Open Journal of Ecology, 2020, 10, 717-728
https://www.scirp.org/journal/oje
ISSN Online: 2162-1993
ISSN Print: 2162-1985
Diversity Assessment of Tree Species in Sitio
Dicasalarin, Barangay Zabali, Baler, Aurora,
Philippines
Ericson E. Coracero1, Pastor L. Malabrigo Jr.2
1
Department of Forestry and Environmental Sciences, Aurora State College of Technology (Baler Campus), Aurora, Philippines
Department of Forest Biological Sciences, University of the Philippines Los Baños, Laguna, Philippines
2
How to cite this paper: Coracero, E.E. and
Malabrigo Jr., P.L. (2020) Diversity Assessment of Tree Species in Sitio Dicasalarin, Barangay Zabali, Baler, Aurora, Philippines. Open Journal of Ecology, 10, 717-728.
https://doi.org/10.4236/oje.2020.1011043
Received: October 10, 2020
Accepted: November 8, 2020
Published: November 11, 2020
Copyright © 2020 by author(s) and
Scientific Research Publishing Inc.
This work is licensed under the Creative
Commons Attribution International
License (CC BY 4.0).
http://creativecommons.org/licenses/by/4.0/
Abstract
This paper provides the diversity assessment of the tree species in Sitio Dicasalarin, Barangay Zabali, Baler, Aurora including the endemism and ecological
status. A total of 2239 individuals from 139 morphospecies, 87 genera and 46
families were recorded. A total of 48 Philippine endemic species and 2 Aurora
Endemic species were found and at least 29 threatened species were listed either in the IUCN Red List of Threatened Species and Philippine List of
Threatened Species. Results of the tree diversity showed that the area is highly
diverse being a well-protected and well-managed area.
Keywords
Sitio Dicasalarin, Tree Diversity, Philippine Endemics, Threatened Species,
Sierra Madre Mountain Range, Aurora Endemics
Open Access
1. Introduction
Philippines is one of the most important countries with potential of conserving
the diversity of life on Earth [1]. Being one of the megadiverse countries in the
world, Philippines holds a wide variety of life forms in both aquatic and terrestrial ecosystems [2]. The country is also one of the hottest biodiversity hotspots
with exceptional concentrations of endemic species but is experiencing a continuous and exceptional loss of habitat [3]. The study showed that Philippines is at
the 23rd rank in the world and 6th in Southeast Asia in being diverse with 5832
endemic species among the total of 7620 documented species in the country. A
number of threatened plant species can be found in the Philippines [4].
Assessing the tree diversity in an area is essential in analyzing forest stand
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status considering that trees play vital roles in maintaining natural ecological
processes and in providing a source for human consumption [5]. Performing
such an assessment can provide necessary information in identifying problems
with respect to the trees present in the country and their status. Appropriate
measures will only be possible if species present in an area are identified [6].
Sitio Dicasalarin is a part of the Sierra Madre Mountain Range. Studies and
researches within the area are lacking especially when it comes to tree diversity
[7]. Studies conducted in the past were more focused on the faunal component.
This tree diversity assessment provides information necessary for the protection
and conservation of the area.
The diversity assessment was conducted from June to July 2017 at Sitio Dicasalarin, Barangay Zabali, Baler, Aurora situated at the Sierra Madre Mountain
Range. This study generally aims to assess the diversity of tree species in Sitio
Dicasalarin and evaluate the conservation status of each species for better execution of the forest management in the area. Specifically, the study aims to: a) inventory and characterize the tree species in the area and; b) assess the biodiversity status, condition, and distribution of the tree species present through diversity indices and importance values computation, photos, and reports.
2. Review of Related Literature
2.1. World’s Biodiversity
Biodiversity considers all types and kinds of organisms existing in the planet including plants, animals and other microorganisms [8]. It has been observed that
there is a continuous reduction in the world’s biodiversity. Statistics found out a
total declination of 40% in the average species abundance, 50% in inland water
species, and 30% in the population of marine and terrestrial species [9]. These
numbers were brought by the drastic change due to rapid reduction of tropical
forests and the increase in human population which both threatened plant and
animal species of the world. Despite the decreasing biodiversity level, an evident
increase in the number of described species continues to show which means that
there is still a large number of species yet to be discovered.
