Stand
structure of a primate rich rainforest region in the central Western Ghats of
southern India
Kuladeep
Roy 1, Mewa Singh 2, H.S. Sushma 3 &
Mridula Singh 4
1,2Biopsychology Laboratory, University of Mysore, Manasagangotri, Mysore,
Karnataka 570006, India
3C/O Dr. K. Vasudevan, Wildlife Institute of India Campus, Chandrabani,
Dehradun, Uttarakhand 248001, India
4Department of Psychology, Maharaja’s College, University of Mysore, Mysore,
Karnataka 570006, India
Email: 2 mewasingh@bsnl.in
(corresponding author)
Date of publication
(online): 26 June 2010
Date of publication
(print): 26 June 2010
ISSN 0974-7907
(online) | 0974-7893 (print)
Editor: Werner Kaumanns
Manuscript details:
Ms # o2415
Received 02 March 2010
Final revised received 08 May 2010
Finally accepted 20 May 2010
Citation: Roy, K., M. Singh, H.S. Sushma &
M. Singh (2010). Stand structure of a primate rich rainforest region in the
central Western Ghats of southern India. Journal of Threatened Taxa 2(6): 930-939.
Copyright: © Kuladeep Roy, Mewa Singh, H.S.
Sushma & Mridula Singh 2010. Creative Commons Attribution 3.0 Unported
License. JoTT allows unrestricted use of this article in any medium for
non-profit purposes, reproduction and distribution by providing adequate credit
to the authors and the source of publication.
Author Details: Kuladeep Royis a research scholar in the Department of Psychology, University of
Mysore. He works on niche
differentiation among sympatric primates. He collected major part of the data for this article.
Prof. Mewa Singhis a Professor at the University of Mysore. He has been involved in research on wildlife, especially
primates, for over three decades. His current interests are the study of ecology and animal behavior. He is the Principal Investigator of the
project during which this article was prepared.
Dr. H.S. Sushma is
a free lancer wildlife researcher. She worked on resource utilization and niche separation among arboreal
mammals in the Western Ghats. She
is currently working on mammalian distribution and conservation education. She was involved in sampling and data
collection for this article in the earlier stages of research.
Dr. Mridula Singhteaches at Maharaja’s College of University of Mysore. She has been involved in research on
primates for over 15 years, and her current interest is in the study of ecology
and behavior of primates of southern India. She is the Co-Principal Investigator in the present project.
Author Contribution: Kuladeep Roy is a research scholar and
collected major part of the data. Dr. H.S. Sushma was involved in data
collection and sampling in the earlier stages of the project. Prof. Mewa Singh and Dr. Mridula Singh
are PI and Co-PI of the project and are responsible for planning the study,
obtaining the grants and analysis and write up.
Acknowledgements: The financial grants
for the present study were received by Mewa Singh and Mridula Singh from the
Department of Science and Technology, Government of India. We thank the Chief
Wildlife Warden, Bangalore, Deputy Conservator of Forests, Honnavara Forest
Division, Range Forest Officer, Gerusoppa Forest Range and the forest staff at
Gerusoppa range for research permits and field assistance. We thank Karnataka
Power Corporation Limited for providing accommodation at Gerusoppa. Our special
thanks to Krishna and other villagers at Matnigadde for their help during field
work.
Abstract: The Western Ghats of southern
India are one of the most important biodiversity regions in the world, not only
due to their faunal diversity and abundance but also due to different habitat
types, floral diversity and the presence of several endemic plant species. The rainforests in the central Western
Ghats are inhabited by several primate species. We investigated the vegetation pattern and tree
species occupancy of one of the prime primate habitats in the central Western
Ghats. Lion-tailed Macaque (Macaca silenus),
Bonnet Macaque (Macaca
radiata), Hanuman Langur (Semnopithecus entellus achates) and Malabar Slender Loris (Loris
lydekkerianus malabaricus) inhabit the study area. We studied the density, dominance,
frequency and Importance Value Index (IVI) of different tree species, using the
belt transect method on randomly selected plots covering 4.1ha. We found that all the plant
species that emerged to be the most dominant species with high IVI in the
forest were also used by the diurnal primates for foraging. Knema attenuata and Syzygium gardneri were found to be the
‘keystone’ species. Since the
forests of the study area do not come under the ‘protected area network’ for
wildlife, the data obtained during this study will be helpful in the forestry
management practices with a view for wildlife conservation of the region.
