B I O D I V E R S I T A S ISSN: 1412-033X
Volume 21, Number 6, June 2020 E-ISSN: 2085-4722
Pages: 2526-2535 DOI: 10.13057/biodiv/d210626
Vegetation and ecoregion analysis at Sipirok Botanic Gardens, South
Tapanuli, North Sumatra, Indonesia
MUSTAID SIREGAR
, DANANG W. PURNOMO, HARTUTININGSIH M -SIREGAR, JOKO RIDHO WITONO
Research Center for Plant Conservation and Botanic Gardens (Bogor Botanic Gardens), Indonesian Institute of Sciences. Jl. Ir. H. Juanda No. 13 Bogor
16122, West Java, Indonesia. Tel./fax.: +62-251-8322-187,
email: [email protected]
Manuscript received: 10 April 2020. Revision accepted: 14 May 2020.
Abstract. Siregar M, Purnomo DW, Siregar HM, Witono JR. 2020. Vegetation and ecoregion analysis at Sipirok Botanic Gardens,
South Tapanuli, North Sumatra, Indonesia. Biodiversitas 21: 2526-2535. Botanic Gardens is an ex-situ plant conservation area.
Enrichment of plant collections of Botanic Gardens in Indonesia is based on ecoregion types. To find out the type of ecoregion, the
existing vegetation, main native species should be known. The research aimed to analyze the existing vegetation and ecoregion type at
Sipirok Botanic Gardens. Existing vegetation has been carried out using a separate plot method 20x20 m which is placed on purposively
in nine locations considered to have different vegetation types, namely remnant forest, young secondary forests and shrubs, rubber
plantation, and grasslands. Around 66 species belonged to 45 genera and 27 families were found in vascular plants (dbh ≥ 10 cm). There
were 66 species of sapling belonged to 54 genera and 35 families, and 110 seedlings belonged to 87 genera and 50 families. The tree
species that have the highest Importance Value Index are Ficus sumatrana (PU-1), Myristica fatua (PU-3), Hevea brasiliensis (PU-4
and PU-7), Artocarpus elasticus (PU-8), and Knema cinerea (PU-9). No trees were found in young secondary forest/shrub plots and
grasslands. Unlike the species dominance index, the species diversity index and species equitability index are higher in natural forest
plots. Beta diversity based on Jaccard similarity index and Whittaker's index shows a relatively different species composition among
plots. Cluster analysis shows the tendency of grouping in 2 types of communities, namely: a) remnant forest communities, and b)
secondary communities. The natural forest community is further divided into two communities consisting of remnant forest tree species
and industrial/plantation plant species also secondary tree species. Secondary communities are also further divided into secondary forest
communities and grasslands. Based on ecoregion analysis using previous publications, altitude, and diversity of plant species in the
study site, Sipirok Botanic Gardens is a transitional zone of the Sumatran lowland rainforest and mountain rainforest.
Keywords: Ecoregion, North Sumatra, Sipirok Botanic Gardens, vegetation analysis
INTRODUCTION
Botanic gardens are ex-situ plant conservation areas
that have a collection of plants documented and arranged
based on taxonomic classification, bioregions, thematic, or
a combination of these patterns for the purpose of
conservation, research, education, tourism, and
environmental services (Presidential Regulation Number
93 in 2011). The development of the botanic gardens
begins with the preparation of the masterplan which guides
the development in the short and long term. Existing data
that includes biotic and abiotic data, as well as social and
cultural community, is very much needed in the preparation
of the masterplan.
According to Witono et al. (2012), development of new
botanic garden in Indonesia is based on ecoregion concept.
Ecoregion is relatively large units of land delineated to
reflect the boundaries of natural communities of animal and
plant species in their natural state (Kier et al. 2005). Based
on the ecoregion map of Indonesia (Olson et al. 2001)
modified by Witono et al. (2012), Indonesia consists of 47
ecoregion types, seven of which exist in Sumatra, namely:
(i) Nias Islands' lowland rainforest on a series of western
islands, (ii) northern Sumatra's mangrove forests on the
east coast of Sumatra, (iii) Sumatran peat swamp forests in
east coast of Sumatra, (iv) Sumatran freshwater swamp
forests on the east coast of Sumatra, (v) Sumatran lowland
rainforests spread in the lowlands of Sumatra, (vi)
Sumatran mountain rain forest in the central part of Lake
Toba, and (vii) tropical pine forests of Sumatra in the
mountain regions of the west and southeast sides of Lake
Toba.
Sipirok Botanic Gardens is botanic gardens that will be
developed in Sumatra. The idea of developing this gardens
originated from the concern of the South Tapanuli District
Government due to the change of function of the
Batangtoru forest and the degradation of the forest that
became the habitat of the Tapanuli orangutan (Pongo
tapanuliensis). Sipirok Botanic Gardens is expected to
become a center for the conservation of native plants in
South Tapanuli and Sumatra that are able to adapt to
environmental conditions in the future. In Sipirok Botanic
Gardens, there are four types of vegetation, namely:
remnant forest, young secondary forest and shrubs, rubber
gardens, and grasslands (Purnomo et al. 2018).
Vegetation and ecoregion analysis is important baseline
study to maintain and/or establish both in situ and ex situ
conservation areas. Previous studies of in situ conservation
areas in Sumatra have been conducted such as Kerinci
Seblat National Park (NP) (Gillison et al. 1996), Batang
Gadis NP (Kartawinata et al. 2004), Bukit Duabelas NP
(Rahmah et al. 2016), and Bukit Tiga Puluh National Park
SIREGAR et al. – Vegetation and ecoregion analysis at Sipirok Botanic Gardens, Indonesia
2527
(Kuswanda and Barus 2019). Whereas in ex situ
conservation areas in botanic gardens, vegetation, and
ecoregion analysis are important step to design zone areas
(Purnomo et al. 2018). According to Presidential
Regulation Number 93 in 2011, at least three zones should
be established, i.e. plant collection, welcoming, and
management zones. Some botanic gardens in Indonesia
have in-situ conservation area for native plants, such as
Cibodas Botanic Gardens (Mutaqien and Zuhri 2011) and
Megawati Soekarnoputri Botanic Gardens in North
Sulawesi (Sugihartatmo et al. 2017).
