochloa holubii, Eragrostis micrantha, Ficinia
acuminata, Fimbristylis complanata, F. ferruginea, Hyparrhenia
dregeana, H. quarrei, Ischaemum fasciculatum, Kyllinga erecta,
Panicum schinzii, Pennisetum sphacelatum, Pycreus macranthus, P. nitidus, Setaria pallide-fusca, Xyris gerrardii. Herbs:
Centella asiatica (d), Ranunculus multifidus (d), Berkheya radula,
B. speciosa, Berula erecta subsp. thunbergii, Centella coriacea,
Chironia palustris, Equisetum ramosissimum, Falckia oblonga,
Geology, Soil & Hydrology Found on
younger Pleistocene to recent sediments
overlying fine-grained sedimentary rocks
of the Karoo Supergroup (on sediments
of both Ecca and Beaufort Groups due to
the large extent of the area of occurrence)
as well as of the much older dolomites of
the Malmani Subgroup of the Transvaal
Supergroup in the northwest. Especially
the areas built by Karoo Supergroup
sediments are associated with the occur632
Inland Azonal Vegetation
L. Mucina
Vegetation & Landscape Features Flat
landscape or shallow depressions filled
with (temporary) water bodies supporting
zoned systems of aquatic and hygrophilous vegetation of temporarily flooded
grasslands and ephemeral herblands.
Figure 13.18 AZf 3 Eastern Temperate Freshwater Wetlands: Small wetland sedge bed surrounded by sub-escarpment grassland in Transkei (Eastern Cape).
S %
19 (2006)
Haplocarpha lyrata, Helichrysum difficile, H. dregeanum, H.
mundtii, Hydrocotyle sibthorpioides, H. verticillata, Lindernia
conferta, Lobelia angolensis, L. flaccida, Mentha aquatica,
Monopsis decipiens, Pulicaria scabra, Pycnostachys reticulata,
Rorippa fluviatilis var. fluviatilis, Rumex lanceolatus, Senecio
inornatus, S. microglossus, Sium repandum, Thelypteris confluens, Wahlenbergia banksiana. Geophytic Herbs: Cordylogyne
globosa, Crinum bulbispermum, Gladiolus papilio, Kniphofia
ensifolia, K. fluviatilis, K. linearifolia, Neobolusia tysonii, Nerine
gibsonii (only in Eastern Cape), Satyrium hallackii subsp. hallackii. Reed & sedge beds Megagraminoids: Phragmites
australis (d), Schoenoplectus corymbosus (d), Typha capensis (d), Cyperus immensus. Graminoid: Carex cernua. Water
bodies Aquatic Herbs: Aponogeton junceus, Ceratophyllum
demersum, Lagarosiphon major, L. muscoides, Marsilea capensis, Myriophyllum spicatum, Nymphaea lotus, N. nouchali var.
caerulea, Nymphoides thunbergiana, Potamogeton thunbergii.
Carnivorous Herb: Utricularia inflexa. Herb: Marsilea farinosa
subsp. farinosa.
Biogeographically Important Taxon (Highveld endemic)
Herb: Rorippa fluviatilis var. caledonica.
Endemic Taxa Marshes Geophytic Herbs: Disa zuluensis,
Kniphofia flammula (northern KwaZulu-Natal), Nerine platypetala. Succulent Herb: Crassula tuberella.
Conservation Target 24%. About 5% statutorily conserved
in the Blesbokspruit (a Ramsar site), Hogsback, Marievale,
Olifantsvlei, Seekoeivlei (a Ramsar site), Wakkerstroom Wetland,
Umgeni Vlei, Umvoti Vlei and Pamula Park Nature Reserves. It
is also protected in private nature reserves such as the Korsman
Bird Sanctuary and Langfontein. Some 15% has been transformed to cultivated land, urban areas or plantations. In places
intensive grazing and use of lakes and freshwater pans as
drinking pools for cattle or sheep cause major damage to the
wetland vegetation. The following aliens are encountered in
this type of wetland: Bidens bidentata, Cirsium vulgare, Conyza
bonariensis, Oenothera rosea, Physalis viscosa, Plantago lanceolata, Rumex crispus, Sesbania punicea, Schkuhria pinnata,
Stenotaphrum secundatum (native on South African coast,
alien on highveld), Trifolium pratense, Verbena bonariensis, V.
brasiliensis, Xanthium strumarium, etc.
References Downing (1966, 1968, 1970), Noble
& Hemens (1978), Müller (1986), Allan (1987),
Begg & Carser (1988, 1989), Behr & Bredenkamp
(1988), Breytenbach (1991), Fuls et al. (1992),
Breen et al. (1993), Breytenbach et al. (1993),
Eckhardt (1993), Eckhardt et al. (1993a, c), Smit et
al. (1993a, 1995, 1997), Bredenkamp et al. (1994),
Coetzee et al. (1994a, b), Malan (1997), Cilliers et
al. (1998), Kotze & O’Connor (2000), Perkins et
al. (2000), Van Wyk et al. (2000), Dingaan et al.
(2001), Siebert et al. (2002), Malan (2003).
Including ‘Wetlands below escarpment’ (Hilliard & Burtt 1987).
Distribution Free State, KwaZulu-Natal, Eastern Cape and
Mpumalanga Provinces as well as in Lesotho: Wetlands (vleis
and lakes) on broad ridges and narrow alluvia of slow- and
fast-flowing mountain streams in deeply incised valleys. Found
from the Stormberg Plateau through the highlands of the
Eastern Cape, KwaZulu-Natal and Lesotho (Drakensberg range).
Outliers occur also on top of tafelbergs such as Korannaberg,
Thaba Nchu and Platberg. Scattered along the Low Escarpment
(between Van Reenen’s Pass and Piet Retief) and then along
the Northern Escarpment. The northernmost patch of this wetland type has thus far been identified on the summit plateau
of the Leolo Mountains in Sekhukhuneland. Embedded within
the high-altitude Grassland Biome found at altitudes roughly
spanning 1 800–2 500 m.
Vegetation & Landscape Features Vleis (sometimes with
open water bodies such as tarns) and fringes of mountain
streams, supporting tall herb vegetation and shrubby vegetation of medium height (reaching thicket density in places) along
upper reaches of mountain streams. Characteristic feature of
the Drakensberg Wetlands is the frequent occurrence of terrestrial orchids and species of Kniphofia and Geranium.
Geology, Soil & Hydrology Geological substrate is formed
by the uppermost (youngest) part of the Karoo Supergroup.
Jurassic basalts and dolerites of the Drakensberg Group as
well as sandstones and mudstones of the Clarens and Elliot
Formations (both Triassic) forming the Eastern Escarpment.
These bedrocks support heavy, clayey soils (e.g. Champagne,
Arcadia, Katspruit soil forms) often with high humus content.
The water bodies are either stagnant (or slow-flowing) and fed
either from springs or slope seeps or to an extent also from
abundant rainfall and snowfall (especially in the Eastern Cape).
Here we have also included vegetation along fast-flowing
mountain streams in sandy gravel and stony (in places built of
large boulders) ravines with only very narrow alluvia—the habitats along the fast-flowing streams can suffer extensive erosion,
especially during heavy-rainfall and stormy local weather situations in summer. Some water bodies freeze in winter.
Climate Seasonal, summer-rainfall regime with maximum
precipitation in December–February (MAP range 543 mm on
K. Kobisi
Remarks Vegetation patterning in the form of concentric belts
(‘rings’) is often found in pans. Pan size and depth may be a
factor limiting vegetation, as large water bodies with shallow
water may experience wave action. This
limits the presence of species with floating leaves as well as some submerged
and marginal macrophytes. The situation is more complex in vleis as these
often have variable microtopography
and soil types within a single wetland.
It is possible for seasonally inundated
zones to occur embedded inside the
permanently inundated zone of a vlei, if
this zone is present.
AZf 4 Drakensberg Wetlands
Figure 13.19 AZf 4 Drakensberg Wetlands: Riparian vegetation (with dominant Leucosidea
sericea) along a stream in a Tšehlanyane gorge in northern Lesotho.
Inland Azonal Vegetation
633
S %
Stormberg Plateau, up to 1 247 mm on upper uKhahlamba).
Especially on the Southern Berg, part of this precipitation occurs
in the form of snow. Sudden melting of the snow cover on
the surrounding high-altitude grasslands may have a profound
(albeit short-term) influence on stream flow and may subsequently cause erosion of the river channels. The temperature
regime is cold-temperate with MAT spanning 9.6°C (Lesotho
Plateau) to 13.1°C (Senqu Valley). See also regional climate diagram for AZf 4 Drakensberg Wetlands (Figure 13.2).
Important Taxa Drainage-line grasslands & herblands
Tree Fern: Cyathea dregei (d). Megagraminoid: Miscanthus
junceus (d). Graminoids: Cyperus congestus (d), Merxmuellera
macowanii (d), Cyperus keniensis, C. marginatus, C. usitatus,
Hyparrhenia quarrei, Pycreus mundii. Herbs: Peltocalathos baurii (d), Epilobium salignum, Geranium wakkerstroomianum,
Nasturtium officinale. Geophytic Herbs: Gunnera perpensa (d),
Galtonia candicans, G. princeps, Littonia modesta, Neobolusia
tysonii, Sandersonia aurantiaca. Drainage-line shrublands
Tall Shrubs: Buddleja salviifolia (d), Cliffortia linearifolia (d),
Leucosidea sericea (d), Cliffortia nitidula, Phygelius aequalis.
Low Shrubs: Cliffortia filicauloides, Erica oatesii, Senecio subrubriflorus. Herbs: Denekia capensis, Persicaria meisneriana,
Salvia aurita. Marshes & seeps Graminoids: Carex acutiformis
(d), C. austro-africana (d), Fuirena pubescens (d), Ascolepis
capensis, Carex cognata, Carpha filifolia, Helictotrichon turgidulum, Juncus oxycarpus, Kyllinga pauciflora, Rhynchospora
brownii, Schoenoxiphium burttii, Scirpus ficinioides, Xyris capensis, X. gerrardii. Herbs: Ranunculus meyeri (d), R. multifidus
(d), Epilobium capense, Eriocaulon hydrophilum, Pycnostachys
reticulata, Rumex lanceolatus, Senecio serratuloides. Geophytic
Herbs: Dierama pauciflorum, Drimia sphaerocephala, Kniphofia
albescens, K. fluviatilis, K. linearifolia, K. northiae, K. triangularis, Moraea ardesiaca, M. trifida, Nerine angustifolia, N. gibsonii (only in Eastern Cape), Satyrium hallackii subsp. hallackii,
S. trinerve, Schizoglossum nitidum, Zantedeschia albomaculata. Streams Graminoid: Isolepis fluitans. Aquatic Herb:
Hydrophilus rattrayi. Tarns Aquatic Herbs: Limosella africana,
L. inflata. Carnivorous Herb: Utricularia prehensilis. Succulent
Herb: Crassula natans. Graminoids: Juncus dregeanus, J. punctorius. Herbs: Lindernia bolusii, L. conferta.
19 (2006)
2–3% has been transformed for cultivation. Invasive aliens do
not play any important role.
Remarks This unit has not been mapped in its full extent due to
a lack of data, particularly for riparian shrubland, which deserves
recognition as a vegetation unit in its own right (as an analogue
to the AZa 1 Fynbos Riparian Vegetation). Important patches of
the riparian thickets occur along many Drakensberg (including
many deeply incised river valleys in Lesotho), Amathole and possibly also Stormberg mountain streams. In the Low Drakensberg
area similar vegetation was found to occur in places even below
1 800 m (Smit et al. 1995). Due to lack of data we did not map
the patches of this wetland along the Eastern Escarpment and
adjacent mountain ranges (see Burgoyne 1995, Burgoyne et
al. 2000).
References Bews (1917), Jacot Guillarmod (1964, 1969, 1972), Nanni
(1972), Smith (1972), Killick (1978a, b), Noble & Hemens (1978), Potgieter
(1982), Deall (1985), Hilliard & Burtt (1987), Begg & Carser (1989), Deall et al.
(1989), Killick & Holcroft (1990), Du Preez (1991), Du Preez & Bredenkamp
(1991), Matthews (1991), Matthews et al. (1992), Smit et al. (1993b, 1995),
Burgoyne (1995), Dely et al. (1995), Eckhardt et al. (1996), Eckhardt (1998),
Burgoyne et al. (2000), Siebert et al. (2002), http://www.ngo.grida.no/soesa/
nsoer/resource/wetland/sa_ramsar.htm.
AZf 5 Lesotho Mires
Distribution Lesotho and to a very small extent also South
Africa (KwaZulu-Natal Province): Lesotho Plateau and adjacent
mountain ranges—wetlands (locally, in Sesotho, called ‘mokhoabo’) embedded within grassland units Gd 10 Drakensberg
Afroalpine Heathland and upper parts of Gd 8 Lesotho Highland
Basalt Grassland. Altitude ranging from 2 500–3 400 m.
Vegetation & Landscape Features Depressions and slight
slopes on the high-altitude plateau. Low grass-herb mire complexes with turf and tussock grassland patches and herblands
built of low creeping herbs as well as luxurious moss cover in
places. Small lakes (tarns) support aquatic vegetation covering
tarn bottoms where shallow water column allows deep penetration of light.
Biogeographically Important Taxa
(all Drakensberg endemic): Drainageline grasslands & herblands Herb:
Geranium pulchrum. Geophytic Herb:
Anemone fanninii. Marshes Herbs:
Cotula paludosa, Felicia uliginosa,
Gnaphalium limicola. Geophytic Herb:
Wurmbea elatior.
Conservation Target 24%, but already
almost perhaps more than 50% conserved in statutory protection areas such
as the uKhahlamba Drakensberg Park
(a Ramsar site), and Sehlabathebe and
Tšehlanyane National Parks and Bokong
Nature Reserve (all Lesotho). Only about
634
Inland Azonal Vegetation
M. Polaki
Endemic Taxa Drainage-line shrublands Herbs: Afrotysonia africana, A.
glochidiata, Felicia drakensbergensis,
Lepidium basuticum, Sebaea pleurostigmatosa, Senecio kalingenwae. Marshes
& seeps Graminoid: Isolepis pellocolea.
Herb: Helichrysum ephelos. Geophytic
Herbs: Disa scullyi, Kniphofia albomontana, K. evansii.
Figure 13.20 AZf 5 Lesotho Mires: Complex of low-altitude mires on Thaba Putsoa in western
Lesotho.