Keywords: Keystone species, Knema attenuata,
primates, Syzygium
gardneri, Western Ghats.
For Figure & Tables - -
click here
INTRODUCTION
Although
ranging up to the snowy region of Japan and Himalayan mountains, most primates
live in warm tropical and subtropical climates. Further, though some of the primate species have adapted to
live on ground, most of the primates live in trees. Therefore, the tropical regions with a wide diversity of
vegetation harbor variety of primate species. In India, the Western Ghats of southern India and the
northeastern Himalayan region are characterized by rainforests as well as deciduous
forests. This floral diversity in
these hills has provided several habitat types and many primate species inhabit
these forests including some of the species even being sympatric (Molur et al.
2003).
The
Western Ghats of southern India range along the west coast covering a
north-south length of about 1600km. Because of the monsoons, the ridge and the western slopes of the Ghats
receive high rain fall resulting in tropical evergreen rainforests. The eastern slopes of these hills are
rain shadow and dominated by deciduous and scrub forests. Due to the diversity of habitat types,
faunal diversity and a high degree of endemism, the Western Ghats have been
considered as one of the ‘hottest hotspots’ of global biodiversity (Myers et
al. 2000). The Western Ghats
harbor several primate taxa including the Mysore Slender Loris (Loris
lydekkerianus lydekkerianus) and Malabar Slender Loris (L. l. malabaricus),
endemic and Endangered Lion-tailed Macaque (Macaca silenus), endemic and Vulnerable Nilgiri
Langur (Trachypithecus
johnii), Dark-bellied Bonnet Macaque (Macaca radiata radiata) and Pale-bellied Bonnet
Macaque (M. r.
diluta), and several taxa of Hanuman Langurs (Semnopithecus achates, S. priam, S. hypoleucos, S.
thersites).
In
order to understand the feeding ecology of a species, it is important that the
habitat is described in terms of its stand structure, species’ distribution,
richness and abundance, and importance value of each plant species. This may also help identify keystone
species (Paine 1969; Stiling 2004). A few studies in the past have provided description of primate habitats
in the Western Ghats. Ramachandran
& Joseph (2000) described the stand structure in Silent Valley, an
important habitat of the rainforest primates in the Western Ghats. Primates were mostly found in areas
with tree associations of Cullenia-Palaquium, Mesua-Palaquium and Mesua-Calophyllum. Lion-tailed Macaques were absent in
areas with associations of Poeciloneuron-Palaquium, Poeciloneuron-Ochlandra and Calophyllum-Ochlandra. In the Anaimalai Hills of the Western
Ghats, primates inhabited the rainforest regions dominated by Cullenia
exarillata, Ficus
microcarpa, Ficus
exasperata and Melisoma pinnata (Sushma & Singh 2006). Krishnamani & Kumar (2000) studied
several rainforest primate habitats in Karnataka and found that five tree
species including Poeciloneuron indicum, Myristica dactyloides, Dimocarpus longan, Olea dioica and Aglaia elaegnoidea had the highest
number of individuals. However,
large areas inhabited by primates in the Western Ghats have not yet been
quantitatively described for the vegetation characteristics.
In
most of the places in the Western Ghats, Lion-tailed Macaques, Nilgiri Langurs
and Malabar Slender Loris are sympatric in the rainforests of the ridge and the
Western slopes, and Bonnet Macaques, Hanuman Langurs and Mysore Slender Loris
are sympatric in relatively drier forests of the eastern slopes (Singh et al.
1997; Kumara & Singh 2004). However, north of Brahmagiri Hills in the Coorg District of the state of
Karnataka, Lion-tailed Macaques, Bonnet Macaques, Hanuman Langurs and Malabar
Slender Loris are found as sympatric species in several ranges of
rainforests. The rainforest region
to the north of Sharavathy River and south of Aghnashini River is one such
region which, due to the high abundance of primates, has been regarded as one
of the most potential regions for long-term primate conservation (Kumara &
Singh 2004). In this article, we
describe the vegetation structure of this prime primate habitat.