It is necessary to designate natural habitat as an in situ
conservation area in Sipirok Botanic Gardens. Protection of
natural habitat is a better way to conserve and safeguard the
species from tourists. Possible changes in the landscape
and infrastructure during the development of the botanic
gardens could potentially disrupt the habitat of native
plants (Witono et al. 2020). This study aimed to analyze the
vegetation and ecoregion types of the Sipirok Botanic
Gardens as basic information for the development of
infrastructure and plant collections in the future.
MATERIALS AND METHODS
Study site
This research was conducted in October 2018 in the
Sipirok Botanic Gardens area, located in Kilangpapan and
Sitorbis Village, Sipirok Sub-district, South Tapanuli
District, North Sumatra Province, Indonesia (Figure 1). The
area of about 88.15 ha is located at an altitude of about
765-915 m a.s.l. with topography ranging from slope to
very steep. In this area, there are 2 types of soil, namely:
entisol which are weathered ignimbrite volcanic sediments
and organosols from weathering plants (PPTA 2000).
Based on the Köppen-Geiger climate classification, the
Sipirok Botanic Gardens area has a climate type Af. The
average annual rainfall is 2387 mm and the average annual
temperature is 26.3°C in Sipirok. The highest rainfall
occurred in December (331.67 mm) and the lowest in
September (89.43 mm). Most rainy days occur in
December (25 days) and rainy days are the least in July (9
days). The warmest temperatures occur in May (an average
of 26.9°C) and the lowest temperatures in November (an
average of 26.0°C) (Purnomo et al. 2018).
Vegetation sampling
Vegetation analysis was carried out using a separate
plot method (Mueller-Dombois and Ellenberg 1974). A
total of 9 plots (named ‘PU’ as main plot) of 20 x 20 m
were placed in each vegetation type with the following
details: 5 PU of remaining forests (1,3,7,8,9 plots), 1 PU of
secondary forests and shrubs (plot 2), 1 PU of gardens (plot
4), and 2 PU of grasslands (5,6 plots) (Figure 1). The main
plot (0.36 ha) has represented the area of vegetation in the
Sipirok Botanic Gardens area. Each PU consists of four
plots of 10 x 10 m for tree-level sampling (dbh ≥ 10 cm). In
a plot of 10 x10 m, some plots of 5x5 m were made for
pole level sampling (2 cm ≤ dbh < 10 cm). In some plots of
5 x 5 m, some plots of 2 x 2 m were made for seedling and
understorey (dbh < 2 cm). All species found in each plot
were recorded by species name, number of individuals for
each species, trunk diameter for trees and poles level
sample as well as cover percentage for seedlings and
understorey. Specimen vouchers for each species were
made for identification. Identification was carried out by
the Bogor Botanical Gardens Registration and Herbarium
staff and partly at the Herbarium Bogoriense.
Figure 1. Study site in the Sipirok Botanic Gardens, in Kilangpapan and Sitorbis Villages, Sipirok Sub-district, South Tapanuli District,
North Sumatra Province, Indonesia
B I O D I V E R S I T A S 21 (6): 2526-2535, June 2020
2528
Data analysis
The data collected was then tabulated and analyzed to
determine the value of density, relative density, frequency,
relative frequency, dominance, relative dominance, and
important value index (Mueller-Dombois and Ellenberg
1974). To analyze alpha diversity was calculated using the
Shannon-Wiener diversity index, species dominance index,
and evenness index, whereas to analyze beta diversity was
calculated using the Whittaker diversity index and Jaccard
species similarity index (Ludwig and Reynold 1988; Magurran
1988). Community types were determined based on the
results of cluster analysis using Jaccard species similarity
index based on the presence-absence of species in each
main plot. All analyzes for alpha diversity, beta diversity, and
cluster analysis were performed using the PAST (Paleontological
Statistics) program version 3:04 (Hammer 2014).
RESULTS AND DISCUSSION
Species composition
Tree level plants (dbh ≥ 10 cm) found in 36 observation
plots (10x10 m) amounted to 66 species included in 45
genera and 27 families Tree species that have the highest
Importance Value Index (IVI) in each main plot (PU) are
Ficus sumatrana (PU-1), Mallotus peltatus (PU-2),
Myristica fatua (PU-3), Hevea brasiliensis (PU-4 and PU-
7), Artocarpus elasticus (PU-8), and Knema cinerea (PU-
9). In young secondary forest plots and shrubs (PU-2) and
grasslands (PU-5 and PU-6), no tree species with dbh > 10
cm were found (Table 1).
Table 1. Five species of trees based on the index of highest importance in each main plot
No Species Family
Density
ha
-1
Basal area
(m
2
ha
-1
)
Frequency
(%)
Importance
Value Index
PU-1
Ficus sumatrana Miq. Moraceae 25 44.32 4.00 52.60
Palaquium sp. Sapotaceae 100 5.48 12.00 32.92
Palaquium obovatum (Griff.) Engl. Sapotaceae 50 10.79 8.00 26.59
Canthium glabrum Blume Rubiaceae 75 2.52 12.00 26.08
Knema sumatrana (Blume) W.J.de Wilde Myristicaceae 50 5.25 8.00 21.00
PU-2
Mallotus peltatus (Geiseler) Müll.Arg. Euphorbiaceae 50 0.39 50 147.39
Mallotus paniculatus (Lam.) Müll.Arg. Euphorbiaceae 25 0.24 25 78.92
Ficus padana Burm.f. Moraceae 25 0.20 25 73.69
PU-3
Myristica fatua Houtt. Myristicaceae 75 3.02 11.11 41.43
Macaranga tanarius (L.) Müll.Arg. Euphorbiaceae 50 3.01 5.56 31.09
Syzygium sp. Myrtaceae 50 2.61 5.56 28.93
Ficus elliptica Kunth Moraceae 25 3.47 5.56 28.74