2.2. Status of Philippine Forest
Philippines was one of the many countries largely covered by forest. In the past,
the country was covered with about 90 percent or 27 million ha of lush tropical
rainforest [10]. It was in 1521 when the Spaniards colonized the Philippines and
as the spread of commercial crops begun during their regime, deforestation
started. In the year 1900, two years after the Spaniards left, the Americans came
while still about 70 percent or 21 million of the country’s land is forested until
they introduced the first modern logging operations in 1904 and the Philippines
became one of the main exporters of Dipterocarp lumbers in the world. Continuous deforestation and cutting of trees happened. The least forest cover that
the country has experienced was around 1988 with only 6.5 million ha of foDOI: 10.4236/oje.2020.1011043
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rested lands. It increased by 0.3 million ha by 2010 making the forest cover 23
percent of the land area or 6.8 million ha [11]. According to DENR, the forest
cover of the country is about 8.205 million ha in 2015 [12]. The continuous decrease in the forest cover of the Philippines shall be a concern and drive to perform studies for conservation and rehabilitation of forests in the country.
2.2. Status of Philippine Floral Species
Philippines as one of the megadiversity countries and biodiversity hotspots has a
significant story to tell when it comes to its floral and faunal composition and
status [13]. The country’s biodiversity together with its forest areas continues to
decrease. Only through the efforts of different studies and research groups can
the concern on the matter be addressed.
The number of threatened floral species in the country increased from the
2007 record of 526 to 984 in the year 2017 [14]. It can be said that there is really
continuous declination due to certain factors including the anthropogenic and
natural factors. It dictates the need to perform activities related to the conservation and rehabilitation of the Philippine forests.
3. Materials and Methods
3.1. Materials
In the conduct of the study, different materials were used starting from site establishment until the preservation of the voucher specimens. Meter tapes, nylon
rope, pegs, and bolo were used in establishing the quadrats and transect belts.
For the collection of voucher specimens and listing of species and its measurements, pencil, meter tape, datasheets, clipboard, specimen tags, bolo, pruning
shears, polyethylene bags, and sacks were used. Transect belts and quadrats were
located using a GPS device in obtaining the coordinates and elevation. Lastly, in
the preservation of the voucher specimens, herbarium bags, denatured alcohol,
pruning shear, newspapers, sacks and packing tape were used.
3.2. Establishment of Quadrats and Transects
Three 2-km transects following the existing trails were established in three different locations (Figure 1). A 20 × 20-meter quadrat was established at every
250-meter interval along each transect at the left and right of the existing trail
(Figure 2). Hence, a total of 27 quadrats were established.
3.3. Survey and Specimen Collection, Preservation,
and Identification
Trees with diameter at breast height (DBH) of at least 5 cm inside the quadrats
were identified and recorded. The total height (TH) and merchantable height
(MH) were also measured. Voucher specimens of each species were collected
photographed and placed inside the herbarium bags for identification and verification purposes. Identification of voucher specimens was performed through
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Figure 1. Location map of the transect and quadrat established in Sitio Dicasalarin.
Figure 2. Form of 20 × 20 m quadrat establishment per transect.
different taxonomic references such as Co’s Digital Flora of the Philippines,
Lexicon of Philippine Trees by Rojo, and Philippine Vascular Plants Checklist by
Leonard Co. Also, digital photo database of fresh plants [15] and herbarium specimens of Pastor L. Malabrigo, Jr. were used in comparison with our pressed
specimens and its photos for identification and verification.
3.4. Data Analysis
Diversity indices (i.e. Shannon, Simpson evenness) were also computed using
the Paleontological Statistics Software Package for Education and Data Analysis
(PAST v.3.14) [16]. Shannon Index measures the diversity using species richness
and distribution. Simpson Evenness measures diversity in terms of evenness in
the distribution of species and individuals per quadrat [17]. Diversity indices
were interpreted using the scheme of Fernando Biodiversity Scale [18] (Table 1).