S %
19 (2006)
Geology, Soil & Hydrology Peat (organic soils) functioning
as sponge in summer and freezing in winter over basaltic lava
flows of the Jurassic Drakensberg Group (top of the Karoo
Supergroup). Eutrophic water rich in CaO, K2O and P2O3 with
pH about 8 (Stockley 1947 sec. Van Zinderen Bakker & Werger
1974), changing in an oligotrophic direction, with ultimate values between pH 4 and 5. Most of the pH (H2O) measurements
of soils by Backéus (1988) in the Thaba-Putsoa range were
below 5.
Climate Seasonal, summer-rainfall regime with MAP 1 500 mm,
much of it in the form of snow. Very cold, high-altitude climate
(MAT 4.0–9.6°C); according to Van Zinderen Bakker & Werger
(1974) the maximum temperatures in summer do not exceed
16°C, while the nightly minimum temperature at soil level is
below freezing point throughout the year. See also climate diagram for AZf 5 Lesotho Mires (Figure 13.2).
Important Taxa Mires Semiparasitic Shrub: Thesium nigrum.
Graminoids: Agrostis bergiana var. bergiana (d), Carex cognata
(d), Isolepis costata (d), Kyllinga erecta (d), Scirpus ficinioides
(d), Agrostis lachnantha, Bulbostylis densa, Juncus dregeanus, Koeleria capensis, Luzula africana, Pennisetum thunbergii. Herbs: Athrixia fontana (d), Haplocarpha nervosa (d),
Ranunculus meyeri (d), Alchemilla woodii, Anagallis huttonii,
Cerastium capense, Cineraria lyrata, Cotula hispida, Eriocaulon
sonderianum, Lobelia flaccida, Ranunculus multifidus, Rorippa
microphylla, Sebaea leiostyla, Senecio macrocephalus, S. polyodon var. subglaber, Trifolium burchellianum. Geophytic Herbs:
Ornithogalum paludosum, Oxalis obliquifolia, Rhodohypoxis
milloides, Wurmbea kraussii. Carnivorous Herb: Utricularia
livida. Tarns Succulent Herbs: Crassula inanis (d), C. natans (d).
Aquatic Herbs: Lagarosiphon muscoides (d), Limosella longiflora (d), L. maior (d), Aponogeton junceus, Limosella africana,
L. vesiculosa.
Biogeographically Important Taxa (all Drakensberg
endemic): Mires Low Shrubs: Erica frigida, Inulanthera thodei.
Graminoids: Agrostis subulifolia, Carex monotropa, Fuirena
tenuis, Schoenoxiphium filiforme. Herbs: Senecio cryptolanatus (d), Alepidea pusilla, Cotula paludosa, Felicia uliginosa,
Helichrysum bellum. Geophytic Herbs:
Rhodohypoxis deflexa, R. rubella, Saniella
verna, Wurmbea elatior. Succulent Herb:
Crassula gemmifera. Tarns Aquatic Herb:
Limosella inflata.
Bakker & Werger (1974), Killick (1978a, b), Backéus (1988), Schwabe
(1989, 1995), Du Preez (1991), Du Preez & Bredenkamp (1991), Lesotho
Government, National Environment Secretariat (2000), Day (2005a), http://
www.ngo.grida.no/soesa/nsoer/resource/wetland/sa_ramsar.htm.
AZf 6 Subtropical Freshwater Wetlands
Distribution KwaZulu-Natal, Mpumalanga, Gauteng, NorthWest, Limpopo and Eastern Cape Provinces as well as in
Swaziland: Wetlands embedded within the Albany Thicket
Biome, the Coastal Belt from Transkei as far as Maputaland
as well as those of Lowveld and the Central Bushveld regions.
Altitude ranging from 0–1 400 m.
Vegetation & Landscape Features Flat topography supporting low beds dominated by reeds, sedges and rushes, waterlogged meadows dominated by grasses. Found typically along
edges of often seasonal pools in aeolian depressions as well as
fringing alluvial backwater pans or artificial dams.
Geology, Soil & Hydrology Waterlogged, clayey soils of
Champagne and Arcadia forms, containing certain levels of
decaying organic matter, especially in very productive reed beds.
These wetlands are underlain mostly by Cenozoic alluvium, less
so by Karoo Supergroup volcanic rocks and sediments, as well
as by the Cretaceous (and younger coastal) sediments of the
Zululand and Maputaland Groups. Waterlogged habitats with
water regularly forming columns of variable depth. The highest
water levels are found in summer, during periods of maximum
seasonal rainfall.
Climate Mainly seasonal, summer rainfall (Lowveld and Central
Bushveld), and to a lesser extent also nonseasonal (Albany
region and the Eastern Cape and KwaZulu-Natal coastal belts)
climate characterised by high precipitation. MAP spanning 454
mm (Makhado) to 963 mm (Maputaland). Subtropical and
tropical temperature regimes are prevalent in winter and summer, respectively. MAT ranging from 18.0°C (Central Bushveld)
to 22.0°C (Makatini Flats). Occurrence of frost is limited to
southernmost localities. See also climate diagram for AZf 6
Subtropical Freshwater Wetlands (Figure 13.2).
Conservation Target 24%. Only
about 4% statutorily conserved in the
Malekgonyane (Ongeluksnek) Wildlife
Reserve and uKhahlamba Drakensberg
Park (a Ramsar site) and in the Bokong
Nature Reserve (Lesotho). Grazing (and
even burning) can be seen as a serious
threat to this unique and fragile vegetation type.
References Bews (1917), Van Zinderen Bakker
(1955, 1965), Jacot Guillarmod (1961, 1962,
1963, 1964, 1968, 1971, 1972), Van Zinderen
W.S. Matthews
Endemic Taxa Mires Semiparasitic
Shrub: Thesium nationae. Graminoids:
Isolepis angelica (d), Colpodium hedbergii. Herbs: Helichrysum flanaganii, Sebaea marlothii. Geophytic Herbs:
Kniphofia caulescens (d), Hesperantha
crocopsis, Romulea luteoflora var. sanisensis. Tarns Aquatic Herb: Aponogeton
ranunculiflorus (d).
Figure 13.21 AZf 6 Subtropical Freshwater Wetlands: Muzi Swamp in an interdune depression
at the edge of the Tembe Elephant Park on the Mozambique border (northern KwaZulu-Natal).
The reed beds of Phragmites mauritianus dominant in the swamp are surrounded by broad-leaved
savanna of the SVl 18 Tembe Sandy Bushveld.
Inland Azonal Vegetation
635
S %
Important Taxa Marshes Small Trees: Hyphaene coriacea (d),
Phoenix reclinata (d). Graminoids: Chloris virgata (d), Cynodon
dactylon (d), Cyperus articulatus (d), Dactyloctenium aegyptium
(d), Diplachne fusca (d), Echinochloa pyramidalis (d), Fimbristylis
obtusifolia (d), Hemarthria altissima (d), Imperata cylindrica (d),
Ischaemum arcuatum (d), Leersia hexandra (d), Pycreus mundii
(d), Sporobolus nitens (d), S. smutsii (d), Urochloa stolonifera
(d), Bolboschoenus glaucus, Courtoisia cyperoides, Cyperus
alopecuroides, C. pectinatus, Digitaria natalensis, Echinochloa
stagnina, Eragrostis chapelieri, E. lappula, Eriochloa meyeriana,
Fimbristylis bisumbellata, Fuirena ecklonii, Oxycaryum cubense,
Paspalidium obtusifolium, Paspalum commersonii, Pycreus
pelophilus, P. polystachyos, Scleria poiformis, Sporobolus consimilis. Herbs: Pentodon pentandrus (d), Persicaria senegalensis
(d), Burmannia madagascariensis, Centella coriacea, Commelina
diffusa, Convolvulus mauritanicus, Desmodium dregeanum,
Eclipta prostrata, Epaltes gariepina, Eriocaulon abyssinicum,
Ethulia conyzoides, Glinus lotoides, Hydrocotyle ranunculoides,
Ludwigia adscendens subsp. diffusa, L. leptocarpa, L. octovalvis,
L. palustris, Neptunia oleracea, Persicaria attenuata subsp. africana, P. hystricula, Rorippa madagascariensis, Sium repandum,
Vahlia capensis. Geophytic Herbs: Eulophia angolensis, Zeuxine
africana. Succulent Herb: Salicornia pachystachya. Semiparasitic
Herb: Buchnera longespicata. Aquatic Herbs: Bergia salaria,
Lagarosiphon crispus. Lakes & ponds Graminoid: Eleocharis
dulcis (forming rafts). Aquatic Herbs: Azolla pinnata var. africana
(d), Ceratophyllum demersum (d), Lemna minor (d), Nymphaea
nouchali var. caerulea (d), Pistia stratiotes (d), Wolffia arrhiza
19 (2006)
(d), Aponogeton desertorum, A. natalensis, A. rehmannii,
Ceratophyllum muricatum, Marsilea macrocarpa, Najas marina
subsp. delilei, N. pectinata, Nymphoides indica subsp. occidentalis, N. rautanenii, Ottelia exserta, Potamogeton crispus, P. pectinatus, P. schweinfurthii, Spirodela polyrhiza, S. punctata, Trapa
natans var. bispinosa. Carnivorous Herbs: Utricularia gibba
subsp. exoleta, U. inflexa, U. subulata. Geophytic Herb: Crinum
paludosum. Reed & sedge beds Megagraminoids: Cladium
mariscus subsp. jamaicense (d), Cyperus papyrus (d), Phragmites
australis (d), P. mauritianus (d), Schoenoplectus corymbosus (d),
S. scirpoideus (d), Typha capensis (d). Graminoids: Cyperus fastigiatus (d), C. difformis, C. digitatus, C. latifolius, C. sexangularis, Fuirena ciliaris.
Biogeographically Important Taxa (all southernmost distribution limit) Streambanks Herb: Floscopa glomerata, Ipomoea
aquatica. Geophytic Herb: Bolbitis heudelotii. Lakes & ponds
Aquatic Herbs: Brasenia schreberi, Ceratopteris cornuta, Wolffia
globosa, Wolffiella welwitschii. Herbs: Hygrophila schulli,
Limnophyton obtusifolius, Marsilea apposita, M. coromandelina, M. minuta, M. villifolia. Reed & sedge beds Graminoids:
Cyperus dives, C. procerus, C. prolifer.
Endemic Taxa Marshes Graminoid: Cyperus sensilis (embedded within Indian Ocean Coastal Belt of KwaZulu-Natal). Lakes
& ponds Geophytic Herbs: Crinum campanulatum (Albany
region). Aquatic Herbs: Isoetes wormaldii (Albany region),
Wolffiella denticulata (Maputaland).
Conservation Least threatened. Target 24%. Some 40–50%
is statutorily conserved in the Greater St Lucia Wetland Park
(including Ramsar sites such as St Lucia System, Kosi Bay System
and Lake Sibaya), Kruger National Park, Ndumo Game Reserve,
Tembe Elephant Park as well as in Nhlabane, Nylsvley (a Ramsar
site), Mkombo, Sileza and Richards Bay Nature Reserves. A further 10% enjoys protection in a number of private game farms
and other reserves in the Limpopo, Mpumalanga and KwaZuluNatal Provinces. So far only about 4% has been transformed
(largely for cultivation), but the pressure of local grazing and
urban sprawl will result in the demise of many subtropical freshwater habitats. Disturbance leads to invasion by alien plants
such as Lantana camara, Chromolaena discolor and Melia azedarach (on the edges of wetlands) and aquatic weeds such as
Eichhornia crassipes, Pistia stratiotes and Salvinia molesta (in
water bodies).
References Dyer (1937), Edwards (1967), Musil (1972), Venter (1972), Musil
et al. (1973), Theron (1973), Noble & Hemens (1978), Howard-Williams
(1979, 1980a), Furness & Breen (1980), Heeg et al. (1980), Rogers (1980,
1984), Furness (1981), Gertenbach (1983), Tinley (1985), Goodman (1987a,
b), Tarboton (1987), Begg & Carser (1988, 1989), Breen et al. (1993), Brown
& Bredenkamp (1994), Barnes et al. (2002), Hattingh & Matthews (2003),
http://www.ngo.grida.no/soesa/nsoer/resource/wetland/sa_ramsar.htm.
Alluvial Vegetation
L. Mucina
Aza 1 Fynbos Riparian Vegetation
Figure 13.22 AZf 6 Subtropical Freshwater Wetlands: Pan wetland
in the Kruger National Park infested by Pistia stratiotes (Araceae), with
a crocodile (Crocodilus niloticus) basking after a meal on the opposite
side of the lake.
636
Inland Azonal Vegetation
Including Brabejum–Rhus Riverine Scrub (Boucher 1978). Elegia capensis–
Miscanthus capensis Scrub & Calopsis paniculata–Cliffortia strobilifera Scrub
(Cleaver et al. 2005).
Distribution Western Cape and (partly) Eastern Cape Provinces:
Vegetation of narrow belts of alluvial thickets and accompanying palmiet (Prionium serratum) vegetation along upper
stretches of the rivers draining mountain fynbos. Altitude from
near sea level to 1 300 m.
S %
19 (2006)
Vegetation & Landscape Features
Narrow, flat or slightly sloping alluvial
flats supporting a complex of reed beds
dominated by tall palmiet (Prionium serratum) and restios (Calopsis, Cannomois,
Elegia, Ischyrolepis and Rhodocoma), low
shrublands with moisture-loving species
of Berzelia, Cliffortia, Helichrysum etc.
With tall riparian thickets of Metrosideros
angustifolia and Brachylaena neriifolia
in places.
L. Mucina
Geology, Soil & Hydrology Alluvial
sandy or silty soils over Quaternary sediments, largely derived from weathering of Table Mountain sandstone, Cape
Supergroup shale and Cape Granite.
The streams are fed mainly during the
winter-rainfall season and later through
seeps carrying acidic water rich in organic
compounds (tannins) and with a characteristic brownish colour (locally called ‘teeFigure 13.23 AZa 1 Fynbos Riparian Vegetation: Boulders along a narrow alluvium of a mounwater’). Large streams carry water all year
tain stream in the Hottentots Holland Nature Reserve near Grabouw, with palmiet (Prionium serraround, while some smaller streams can
tum) in the river channel and Brachylaena neriifolia (Asteraceae) and Ischyrolepis subverticillata
turn into a series of disconnected pools
(Restionaceae) on the river terrace.
in the upper reaches in summer. Even
Conservation Due to a very extensive system of nature reserves
in relatively small streams flooding can be quite violent, with
and wilderness areas administered by CapeNature, Eastern
strong flows especially in narrow gorges. Many trees and shrubs
Cape Nature Conservation Service and partly also by South
are adapted to uprooting or heavy damage by spates. The heavy
African National Parks (especially in the southern Cape), many
erosion also results in a soil-poor substrate and plant cover is
patches of this vegetation type are well protected. This vegetaoften very patchy, located in small depressions with some soil
tion is, however, prone to infestation by alien woody plants
development or between boulders.
such as Acacia mearnsii.