Arenga pinnata (Wurmb) Merr. Arecaceae 25 1.46 5.56 18.08
PU-4
Hevea brasiliensis (Willd. ex A.Juss.) Müll.Arg. Euphorbiaceae 750 14.84 100 300.00
PU-5
-
PU-6
-
PU-7
Hevea brasiliensis (Willd. ex A.Juss.) Müll.Arg. Euphorbiaceae 75 6.80 11.11 55.39
Arenga pinnata (Wurmb) Merr. Arecaceae 75 5.83 11.11 51.21
Palaquium obovatum (Griff.) Engl. Sapotaceae 25 3.90 5.56 27.35
Turpinia sphaerocarpa Hassk. Staphyleaceae 50 0.78 11.11 24.47
Macropanax undulatus (Wall. ex G.Don) Seem. Araliaceae 50 0.57 11.11 23.57
PU-8
Artocarpus elasticus Reinw. ex Blume Moraceae 75 20.43 15.79 71.82
Arytera littoralis Blume Sapindaceae 75 1.89 15.79 35.31
Symplocos racemosa Roxb. Symplocaceae 25 7.07 5.26 24.45
Nothaphoebe sp. Lauraceae 50 1.14 10.53 23.30
Sterculia foetida L. Malvaceae 25 5.22 5.26 20.81
PU-9
Knema cinerea Warb. Myristicaceae 50 8.53 5.00 33.37
Styrax benzoin Dryand. Styracaceae 50 4.37 10.00 28.15
Arenga pinnata (Wurmb) Merr. Arecaceae 50 5.80 5.00 26.67
Syzygium papyraceum B.Hyland Myrtaceae 75 3.19 5.00 23.96
Meliosma simplicifolia (Roxb.) Walp. Sabiaceae 50 2.52 10.00 23.60
SIREGAR et al. – Vegetation and ecoregion analysis at Sipirok Botanic Gardens, Indonesia
2529
Table 2. Five species of poles based on the important value index in each main plot
No Species Family
Density
ha
-1
Basal area
(m
2
ha
-1
)
Frequency
(%)
Importance
Value Index
PU-1
Castanopsis motleyana King Fagaceae 100 0.71 14.29 76.58
Canthium glabrum Blume Rubiaceae 100 0.13 14.29 37.08
Picrasma javanica Blume Simaroubaceae 100 0.30 14.29 49.02
Sterculia rubiginosa Zoll. ex Miq. Malvaceae 100 0.15 14.29 38.41
Cassine japonica (Franch. & Sav.) Kuntze Celastraceae 100 0.13 14.29 37.51
PU-2
Homalanthus populneus (Geiseler) Pax Euphorbiaceae 1,100 2.40 16.67 86.34
Mallotus peltatus (Geiseler) Müll.Arg. Euphorbiaceae 900 1.82 25.00 79.99
Mallotus paniculatus (Lam.) Müll.Arg. Euphorbiaceae 500 2.06 25.00 70.51
Breynia sp. Phyllanthaceae 300 0.52 8.33 25.46
Nothaphoebe sp. Lauraceae 100 0.14 8.33 13.59
PU-3
Quercus sp. Fagaceae 400 0.78 4.17 32.42
Nothaphoebe sp. Lauraceae 200 0.54 8.33 25.21
Syzygium sp. Myrtaceae 200 0.54 8.33 25.21
Ficus sinuata Thunb. Moraceae 100 0.64 4.17 19.43
Acronychia pedunculata (L.) Miq. Rutaceae 100 0.50 4.17 16.95
PU-4
-
PU-5
Eurya acuminata DC. Pentaphylacaceae 200 0.18 66.67 214.29
Litsea sp. Lauraceae 100 0.04 33.33 85.71
PU-6
-
PU-7
Macaranga tanarius (L.) Müll.Arg. Euphorbiaceae 300 0.88 11.11 41.32
Nothaphoebe sp. Lauraceae 300 0.83 11.11 40.43
Macropanax undulatus (Wall. ex G.Don) Seem. Araliaceae 200 1.04 5.56 33.90
Shorea acuminata Dyer Dipterocarpaceae 200 0.64 11.11 32.15
Homalanthus populneus (Geiseler) Pax Euphorbiaceae 200 0.21 11.11 24.51
PU-8
Arytera littoralis Blume Sapindaceae 300 0.42 18.75 45.60
Coffea arabica L. Rubiaceae 100 0.11 6.25 14.55
Ficus sinuata Thunb. Moraceae 100 0.05 6.25 12.86
Knema cinerea Warb. Myristicaceae 300 0.49 12.50 41.37
Knema sp.1 Myristicaceae 300 0.63 6.25 38.73
PU-9
Pyrenaria sp. Theaceae 400 0.80 13.04 57.07
Nothaphoebe sp. Lauraceae 300 0.19 8.70 27.28
Syzygium acuminatum (Roxb.) Miq. Myrtaceae 200 0.19 8.70 23.16
Cryptocarya ferrea Blume Lauraceae 100 0.26 4.35 17.34
Daemonorops sp. Arecaceae 100 0.26 4.35 17.34
Pole level plants (2 cm < dbh <10 cm) found in 36
observation plots (5x5 m
2
) amounted to 66 species included
in 54 genera and 35 families. Pole species that have the
highest IVI in each main plot (PU) are Castanopsis
motleyana (PU-1), Homalanthus populneus (PU-2),
Quercus sp. (PU-3), Eurya acuminata (PU-5), Macaranga
tanarius (PU-7), Arytera littoralis (PU-8), and Pyrenaria
sp. (PU-9). In the rubber plantation (PU-4) and grassland
(PU-6) plots, no pole species were found (Table 2).
Seedlings and understorey (dbh < 2 cm) found in 36
observation plots (2x2 m) of 110 species included in 87
genera and 50 families. Seedlings that have the highest IVI
in each main plot are Orophea enterocarpa (PU-1),
Etlingera megalocheilos (PU-2), Selaginella plana (PU-3),
Clidemia hirta (PU-4), Etlingera elatior (PU-5), Bromus
racemosus (PU-6), Cinnamomum sintoc (PU-7). Coffea
arabica (PU-8), and Boesenbergia rotunda (PU-9) (Table
3).
The remaining forest in the Sipirok Botanic Gardens is
generally filled with species that grow in old secondary
forests or primary forests that have been disturbed, such as:
Castanopsis motleyana, Canthium glabrum, Picrasma
javanica, Sterculia rubiginosa, Cassine japonica, Quercus
sp., Nothaphoebe sp., Syzygium sp., Ficus sinuata,
Acronychia pedunculata, Arenga pinnata, Palaquium
obovatum, Turpinia sphaerocarpa, Macropanax undulatus,
Artocarpus elasticus, Arytera littoralis, Symplocos
racemosa, Sterculia foetida, Knema cinerea, Styrax
benzoin, Syzygium papyraceum and Meliosma simplicifolia
(Table 1). These species also grow dominantly in the pole
B I O D I V E R S I T A S 21 (6): 2526-2535, June 2020
2530
phase, such as Canthium glabrum, Nothaphoebe sp.,
Syzygium sp., Ficus sinuata, Acronychia pedunculata,
Macropanax undulatus, and others (Table 2). This is an
indication that the natural regeneration process of native
plant species has been going well. Several species of
pioneer trees, such as Macaranga tanarius, are found in the
pole phase. Most of these species do not include
commercial wood species and do not have high economic
value. However, some Shorea acuminata
(Dipterocarpaceae) individuals are still found in this
location in the pole phase.