Endemism, conservation status, and distribution record of each species were assessed and verified. For the conservation status, worldwide category was based
on the International Union for Conservation of Nature Redlist [19]. While for
the Philippine scheme, the local list of threatened species under DAO 2017-11
was used [12]. Importance values were also computed using the data collected
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Table 1. Fernando biodiversity scale.
Relative Values
Shannon Index
Evenness Index
Very high
3.5 and above
0.75 - 100
High
3.0 - 3.49
0.5 - 0.74
Moderate
2.5 - 2.99
0.25 - 0.49
Low
2.0 - 2.49
0.15 - 0.24
Very low
1.9 and below
0.05 - 0.14
during the collection: individual count per species, frequency of plot occurrence,
and dominance (using DBH) [20]. Below are the formulas for IV computation.
• Dominance equals to (0.7854) × Diameter2
• Relative dominance equals to (dominance of a species/sum of the dominance
of all species) × 100
• Frequency equals to (total number of quadrats in which species occurred/total number of quadrats studied)
• Relative frequency equals to (frequency of a species/sum of frequency of all
species) × 100
• Density equals to (Total number of individuals of species/ Total number of
individuals of all species)
• Relative density equals to (density of a species/sum of density of all species) ×
100
• IV equals to Relative dominance + Relative frequency + Relative density
4. Results and Discussion
4.1. Tree Species
A total of 139 morpho-species were recorded along the tree transects with a total
of 2239 individuals from 87 genera and 46 families. Number of tree individuals
per quadrat varies from 38 to 132. Diameter of trees ranges from 5 cm to 130
centimeters. Only four individuals of trees exceeded 100 cm-diameter which belong to only one species, Dangula (X. philippinensis), belonging to the family of
myrtles or Myrtaceae. Majority of the species was measured to have DBH of less
than 50 cm indicating that the forest is secondary growth.
The importance values (IVs) of the species were computed as the sum of the
relative dominance, relative density, and relative frequency. Based on the computed IVs, the five most important species in terms of dominance, frequency,
and density are Dangula (T. ahernianum) (35.29), Bagoadlau (X. philippinensis)
(31.49), Yakal malibato (S. malibato) (16.60), Bitanghol (C. blancoi) (15.51), and
Malabetis (M. oblongifolia) (11.01) (Table 2). These species belong to five different families. All these species except Bitanghol and Dangula are threatened
both in the IUCN Redlist and the Philippine Redlist of Forest Plants. Dangula
was found to be the most important species in the area which according to studies is still abundant in tropical areas particularly in Asia [21].
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4.2. Diversity Indices
The computed diversity indices of Sitio Dicasalarin falls on the category of a very
highly diverse area (Shannon diversity = 4.096, Evenness = 0.9735) (Table 3).
Transect 3 has the highest diversity with Shannon diversity of 3.856 and Simpson’s Evenness value of 0.967 which are both very high values. There were only
minimal disturbances (e.g. fallen trees) observed in the site which has potentially
no to low effect on the diversity as the diversity index values showed. Studies
showed that disturbing activities such as excessive and improper logging can
lessen the richness of species in an ecosystem [22].
In terms of diversity per quadrat, 14 fell under the classification of having
high diversity: 5 from Transect 1, 4 from Transect 2, and 5 from Transect 3
(Table 4). Quadrat 8 in Transect 1 has the highest diversity (Shannon = 3.367,
Simpson = 0.9554). The remaining quadrats fell in the category of having moderate diversity. Considering the small dimensions of the quadrats, it is assuring
to know that there is still a relatively high diversity since studies showed that
Shannon Index values typically ranges from 1.5 to 3.5, while areas with Shannon
values of 4 are very rare [23].
4.3. Noteworthy Species
As part of the tree diversity assessment, there is a need to look for noteworthy
species such as the endemic tree species in the country and those species which
Table 2. Top ten trees with highest Importance Value (IV).
Species
Count
Rden
RF
Rdom
IV
Teijsmanniodendron ahernianum
168
7.50
3.21
24.57
35.29
Xanthostemon philippinensis
129
5.76
1.74
23.99
31.49
Shorea malibato
93
4.15
2.81
9.64
16.60
Calophyllum blancoi
117
5.23
2.81
7.48
15.51
Madhuca oblongifolia
62
2.77
2.81
5.43
11.01
Memecylon sympliciforme
81
3.62
2.01
2.16
7.79
Discocalyx psychotrioides
69
3.08
2.14
2.03
7.25
Timonius arboreus
73
3.26
2.54
1.31
7.11
Meiogyne mindorensis
72
3.22
2.27
1.53
7.02
Palaquium ovatum
44
1.97
1.74
2.70
6.40
Table 3. Diversity indices values per transect.