Climate Similar to the climate of the surrounding mountains
Remark 1 Due to the small scale as well as lack of data, the
(see climate diagrams for mesic types of fynbos such as those of
the FFs and FFh groups; see the chapter on Fynbos in this book), current mapping coverage of the unit on the national vegetation map is only a rough indication of its occurrence (few
although the presence of a river influences the microclimate
patches in the Cederberg area). The riparian thickets and
of the valley considerably, making it cooler, moister and better
accompanying palmiet reeds occur regularly along the fynbos
sheltered from wind. The most detailed study on the climate in
a river valley (Jonkershoek) was published by Wicht et al. (1969). mountain streams in many of the Cape Fold Mountains (from
the Bokkeveld Plateau as far as Van Stadens Mountains near
(See also climate diagram in Figure 13.2.)
Port Elizabeth), and we hope they will receive proper attention
C
P
Important Taxa ( Endemic to Capensis, Sharing with
in future. Many important species of riparian scrub vegetation
Pondoland) Small Trees: Brabejum stellatifolium C (d),
do not occur east of Mossel Bay.
C
C
Brachylaena neriifolia (d), Cunonia capensis (d), Kiggelaria
africana, Pseudoscolopia polyanthaP, Widdringtonia nodiflora. Remark 2 This vegetation unit bears floristic (and partly also
Tall Shrubs: Berzelia lanuginosaC (d), Cliffortia strobilifera (d), ecological) similarity to the Western Cape Talus Forest (subtype:
Western Cape Riverine Forests) of Von Maltitz et al. (2003) and
Metrosideros angustifoliaC (d), Psoralea pinnataC (d), Berzelia
Geldenhuys & Mucina (2006)—well-developed riparian forests
squarrosaC, Cassine schinoidesC, Cliffortia atrataC, Diospyros
glabraC, Erica caffra, Freylinia lanceolata, Halleria ellipticaC, along several rivers of the Cape Fold Mountains.
Maytenus oleoides, Podalyria calyptrataC, Psoralea aphyllaC. Low
References Marloth (1908), Rycroft (1953), Harrison & Elsworth (1958),
Shrubs: Helichrysum cymosum, H. helianthemifoliumC, Penaea
Martin & Noel (1960), Grobler (1964), Harrison (1964), Wicht et al. (1969),
C
C
cneorum , Pseudobaeckea africana . Semiparasitic Shrub:
Boucher (1972, 1978, 1987, 1994, 1996a, 1999a, b), Werger et al. (1972a,
Osyris compressa (d). Woody Climber: Asparagus scandens. b), Kruger (1974, 1979), Campbell (1975), Acocks (1976), Linder (1976), Le
Megagraminoids: Prionium serratumP (d), Calopsis paniculata (d), Roux (1977), Priday (1977), Van Zyl (1977), Parkman (1978), Taylor (1978),
Seydack & Home (1980), McDonald (1985, 1988), Van Wilgen & Kruger
Ischyrolepis subverticillataC (d), Cannomois virgataC, Ehrharta
(1985), Sieben (2003), Cleaver et al. (2005).
C
rehmannii, Elegia capensis , Merxmuellera cincta, Miscanthus
C
capensis, Rhodocoma capensis . Graminoids: Ficinia brevifolia
(d), Isolepis digitataC, Juncus capensis, Pentaschistis curvifolia,
AZa 2 Cape Lowland Alluvial Vegetation
P. pallida, Tetraria cuspidata. Herbs: Grammatotheca bergianaP,
Persicaria decipiens. Geophytic Herbs: Wachendorfia thyrsi- Riparian vegetation p.p. (Boucher 1978).
floraC (d), Blechnum punctulatum, Disa tripetaloidesP, Osmunda
Distribution Western Cape Province: Vegetation of broad
regalis, Pteridium aquilinum, Todea barbata. Carnivorous Herbs:
alluvia
of middle and lower stretches of rivers of the Western
Drosera capensisC, Utricularia bisquamata.
Cape such as the upper Olifants, Berg, Eerste, Lourens, Palmiet,
Endemic Taxa Tall Shrub: Ixianthes retzioides. Low Shrub:
Bot, Klein, Breede, Goekoe, Gouritz, Hartebeeskuil, Klein Brak,
Metalasia riparia. Herb: Pelargonium pseudoglutinosum. Groot Brak, Keurbooms and a number of small tributaries of
Graminoid: Isolepis digitata (d; aquatic). Moss: Wardia hygro- the above-mentioned water courses. Altitude ranging from
metrica (aquatic; representative of monotypic endemic family).
20–300 m.
Inland Azonal Vegetation
637
S %
19 (2006)
bulbosa complex, Watsonia galpiniiC,
Zantedeschia aethiopica. Open water
Aquatic Herb: Myriophyllum spicatum.
Endemic Taxon Riparian thickets Small
Tree: Salix mucronata subsp. hirsuta (d;
only Olifants River and maybe Berg River
catchments; see Jordaan 2005).
L. Mucina
Conservation Critically endangered.
Target 31%, but so far only about 1%
statutorily (Bontebok National Park,
Verlorenvlei (a Ramsar site), Broomvlei,
Marloth Nature Reserves) or privately
(Wadrif) conserved. Some 72% of the
area has been transformed for cultivation, urban development and road building. Disturbance and alien infestation are
very common in this type. Among the
most vigorous woody alien invaders are
Acacia saligna, A. mearnsii and A. longifolia as well as Alnus glutinosa, Quercus
robur, Salix babylonica and Sesbania
Figure 13.24 AZa 2 Cape Lowland Alluvial Vegetation: Bottom of temporary water course
feeding into Verlorenvlei Lake, with Phragmites australis reed bed near Redelinghuys
punicea. The high nutrient status of
(Western Cape).
alluvial soils attracts fast-growing herbaceous alien weeds such as Xanthium speVegetation & Landscape Features Flat landscape with slow- cies, Sonchus oleraceus, Rumex crispus, Stellaria media etc. as
well as garden escapes such as Tropaeolum majus, Tradescantia
flowing (in place meandering) lowland rivers fringed on banks
fluminensis, Pennisetum clandestinum (kikuyu grass), Colocasia
by extensive tall reeds dominated by Phragmites australis and
esculenta and Lupinus angustifolius (see for instance Duvenhage
Typha capensis as well as by flooded grasslands and herblands
and tall riparian thickets (gallery forests) with Salix mucronata 1993 and Ahmed 1995).
subsp. capensis on the river terraces.
Geology, Soil & Hydrology Alluvial fine sandy, silty and clayey
soils over Quaternary sediments, largely derived from weathering of Table Mountain sandstone, Bokkeveld Group shales and
Cape Granite (specifically the George Batholith). The streams
are fed mainly during the winter-rainfall season. An important factor on the flood regime are the numerous dams built
for water storage, which can simulate features of a natural
flood regime by means of several quick releases of water from
the reservoir.
Climate Identical to the climate of the surrounding lowland
vegetation, and due to the large geographical span of the scattered patches of this vegetation unit, it typically encompasses
winter rainfall as well as transitional winter-summer rainfall in
both facies (with prevalence of either). The local MAP spans 320
mm (Breede River Valley) to 700 (Garden Route) while the MAT
spans 15.9°C (Overberg) to 17.2°C (Garden Route). See also
climate diagram for AZa 2 Cape Lowland Alluvial Vegetation
(Figure 13.2).
Important Taxa ( CEndemic to Capensis, PSharing with
Pondoland) Riparian thickets Small Trees: Salix mucronata
subsp. mucronata (d), Virgilia divaricataC, Podocarpus elongatusC.
Tall Shrubs: Buddleja saligna, B. salviifolia, Cliffortia strobilifera,
Freylinia lanceolata, Rhus angustifolia. Low Shrubs: Cliffortia
odorata (d), Senecio halimifolius (d), Cliffortia ferrugineaC.
Flooded grasslands & herblands Tall Shrub: Melianthus
major (d). Megagraminoids: Prionium serratumP (d), Calopsis
paniculata, Cyperus thunbergii. Graminoids: Cynodon dactylon
(d), Cyperus congestus, C. denudatus, C. textilis, Eragrostis sarmentosa, Ficinia distans, Fuirena hirsuta, Hemarthria altissima,
Isolepis cernua, I. prolifera, Juncus capensis, J. lomatophyllus,
Leersia hexandra, Merxmuellera cincta, Paspalum distichum,
Pennisetum macrourum. Herbs: Conyza scabrida, Helichrysum
helianthemifoliumC, Laurembergia repens, Persicaria decipiens. Geophytic Herbs: Wachendorfia thyrsifloraC (d), Triglochin
638
Inland Azonal Vegetation
References Duthie (1929), Muir (1929), Stephens (1929), Harrison &
Elsworth (1958), Harrison (1964), Grobler & Marais (1967), Acocks (1976),
Boucher (1978, 1987, 1996a, b, 1997), Noble & Hemens (1978), Rebelo et
al. (1991), Duvenhage (1993), Ahmed (1995), Sieben (2003), http://www.
ngo.grida.no/soesa/nsoer/resource/wetland/sa_ramsar.htm.
AZa 3 Lower Gariep Alluvial Vegetation
Distribution Northern Cape Province: Broad alluvium (floodplains and islands) of the Orange (Gariep) River between
Groblershoop and the mouth into the Atlantic Ocean at
Oranjemund (Namibia). This river stretch is embedded within
Desert (Oranjemund to roughly Pofadder) and Nama-Karoo
(further upstream as far as Groblershoop). Altitude ranging
from 0–1 000 m.
Vegetation & Landscape Features Flat alluvial terraces and
riverine islands supporting a complex of riparian thickets (dominated by Ziziphus mucronata, Euclea pseudebenus and Tamarix
usneoides), reed beds with Phragmites australis as well as
flooded grasslands and herblands populating sand banks and
terraces within and along the river.
Geology, Soil & Hydrology Recent alluvial deposits of the
Orange River supporting soil forms such as Dundee and Oakleaf.
The river cuts through a great variety of Precambrian metamorphic rocks. Ia land type. Subject to floods, especially in summer,
caused by high precipitation on the highveld.
Climate Region with very arid (desert) to subarid (semidesert)
climate and erratic, unimodal (winter-rainfall) regime in the
extreme west (near the Orange River mouth) to bimodal, equinoctial with major peak in March and less pronounced peak in
November in the extreme east (near Upington). MAP 40–150
mm and MAT between 15.4°C (Alexander Bay) and 20.5°C
(Upington). See also climate diagram for AZa 3 Lower Gariep
Alluvial Vegetation (Figure 13.2).
S %
19 (2006)
These river stretches are surrounded by
vegetation units of broad transitional
regions between the dry facies of the
Savanna and Grassland and northern regions of the Nama-Karoo Biome.
Altitude ranging from 1 000–1 500 m.
L. Mucina
Vegetation & Landscape Features
Flat alluvial terraces supporting complex of riparian thickets (gallery forests)
dominated by native Acacia karroo and
Diospyros lycioides, flooded grasslands,
reed beds and ephemeral herblands
populating mainly sand banks within the
river and on its banks.
Figure 13.25 AZa 3 Lower Gariep Alluvial Vegetation: Alluvial grasslands with Cynodon dactylon and riparian thickets with Tamarix usneoides on rocky banks of the Orange River at Grasdrif
(Richtersveld National Park).
Important Taxa Riparian thickets Small Trees: Acacia karroo (d), Euclea pseudebenus (d), Salix mucronata subsp. mucronata (d), Schotia afra var. angustifolia (d), Ziziphus mucronata
(d), Acacia erioloba, Combretum erythrophyllum, Ficus cordata,
Maerua gilgii, Prosopis glandulosa var. glandulosa, Rhus lancea. Tall Shrubs: Gymnosporia linearis (d), Tamarix usneoides (d),
Ehretia rigida, Euclea undulata, Sisyndite spartea. Low Shrub:
Asparagus laricinus. Woody Climber: Asparagus retrofractus.
Succulent Shrub: Lycium bosciifolium. Herb: Chenopodium
olukondae. Reed beds Megagraminoid: Phragmites australis
(d). Flooded grasslands & herblands Low Shrubs: Tetragonia
schenckii (d), Litogyne gariepina. Graminoids: Cynodon dactylon
(d), Setaria verticillata (d), Cenchrus ciliaris, Cyperus laevigatus,
Eragrostis echinochloidea, Leucophrys mesocoma, Polypogon
monspeliensis, Stipagrostis namaquensis. Herbs: Amaranthus
praetermissus, Coronopus integrifolius, Frankenia pulverulenta,
Gnaphalium confine, Pseudognaphalium luteo-album.
Geology, Soil & Hydrology Recent alluvial deposits underlain mostly by Karoo
Supergroup sediments and tillites, supporting soils typical of Ia group land
types. Subject to flooding, especially in
summer.
Climate Bimodal (equinoctial) climate
with a major peak in March and with
a lesser peak in November–December.
The overall MAP is 325 mm (range 230–600 mm for Prieska
and Wepener, respectively). MAT for the entire area averages
17°C (range 19.3–15.4°C for Prieska and Aliwal North, respectively). See also climate diagram for AZa 4 Upper Gariep Alluvial
Vegetation (Figure 13.2).
Important Taxa Riparian thickets Small Trees: Acacia karroo (d), Celtis africana (d), Salix mucronata subsp. mucronata
(d). Tall Shrubs: Diospyros lycioides (d), Melianthus comosus (d),
Rhus pyroides. Low Shrubs: Asparagus setaceus, A. suaveolens.
Woody Climber: Clematis brachiata. Succulent Shrubs: Lycium
arenicola, L. hirsutum. Herb: Rubia cordifolia. Flooded grasslands & herblands Graminoid: Melica decumbens (d). Herbs:
Cineraria dregeana, C. lobata.
Conservation Vulnerable. Target 31%. Only about 3% statutorily conserved in Tussen Die Riviere, Gariep Dam and Oviston
Nature Reserves. More than 20% transformed for cultivation
Conservation Endangered. Target
31%. About 6% statutorily conserved
in the Richtersveld and Augrabies Falls
National Parks. Some 50% transformed
for agricultural purposes (vegetables
and grapes) or alluvial diamond mining.