Table 3. The five main species of seedlings and understorey based on the magnitude of the important value index in each main plot
No Species Family
Crown Cover
(%)
Frequency
(%)
Importance
Value Index
PU-1
Orophea enterocarpa Maingay ex Hook.f. & Thomson Annonaceae 38.00 10.34 31.11
Harpullia cupanioides Roxb. Sapindaceae 25.00 3.45 17.11
Coffea arabica L. Rubiaceae 12.00 6.90 13.45
Canthium glabrum Blume Rubiaceae 7.00 6.90 10.72
Cryptocarya murrayi F.Muell. Lauraceae 12.00 3.45 10.01
PU-2
Etlingera megalocheilos (Griff.) A.D.Poulsen Zingiberaceae 80.00 12.90 42.87
Oplismenus compositus (L.) P.Beauv. Poaceae 50.00 6.45 25.18
Nephrolepis cordifolia (L.) C. Presl Nephrolepidaceae 30.60 12.90 24.36
Vernonia potamophila Klatt Compositae 40.00 3.23 18.21
Bromus racemosus L. Poaceae 20.00 6.45 13.94
PU-3
Selaginella plana (Desv. ex Poir.) Hieron. Selaginellaceae 125.00 19.05 71.79
Pandanus sp. Pandanaceae 20.00 4.76 13.20
Amomum sp. Zingiberaceae 10.00 4.76 8.98
Etlingera elatior (Jack) R.M.Sm. Zingiberaceae 10.00 4.76 8.98
Mucuna sp. Leguminosae 10.00 4.76 8.98
PU-4
Clidemia hirta (L.) D. Don Melastomataceae 95.00 9.76 40.65
Spermacoce laevis Lam. Rubiaceae 58.00 7.32 26.18
Sida rhombifolia L. Malvaceae 40.00 2.44 15.45
Crassocephalum crepidioides (Benth.) S.Moore Compositae 10.00 7.32 10.57
Asystasia gangetica (L.) T.Anderson Acanthaceae 9.00 7.32 10.24
PU-5
Etlingera elatior (Jack) R.M.Sm. Zingiberaceae 48.00 9.68 29.35
Vernonia potamophila Klatt Compositae 37.00 12.90 28.07
Nephrolepis cordifolia (L.) C. Presl Nephrolepidaceae 25.00 9.68 19.92
Centrosema sp. Leguminosae 16.00 12.90 19.46
Axonopus compressus (Sw.) P.Beauv. Poaceae 18.00 6.45 13.83
PU-6
Bromus racemosus L. Poaceae 320.00 20.00 80.49
Mucuna sp. Leguminosae 55.00 20.00 30.40
Melastoma malabathricum L. Melastomataceae 60.00 10.00 21.34
Vernonia potamophila Klatt Compositae 18.00 15.00 18.40
Rhodomyrtus tomentosa (Aiton) Hassk. Myrtaceae 23.00 10.00 14.35
PU-7
Cinnamomum sintoc Blume Lauraceae 21.00 11.11 24.24
Nephrolepis cordifolia (L.) C. Presl Nephrolepidaceae 15.00 14.81 24.19
Coffea arabica L. Rubiaceae 18.00 11.11 22.36
Macaranga tanarius (L.) Müll.Arg. Euphorbiaceae 20.00 7.41 19.91
Clidemia hirta (L.) D. Don Melastomataceae 17.00 7.41 18.03
PU-8
Coffea arabica L. Rubiaceae 41.00 14.29 33.27
Asystasia gangetica (L.) T.Anderson Acanthaceae 28.00 10.71 23.68
Diplazium esculentum (Retz.) Sw. Athyriaceae 30.00 3.57 17.46
Clidemia hirta (L.) D. Don Melastomataceae 11.00 10.71 15.81
Dracaena angustifolia (Medik.) Roxb. Asparagaceae 12.00 7.14 12.70
PU-9
Boesenbergia rotunda (L.) Mansf. Zingiberaceae 110.00 10.00 43.95
Coffea arabica L. Rubiaceae 27.00 13.33 21.67
Clidemia hirta (L.) D. Don Melastomataceae 15.00 13.33 17.96
Suregada glomerulata (Blume) Baill. Euphorbiaceae 40.00 3.33 15.68
Uvaria rufa Blume Annonaceae 20.00 6.67 12.84
SIREGAR et al. – Vegetation and ecoregion analysis at Sipirok Botanic Gardens, Indonesia
2531
One species of introduction tree that is found and grows
extensively in the remaining forest is Hevea brasiliensis.
This species was cultivated in several locations by the
community before the area was designated as Sipirok
Botanic Gardens (Irwansah Harahap 2018. pers. Com.). H.
brasiliensis is a species of estate crop originating from
Brazil and has adapted to environmental conditions and
grows widely in the Sipirok Botanic Gardens. At the
location of the remaining forests, there are several species
of plants that have economic value both native species,
such as: Styrax benzoin and Arenga pinnata, and
introduced species, such as Coffea arabica.
The density of trees in the 5 main plots of remaining
forest (PU-1, PU-3, PU-7, PU-8, PU-9) is 475-675 ha
-1
trees with an average of 565 ha
-1
trees. The base area is
18.82-99.04 m
2
ha
-1
with an average of 46.50 m
2
ha
-1
.
Based on several research results, forests in Sumatra have a
density range of 414-687 ha
-1
trees with an average of 542
ha
-1
trees, and a range of basal areas of 22.9-41.55 m
2
ha
-1
with an average of 28.46 m
2
ha
-1
(Mirmanto et al. 1992;
Sambas and Siregar 1999; Kartawinata et al. 2004; Sambas
and Siregar 2004; Priatna et al. 2006; Samsoedin and
Heriyanto 2010; Rahmah et al. 2016). The vegetation of
remaining forest within the Sipirok Botanic Gardens area is
relatively good compare to the level of tree density and
area of the base area (Table 4). Tree species that have dbh
> 50 cm in PU-1 are Ficus sumatrana (150.2 cm), Alstonia
spectabilis (66.2 cm), Castanopsis motleyana (65.9 cm)
and Palaquium obovatum (52.5 cm). In PU-8, Artocarpus
elasticus (66.5 cm), Symplocos racemosa (60.0 cm),
Artocarpus elasticus (59.5 cm), Sterculia foetida (51.6 cm),
and Dysoxylum alliaceum (50.0 cm). Only one tree which
is found in PU-9 that is Knema cinerea (57.0 cm). In PU-3
and PU-7, there is no trees that have dbh > 50 cm. The
largest tree with dbh of 42.0 cm in PU-3 is Ficus elliptica.