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Diversity Indices
Transect 1
Transect 2
Transect 3
DICASALARIN
Taxa/Species
88
79
85
139
Individuals
699
934
606
2239
Simpson Evenness
0.963
0.957
0.967
0.9735
Shannon
3.791
3.567
3.856
4.096
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Table 4. Quadrats with high diversity.
Transect
Quadrat
Taxa
Individuals
Simpson
Shannon
1
8
37
71
0.9554
3.367
2
1
40
125
0.9516
3.323
3
5
35
81
0.9447
3.234
3
9
33
81
0.9505
3.23
1
7
35
82
0.9453
3.227
1
5
32
85
0.95
3.212
2
7
30
132
0.9525
3.191
3
8
29
71
0.9443
3.103
2
6
29
119
0.9447
3.095
2
5
28
61
0.9417
3.085
1
6
32
87
0.9372
3.084
3
7
29
109
0.9376
3.03
1
9
27
59
0.9377
3.02
3
2
29
80
0.9316
3.019
are critically important in terms of their conservation status. This information is
essential to be able to manage an area’s conservation and rehabilitation.
4.3.1. Philippine Endemics
Among the 139 recorded species found in the area, 48 (34.53%) were found to be
Philippine Endemic (Table 5). Noteworthy among the endemics is the Cinna-
momum nanophyllum Kosterm, which was, so far, only recorded in Aurora (Mt.
Alzapan).
4.3.2. Aurora Endemics
Table 6 shows the species which only have recorded occurrence in the province
of Aurora. It includes Cinnamomum nanophyllum Kosterm. which was recorded to be found at Mt. Alzapan, and Syzygium ramosii (C.B.Rob.) Merr. Recorded
in the province of Aurora.
4.3.3. Threatened Species
Philippine forests are homes to different critically important species. In the
study, 29 species were found to be threatened as listed in the International Union for Conservation of Nature (IUCN) Redlist of Threatened Species and/or in
the DENR Administrative Order (DAO) No. 2017-11 or the Updated National
List of Threatened Philippine Plants and their Categories (Table 7).
Based on the IUCN red list the threatened species found in the area include 5
critically endangered (CR) species, 7 endangered (EN) species, and 8 vulnerable
(VU) species. In the categorization of the DENR in the DAO No. 2017-11 there
are 6 critically endangered (CR), 6 endangered (EN), and 7 vulnerable (VU) species. 5 other threatened species (OTS), and 5 are not in the list. All the critically
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Table 5. Taxonomic list of Philippine Endemic species in Sitio Dicasalarin
No.
Species
Family
Transect
1
Actinodaphne dolichophylla (Merr.) Merr.
Lauraceae
1
2
Adenanthera intermedia Merr.
Fabaceaea
3
3
Artocarpus blancoi (Elmer) Merr.
Moraceae
2&3
4
Artocarpus rubrovenius Warb.
Moraceae
3
5
Brackenridgea fascicularis (Blanco) Fern.-Vill.
Ochnaceae
1, 2, & 3
6
Canthium obovatifolium (Merr.) Merr.
Rubiaceae
1
7
Canthium subcapitatum (Merr.) Merr.
Rubiaceae
1&3
8
Chionanthus remotinervius (Merr.) Kiew
Oleaceae
2
9
Cinnamomum mercadoi S.Vidal
Lauraceae
2&3
10
Cinnamomum nanophyllum Kosterm.
Lauraceae
3
11
Dillenia luzoniensis (Vidal) Merr.
Dilleniaceae
1, 2, & 3
12
Diospyros pilosanthera Blanco
Ebenaceae
3
13
Diospyros vera (Lour.) A.Chev.
Ebenaceae
1, 2, & 3
14
Discocalyx micrantha Merr.