Prosopis species, Nicotiana glauca and
Argemone ochroleuca can invade the
alluvia in places.
References Acocks (1976), Werger & Coetzee
(1977), Werger & Ellenbroek (1978), Werger
(1980), Bezuidenhout (1996), Bezuidenhout &
Jardine (2001), Jürgens (2004).
Including Riverine Communities (Diospyros lycioides) (Werger 1980).
Distribution Free State and Northern
Cape Provinces: Broad alluvia of the
Orange River, lower Caledon as well as
lower stretches of the Vaal, Riet and
Modder Rivers as far as Groblershoop.
P.J. du Preez
AZa 4 Upper Gariep
Alluvial Vegetation
Figure 13.26 AZa 4 Upper Gariep Alluvial Vegetation: Riparian thickets with dominant Acacia
karroo and Diospyros lycioides fringing the banks of the Orange River near Colesberg.
Inland Azonal Vegetation
639
S %
(vegetables, grapes) and building of dams. Exotic woody species such as Salix babylonica, Eucalyptus camaldulensis, E. sideroxylon, Prosopis and Populus species have become common
dominants in patches of heavily disturbed alluvial vegetation.
References Werger (1973, 1980), Acocks (1976), Werger & Ellenbroek
(1978), Du Preez (1991), Du Preez & Bredenkamp (1991).
AZa 5 Highveld Alluvial Vegetation
Distribution Free State, North-West, Mpumalanga and
Gauteng Provinces as well as in Lesotho and Swaziland:
Alluvial drainage lines and floodplains along rivers embedded
within the Grassland Biome and marginal (eastern) units of
the Kalahari (Savanna Biome), such as along upper Riet, Harts,
upper Modder, upper Caledon, Vet, Sand, Vals, Wilge, Mooi,
middle and upper Vaal Rivers etc. and their numerous tributaries. Altitude ranging from 1 000–1 500 m.
Vegetation & Landscape Features Flat topography supporting riparian thickets mostly dominated by Acacia karroo,
accompanied by seasonally flooded grasslands and disturbed
herblands often dominated by alien plants.
Geology, Soil & Hydrology Deep sandy to clayey (but mostly
coarse sand) alluvial soils developed over Quaternary alluvial
(fluviatile) sediments. Oakleaf, Dundee, Shortlands, Glenrosa
and Mispah soil forms were identified in the Vaal River floodplain (Bezuidenhout 1994). The rivers are perennial, often in
flood in summer. Erosion of banks and deposition of new fine
soil on alluvium can be of considerable extent. Some smaller
anastomosing channels of major rivers can dry out in winter.
Climate Seasonal, mainly summer rainfall. Precipitation in the
western part of the highveld is erratic (MAP 300–400 mm),
increasing sharply towards the east and north (up to 600 mm
in places). The overall MAP is almost 500 mm (range 373 mm
at the western distribution limit and 593 mm at the northern
distribution limit near Carletonville). Typical continental thermal
regime, showing subtropical features is typical of the summer
season (daily temperature often surpassing 35°C), while coldtemperate features (such as frequent frost) prevail in winter. See
also climate diagram for AZa 5 Highveld Alluvial Vegetation
(Figure 13.2).
Important Taxa Riparian thickets Small Trees: Acacia karroo (d), Salix mucronata subsp. mucronata (d), S. mucronata
subsp. woodii (d, within subescarpment grasslands of KwaZuluNatal), Ziziphus mucronata (d), Celtis africana, Rhus lancea. Tall
Shrubs: Gymnosporia buxifolia (d), Rhus pyroides (d), Diospyros
lycioides, Ehretia rigida, Grewia flava. Low Shrubs: Asparagus
laricinus (d), A. suaveolens (d). Woody Climber: Clematis brachiata. Succulent Shrub: Lycium hirsutum (d). Graminoids: Setaria
verticillata (d), Panicum maximum. Herb: Pollichia campestris.
Reed beds Megagraminoid: Phragmites australis (d). Flooded
grasslands & herblands Low Shrubs: Gomphocarpus fruticosus (d), Felicia muricata. Succulent Shrub: Salsola rabieana.
Graminoids: Agrostis lachnantha (d), Andropogon eucomus (d),
Chloris virgata (d), Cynodon dactylon (d), Eragrostis plana (d),
Hemarthria altissima (d), Imperata cylindrica (d), Ischaemum
fasciculatum (d), Miscanthus junceus (d), Paspalum distichum
(d), Andropogon appendiculatus, Brachiaria marlothii, Cyperus
denudatus, C. longus, Echinochloa holubii, Eragrostis obtusa,
E. porosa, Fimbristylis ferruginea, Panicum coloratum, Pycreus
mundii, Sporobolus africanus, S. fimbriatus, Themeda triandra, Urochloa panicoides. Herbs: Persicaria lapathifolia (d),
Alternanthera sessilis, Barleria macrostegia, Corchorus asplenifolius, Equisetum ramosissimum, Galium capense, Hibiscus pusillus, Lobelia angolensis, Nidorella resedifolia, Persicaria amphibia,
640
Inland Azonal Vegetation
19 (2006)
P. hystricula, Pseudognaphalium oligandrum, Pulicaria scabra,
Rorippa fluviatilis var. fluviatilis, Senecio inornatus, Stachys
hyssopoides, Vahlia capensis. Geophytic Herbs: Crinum bulbispermum, Haplocarpha lyrata. Open water Aquatic Herb:
Myriophyllum spicatum.
Conservation Least threatened. Target 31%. Nearly 10% statutorily conserved in the Barberspan (a Ramsar site), Bloemhof
Dam, Christiana, Faan Meintjes, Sandveld, Schoonspruit,
Soetdoring and Wolwespruit Nature Reserves. More than a
quarter has been transformed for cultivation and by building
of dams (Bloemhof, Erfenis, Krugersdrif, Mockes and Vaalharts
Dams). The highveld alluvia are prone to invasion by a number
of weeds, obviously encouraged by the high nutrient status of
soils and ample water supply. Woody plants such as Salix babylonica, Schinus molle, Melia azedarach, Celtis sinensis, Morus
alba, Populus x canescens, Nicotiana glauca and N. longiflora
and forbs such as Argemone ochroleuca, Chenopodium strictum, Conyza canadensis, Datura stramonium, Melilotus alba,
Oenothera indecora, Paspalum dilatatum, P. urvillei, Pennisetum
clandestinum, Tagetes minuta, Verbena bonariensis, Xanthium
strumarium agg. and Zinnia peruviana (see Cilliers et al. 1998,
Malan et al. 2001a, b, L. Mucina, unpublished data) often dominate either the riverine thickets or grasslands or form ruderal
communities in disturbed habitats. The undergrowth of the
alluvial riparian thickets and the accompanying grasslands suffer from heavy overgrazing in many places.
Remark Many patches of this vegetation escaped our mapping
efforts due to a lack of proper geographical coverage.
References Acocks (1976), Roussouw (1983), Müller (1986), Bezuidenhout
(1988, 1994), Bredenkamp et al. (1989), Bredenkamp & Bezuidenhout
(1990), Du Preez & Venter (1990), Kooij et al. (1990a, b), Du Preez (1991),
Du Preez & Bredenkamp (1991), Eckhardt et al. (1993b, 1996), Bezuidenhout
et al. (1994), Bredenkamp et al. (1994), Hoare (1997), Cilliers et al. (1998),
Eckhardt (1998), Malan (1998), Boucher & Tlale (1999a, b), Hoare &
Bredenkamp (1999), Myburgh (2000, 2001), Van Wyk et al. (2000), Dingaan
et al. (2001), Malan et al. (2001a, b), Myburgh & Bredenkamp (2004), http://
www.ngo.grida.no/soesa/nsoer/resource/wetland/sa_ramsar.htm.
AZa 6 Albany Alluvial Vegetation
Including Stream-bank Bush (Story 1952). Riverine Bush (Martin & Noel
1960). Baviaans Doringveld, Gamtoos Doringveld & Sundays Doringveld
(Vlok & Euston-Brown 2002, Vlok et al. 2003).
Distribution Eastern Cape Province: Between East London and
Cape St Francis on wide floodplains (usually close to the coast
where the topography becomes flatter) of the large rivers such
as the Sundays, Zwartkops, Coega, Gamtoos, Baviaanskloof,
Great Fish River etc. This alluvial unit is embedded within the
Albany Thicket Biome. Altitude ranging from 20–1 000 m.
Vegetation & Landscape Features Two major types of vegetation pattern are observed in these zones, namely riverine
thicket and thornveld (Acacia natalitia). The riverine thicket
tends to occur in the narrow floodplain zones in regions close
to the coast or further inland, whereas the thornveld occurs on
the wide floodplains further inland.
Geology, Soil & Hydrology Underlain by Jurassic-Cretaceous
sediments of the Uitenhage Group. The alluvial zones (recent
alluvial deposits of various textures, but usually with high clay
content) can become flooded following the west-east passage
of frontal systems in autumn and winter or during intensive
local storms in summer. Ia land type.
Climate Characterised by undifferentiated, year-round precipitation regime, with only two slight peaks in March and November.
S %
19 (2006)
Conservation Endangered. Target 31%. Only about 6% statutorily conserved in the Greater Addo Elephant National Park,
Baviaanskloof Wilderness Area, Loerie Dam, Springs, Swartkops
Valley and Yellowwoods Nature Reserves and the Double Drift
Reserve Complex. About 2% enjoys protection in eight private
conservation areas. More than half of the area has been transformed for cultivation, urban development, road building and
plantations. Alien invaders include Acacia saligna, Nerium oleander and Eucalyptus species.
Remarks Vlok & Euston-Brown (2002) consider this vegetation as important temporary habitats and migration corridors
for larger herbivores such as elephant (in the past), rhinoceros,
eland and kudu.
References Story (1952), Martin & Noel (1960), Jessop & Jacot Guillarmod
(1969), Jacot Guillarmod (1973), Acocks (1976), Cowling & McKenzie
(1979), Vlok & Euston-Brown (2002), Vlok et al. (2003).
AZa 7 Subtropical Alluvial Vegetation
L. Mucina
Including Riverine Bush (Comins 1962). Salvadora angustifolia Floodplains
(Gertenbach 1983).
Figure 13.27 AZa 6 Albany Alluvial Vegetation: Acacia natalitia
thickets fringing the Great Fish River in the former Double Drift Nature
Reserve near Fort Beaufort (Eastern Cape).
Important Taxa (BBrackish habitats):
Riparian thickets Small Trees: Acacia
natalitia (d), Salix mucronata subsp.
mucronata (d), Schotia afra var. afra
(d), Acacia caffra, Rhus longispina.
Succulent Trees: Aloe africana, A. ferox.
Tall Shrubs: Azima tetracantha, Cadaba
aphylla. Low Shrubs: Pentzia incana
(d), Asparagus striatus, A. suaveolens,
Carissa haematocarpa. Succulent Shrubs:
Amphiglossa callunoides, Lycium cinereum. Graminoids: Sporobolus nitens
(d), Digitaria eriantha, Eragrostis curvula,
E. obtusa. Reed beds Megagraminoids:
Cyperus papyrus (d), Phragmites australis
(d). Flooded grasslands & herblands
Succulent Shrubs: Cotyledon campanulataB, Glottiphyllum longumB, Malephora
luteaB, M. uitenhagensisB. Semiparasitic
Shrub: Thesium junceum B. Succulent
Herbs: Haworthia sordida var. sordidaB,
Orbea pulchellaB. Herb: Rorippa fluviatilis
var. fluviatilis. Graminoid: Cynodon dactylonB (d).
Vegetation & Landscape Features Flat alluvial riverine terraces supporting an intricate complex of macrophytic vegetation (channel of flowing rivers and river-fed pans), marginal
reed belts (in sheltered oxbows and along very slow-flowing
water courses) as well as extensive flooded grasslands, ephemeral herblands and riverine thickets.
Geology, Soil & Hydrology Recent alluvial deposits with deep
fine-structured sandy to loamy soils (Dundee, Estcourt, Valsrivier,
Sterkspruit, Oakleaf forms), waterlogged as it is often exposed
to floods (especially during the rainy summer season). Salt often
L. Mucina
The overall MAP is 350 mm (range 300–717 mm). Warm-temperate climate (overall MAT 18°C; range 15.7–18.3°C). The
river valleys are often hotter than the surrounding landscape
(due to exposed steep slopes), whereas riverine zones closer
to the coast enjoy an ameliorated climate due to its proximity
to the sea. See also climate diagram for AZa 6 Albany Alluvial
Vegetation (Figure 13.2).
Distribution Limpopo, Mpumalanga and KwaZulu-Natal
Provinces and in Swaziland: Broad river alluvia and around
some river-fed pans in the subtropical regions of eastern South
Africa, in particular in the Lowveld, Central Bushveld and in
northern KwaZulu-Natal. The most important alluvia include
the Limpopo, Luvubu, Olifants, Sabie, Crocodile, Phongolo,
Usutu and Mkuze Rivers. This unit is fully embedded within the
Savanna Biome. Altitude ranging from 0–1 000 m.
Figure 13.28 AZa 7 Subtropical Alluvial Vegetation: Complex of reed beds (Phragmites
mauritanicus) and alluvial shrublands along the White Mfolozi River (Hluhluwe-iMfolozi Park,
KwaZulu-Natal).
Inland Azonal Vegetation
641
S %
accumulates in the alluvial soils (due to strong evaporation). Ia
land type.
Climate Subtropical, seasonal summer-rainfall climate with
broad range of temperature (19.3°C in western Central Bushveld
and 22.0°C in Mopane) and precipitation (MAP 311–672 mm
for Limpopo Valley and Maputaland, respectively) due to large
latitudinal and longitudinal ranges. See also climate diagram for
AZa 7 Subtropical Alluvial Vegetation (Figure 13.2).