The largest tree with dbh of 44.6 cm in PU-7 is Palaquium
obovatum.
In young secondary forest vegetation types and shrubs
(PU 2), tree species are dominated by Mallotus peltatus, M.
paniculatus, and Ficus padana. These species are native
plants of South Tapanuli (www.theplantlist.org 2020). At
the pole level, Mallotus peltatus and M. paniculatus are still
classified as the main species based on their importance, but
the most abundant poles species are Homalanthus
populneus (1100 trees ha
-1
) (Table 2). H. populneus,
Breynia sp., and Nothaphoebe sp. which are native species
of South Tapanuli do not grow in the tree phase, but H.
populneus is expected to dominate the tree level in the next
succession phase. The seedling and understorey phases are
dominated by pioneer species that grow in the early phases
of ecological successions, such as Etlingera megalocheilos,
Oplismenus compositus, Nephrolepis cordifolia, Vernonia
potamophila, and Bromus racemosus.
In terms of rubber plantation type (PU 4), Hevea
brasiliensis is the only species found in this area. This
means that the maintenance of the rubber tree is carried out
intensively by the manager by controlling other species of
trees and pole phase rubber plants. This is indicated by the
absence of rubber plants in the pole phase at that location.
The seedling and understorey phases are dominated by
pioneer species that grow in the early phases of ecological
successions, such as: Clidemia hirta, Spermacoce laevis,
Sida rhombifolia, Crassocephalum crepidioides, and
Asystasia gangetica.
In terms of grassland vegetation types (PU 5 and 6),
there are 2 species of pole, namely Eurya acuminata and
Litsea sp. The dominant species of seedlings and
understorey are shrubs (Melastoma malabathricum,
Vernonia potamophila, Rhodomyrtus tomentosa), herbs
(Etlingera elatior, Axonopus compressus, Bromus
racemosus, and Nephrolepis cordifolia), and liana (Mucuna
sp.). Ecological succession has begun to take place with the
presence of these two species of poles which are
categorized as shrubs to small trees.
Table 4. Comparison of the density and basal area of trees (dbh ≥ 10 cm) in the remaining forest vegetation in the Sipirok Botanic
Gardens with some forest plots in Sumatra
Location
Density
ha
-1
Basal Area
(m
2
ha
-1
)
Sipirok Botanic Gardens:
-PU-1 650 99.04
-PU-3 525 18.82
-PU-7 500 23.22
-PU-8 475 50.77
-PU-9 675 40.68
Ulu Talo Bengkulu (Mirmanto et al. 1992) 528 32.42
Air Putih Bengkulu (Mirmanto et al. 1992) 554 23.11
Mt. Muncung Singkep (Sambas and Siregar 1999) 453 22.90
Batang Gadis National Park (Kartawinata et al. 2004) 583 40.56
Ketambe, Gunung Leuser National Park (Sambas and Siregar 2004) 546 30.76
Ketambe, Gunung Leuser National Park (Priatna et al. 2006) 573 27.68
Gunung Leuser National Park (Samsoedin and Heriyanto 2010) 687 24.52
Bukit Dua Belas National Park (Rahmah et al. 2016) 414 25.71
B I O D I V E R S I T A S 21 (6): 2526-2535, June 2020
2532
Diversity index
Tree level alpha diversity calculated based on Shannon-
Wiener diversity index (H ') using species abundance data
obtained the highest value at PU-3 (H = 2.756), followed
by PU-9 (H = 2.712), PU-1 (H = 2.705 ), PU-7 (H = 2.528),
PU-8 (H = 2.525) and PU-2 (H = 1.040). Based on the
Shannon-Wiener diversity index value criteria (Odum and
Barrett 2005), species diversity in the remaining forests is
classified as moderate (1<H'≤3). According to Gaines et al.
(1999), species diversity indices consider the species
abundance and wealth generally ranging 1.5-3.5 and rarely
reaching 4.5. This means that PU-2, which is a young
secondary forest and shrub, is classified into species that is
very low in tree species diversity. The average index value
of tree species using species abundance data shows that the
tree species in the remaining forest plots and secondary
forests are high with values close to 1. The highest value is
obtained at PU-9 (E = 0.978), followed by PU-3 (E =
0.973), PU-7 (E = 0.958), PU-8 (E = 0.957), PU-1 (E =
0.955) and PU-2 (0.946). According to Kendeigh (1980),
an evenness index of species close to one indicates that the
populations in the community are evenly distributed. If the
equity index is close to zero, the populations in the
community are unevenly distributed.
If all species (trees, poles, seedlings, and understory)
are analyzed based on their presence in each plot, the value
of species diversity in the remaining forest plots (PU-1,
PU-3, PU-7, PU-8, PU-9), secondary forests and shrubs
(PU-2) and rubber plantations (PU-4) are classified as high
(H> 3), while in the meadow plots (PU-5, PU-6) are
classified as moderate (Figure 2a ). It appears that the level
of species diversity increases with the level of vegetation
development. Remaining natural forests (PU-1, PU-3, PU-
7, PU-8, and PU-9) have a higher species diversity index
than rubber plantations (PU-4), young secondary forests
and shrubs (PU-2) and the lowest one is in pasture plot
(PU-5, PU-6).