METHODS
Study
site: We carried out the present study in the rainforests of
the Western Ghats lying between 14015’-14025’N & 74035’-74047’E
in the Gerusoppa Forest Range of Honnavara Forest Division in the State of
Karnataka, India (Fig. 1). This
forest region constitutes the northern limit of the evergreen forests of the
plains and low elevations of southern India (Pascal 1988). Champion & Seth (1968) broadly
classify this forest as ‘west coast tropical evergreen forest’. The forest is primarily distinguished
as Persea
macrantha-Diospyros spp.-Holigarna spp. type with abundance of heleiophilic or light
tolerant species. The official status of the forest is a Reserve Forest with
interspersed revenue lands (Kumara & Singh 2004). Four primate species including the Endangered Lion-tailed
Macaque (Macaca silenus)
(Kumar et al. 2008), Bonnet Macaque (Macaca radiata), taxonomically controversial
Hanuman Langur (Semnopithecus
entellus achates) (Molur et al. 2003)
and Malabar Slender Loris (Loris lydekkerianus malabaricus) inhabit the study area. This place is one of the few places in
the Western Ghats of India where four primate species are sympatric.
Data
collection: Between April 2006 and March 2007, we laid 10 belt
transects traversing through the study site covering almost all vegetation
types of the study area. The
length of transects varied from 150 to 300 m covering a total length of
2050m. On each side of a belt
transect, we included 10m width as vegetation sampling plots amounting to a
total sampling area of 4.1ha. Inside each sampling plot, all plants (excluding climbers, lianas and
herbs) with a girth more than 12cm were numbered with aluminum tags. However, we sorted the trees with a
girth of >30cm for vegetation analysis. We identified the plant species with the help of field guide
books (Gamble 1935; Pascal & Ramesh 1997). In most of the cases, we preserved sample plant parts
including leaf, flower and fruit for confirmation of identification by plant taxonomists.
We identified most of the plants up to the species level.
The
vegetation analysis including density, dominance and frequency (Curtis &
McIntosh 1950) and importance value index (Curtis 1959) of different tree
species were estimated using the following methods:
Basal
area = πr2 (where r is radius of the plant girth at breast height)
(Basal area represents dominance of a plant species)
Density
= total number of plants of any species/ number of plots
Frequency
= (number of plots with the presence of a species/number of plots) x 100
Relative
dominance = (dominance of a plant species/ total dominance of all plant
species) x 100
Relative
frequency = (frequency of a plant species/ total frequency of all plant
species) x 100
Relative
density = (density of a plant species/ total density of all plant species) x
100
Importance
Value Index (IVI) = Relative dominance+Relative frequency+Relative density
We
recorded the data on feeding by primates through instantaneous scan sampling
(Altmann 1974). On the basis of
feeding records, we identified the use of high IVI plant species by the three
diurnal primates including Lion-tailed Macaque, Bonnet Macaque and Hanuman
Langur.
RESULTS
In
this section, we present the data on tree species, their abundance and IVI, and
their use by the primate species.
Table
1 presents the data on tree species, their density, dominance and percent
frequency in the study area. We
recorded a total of 81 tree species belonging to 33 families in the sampled
area. All species were almost
randomly distributed in all sample plots.
In
the study area, Knema
attenuata had the highest density (29.5) followed by Aglaia roxburghii (20.4), Hopea ponga (15.6),Dimocarpus
longan (10.8), Holigarna grahamii (10.4), Olea dioica (10.3), Syzygium gardneri (8.3) and Garcinia gummigutta(5.7). However, when dominance was
calculated, Syzygium
gardneri had the highest ground cover (20.02) followed by Knema attenuata(14.34), Olea
dioica (13.30), Aglaia roxburghii (12.43), Hopea ponga (9.70), Holigarna grahamii (8.22), Dimocarpus longan(7.99), Ficus
nervosa (7.37) and Diospyros crumenata (6.88). These important tree species had 100 percent frequency as they were
distributed throughout the study area. In addition, some other tree species including Garcinia gummigutta, Diospyros sp.,Litsea sp.,
also had 100 percent frequency of presence.
Table
2 presents the data on relative density, relative abundance, relative frequency
and IVI (arranged in a descending order) of the tree species in the study area. Knema attenuata had the highest IVI
followed by Aglaia
roxburghii, Syzygium
gardneri, Hopea
ponga, Olea
dioica, Dimocarpus
longan and Holigarna
grahamii. All other tree
species had an IVI value smaller than 8.00.
Table
3 presents the data on the proportion of consumption (of total diet) of items from
the top ten tree species by the primates. Knema attenuata and Holigarna grahamii were used by all primate
species. Rest of the tree species
were foraged by some primate species or the other. Only Olea dioica and Ficus nervosa were used by a single primate species.