Important Taxa Riparian thickets Small Trees: Acacia natalitia (d), A. robusta (d), Boscia foetida subsp. rehmanniana (d),
Combretum erythrophyllum (d), Phoenix reclinata (d), Salix
mucronata subsp. woodii (d), Ziziphus mucronata (d), Acacia
luederitzii, A. nebrownii, A. nigrescens, A. tortilis, A. xanthophloea, Colophospermum mopane, Combretum hereroense,
Philenoptera violacea, Pseudoscolopia polyantha (Pondoland,
sharing with Capensis). Tall Shrubs: Salvadora angustifolia (d),
Commiphora glandulosa, C. pyracanthoides, Euclea divinorum,
Grewia bicolor, Gymnosporia senegalensis. Low Shrubs: Justicia
flava, Ocimum canum. Graminoids: Eragrostis trichophora (d),
Panicum maximum (d), Setaria incrassata (d), Sporobolus ioclados
(d), Chloris virgata, Dactyloctenium aegyptium, Enneapogon
cenchroides, Urochloa mosambicensis. Herbs: Commelina
benghalensis (d), Abutilon austro-africanum, Acalypha indica,
Achyranthes aspera, Boerhavia erecta, Commicarpus fallacissimus, Cucumis zeyheri, Heliotropium ovalifolium, Lobelia
angolensis, Oxygonum sinuatum, Pupalia lappacea, Ruellia
patula. Geophytic Herb: Crinum moorei. Succulent Herb:
Portulaca quadrifida. Reed beds Megagraminoids: Phragmites
australis (d), P. mauritianus (d), Prionium serratum (only along
few rapids in Pondoland). Flooded grasslands & herblands
Megagraminoid: Cyperus immensus. Graminoids: Cynodon
dactylon (d), Cyperus articulatus (d), Echinochloa pyramidalis (d),
Urochloa mosambicensis (d), Bolboschoenus glaucus, Chloris
mossambicensis, C. virgata, Cyperus corymbosus, C. difformis,
C. distans, C. fastigiatus, C. sexangularis, Dactyloctenium aegyptium, Hemarthria altissima, Ischaemum afrum, Paspalidium
obtusifolium, Setaria sphacelata, Sporobolus consimilis, S. fimbriatus. Herbs: Alternanthera sessilis, Amaranthus praetermissus,
Grammatotheca bergiana (Pondoland), Marsilea ephippiocarpa,
Scutellaria racemosa. Geophytic Herb: Trachyandra saltii. Aquatic
Herbs: Ceratophyllum muricatum, Ottelia
exserta.
19 (2006)
ests), and both are usually embedded within various bushveld
types of the Savanna Biome. The major distinction between this
type of alluvial vegetation and other alluvia is the presence and
importance of subtropical and tropical floristic elements and the
pronouncedly subtropical climate. One of the best researched
subtropical alluvial systems in South Africa is the Nylsvlei east
of the Modimolle–Mookgophong line, especially in the Nylsvlei
Nature Reserve (Coetzee et al. 1976).
Remark 2 The current mapping coverage of Subtropical Alluvial
Vegetation reflects our current poor knowledge and the lack of
data from all around the Central Bushveld as well as Lowveld
regions.
References Comins (1962), Edwards (1967), Musil (1972), Musil et al.
(1973), Theron (1973), Acocks (1976), Coetzee et al. (1976), De Moor et al.
(1977), Noble & Hemens (1978), Furness & Breen (1980), Heeg et al. (1980),
Rogers (1980, 1984), Furness (1981), Gertenbach (1983), Goodman (1987a,
b), Begg & Carser (1988, 1989), Breen et al. (1993), Brown & Bredenkamp
(1994), Bredenkamp & Deutschländer (1995), Brown et al. (1995, 1996,
1997), Breebaart & Deutschländer (1997), Kotschy et al. (2000), Barnes et al.
(2002), Götze (2002), Götze et al. (2003), O’Keeffe & Rogers (2003).
Inland Saline Vegetation
AZi 1 Namaqualand Riviere
Distribution Northern and Western Cape Provinces: Along dry
riverbeds throughout Namaqualand, but especially the Buffels,
Bitter, Spoeg, Groen, Sout, Doring Rivers and lower reaches
of the Olifants River. Within this unit we also classify alluvia of
intermittent rivers of the Hantam region. Altitude ranging from
0–800 m.
Vegetation & Landscape Features Complex of alluvial shrubland (Suaeda fruticosa, Zygophyllum morgsana, Ballota africana and Didelta spinosa) and patches of tussock graminoids
occupying riverbeds and banks of intermittent rivers. In places
low thickets of Acacia karroo and Tamarix usneoides can be
encountered.
Conservation Target 31%. Large
patches are statutorily conserved in the
Kruger and Mapungubwe National Parks,
Vemre and D’nyala Nature Reserves,
Ndumo Game Reserve and Greater St
Lucia Wetland Park (Mkhuze Game
Reserve) as well as in a number of private reserves fringing the western borders of the Kruger National Park and the
Limpopo River. The Ndumo Game Reserve
and Greater St Lucia Wetland Park are
Ramsar sites. Much of the area has been
transformed for cultivation, urban development and road building. Alien woody
species commonly occurring in this vegetation types include Melia azedarach,
Chromolaena discolor and the like.
Remark 1 The vegetation of the
Lowveld alluvia is found in a complex of
Subtropical Riverine Forests (gallery for642
Inland Azonal Vegetation
L. Mucina
Endemic Taxon Flooded grasslands &
herblands Herb: Crotalaria mollii.
Figure 13.29 AZi 1 Namaqualand Riviere: Broad sandy-loamy alluvium of the Varsch River
northwest of Vanrhynsdorp, with Acacia karroo (yellow-flowered shrub) and species of Salsola
and Galenia (low greyish shrubs).
S %
19 (2006)
Herb: Crinum variabile. Succulent Herbs: Conicosia elongata,
Mesembryanthemum guerichianum.
Endemic Taxon Dry river bottoms Succulent Shrub:
Sarcocornia terminalis (d).
Conservation Least threatened. Target 24%. Only very small
portion statutorily protected in nature reserves (Lutzville).
Almost 20% transformed for cultivation (vineyards along the
entire lower reaches of the Olifants River) or by building of dams
(Driekoppies Dam). Exotic shrubs Nicotiana glauca and Prosopis
species are often found in riverbeds. The latter is probably the
most important woody invader species found in Namaqualand.
In some years invasive indigenous Gomphocarpus fruticosus
may appear in abundance in the alluvia, while in other years it
would disappear completely. Another invasive indigenous species is Galenia africana which can be dominant along some of
the water courses, especially in the south.
Reference Boucher (2003).
L. Mucina
AZi 2 Namaqualand Salt Pans
Figure 13.30 AZi 1 Namaqualand Riviere: Salty bottom of intermittent semidesert river on the Knersvlakte with Sarcocornia terminalis
(endemic Chenopodiaceae), Galenia africana and salt-loving Limonium
dregeanum (Plumbaginaceae, dark green tussocks).
Geology, Soil & Hydrology Alluvial sandy soils on Quaternary
fluviatile sediments that overlie Namibian-age sediments and
Mokolian gneisses. Seasonally wet (late winter). The riverbed
sometimes carries torrential flood waters. In summer, patches
of crystallised salt film may cover the soil surface in slight, clayey
depressions.
Climate Arid, seasonal climate with MAP around 150 mm (with
100 mm on the coast and 250 mm on the Hantam Plateau).
Most of the erratic rainfall occurs between June and August.
Hot summers (marked by extremely high evapotranspiration)
and cool winters, with fairly frequent frost. MAT 18.1°C (range
15.7°C for Hantam Plateau and 18.5°C for Knersvlakte). See also
climate diagram for AZi 1 Namaqualand Riviere (Figure 13.2).
Important Taxa Riparian thickets Small Tree: Acacia karroo
(d). Tall Shrubs: Melianthus pectinatus, Rhus burchellii, Tamarix
usneoides. Low Shrub: Ballota africana (d). Semiparasitic Epiphytic
Shrub: Viscum capense. Dry river bottoms Tall Shrub: Lebeckia
sericea. Low Shrubs: Galenia africana (d), Gomphocarpus
fruticosus (d), Hermannia disermifolia, Jamesbrittenia fruticosa, Salvia dentata. Succulent Shrubs: Suaeda fruticosa (d),
Zygophyllum morgsana (d), Atriplex cinerea subsp. bolusii,
Didelta carnosa var. carnosa, Lycium horridum, Salsola tuberculata, Tetragonia fruticosa, T. pillansii, Zygophyllum retrofractum. Herbaceous Climber: Didymodoxa capensis. Graminoids:
Cynodon dactylon (d), Odyssea paucinervis (d), Cyperus marginatus, Diplachne fusca, Ehrharta longiflora, Isolepis antarctica,
Scirpus nodosus. Herbs: Limonium dregeanum (d), Arctotheca
calendula, Cotula coronopifolia, Galium tomentosum. Geophytic
Distribution Northern and Western Cape Provinces: Smaller
and larger areas along the coastal plains of Namaqualand,
including Sonnekwa, Hondevlei (both southeast of Kleinzee),
Bloupan, Dryerspan, Karaspan (north of Kleinzee) and Soutpan
(southeast of Port Nolloth). The cut-off supratidal terraces of
the Olifants River mouth qualify as salt pans as well. Altitude
ranging from 0–250 m.
Vegetation & Landscape Features Flat surfaces of depressions, mostly without vegetation and only occasionally covered with sparse, highly salt-tolerant succulent shrubs (Salsola,
Malephora). The highest vegetation cover has been found in
the salt pan at the Olifants River mouth, where the succulent
shrubs Salsola, Psilocaulon and Sarcocornia are dominant.
Geology, Soil & Hydrology Large depressions (pans) of marine
origin (remnants of former larger marine transgression-forming
coastal lagoons) with white to grey silt and clay soils, seasonally
moist. These pans are formed on the Cenozoic alluvium, sand
and calcrete that were deposited over Mokolian-age schists
and gneisses as well as metavolcanics and metasediments of
Namibian age. Namaqualand salt pans are nearly permanently
dry (only seldom intermittent pools of standing water are found
in the lowest depressions) and especially in the Kleinzee area
they disappear and are buried under layers of wind-borne
sand.
Climate Arid, erratic seasonal rainfall of which most falls
between May and August. Overall MAP 100 mm, ranging from
45 mm at Alexander Bay to 126 mm on the Knersvlakte below
the Bokkeveld Escarpment. Along the Richtersveld coast the
lack of rainfall is partly compensated by more frequent coastal
winter fog. Hot summers (accompanied by high evapotranspiration rates) alternate with cool winters. MAT ranging from
17.6°C, with narrow range of 17.3–18.6°C. See also climate
diagram for AZi 2 Namaqualand Salt Pans (Figure 13.2).
Important Taxa Succulent Shrubs: Salsola aphylla (d),
Sarcocornia mossiana agg. (d), Atriplex cinerea subsp. bolusii.
Succulent Herbs: Mesembryanthemum guerichianum, Salicornia
meyeriana. Graminoids: Juncus rigidus (d), Sporobolus
virginicus.
Biogeographically Important Taxa ( NQ Namaqualand
endemic, GGariep endemic, WWest Coast endemic): Low Shrub:
Frankenia pomonensisG. Succulent Shrub: Lycium tetrandrumW.
Herbs: Malephora purpureo-croceaNQ (d), Limonium equiInland Azonal Vegetation
643
S %
setinumW. Succulent Herb: Psilocaulon dinteriW. Graminoid:
Schoenoplectus scirpoides.
Conservation Least threatened. Target 24%. None conserved
in statutory conservation areas. Only small portion transformed
(road building).
Remarks The Namaqualand pans are superficially (physiognomy, ecology) very similar to those of Bushmanland such as
Verneukpan and other ‘vloere’, but they differ in terms of origin
(marine versus fluviatile) and also in constituent flora. The salt
pan at the Olifants River mouth is an example of an ‘inland’
pan in stadio nascendi—some supratidal terraces of the original
estuarine salt marsh are becoming isolated from any influence
of the tidal regime, forming an isolated saline system resulting
in a pan.
References Bornman (2002), Bornman et al. (2002, 2004).
AZi 3 Southern Kalahari Mekgacha
Distribution Northern Cape and North-West Provinces: Valleys
(including beds and adjacent slopes) of the intermittent rivers draining the dry savanna south of the Bakalahari Schwelle
(broad interfluve at 1 000–1 100 m altitude) in the South
African part of the Kalahari region. The major mekgacha of the
region include the Nossob, Auob, Molopo and Kuruman Rivers.
A more extensive (endorheic) system of mekgacha is found
north of the Bakalahari Schwelle in central Botswana. Altitude
ranging from 850 m to mainly 1 100 m, with a few occurrences
as high as 1 500 m.
Geology, Soil & Hydrology The river channels are embedded within prevalently sandy Kalahari sediments that cover the
Precambrian metamorphic crust of the area. The substrate of
the dry riverbeds are silty, sandy and rocky, poorly drained and
rich in nutrients though the ionic composition of the soils in
particular rivers show considerable differences. The banks of
the dry rivers can cut deep into duricrust (calcrete or silcrete and
various transitions between these end-members, and in places
also ferricretes), sometimes vertical bluffs (steep cliffs) of a few
metres high may develop (Werger 1978, Thomas & Shaw 1991).
The mekgacha may stay without any water for a very long time
and floods (sometimes of considerable magnitude) occur only
in response to dramatic short-term precipitation events, for
example the Nossob was in flood in 1806, 1963 and 1987 and
the Auob was in flood in 1973, 1974 and 2000 (Thomas &
Shaw 1991; H. Bezuidenhout, personal communication). Some
of the rivers such as the Kuruman must experience effective
subsurface flow of water judging from the near-continuous belt
of trees.
Climate Subarid region with seasonal, summer-rainfall regime
with a slight shift of the major peak towards late summer
(February–March). Overall MAP 240 mm (ranging from 180
mm at southwestern boundary to as much as 420 mm further
north). High thermic continentality is obvious from the extreme
differences between the mean daily maximum and minimum
temperatures in January and July: 34°C and 1°C, respectively,
great daily temperature differences (sometimes reaching amplitude between 25°C and 30°C, especially in transitional climatic
periods) as well as the fairly frequent occurrence of frost. The
overall MAT of 19°C (range 17.5–19.1°C) is indicative of a subtropical climate, classified in the Köppen’s system as BWKw’ in
its southernmost regions and as BWhw further north (Coetzee
& Werger 1975, Schultze & McGee 1978, Werger 1978). See
also climate diagram for AZi 3 Southern Kalahari Mekgacha
(Figure 13.2).
Important Taxa Dry river bottoms Tall Shrubs: Lebeckia
linearifolia (d), Sisyndite spartea (d), Deverra denudata subsp.
aphylla. Herbs: Amaranthus dinteri subsp. dinteri, A. praetermissus, A. schinzianus, Boerhavia repens, Chamaesyce inaequilatera, Cucumis africanus, Geigeria
ornativa, G. pectidea, Heliotropium
lineare, Indigofera alternans, I. argyroides, Kohautia cynanchica, Lotononis
platycarpa, Osteospermum muricatum,
Platycarpha carlinoides, Radyera urens,
Stachys spathulata, Tribulus terrestris.