The dominance index of all species shows the opposite
of the species diversity index. Remnant forest plots show
lower species dominance index than secondary forest plots
and shrubs (PU-2), rubber plantations (PU-4), and
grasslands (PU-5, PU-6) (Figure 2b). The evenness index
of species is directly proportional to the species diversity
index which appears higher in remnant forest plots and the
lowest is in grassland vegetation plots (Figure 2c). Thus,
the species wealth index is directly proportional to the
species diversity index and the evenness index of the
species and inversely proportional to the species
dominance index. A common phenomenon in tropical
rainforests is the more species are found, the more index
value of species diversity will be (Barbour et al. 1987). The
high dominance index value on PU-6 (Figure 2b) shows the
presence of a very dominant species, namely Bromus
racemosus (Table 3). According to Smith (1977), in
general, the dominant species is the species that can utilize
the environment where it grows efficiently. However, the
level of vegetation stability in communities dominated by
few species is generally low such as PU-6 (Figure 2c). This
is different from vegetation that has a high degree of
diversity and evenness of species, or there are no species
that is very dominant, so the stability of the community is
relatively high on environmental changes (Barbour et al.
1987; Odum and Barrett 2005).
Beta diversity calculated using the Jaccard species
similarity index (ISj) generally shows relatively low values.
Two communities are considered to have large species
similarity if they have a Jaccard similarity index > 50%
(Mueller-Dombois and Ellenberg 1974). The highest
species similarity is found in the pairs of PU-4 and PU-5
with a species similarity index value of 24.2%, followed by
PU-2 and PU-5 (ISj = 21.2%), PU-7 and PU-9 (ISj =
18.8% ), PU-3 and PU-9 (ISj = 17.9%), PU-8 and PU-9
(ISj = 16.4%) and the lowest is between pasture plots (PU-
6) and remaining forest (PU-7, PU-8 and PU-9) without
any species at all (ISj = 0.0%) (Table 5). These results
indicate the tendency of the main plot with the same
vegetation type to have a higher species similarity value
compares to the main plot that has a different vegetation
type.
Based on the results of cluster analysis of species
presence data using the Jaccard formula in each main plot,
there is a tendency for grouping into 2 clusters, namely: a)
Remnant forest vegetation (PU-1, PU-3, PU-7, PU-8, and
PU-9), and b) other vegetation. The remaining forest
community is further divided into 2 sub-clusters, namely
PU-8 and PU-1 which are dominated by native tree species,
such as Ficus sumatrana, Palaquium sp., Artocarpus
elasticus, and Arytera littoralis and PU-3, PU-7, PU-9
dominated by industrial/plantation tree species and
secondary tree species such as Myristica fatua, Macaranga
tanarius, Hevea brasiliensis, Arenga pinnata, Knema
cinerea, and Styrax benzoin. Cluster 2 of other
communities are also divided into 2 sub-clusters, namely
subcluster 1 consisting of young secondary forest
vegetation and shrubs (PU-2), rubber gardens (PU-4) and
grasslands (PU-5); and subcluster 2 consisting of grassland
vegetation (PU-6) (Figure 3).
Based on the results of the analysis with the Whittaker
beta diversity index (Whittaker's index), the change in
species composition from one location to another is
relatively large, as seen from the value that approaches 1.
The value of the beta diversity index ranges from 0-1. If
beta diversity = 0, then the change in species composition
from location 1 to location 2 is small or there is no change.
Conversely, if the understanding of beta = 1, then there is a
change in the composition of species that is real from
location 1 to location 2 (Tothmeresz 2013). The smallest
Whittaker's index value or location that is relatively similar
is found in the pairs of PU-4 and PU-5 (0.610), while the
highest value (1.0) or the main plots that have large
composition changes are between PU-6 which is a meadow
with natural forest plots on PU-1, PU-7, PU-8 and PU-9
(Table 6).
Ecoregion
Based on the ecoregion map of Indonesia (Olson et al.
2001) modified by Witono et al. (2012), there are at least 7
types of ecoregions in North Sumatra. There are different
opinions of experts regarding the upper boundary of the
lowland rainforest and the lower limit of the sub-montane
SIREGAR et al. – Vegetation and ecoregion analysis at Sipirok Botanic Gardens, Indonesia
2533
rainforest. The lower limit of the sub-montane region is at
an altitude of about 750-1200 m above sea level (Whitmore
1984), 750-1000 m above sea level (van Steenis 2006;
Kartawinata 2013), and 1200 m above sea level (Whitten et
al. 1984). The temperature and cloud level are the main
determinants of the boundaries of the two forest zones
(Whitten et al. 1984). The difference is also influenced by
the location and isolation of the mountain. In isolated small
mountains and outermost mountains of the main range, the
upper limit of lowland rainforest is around 700-900 m
above sea level. In the lower mountain rainforests, the limit
is around 1200-1600 m above sea level. In the main ridge,
the range of boundaries is higher, each boundary is around
1200-1500 m above sea level and 1800-2300 m above sea
level. This phenomenon is known as the 'Massenerhebung'
effect (Grubb 1971).
Figure 3. Analysis of 9 main plot (PU) clusters based on species
presence
A B C
Figure 2. Diversity index, dominance index and evenness index of all species (trees, poles, seedlings) based on their presence in each
plot (presence-absence)
Table 5. Jaccard species similarity index values between main plot pairs
PU-1 PU-2 PU-3 PU-4 PU-5 PU-6 PU-7 PU-8
PU-2 0.0156
PU-3 0.0682 0.0135
PU-4 0.0154 0.1463 0.0270
PU-5 0.0172 0.2121 0.0455 0.2424
PU-6 0.0000 0.1379 0.0164 0.1333 0.0800
PU-7 0.1159 0.0943 0.1299 0.0727 0.1304 0.0000
PU-8 0.1268 0.0339 0.0843 0.0690 0.0784 0.0000 0.1061
PU-9 0.1410 0.0145 0.1786 0.0290 0.0323 0.0000 0.1884 0.1644
Table 6. Beta diversity index values based on Whittaker's index formula between main plot pairs
PU-1 PU-2 PU-3 PU-4 PU-5 PU-6 PU-7 PU-8
PU-2 0.9692
PU-3 0.8723 0.9733
PU-4 0.9697 0.7447 0.9474
PU-5 0.9661 0.6500 0.9130 0.6098
PU-6 1.0000 0.7576 0.9677 0.7647 0.8519
PU-7 0.7922 0.8276 0.7701 0.8644 0.7692 1.0000
PU-8 0.7750 0.9344 0.8444 0.8710 0.8546 1.0000 0.8082
PU-9 0.7528 0.9714 0.6970 0.9437 0.9375 1.0000 0.6829 0.7177
B I O D I V E R S I T A S 21 (6): 2526-2535, June 2020
2534
According to Grubb (1971), Whitmore (1984), van
Steenis (2006) and Kartawinata (2013), research locations
are at an altitude of 765-915 m above sea level including
the transition zone lowland rainforest and Sumatra's
mountain rainforest. In contrast, according to Whitten et al.