Primulaceae
1, 2, & 3
15
Discocalyx psychotrioides Elmer
Primulaceae
1, 2, & 3
16
Ficus balete Merr.
Moraceae
3
17
Garcinia rubra Merr.
Clusiaceae
1, 2, & 3
18
Greeniopsis discolor Merr.
Rubiaceae
3
19
Guioa discolor Radlk.
Sapindaceae
2
20
Helicia rigidiflora var robusta
Proteaceae
1&2
21
Homalium bracteatum Benth.
Salicaeae
3
22
Hopea acuminata Merr.
Dipterocarpaceae
1
23
Hopea malibato Foxw.
Dipterocarpaceae
1
24
Kibatalia elmeri Woodson
Apocynaceae
3
25
Lithocarpus apoensis (Elmer) Rehder
Fagaceae
1, 2, & 3
26
Litsea leytensis Merr.
Lauraceae
3
27
Madhuca lenceolata (Merr.) Merr.
Sapotaceae
2
28
Madhuca oblongifolia (Merr.) Merr.
Sapotaceae
1, 2, & 3
29
Mangifera altissima Blanco
Anacardiaceae
1, 2, & 3
30
Memecylon symplociforme Merr.
Memecylaceae
1, 2, & 3
Annonaceae
1&2
31
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Mitrephora multifolia Elmer ex Weeras. &
R.M.K.Saunders Elmer
32
Myristica colinridsdalei W.J.de Wilde
Myristicaceae
1&2
33
Myrsine fastigiata (Elmer) Pipoly
Primulaceae
1, 2, & 3
34
Osmoxylon eminens (W.Bull) Philipson
Araliaceae
1
35
Palaquium glabrum Merr.
Sapotaceae
1&3
36
Podocarpus macrocarpus de Laub.
Podocarpaceae
1&2
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E. E. Coracero, P. L. Malabrigo Jr.
Continued
37
Psychotria luzoniensis (Cham. & Schltdl.) Fern.-Vill.
Rubiaceae
1, 2, & 3
38
Radermachera coriacea Merr.
Bignoniaceae
2
39
Shorea malibato Foxw.
Dipterocarpaceae
1, 2, & 3
40
Shorea polysperma Merr.
Dipterocarpaceae
1&2
41
Sindora supa Merr.
Fabaceaea
3
42
Syzygium curranii (C.B.Rob.) Merr.
Myrtaceae
1
43
Syzygium ramosii (C.B.Rob.) Merr.
Myrtaceae
1, 2, & 3
44
Terminalia darlingii Merr.
Combretaceae
1, 2, & 3
45
Trigonostemon longipes (Merr.) Merr.
Euphorbiaceae
1, 2, & 3
Myrtaceae
1, 2, & 3
46
Tristaniopsis micrantha (Merr.) Peter G.Wilson &
J.T.Waterh.
47
Weinmannia luzoniensis S.Vidal
Cunoniaceae
1&2
48
Xanthostemon philippinensis Merr.
Myrtaceae
1, 2, & 3
Table 6. Taxonomic list of Aurora Endemic species in Sitio Dicasalarin.
No.
Species
Family
Transect
1
Cinnamomum nanophyllum Kosterm.
Lauraceae
3
2
Syzygium ramosii (C.B. Rob) Merr.
Myrtaceae
1,2, &3
Table 7. Taxonomic list of threatened species in Dicasalarin.
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IUCN
DAO
Transects
Redlist 2017-11
No.
Species
Family
1
Adenanthera intermedia Merr.
Fabaceaea
VU
OTS
3
2
Anisoptera thurifera ssp thurifera
Dipterocarpaceae
VU
-
1&2
3
Bhesa robusta (Roxb.) Ding Hou
Celastraceae
LC
-
3
4
Cinnamomum mercadoi S.Vidal
Lauraceae
VU
OTS
2&3
5
Dillenia luzoniensis (Vidal) Merr.
Dilleniaceae
-
VU
1, 2, & 3
6
Diospyros discolor Willd.
Ebenaceae
-
VU
3
7
Diospyros pilosanthera Blanco
Ebenaceae
EN
-
3
8
Diospyros pyrrhocarpa Miq.
Ebenaceae
-
VU
2
9
Diospyros vera (Lour.) A.Chev.