Succulent Herb: Zygophyllum simplex (d).
Graminoids: Cenchrus ciliaris (d), Chloris
virgata (d), Enneapogon desvauxii (d),
Eragrostis annulata (d), E. bicolor (d),
Odyssea paucinervis (d), Panicum coloratum (d), Eragrostis porosa, Panicum
impeditum, Sporobolus nervosus. Rocky
slopes of river canals Tall Tree: Acacia
erioloba (d). Low Shrubs: Aptosimum
lineare, Pechuel-Loeschea leubnitziae.
Graminoids: Setaria verticillata (d),
Enneapogon scaber, Oropetium capense,
Stipagrostis uniplumis, Tragus racemosus.
Herb: Dicoma capensis.
L. Mucina
Vegetation & Landscape Features Sparse, patchy grasslands, sedgelands and low herblands dominated by C4 grasses
(Panicum, Eragrostis, Enneapogon, Tragus, Chloris, Cenchrus)
on the bottom of (mostly) dry riverbeds. Low shrublands in
places with patches of taller shrubland (with Schotia afra) on
the banks of the rivers. Relatively tall Acacia erioloba trees can
form a dominant belt along some of the rivers, for example the
middle and lower reaches of the Kuruman River. In some other
rivers the taller trees are scattered.
19 (2006)
Figure 13.31 AZi 3 Southern Kalahari Mekgacha: Dry Nossob River in the Kgalagadi Transfrontier Park against the backdrop of sparsely vegetated dunes in neighbouring Botswana. For
springbok (Antidorcas marsupialis) and other hoofed as well as carnivorous wildlife the open
landscape of the intermittent rivers is a favourite grazing, resting and hunting ground.
644
Inland Azonal Vegetation
Conservation Least threatened. Target
24%. Already 18% statutorily conserved
in the Kgalagadi Transfrontier Park and
Molopo Nature Reserve. About 2% has
been transformed by road building. The
S %
19 (2006)
mekgacha are under strong utilisation
pressure, both from wildlife (to graze
and for salt licks) and domestic animals
(grazing, browsing and animal penning).
Alien woody Prosopis species occur as
invasive plants in places.
L. Mucina
Remark 1 The term ‘mekgacha’ (singular ‘mokgacha’) is of Setswana origin and
means ‘dry (river) valley’. Mekgacha are
considered to be remnants of an ancient
extensive riverine system of the ‘Kalahari
River’, which drained the Kalahari Basin
and used the current lower Orange River
channel from Kakamas downstream. In
the early Tertiary, the Kalahari River captured the upper parts of the Karoo River
(draining the inland plateau of southern
Africa into the southern Atlantic Ocean
at the current mouth of the Olifants River
on the West Coast and with the present
offshore submarine Cape Canyon as
Figure 13.32 AZi 4 Southern Kalahari Salt Pans: A salt pan in the northern Kgalagadi Transfrontier Park near a dry riverbed of the Nossob, surrounded by shrubby savanna with Rhigozum
outlet) as a result of accelerated uplift of
trichotomum (Bignoniaceae) and Schmidtia kalahariensis (Poaceae) dominant.
the southern and eastern subcontinental
margins ca. 100 to 80 mya (De Wit 1999,
Goudie 2005). The flow of the Kalahari River system was inter- Supergroup). Extensive pan-like areas occur locally in slightly
higher-lying portions of dry riverbeds (mekgacha), where they
rupted by the dry periods of the Eocene-Miocene transition and
are isolated from the river course by a raised, compact calcarefurther decimated during Plio-Pleistocene dry periods.
ous sand formation—the pan-like alluvium consists of sandy
Remark 2 The Southern Kalahari Mekgacha differ from the
loam and a fairly high content of calcium and phosphate
Bushmanland Vloere and Southern Karoo Riviere in climatic,
(Leistner & Werger 1973, Werger 1978). The pan soils consist
geological (origin) and floristic terms. The Bushmanland pans
of white (washed) sand in shallow pans (‘sand pans’), rocky
(vloere) are distinguished by an increased occurrence of shrubby
soils on calcrete outcrops and most typically of clays and sandy
elements (especially Salsola and similar karoo dwarf shrubs),
clays very rich in Na, K, Mg and are characterised by high a pH,
while the Southern Karoo Riviere have well-developed tall-shrub
reaching values of 9. The pan bottoms are exposed for most of
structures fringing the riverbeds but lack the Acacia erioloba of
the year and carry shallow pools for a short time only after very
the Mekgacha.
good rains (March–April).
Remark 3 Some of the longer rivers in the region, especially the
Climate For the climate account of this unit see AZi 3 Southern
Molopo, have a generally progressive reduction in larger woody
Kalahari Mekgacha, sharing basically the same region in South
plant cover in a downstream direction due to reduced penetraAfrica. See also climate diagram for AZi 4 Southern Kalahari Salt
tion of water flow with increasing distance into the more arid
Pans (Figure 13.2).
regions.
Important Taxa Succulent Shrubs: Zygophyllum tenue (d),
References Leistner (1967), Leistner & Werger (1973), Werger & Leistner
Salsola
scopiformis. Herbs: Hirpicium gazanioides, Tribulus ter(1975), Werger & Coetzee (1977), Noble & Hemens (1978), Werger
restris. Succulent Herb: Trianthema triquetra subsp. parvifolia.
(1978), Thomas & Shaw (1991), De Wit (1999), Smit (2000), Malan (2003),
Graminoids: Enneapogon desvauxii (d), Eragrostis truncata
Goudie (2005).
(d), Sporobolus coromandelianus (d), S. rangei (d), Panicum
impeditum.
AZi 4 Southern Kalahari Salt Pans
Distribution Northern Cape and North-West Provinces and
neighbouring Kalahari regions of Botswana and Namibia:
System of endorheic, closed depressions (pans) in the southern
Kalahari as defined by Thomas & Shaw (1991) south of the
Bakalahari Schwelle. The largest concentrations of such pans in
South Africa are found near Groot-Mier in western Gordonia.
Altitude ranging from 800–1 500 m.
Vegetation & Landscape Features Low grasslands on pan
bottoms (these often devoid of vegetation) often dominated
by Sporobolus species, with a mixture of dwarf shrubs. The low
shrubland dominated by Lycium and/or Rhigozum usually forms
the outer belt in the salt-pan zonation systems.
Geology, Soil & Hydrology Most of the pans formed on
the sandy sediments of the Cenozoic Kalahari Group; in the
southeast some formed on the dolomites of the Campbell
Group (Vaalian-age Griqualand West Supergroup) and in the
west some formed on diamictites of the Dwyka Group (Karoo
Conservation Least threatened. Target 24%. About 8% statutorily conserved in the Kgalagadi Transfrontier Park. The vegetation of the pans is subject to natural degradation/regeneration
cycles controlled by concentration of grazing animals (antelopes
in particular).
References Leistner (1967), Leistner & Werger (1973), Werger & Leistner
(1975), Werger & Coetzee (1977), Noble & Hemens (1978), Werger (1978),
Lancaster (1986), Skarpe (1986), Thomas & Shaw (1991), Bezuidenhout
(1995), Smit (2000).
AZi 5 Bushmanland Vloere
Distribution Northern Cape Province: Vloere (salt pans) of the
central Bushmanland Basin as well as the broad riverbeds of
the intermittent Sak River (functioning as temporary connection between some of the pans) as well as its numerous ancient
(today dysfunctional) tributaries. The patches of this vegetation
unit are embedded especially within NKb 6 Bushmanland Basin
Inland Azonal Vegetation
645
S %
19 (2006)
aphylla (d), S. glabrescens (d), S. rabieana
(d), Lycium pumilum, Salsola gemmifera.
Herbs: Amaranthus dinteri subsp. dinteri, Lotononis minima. Geophytic Herb:
Crinum variabile. Graminoids: Stipagrostis
ciliata (d), S. obtusa (d), Sporobolus nervosus, Stipagrostis namaquensis.
L. Mucina
Conservation Least threatened. Target
24%. None conserved in statutory conservation areas. About 2% transformed
for cultivation or building of dams
(Vanwyksvlei Dam). Alien Prosopis occurs
as scattered in some vloere and dry riverbeds. Several of the pans are mined for
salt production.
Remark 1 We have refrained from distinguishing pans and the channels of intermittent rivers (unlike in Namaqualand,
Kalahari
and Highveld regions) as difFigure 13.33 AZi 5 Bushmanland Vloere: Shrubland with dominant Rhigozum trichotomum
ferent major habitat complexes, hence
(Bignoniaceae) in a ‘vloer’ near Brandvlei in central Bushmanland (Northern Cape). The yellowdifferent vegetation units deserving
flowered plant is the annual Gazania lichtensteinii (Asteraceae).
independent status. The pans (vloere)
and the intermittent rivers of Bushmanland are closely related
Shrubland and NKb 3 Bushmanland Arid Grassland and to a
lesser extent also within NKb 4, NKu 1, NKu 2 as well as mar- in terms of origin, geology and the floristic composition of
the vegetation they support and they merge into each other
ginal Succulent Karoo units summarised within the bioregion of
at many localities, making the separation virtually impossible.
Trans-Escarpment Succulent Karoo. Altitude 850–1 450 m.
The extensive pan and river system of Bushmanland is a remVegetation & Landscape Features Flat and very even surfaces
nant of the ancient Karoo River and later Palaeo-Orange River
of pans and broad bottoms of intermittent rivers. The centre of
which have been draining the centre of the region since the
a pan (or the river drainage channel itself) is usually devoid of
Late Cretaceous (for development of these riverine systems see
vegetation; loosely patterned scrub dominated by Rhigozum
Dingle & Hendey 1984, De Wit 1999 and Goudie 2005). An
trichotomum and various species of Salsola and Lycium, with a
important role in (trans)formation of the Bushmanland riverine
mixture of nonsucculent dwarf shrubs of Nama-Karoo relationsystem was played by the Koa River, which drained the area
ship. In places loose thickets of Parkinsonia africana, Lebeckia
(then covered by dense tropical forest) from Miocene to Late
lineariifolia and Acacia karroo can be found.
Quaternary (Pleistocene). The Koa River left its traces through
a series of pans spanning Commisioner’s Pan located west of
Geology, Soil & Hydrology Endorheic pans and alluvia of
Brandvlei and Bosluis se Pan found south of Aggeneys as well
associated intermittent rivers filled with silty and clayey alluvial
deposits with a high content of concentrated salt (sodic soils), as through a broad valley filled with deep red sands in the
present-day Koa Valley in northern Bushmanland (see also NKb
supported by Ecca Group shales and Dwyka diamictites (Karoo
Supergroup). Watkeys (1999) found that in the pan of Brandvlei, 4 Bushmanland Sandy Grassland).
the orthic A horizon is underlain by a soft carbonate subsoil and
Remark 2 A reliable floristic characterisation of this unit is not
the soils of the alluvial terraces of the Sak River are deep (more
feasible at this stage due to the pending taxonomic revision
than 1 000 mm), stratified and weakly structured and calcareof the South African representatives of the genus Salsola, one
ous. Ia land type. Erosion in some places can be considerable,
of the most important generic components of vegetation of
especially after unpredictable heavy thunderstorms leading to
Bushmanland. The vegetation of the AZi 5 Bushmanland Vloere
sudden swelling of the Sak River. The pans can be filled in wet
remains of the least studied in the country.
summers and in autumn.
Climate Arid, seasonal climate with bimodal (equinoctial) precipitation regime—two peaks, one in March and another in
November. Overall MAP 141 mm (range 91 mm in western
Bushmanland to 306 mm at northern edges of the Roggeveld).
Overall MAT 16.8°C (range 17.4°C in northern Bushmanland to
14.5°C on northern edge of the Roggeveld). The region where
the Bushmanland Vloere occur, is known for thermic extremes,
both long-term (mean daily temperature in January approaching 32°C and in July only several degrees above zero) and shortterm (daily temperature amplitude around 25°C). Frequent
occurrence of frost is also indicative of the high thermic continentality of the region. See also climate diagram for AZi 5
Bushmanland Vloere (Figure 13.2).
Important Taxa Tall Shrubs: Parkinsonia africana, Xerocladia
viridiramis. Low Shrubs: Rhigozum trichotomum (d), Aizoon
schellenbergii, Asparagus glaucus, Eriocephalus decussatus, E.
spinescens, Pegolettia retrofracta. Succulent Shrubs: Salsola
646
Inland Azonal Vegetation
References Acocks (1953), Noble & Hemens (1978), Le Roux et al. (1985),
Day (2005b).
AZi 6 Southern Karoo Riviere
Including Mesic Riparian Bush & Xeric Riparian Bush (Van der Walt 1980).
Riparian Thicket (Palmer 1991). Lycium cinereum-Salsola aphylla Shrubland
& Acacia karroo-Stipagrostis namaquensis Riparian Woodland (Rubin &
Palmer 1996). Becium burchellianum-Acacia karroo Woodland (Brown &
Bezuidenhout 2000).
Distribution Western and Eastern Cape Provinces: Alluvia of
the Buffels, Bloed, Dwyka, Gamka, Sout, Kariega, and Sundays
Rivers and their tributaries), east of Laingsburg as far west as
Graaff-Reinet and Jansenville. This vegetation unit is embedded within the Koedoesberge-Moordenaars Karoo, Prince
Albert Succulent Karoo, Gamka Karoo, Eastern Lower Karoo,
and southern parts of the Eastern Upper Karoo as well as some
S %
19 (2006)
Tamarix usneoides (d), Cadaba aphylla, Euclea undulata, Grewia
robusta, Gymnosporia buxifolia, Melianthus comosus. Low
Shrub: Asparagus striatus. Succulent Shrubs: Lycium cinereum
(d), Amphiglossa callunoides, Lycium hirsutum, L. oxycarpum. Rocky slopes of river canals Graminoid: Stipagrostis
namaquensis (d). Alluvial shrublands & herblands Low
Shrubs: Ballota africana, Bassia salsoloides, Carissa haematocarpa, Pentzia incana. Succulent Shrubs: Malephora uitenhagensis (d), Salsola aphylla (d), S. arborea (d), Drosanthemum
lique, Salsola geminiflora, S. gemmifera. Graminoids: Cynodon
incompletus (d), Cenchrus ciliaris, Cyperus marginatus. Reed
beds Megagraminoid: Phragmites australis (d).
parts of the Albany Thicket Biome south of Cradock. Altitude
ranging from 250–1 550 m.