(1984), it is categorized into the lowland rainforest zone.
From the results of vegetation analysis conducted at the
Sipirok Botanic Gardens, species that often inhabit lowland
rainforest, such as: Anthersma ghaesembilla, Carallia
brachiata, Cryptocarya murrayi, and Pimelodendron
macrocarpum can be found in remnant forest vegetation.
Likewise, several species of Dipterocarpaceae which often
inhabit lowland rainforest can still be found at the study
site. Cyathea contaminans, which are often found in lower
mountain forests (Whitten et al. 1984), are also found at the
study site. According to Holttum (1963), C. contaminans
spreads at an altitude of 200-1600 m above sea level. Based
on the results of research Hanum et al. (2014), C.
contaminans on Bali Island spreads at an altitude of 975-
1930 m above sea level.
The Fagaceae and Lauraceae family which are often
used to identify mountain forests (Whitten et al. 1984) can
be found at the study site. However, the species found in
the study plots generally have a broad distribution ranging
from lowlands to mountains, such as Cinnamomum
porrectum, Cinnamomum sintoc, Cryptocarya murrayi, and
Persea americana (Lauraceae). Some species even inhabit
lowland rainforests, such as Cinnamomum burmanni,
Cinnamomum camphora, Litsea firma (Lauraceae), and
Castanopsis motleyana (Fagaceae). In general, the species
found at the study site came from both types of habitat with
a wide distribution ranging from the lowlands to the
mountains below (<2000 m asl), such as: Aglaia argentea,
Arytera litoralis, Canthium glabrum, Dysoxylum alliaceum,
Harpullia cupanioides, Macropanax undulatus, Meliosma
simplicifolia, Syzygium papyraceum, and Turpinia
sphaerocarpa.
Dacrycarpus imbricatus (Podocarpaceae) is one of the
characteristics of mountain forests. This species is often
found in tropical rainforests in a scattered pattern
(scattered), and sometimes appears as a dominant species at
an altitude of 800-2500 m above sea level. (Lemmens et al.
1995). On Mount Pangrango-West Java, D. imbricatus is
found at an altitude of 1660 m above sea level (Yamada
1976). This species is also the dominant tree in the
mountain forests of Bukit Raya in West Kalimantan, the
Batukahu Nature Reserve in Bali, and Mount Ciremai in
West Java (Kartawinata 2013). In the lower mountains
where the ‘Massenerhebung’ effect can be found at lower
altitudes such as Mount Silam-Sabah at an altitude of 540-
790 m above sea level (Proctor et al. 1988). In the Dolok
Sibual-buali Nature Reserve-North Sumatra, this species is
found in the northern part which spreads at an altitude of
1300-1600 m above sea level (Anon 1993). Whitten et al.
(1984) reported that D. imbricatus in Sumatra is commonly
found in upper mountain forests. In the list of Sumatran
orangutan forage plants (Onrizal 2011), D. imbricatus is a
species that grows in the Batangtoru forest at an altitude of
fewer than 1000 m above sea level. However, D.
imbricatus is not found in the Sipirok Botanic Gardens.
Based on the altitude and analysis of the distribution of
plant species at the study site, the Sipirok Botanic Gardens
is in the ecoregion transition zone of the lowland rainforest
and the Sumatran mountain rainforest. As a Botanic
Gardens that will collect various species of forest plants,
the potential number of plants that can be collected will be
higher, especially those that live in lowland to lower
mountain forests.
ACKNOWLEDGEMENTS
This research was funded by the South Tapanuli
District Government, North Sumatra Province, Indonesia.
Thank you to Abadi Siregar, Head of the Regional
Planning Agency (Bappeda) of South Tapanuli District,
Irwansah Harahap, Secretary of Bappeda, and South
Tapanuli District Bappeda staff. Thank you also to Ikar
Supriatna of the Bogor Botanic Gardens staff who helped
carry out this research.
REFERENCES
Anon. 1993. Environmental Baseline Study of the Dolok Sibual-buali
Nature Reserve Area. Pertamina-Unocal North Sumatra Geothermal
Ltd. Indonesian Institute of Sciences, Bogor.
Barbour GM, Burk JK, Pitts WD. 1987. Terrestrial Plant Ecology. The
Benyamin/Cummings Publishing Company, Inc. New York.
Gaines WL, Harrod JR, Lehmkuhl JF. 1999. Monitoring biodiversity:
quantification and interpretation. General Technical Report PNW-
GTR-443, USDA Forest Service, Pacific North-West Research
Station, Corvallis, OR.
Gillison AN, Liswanti N, Arief Rachman I. 1996. Rapid Ecological
Assessment Kerinci Seblat National Park Buffer Zone. Report for
Plant Ecology. Center For International Forestry Research (CIFOR)
Working Paper No. 14. Cifor, Bogor.
Grubb PJ. 1971. Interpretation of the ‘Massenerhebung’ effect on tropical
mountains. Nature 229: 44-45
Hammer Ø. 2014. PAST-Paleontological Statistics version 3.04. Natural
History Museum, University of Oslo , Oslo, Norway.
http://folk.uio.no/ohammer/past/.
Hanum SF, Hendriyani E, Kurniawan A. 2014. Distribution, population
and habitat of tree ferns (Dicksonia spp. and Cyathea spp.) in Bali
Island. Forest Rehabilitation Journal 2 (2): 111-122. [Indonesian]
Holttum RE. 1963. Cyatheaceae. Flora Malesiana Series II (1). Wolters-
Noordhoff Publishing, Groningen, The Netherlands.
IUCN. 2019. Shorea acuminata. The IUCN Red List of Threatened
Species. Version 2019-2. https://www.iucnredlist.org/species/
33921/68072072
Kartawinata K, Samsoedin I, Heriyanto M, Afriastini JJ. 2004. A tree
species inventory in a one-hectare plot at the Batang Gadis National
Park, North Sumatra, Indonesia. Reinwardtia 12 (2): 145-157.
Kartawinata K. 2013. Diversity of Indonesia's Natural Ecosystem. A short
information with photos and pictures. LIPI Press-Yayasan Pustaka
Obor Indonesia, Jakarta. [Indonesian]
Kendeigh SC. 1980. Ecology with Special Reference to Animal and Man.
Prentice Hall of India Pvt. Ltd., New Delhi.