Ebenaceae
EN
VU
1, 2, & 3
10
Greeniopsis discolor Merr.
Rubiaceae
-
CR
3
11
Guioa discolor Radlk.
Sapindaceae
EN
VU
2
12
Hopea acuminata Merr.
Dipterocarpaceae
CR
EN
1
13
Hopea malibato Foxw.
Dipterocarpaceae
CR
CR
1
14
Kibatalia elmeri Woodson
Apocynaceae
VU
OTS
3
15
Lithocarpus apoensis (Elmer) Rehder
Fagaceae
-
VU
1, 2, & 3
16
Litsea leytensis Merr.
Lauraceae
VU
EN
3
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Continued
17
Madhuca lenceolata (Merr.) Merr.
Sapotaceae
EN
-
2
18
Madhuca oblongifolia (Merr.) Merr.
Sapotaceae
VU
EN
1, 2, & 3
19
Mangifera altissima Blanco
Anacardiaceae
VU
-
1, 2, & 3
20
Myristica colinridsdalei W.J.de Wilde
Myristicaceae
VU
CR
1&2
21
Myristica philippinensis Gand.
Myristicaceae
-
OTS
3
22
Nageia wallichiana (C.Presl) Kuntze
Podocarpaceae
-
OTS
1
23
Podocarpus macrocarpus de Laub.
Podocarpaceae
EN
EN
1&2
24
Radermachera coriacea Merr.
Bignoniaceae
-
VU
2
25
Shorea malibato Foxw.
Dipterocarpaceae
CR
CR
1, 2, & 3
26
Shorea polysperma Merr.
Dipterocarpaceae
CR
CR
1&2
27
Sindora supa Merr.
Fabaceaea
EN
EN
3
28
Terminalia darlingii Merr.
Combretaceae
EN
EN
1, 2, & 3
29
Xanthostemon philippinensis Merr.
Myrtaceae
CR
CR
1, 2, & 3
endangered species (IUCN and DAO classification) in the area are present in
Transect 1. Thus, the conservation is mostly needed in this transect having all
the species with the highest category of threatened species in the area.
5. Conclusion and Recommendations
Based on the results of the tree diversity study conducted, it is safe to say that Sitio Dicasalarin is a very highly diverse area. The study site is home to at least 139
species and 46 families. It obtained a very high Shannon Index value of 4.195
which indicates a very high diversity. The most abundant, most frequent and
most important species found in the area was Teijsmanniodendron ahernianum
(Merr.) Bakh. with 168 individuals and occurred in 24 out of 27 quadrats.
Hence, it emerged as the most important species in the area having an importance value of 35.29 or 11.76% of the total value of all species.
The area can be considered very important for having so many noteworthy
species. There were 48 Philippine endemic species wherein 2 of those were only
found to have occurred in the province of Aurora. Lastly, there were 29 species
found to be threatened as listed in IUCN and DAO 2017-11.
The study yielded important and vital results that can be useful in the field of
science. However, there were certain limitations of the study that can be addressed in the future research undertakings. Firstly, the survey was only conducted in 1.08 ha divided into three transects with nine 20 by 20 m quadrat each
in the forests of Sitio Dicasalarin of the Sierra Madre Mountain Range. It would
be better to conduct studies in other parts of the mountain range to better assess
its diversity. Some of the species were not fully identified to species level due to
the absence of reproductive parts. Thus, species endemism and conservation
status of the unidentified specimens remained unknown together with its identity. The collection of reproductive parts of the species must be performed in the
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field in order to perform more accurate and convenient identification.
Acknowledgements
The authors are very thankful to the late Senator Edgardo Angara for allowing
the conduct of the diversity research in his property. E. E. Coracero would like to
express his gratitude to Forester Denis Pulan and Prof. Pastor Malabrigo Jr. for
the guidance and verification of the plant identity. Lastly, this publication will
not be possible without the support from the Aurora State College of Technology, Baler, Aurora Campus especially from Dr. Eutiquio L. Rotaquio Jr. (College
President) and Dr. Rb Gallego (Director of the Department of Graduate Studies).
Conflicts of Interest
The authors declare no conflicts of interest regarding the publication of this paper.
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