Vegetation & Landscape Features Narrow riverine flats supporting a complex of Acacia karroo or Tamarix usneoides thickets (up to 5 m tall), and fringed by tall Salsola-dominated shrubland (up to 1.5 m high), especially on heavier (and salt-laden)
soils on very broad alluvia. In sandy drainage lines Stipagrostis
namaquensis may occasionally also dominate. Mesic thicket
forms in the far eastern part of this region (see Van der Walt
1980: Table 4) may also contain Leucosidea sericea, Rhamnus
prinoides and Ehrharta erecta.
Geology, Soil & Hydrology Recent sandy-clayey alluvial deposits rich in salt occurring on mudrocks and sandstones of the
Adelaide Subgroup (Beaufort Group of the Karoo Supergroup)
that support soils typical of Ia land type. Torrential convectional
rains in summer cause sudden flood surges which remodel the
riverbed and adjacent alluvium.
Endemic Taxon Alluvial shrublands & herblands Graminoid:
Isolepis expallescens.
Conservation Least threatened. Target 24%. Only about 1.5%
statutorily conserved in the Karoo National Park as well as in the
Aberdeen, Bosberg, Commando Drift, Gamkapoort and Karoo
Nature Reserves and in about 10 private reserves, mainly set
up for game farming. Some 12% transformed for cultivation
and building of dams, including Beaufort West, Beervlei, De
Hoop, Floriskraal, Kommandodrift, Lake Arthur, Leeu-Gamka,
Mentz and Vanryneveldspas Dams. Frequent disturbance
(floods, concentrated grazing pressure), and associated input of
nutrients, increase vulnerability of these habitats to invasion of
alien woody species such as Agave americana, Opuntia species,
Prosopis species, Salix babylonica and Schinus molle, and forbs
including Atriplex eardleyae, A. lindleyi subsp. inflata, Cirsium
vulgare, Salsola kali and Schkuhria pinnata.
Climate Transitional, bimodal (equinoctial) rainfall patterns
with peaks in March (major) and November (minor). Climate is
subarid on the whole, with overall MAP of 243 mm (range from
165 mm in the Gamka Karoo basin to 430 mm in the vicinity of
Bedford). Overall warm-temperate regime, with MAT of 16.3°C,
ranging from 14.6°C (Upper Karoo) to 18.3ºC (upper reaches
of Sundays River). Frost occurs frequently in winter. See also
climate diagram for AZi 6 Southern Karoo Riviere (Figure 13.2).
Important Taxa Riparian thickets Small Trees: Acacia karroo (d), Rhus lancea (d). Tall Shrubs: Diospyros lycioides (d),
Remark 1 Due to the lingering taxonomic problems, the identity
of South African species of Salsola sect. Caroxylon cited in various papers (see below), should be approached with caution.
Remark 2 Plants of drainage lines may be resistant to damage by hail storms. At the Tierberg Karoo Research site, 36
of the 44 species in drainage lines were undamaged after a
hail storm, with the remaining species only slightly damaged
(Milton & Collins 1989). This contrasted with much higher levels of damage to plants of the surrounding habitats (flats and
heuweltjies).
References Acocks (1979), Van der Walt (1980), Palmer (1988, 1989, 1991),
Milton (1990), Rubin & Palmer (1996), Brown & Bezuidenhout (2000).
AZi 7 Tanqua Wash Riviere
L. Mucina
Distribution Western Cape and (to a smaller extent) Northern
Cape Provinces: Alluvia of the Tankwa and Doring Rivers and
sheet-wash plains of their less important tributaries embedded within SKv 5 Tanqua Karoo. Altitude ranging from
300–1 000 m.
Figure 13.34 AZi 6 Southern Karoo Riviere: Acacia karroo thickets on
valley alluvium below the Molteno Pass near Beaufort West (Western
Cape).
Vegetation & Landscape Features Deeply incised valleys
(sometimes several hundred metres broad) of intermittent rivers supporting a mosaic of succulent shrublands with Salsola
and Lycium alternating with Acacia karroo gallery thickets. The
broad sheet-wash plains support sparse vegetation of various
Salsola species, often building phytogenic hillocks interrupting
the monotonous barren face of a sheet wash. Occasional rainfalls in early winter result in localised displays of annuals and
early flowering geophytes along washes.
Geology, Soil & Hydrology Broad Quaternary alluvial floors
and drainage lines filled with recent sediments mostly from
eroded Karoo Supergroup sediments. Sodic loamy to sandy soils
(Ia land type) are predominantly supported by sediments of the
Ecca and Dwyka Groups of the Karoo Supergroup. In the west,
rocks of the Devonian Bokkeveld Group (Cape Supergroup) and
Inland Azonal Vegetation
647
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Augea capensis, Salsola aphylla. Herbs:
Euryops annuus, Gazania lichtensteinii,
Osteospermum pinnatum, Ursinia nana.
L. Mucina
Endemic Taxa Alluvial shrublands
& herblands Herbs: Limonium sp. nov.
(Mucina 310104/1 STEU). Sheet washes
Succulent Shrub: Salsola ceresica (d).
Conservation Least threatened. Target
19%. About 13% statutorily conserved
in the Tankwa National Park and in
some private reserves (Inverdoorn,
Jakkalsfontein, Uintjieskraal, Groote
Kapelsfontein, Vaalkloof). About 3%
already transformed for cultivation or
dam building (Oudebaaskraal Dam and
Swartkop se Dam). Alien Atriplex lindleyi
subsp. inflata and Prosopis species can
become frequent in places.
Remarks We acknowledge that this
unit is of heterogeneous character at
present and the ecological and floristic
relationship between the Acacia karroodominated riparian vegetation on the one hand and the Salsoladominated sheet-wash vegetation on the other, deserves reevaluation in the light of new data still to be collected.
Figure 13.35 AZi 7 Tanqua Wash Riviere: Riparian thickets dominated by Acacia karroo and
Salsola arborea with fringing alluvial gannabosveld along the Tankwa River.
in the east, the Permian Adelaide Subgroup (Karoo Supergroup)
also support these soils. The run-off in these habitats is very low
and spread over large areas.
Climate Region characterised by arid to hyperarid climate, with
MAP ranging between 100 mm and 170 mm (lowest long-term
average is 72.3 mm for Elandsvlei on the Tankwa River). Overall
MAP 162 mm, mainly falling in autumn and winter. Mean daily
maximum and minimum temperatures are 32.5°C and 3.0°C for
January and July, respectively. Overall MAT is slightly higher than
17°C. Due to basin macrotopography the occurrence of frost
is fairly frequent. See also climate diagrams for AZi 7 Tanqua
Wash Riviere (Figure 13.2) and SKv 5 Tanqua Karoo (Figure 5.65
in Chapter on Succulent Karoo in this book).
Important Taxa Riparian thickets Small Tree: Acacia karroo
(d). Alluvial shrublands & herblands Low Shrub: Galenia africana. Succulent Shrubs: Lycium cinereum (d), Malephora luteola,
Salsola arborea, Sarcocornia mossiana agg. Geophytic Herbs:
Moraea speciosa, Tritonia florentiae. Graminoids: Cladoraphis
spinosa, Stipagrostis obtusa. Sheet washes Succulent Shrubs:
Reference Rubin (1998).
AZi 8 Muscadel Riviere
Distribution Western Cape Province: River alluvia of the lower
Breede River (between Worcester and Bonnievale) as well as
those embedded within the western Little Karoo (Montagu
area) and eastern Little Karoo (the rivers draining the basin
around Oudtshoorn). Altitude 150–600 m.
Vegetation & Landscape Features Flat, in places very broad
alluvia originally supporting a complex of riverine thickets dominated by Acacia karroo and accompanying succulent gannabos
(Salsola species) and low vygie shrublands. Today the typical
landscape view of these alluvia is dominated by extensive vineyards and orchards, with a narrow alley of alien woody species (Eucalyptus species, Salix babylonica)
fringing the riverbanks.
L. Mucina
Geology, Soil & Hydrology Recent
sandy and clayey alluvial (riverine) sediments mostly derived from the clastic
sediments of the Jurassic-Cretaceous
Uitenhage Group supporting soils typical of Ia land type. These alluvial habitats
frequently suffer from devastating floods
occurring especially with the first cold
western frontal systems bringing torrential rain to the Cape (such as recently in
1981, 2002, 2004 and 2005).
Figure 13.36 AZi 7 Tanqua Wash Riviere: Gannabos (Salsola ceresica) on sparsely vegetated
sheet wash-plain in the desert-like western part of Tankwa National Park (Western Cape).
648
Inland Azonal Vegetation
Climate The regional climate diagram for
this unit suggests almost evenly spread
precipitation. However, winter rainfall
prevails in the western part of the region
and becomes nonseasonal towards the
eastern limits of the distribution of this
vegetation type (eastern Little Karoo).
MAP is low (210 mm; range 220 mm
in the rainshadow of the Langeberg to
S %
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Endemic Taxon Alluvial shrublands & herblands Herb:
Pelargonium citronellum.
Conservation Endangered. Target 16%. Small patches of
this vegetation are protected in the Vrolijkheid Nature Reserve
near McGregor (Van der Merwe 1977a) and Kammanassie
Nature Reserve (Cleaver et al. 2005) as well as on private land
(Greylands, Die Poort). More than 60% already transformed
for cultivation (vineyards, orchards) or road building. Aliens
Arundo donax, Atriplex lindleyi subsp. inflata, Chenopodium
species, Datura species, Prosopis glandulosa, Ricinus communis,
Schinus molle, Tamarix chinensis and T. ramosissima cause local
infestations.
Remark 1 The classification of the ‘Calpurnia intrusa-Rhus pallens Woodland’ by Cleaver et al. (2005) described from streambanks of the Vermaaks River (Kammanassie Mountains, eastern
Little Karoo) from altitudes 543–675 m remains only tentative.
Two communities described within this woodland show transitional character between riparian thickets of the Muscadel
Riviere on the one hand and eastern facies of Cape thickets (see
chapter on the Fynbos Biome in this book) on the other.
Remark 2 The name of this unit celebrates the marvellous
sweet fortified wines (mainly muscadel, but also local port
wine) made from grapes grown on the alluvial soils of the summer-hot Robertson Karoo and Little Karoo.
References Joubert (1968), Van der Merwe (1977a), Vlok (2002), Cleaver
et al. (2005).
L. Mucina
AZi 9 Cape Inland Salt Pans
Figure 13.37 AZi 8 Muscadel Riviere: Alluvial thicket (with dominant
Acacia karroo) at the bottom of the Huis River in the Huisrivier Pass west
of Calitzdorp. Part of the alluvium has been cleared for agriculture.
Important Taxa Riparian thickets
Trees: Acacia karroo (d), Salix mucronata subsp. mucronata (d), Rhus lancea.
Alluvial shrublands & herblands Tall
Shrubs: Cliffortia strobilifera, Melianthus
comosus, Tamarix usneoides. Low Shrubs:
Galenia africana (d), Pentzia incana
(d), Atriplex vestita var. appendiculata,
Chrysanthemoides incana, Polygala virgata var. virgata, Pteronia oblanceolata.
Succulent Shrubs: Malephora luteola
(d), Salsola aphylla (d), S. arborea (d),
Bassia salsoloides, Lycium arenicola,
Suaeda fruticosa, Zygophyllum sessilifolium. Herb: Berkheya spinosa. Succulent
Herb: Psilocaulon junceum. Graminoids:
Ehrharta calycina, E. delicatula. Reed
beds Megagraminoids: Phragmites australis (d), Typha capensis (d).
L. Mucina
368 mm in the Breede River Valley) due to the rainshadow
effect from the surrounding mountain ranges of the Cape
Fold Belt. The region is characterised by relatively high MAT
(17.9°C; range 16.0°C in Breede River Valley to 17.2°C near
Willowmore) and particularly hot summers (with temperatures reaching above
40°C (especially in Worcester). See also
climate diagram for AZi 8 Muscadel
Riviere (Figure 13.2).
Distribution Western and Eastern Cape (to smaller extent)
Provinces: Jakkalsrivier Valley between Graafwater and
Lambert’s Bay, Rocher Pan and other pans near Dwarskersbos
(near Velddrif), Soutpan near Yzerfontein, Rondevlei, Paardevlei,
Noordhoek (all near Cape Town), salt vleis of the Agulhas Plain,
Zoutpan and several other smaller salt pans in the Albertinia
region (Zoutpan, Melkhoutfontein, Vogelvlei). We also include
saline habitats near Worcester and an extensive system of saline
alluvia, saline floodplain flats (Karsrivier) and slope saline scars
scattered around the Overberg region (e.g. the vicinity of Napier,
Bredasdorp, Stormsvlei and Swellendam). These pans occur
Figure 13.38 AZi 9 Cape Inland Salt Pans: A salt pan on the Agulhas Plain (Overberg region,
Western Cape) housing sparse population of an undescribed species of Salicornia (Chenopodiaceae) and local endemic Limonium kraussianum (Plumbaginaceae).
Inland Azonal Vegetation
649
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19 (2006)
Polypogon monspeliensis, Prionanthium
pholiuroides, Tribolium hispidum.
L. Mucina
Endemic Taxa Succulent Shrubs:
Disphyma dunsdonii (d), Drosanthemum
salicola, Lampranthus salicola. Herbs:
Dymondia margaretae (d), Limonium anthericoides. Succulent Herb: Dorotheanthus
clavatus. Aquatic Herb: Pseudalthenia
aschersoniana.
Figure 13.39 AZi 9 Cape Inland Salt Pans: Small-scale hypersaline pans near Yzerfontein on the
Cape West Coast. Vegetation is dominated by Sarcocornia natalensis var. affinis, Suaeda inflata,
Plantago crassifolia complex, Frankenia repens, Salicornia meyeriana, Sporobolus virginicus
and Limonium equisetinum.
as far east as the broader surrounds of the Nelson Mandela
Metropole (Soutpan near Dispatch and smaller pans near
Uitenhage, Port Elizabeth and Addo). Altitude ranging from
0–150 m, with few isolated pans at around 500 m.
Vegetation & Landscape Features Small depressions dominated by low succulent scrub composed of creeping chenopods
and salt-tolerant herbs and grasses. The saline Overberg alluvia
are dominated by a low succulent shrub, Sarcocornia mossiana.