Kier G, Mutke J, Dinerstein E, Ricketts TH, Kuper W, Kreft H, Barthlott
W. 2005. Global patterns of plant diversity and floristic knowledge. J.
Biogeogr 32: 1-10. DOI: 10.1111/j.1365-2699.2005.01272.x
Kuswanda W, Barus SP. 2019. Characteristic and Diversity Vegetation of
Bukit Tiga Puluh National Park as Dietary Sources for Reintroduced
Sumatran Orang Utan (Pongo abelii Lesson). Bull Plasma Nutfah 25
(1): 53-66.
SIREGAR et al. – Vegetation and ecoregion analysis at Sipirok Botanic Gardens, Indonesia
2535
Lemmens RHMJ, Soerianegara I, Wong WC (eds.). 1995. Plant Resources
of Southeast Asia No 5 (2): Timber Trees Minor Commercial
Timbers. Prosea, Bogor.
Ludwig JA, Reynold JF. 1988. Statistical ecology: a primer of methods
and computing. Wiley Press, New York.
Magurran AE. 1988. Ecological Diversity and its Measurement. Croom
Helm, London.
Mirmanto E, Sambas EN, Soedjito H. 1992. Fitosociology of Bengkulu
forest. Proceedings of the Research and Development of Biological
Resources 1991/1992. Puslitbang Biologi, LIPI: 174-182 [Indonesian]
Mueller-Dombois D, Ellenberg H. 1974. Aims and Methods of Vegetation
Ecology. John Wiley & Sons, New York.
Mutaqien Z, Zuhri M. 2011. Establishing a long-term permanent plot in
remnant forest of Cibodas Botanic Garden, West Java. Biodiversitas
12 (4): 218-224.
Odum EP, Barrett GW. 2005. Fundamentals of Ecology. Thomson
Brooks/Cole, Belmont, CA.
Olson DM, Dinerstein E, Wikramanayake ED, Burgess ND, Powell GVN,
Underwood EC, D`amico JA, Itoua I, Strand HE, Morrison JC,
Loucks CJ, Allnutt TF, Ricketts TH, Kura Y, Lamoreux JF,
Wettengel WW, Hedao P, Kassem KR. 2001. Terrestrial ecoregions
of the world: a new map of life on earth. BioScience 15 (11): 933-
938.
Onrizal. 2011. The potential trees for Sumatran orangutans for activities in
the West and East Blocks of the Batang Toru Forest, specifically the
Batang Toru Orangutan Corridor, North Sumatra Province. [Report]
TFCA Sumatra Programme, Jakarta.
Priatna D, Kartawinata K, Abdulhadi R. 2006. Recovery of a lowland
dipterocarp forest twenty-two years after selective logging at
Sekundur, Gunung Leuser National Park, North Sumatra, Indonesia.
Reinwardtia 12 (3): 237-255
Proctor J, Lee YF, Langley AM, Munro WRC, Nelson T. 1988.
Ecological studies on Gunung Silam, a small ultrabasic mountain in
Sabah, Malaysia. 1. Environment, forest structure and floristics. J
Ecol 76 (2): 320-340.
Purnomo DW, Puspitaningtyas DM, Siregar M, Witono JR, Suhendar,
Widoretno A, Lubis RF, Wahyuni S, Usmadi D, Supriatna I, Asnidar
Y, Guswandi D, Suyanto, Riyono. 2018. Masterplan of Sipirok
Botanic Garden, Tapanuli Selatan. [Final Report]. Center for Plant
Conservation and Botanic Gardens, Indonesian Institute of Sciences,
Bogor. [Indonesian]
Rahmah, Kartawinata K, Nisyawati, Wardhana W, Nurdin E. 2016. Tree
species diversity in the lowland forest of the core zone of the Bukit
Duabelas National Park, Jambi, Indonesia. Reinwardtia 15 (1): 11-26
Sambas EN, Siregar M. 1999. Flora composition of the forests of Mount
Muncung, Singkep, Riau. The Botanic Gardens Bulletin 9 (1): 7-17.
[Indonesian]
Sambas EN, Siregar M. 2004. Flora of Alas River Bank, Ketambe,
Gunung Leuser National Park. BioSmart 6 (1): 33-38.
Samsoedin I, Heriyanto NM. 2010. Structure and composition of illegal
logged-over forests in the Sei Lepan forest group, Sei Serdang,
Gunung Leuser National Park, North Sumatera. Jurnal Penelitian
Hutan dan Konservasi Alam 7 (3): 299-314. [Indonesian]
Smith RL. 1977. Element of ecology. Harper & Row Publisher, New
York.
Sugihartatmo, Maesuroh, Mantiri DMH, Witono JR, Purnomo DW,
Mamonto P, Siregar M, Hasibuan P, Hadi A. 2017. Megawati
Soekarnoputri Botanic Gardens: Journey towards the Creation of a
Botanic Garden on Reclaimed Gold Mining Land in Ratatotok,
Southeast Minahasa. Yayasan Pembangunan Berkelanjutan Sulawesi
Utara (YPBSU). Jakarta.
Tothmeresz B. 2013. Diversity. University of Debrecen, Debrecen,
Hungary.
van Steenis CGGJ. 2006. The Mountain Flora of Java. Brill, Leiden.
Whitmore, TC. 1984. Tropical Rainforest of the Far East. Clarendon
Press, London.
Whitten AJ, Damanik SJ, Anwar J, Hisyam N. 1984. The Ecology of
Sumatra. Gadjah Mada Univ. Press, Yogyakarta.
Witono JR, Purnomo DW, Usmadi D, Pribadi DO, Asikin D, Magandhi
M, Sugiarti, Yuzammi. 2012. Indonesian Botanic Gardens
Development Plan. Center for Plant Conservation and Botanic
Gardens, Indonesian Institute of Sciences, Bogor. [Indonesian]
Witono JR, Usmadi D, Wihermanto, Purnomo DW, Safarinanugraha D,
Pakiding Y, Netoseso N. 2020. Autecology of Drosera burmanni in
the Wolobobo Botanic Gardens, Ngada District, Flores Island,
Indonesia. Biodiversitas 21 (5): 2137-2145. DOI:
10.13057/biodiv/d210542.
Yamada I. 1976. Forest ecological studies of the montane forest of Mt.
Pangrango, West Java. 1. Stratification and floristic composition of
the montane rainforest near Cibodas. South East Asian Stud 13 (3):
402-426.