Geology, Soil & Hydrology Originally, most of the saline pans
were coastal lagoons but they became dry after having been
cut off from the sea—they may become temporarily flooded
by winter rains and remain mostly dry in summer. Some of the
smaller salt pans along the coast might have originated through
deflation processes on easy-eroding coastal calcrete. The pans
in the Overberg region are mostly on Bokkeveld Group shales
as well as the much younger sandstone and limestone of the
Bredasdorp Group nearer the coast. The saline alluvia of some
Overberg rivers were formed by sediments that originated from
erosion scars of salt-bearing Bokkeveld shale.
Climate The occurrence of Cape inland salt pans spans typical
winter-rainfall (West Coast) and transitional (winter-summer)
rainfall regions (Port Elizabeth and Grahamstown areas). MAP
ranges from 278 mm (Langebaan) to 627 mm (Humansdorp),
while the range of MAT is less pronounced: 15.9°C for the
Overberg to 17.5°C for the Sundays River Valley. The ocean
has an ameliorating effect on temperature patterns in hot, dry
summers. See also climate diagram for AZi 9 Cape Inland Salt
Pans (Figure 13.2).
Important Taxa Low Shrubs: Morella cordifolia, Orphium frutescens, Senecio halimifolius. Succulent Shrubs: Sarcocornia capensis (d), S. mossiana complex (d), Atriplex cinerea subsp. bolusii,
Lycium cinereum, Sarcocornia pillansii, Suaeda inflata. Herbs:
Frankenia repens (d), Limonium equisetinum (d), L. kraussianum
(d), Chironia baccifera, C. decumbens, C. tetragona. Succulent
Herbs: Malephora luteola (d), Plantago crassifolia complex (d),
Sarcocornia natalensis (d), Halopeplis amplexicaulis. Graminoids:
Chondropetalum microcarpum (d), C. nudum (d), Sporobolus
virginicus (d), Elegia verreauxii, Ficinia lateralis, F. ramosissima,
650
Inland Azonal Vegetation
Conservation Vulnerable. Target 24%.
Some 20% statutorily conserved in the
Agulhas and West Coast National Parks
as well as in the Soetendalsvlei and
Rocherpan Nature Reserves. Furthermore,
almost 3% enjoys protection on private
land (Rietvlei, Rhenosterkop). More than
20% has been transformed for cultivated
land, mines (in the past some of the pans
near Albertinia were exposed to salt mining; Muir 1929) or by urban sprawl. Alien
(Australian) herbaceous Atriplex species
show invasive behaviour in places.
References Muir (1929), Noble & Hemens
(1978), Van Rooyen (1981), Olivier (1983), Gray
(1997), Harding et al. (2000).
AZi 10 Highveld Salt Pans
Distribution Northern Cape, Eastern Cape, North-West, Free State
and Gauteng Provinces: Pans scattered on broad Grassland/Karoo
and Grassland/Savanna interface roughly between Mafikeng/Koster
in the north and Britstown/Middelburg in the south. The highest
concentrations of pans are found around Dealesville, Bultfontein,
Wesselsbron, Delareyville and Petrusburg. The average size of the
playas in the western Free State is 0.2 km2, with a number of the
largest ones (e.g. Florisbad Pan and Annaspan) measuring several
kilometres across (Goudie & Thomas 1985). Altitude ranging
from 1 000–1 600 m.
Vegetation & Landscape Features Depressions in plateau
landscape containing temporary (and less frequently also permanent) water bodies. Central parts of the pans often seasonally inundated and sometimes with floating macrophyte vegetation or the vegetation cover develops on drained bottoms of
the pans and forms typical concentric zonation patterns. On the
pan edges open to sparse grassy dwarf shrubland may develop,
especially when the pan is under heavy grazing pressure.
Geology, Soil & Hydrology The bottoms of the pans are usually formed by shales of the Ecca Group giving rise to vertic clays.
The environment of the pans undergoes dramatic changes from
freshwater systems during the wet season to saline systems as
the dry season progresses and evaporation intensifies. Wind
erosion is of particular significance during the dry season, when
the playa basin is dry and marginal vegetation is short and
sparse (Allan et al. 1995). Dense dust can reach several thousand metres into the air under such windy conditions.
Climate These salt pans occur in arid and semi-arid elevated
regions of the Highveld, receiving less than 500 mm rain per
year. Overall MAP 400 mm (range from 275 mm in the Upper
Karoo to 654 mm in Gauteng). Characterised by thunderstorms
leading to high water run-off and low soil absorption. The climate pattern spans bimodal (equinoctial) to typically summerrainfall in the northeastern regions. The overall MAT of 16.7°C
(range 14.3°C near Aliwal North to 18.3°C near Mafikeng).
Frequent incidence of frost corresponds to high thermic
S %
19 (2006)
L. Mucina
Rosmead, Hanover and Colesberg) eroding calcrete outcrops in wide pan-like
depressions form an interesting microhabitat. It is characterised by shallow,
white, powdery and highly alkaline soils
(Werger 1980 measured pH values above
8) usually supporting dominants similar to those of true salt pans, including
Salsola glabrescens, Zygophyllum incrustatum, Eragrostis truncata, Sporobolus
species and Pentzia globosa as well as
some odd vygies such as Trichodiadema
pomeridianum, Titanopsis schwantesii
and Delosperma ‘ornatulum’ (Werger
1980, p. 77).
Figure 13.40 AZi 10 Highveld Salt Pans: Salt pan at Hutchinson (Northern Cape).
continentality. See also climate diagram for AZi 10 Highveld Salt
Pans (Figure 13.2).
Important Taxa Low Shrubs: Atriplex vestita, Felicia filifolia, F.
muricata, Nenax microphylla, Nestlera conferta, Pentzia globosa,
P. incana. Succulent Shrubs: Salsola glabrescens (d), Lycium
cinereum, Malephora herrei, Suaeda fruticosa, Titanopsis hugoschlechteri. Megagraminoids: Cyperus congestus, Phragmites
australis, Typha latifolia. Graminoids: Chloris virgata (d),
Cynodon dactylon (d), C. transvaalensis (d), Cyperus laevigatus
(d), C. marginatus (d), Diplachne fusca (d), Eragrostis bicolor (d),
E. chloromelas (d), E. plana (d), Hemarthria altissima (d), Juncus
rigidus (d), Panicum coloratum (d), P. laevifolium (d), P. schinzii (d), Setaria incrassata (d), Andropogon eucomus, Aristida
adscensionis, Brachiaria marlothii, Cyperus longus, C. rigidifolius, Echinochloa holubii, Eleocharis palustris, Enneapogon
desvauxii, Eragrostis curvula, E. micrantha, E. obtusa, E. stapfii,
Fuirena coerulescens, F. pubescens, Juncus exsertus, Scirpoides
dioecus, Sporobolus albicans, S. fimbriatus, S. ioclados, S. tenellus, Tragus berteronianus, T. racemosus. Herbs: Alternanthera
sessilis, Amaranthus praetermissus, Aponogeton rehmannii,
Atriplex suberecta, Chenopodium mucronatum, Gnaphalium
declinatum, Mollugo cerviana, Phyla nodiflora, Platycarpha
parvifolia, Pterodiscus speciosus, Senecio reptans. Succulent
Herb: Zygophyllum simplex.
Biogeographically Important Taxon (Highveld endemic)
Herb: Rorippa fluviatilis var. caledonica.
Endemic Taxon Herb: Gnaphalium simii.
Conservation Target 24%. Only very small portion statutorily
conserved in the Vaalbos National Park and in the Bloemhof
Dam, Soetdoring, Willem Pretorius, Barberspan (a Ramsar site)
and S.A. Lombard Nature Reserves. About 4% has been transformed so far, but threats by agriculture, road building, mining and urbanisation are still increasing. Alien plants such as
Atriplex semibaccata, Conyza albida, Flaveria bidentis, Salsola
kali, Schkuhria pinnata, Sonchus oleraceus, Spergularia rubra,
Tagetes minuta, Verbena brasiliensis and Xanthium species
(Cilliers & Bredenkamp 2003, Janecke et al. 2003) have been
recorded in the vegetation of these salt pans.
Remark 1 In the northeastern regions of the NKu 4 Eastern
Upper Karoo (e.g. along the upper Orange River Valley between
Aliwal North and Petrusville, in the broad area of Middelburg,
Remark 2 The vegetation of the
Highveld Salt Pans differs greatly from
that of other pan types (Namaqualand
Salt Pans, Bushmanland Vloere, Southern
Kalahari Salt Pans and Cape Inland Salt
Pans) mainly due to the dominance of
cyperoids.
Remark 3 Geldenhuys (1982) distinguished the six pan types
based on the presence of emergent vegetation—bare, sedge,
scrub, mixed grass, closed, and open Leptochloa playas.
References Noble & Hemens (1978), Werger (1980), Seaman (1987), Kooij
et al. (1990b), Seaman et al. (1991), Breen et al. (1993), Allan et al. (1995),
Bezuidenhout (1995), Malan (1998), Janecke (2002), Cilliers & Bredenkamp
(2003), Janecke et al. (2003).
AZi 11 Subtropical Salt Pans
Distribution Limpopo, Mpumalanga and KwaZulu-Natal Provinces
and in Swaziland: Pans in the subtropical regions of eastern southern Africa, in particular in the Lowveld, Maputaland and northern
KwaZulu-Natal. Altitude ranging from 0–1 400 m.
Vegetation & Landscape Features Shallow depressions, often
found on old alluvial terraces of rivers, surrounded by zones of bank
reeds or low herblands and in more perennial pans also filled with
a dense carpet of macrophytic floating vegetation.
Geology, Soil & Hydrology The pans occur on Cenozoic alluvium, sand and calcrete, but also significantly on sediments of the
Cretaceous Zululand Group. Large perennial-water pans are found
in the alluvia of the Phongolo and Usutu Rivers. During the drier
winter period, the water may recede below ground and salt may
precipitate on the banks (this especially in the case of small zoogenic pans in the Kruger National Park), the water in the pans consequently becoming brackish and even saline. The salinity of water
of some other pans (such as the Nyamithi Pan in the Ndumo Game
Reserve) is attributed to leaching of salt from Cretaceous sediments
of marine origin (Hattingh & Matthews 2003).
Climate Seasonal, summer-rainfall regime with MAP ranging
from 311 mm in the Limpopo Valley to 964 mm in Maputaland.
Subtropical temperature regime with MAT ranging from 18.0°C
in the Central Bushveld to 22.0°C in Maputaland), with very
infrequent incidence of frost (only in marginal areas of contact
with the Grassland Biome in the Central Bushveld). See also
climate diagram for AZi 11 Subtropical Salt Pans (Figure 13.2).
Important Taxa Drained pan bottoms Graminoids: Cynodon
dactylon (d), Diplachne eleusine (d), Eragrostis rotifer (d), Chloris
virgata, Cyperus indecorus. Herbs: Isoetes schweinfurthii, Persicaria
senegalensis. Pan edges Megagraminoid: Phragmites mauritianus (d). Graminoids: Digitaria didactyla, Echinochloa pyramida-
Inland Azonal Vegetation
651
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19 (2006)
classified after extensive field work. The
Namaqualand salt pans were mapped by
A. le Roux, while parts of the coverage for
alluvial and freshwater wetlands of the
Capensis were provided by A.G. Rebelo, C.
Boucher (both within the Fynbos Biome)
and J.C. Manning (vernal pools).
L. Mucina
The introductory text was written by L.
Mucina, with contributions by J. Gerber
(Section 5). L. Mucina wrote descriptions of
all vegetation units as first author except for
AZi 1 and 2, where he assisted A. le Roux.
The following colleagues co-authored several descriptions: M.C. Rutherford (AZi 3, 5
and 6), G.J. Bredenkamp (AZa 5 and AZi
10), P.J. du Preez (AZa 4 and AZi 10), J.C.
Manning (AZf 2 and AZi 7), E.J.J. Sieben
(AZa 1 and 2), H. Bezuidenhout (AZa 3),
S.S. Cilliers (AZi 10), J. Gerber (AZf 3), D.B.
Hoare (AZa 6) and F. Siebert (AZa 7). The
species lists were compiled by L. Mucina
Figure 13.41 AZi 11 Subtropical Salt Pans: A pan near Masinda Camp in the Hluhluwe-iMfolozi
Park with a reed bed of Typha capensis and resting zebra (Equus burchellii).
with the technical help of L.W. Powrie. The
data for the Conservation sections of the
lis, Paspalum vaginatum, Sporobolus smutsii. Herbs: Eclipta prost- descriptions were compiled by L.W. Powrie and the sections on
rata, Marsilea ephippiocarpa, Persicaria hystricula, Syngonanthus
Geology, Soil & Hydrology were corrected by R.A. Ward. M. Rouget,
and others within the Directorate of Biodiversity Programmes,
wahlbergii. Pan lakes Herb: Ludwigia stolonifera (d). Aquatic
Policy & Planning of SANBI, provided quantitative information
Herbs: Azolla pinnata var. africana (d), Ceratophyllum demersum
(d), Nymphaea nouchali var. caerulea (d), Potamogeton crispus (d), for each vegetation unit on conservation status and targets,
areas currently conserved and areas transformed.
Trapa natans var. bispinosa (d), Wolffia arrhiza (d), Monochoria
africana, Najas pectinata, Nymphaea lotus. Carnivorous Herb:
The climate diagrams were prepared by M.C. Rutherford and L.W.
Utricularia inflexa (d).
Powrie. Most of the photographs were provided by L. Mucina
except for those kindly contributed by W.S. Matthews, M.C. Lötter
Endemic Taxon Pan edges Aquatic Herb: Marsilea fenestrata.
and J.C. Manning. L. Scott, J. Grobbelaar, K. Kobisi, M. Polaki and
Conservation Least threatened. More than 40% (well over the tarJ.R.U. Wilson provided some less accessible literature sources. C.R.
get of 24%) statutorily conserved in the Greater St Lucia Wetland
Scott-Shaw and P.S. Goodman provided valuable comments on
Park, Ndumo Game Reserve (both Ramsar sites), Kruger National
parts of the text.
Park as well as in the private Zoutpan Nature Reserve. About 11%
has been transformed for mines, cultivation and plantations. Aliens
Cardiospermum halicacabum and Argemone ochroleuca invade
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Remark 1 Subtropical salt pans have always served as an important
source of water (and salt) for ungulates abundant in the Savanna
Biome. In winter wild animals teem around the water ‘holes’ (often
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attracting thousands of local and overseas tourists.
Remark 2 At least one salt pan has been recognised as a result of
a meteorite impact that resulted in a crater, the floor of which later
developed into a temporary flooded salt pan. This is the Tswaing
Crater (formerly Pretoria Salt Pan) 40 km north of Pretoria and it is
200 000 years old.
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