Table
4 lists the common tree species used by different primate species’ pairs. Almost all of the high IVI tree species
were used by more than one primate species. There were also several tree species that were used
exclusively by one primate species or the other (Table 5).
DISCUSSION
The
study of stand structure helps in not only describing the vegetation type and
the abundance of various tree species etc., but also in identification of
keystone species in a forest. The
Western Ghats are characterized by several ecozones. The present study area marks the northern end of the
distribution of low and medium elevation dipterocarp forests (Pascal 1998). This region is also the northern
end of the distribution of the threatened Lion-tailed Macaques (Kumara &
Singh 2004). The results of the
present study reveal that the rainforests to the north and south of Sharavathy
and Aghnashini rivers respectively in the Western Ghats are characterized by a
high diversity of vegetation including lianas, shrubs and trees. Many tree species were distributed
throughout the study area, but these might not be considered as important trees
species. Only a few tree species
were important by dominance, density and frequency. High IVI value is considered only for those species which
have a major impact on community and are defined as major vegetation type. Some
tree species such as Garcinia gummigutta, Litsea sp., Diospyros sp., Caryota urens, Cassine glauca, Garcinia morella, Mimusops elengi etc were also distributed almost
throughout the study site, but these were poor in density or dominance. Even important tree species such as Syzygium gardneriand Olea
dioica were poor in their overall density compared to the other important
tree species. However, they had a
large ground cover with high basal area.
Of
the 81 plant species recorded in the study area, 62 (76.54%) were used for
feeding by one primate species or the other. The primarily folivorous langurs used the largest number of
plant species followed by the primarily frugivorous macaques. All of the high IVI tree species were
used by the primates indicating that the characteristic vegetation of the
region is also a major food resource for the primates.
In
the present study, the important tree species might be considered as the
keystone species. Keystone species
may not necessarily be the dominant species, though a dominant species has an
effect on community because it is common (Paine 1966, 1969; Stiling 2004). Generally, keystone species are those
whose absence has an effect on overall foodchain of the community. However, producers are also considered
as keystone prey in some cases as those are mostly used by maximum number of
consumers; palm-nuts, figs and nectar could be keystone prey because they are
critical to tropical forest fruit-eating guilds including primates, rodents and
many birds (Terborgh 1983). In the
present study area, the important tree species were also important fodder
plants for different primate species. Out of the major resource trees of primates, more than 50 percent were
the important tree species in the present study area, and some important trees
were also used as minor diet by the primates. In the rainforests of the Western Ghats south of the Palghat
Gap, Cullenia exarillatais the keystone species for primates as it constitutes a major food resource in
the Anaimalai Hills (Sushma & Singh 2004) and in the forests of the Silent
Valley (Joseph & Ramachandran 2001). Knema attenuata and Syzygium gardneri could be considered as the
keystone tree species in the present study area according to their presence as
well as their use as major resource items. All three primate species used different plant part of these
two trees as major food items and some resource items were also shared by
different species-pairs. Retention
of such tree species, therefore, is a key element in the forest management of
this primate rich region which, at present, does not form a part of the
‘protected area’ network for wildlife conservation.
REFERENCES
Altmann.
J. (1974). Observational study of behavior: sampling methods. Behaviour 49:
227-267.
Champion,
H.G. & S.K. Seth (1968). A Revised Survey of the Forest Type of India,
Govt. of India Press, Nashik, Maharashtra, India, 404pp.
Curtis,
J.T. (1959). The Vegetation of Wisconsin. An Ordination of Plant
Communities. University of Wisconsin Press, Madison,
Wisconsin, 657pp.
Curtis,
J.T. & R.P. McIntosh (1950). The interrelations of certain
analytic and synthetic photosociological characters. Ecology 31: 438-455.
Gamble,
J.S. (1967). Flora of the Presidency of Madras. Botanical Survey of India,
Calcutta, 1389pp.
Krishnamani,
R. & A. Kumar (2000). Phyto-ecology of the Lion-tailed
Macaque (Macaca
silenus) habitat in Karnataka, India: floristic structure and density of
food-trees. Primate
Report 58: 27-56.
Kumar,
A., M. Singh & S. Molur (2008). Macaca silenus. In: IUCN 2010. IUCN Red
List of Threatened Species. Version 2010.1. <www.iucnredlist.org>.
Downloaded on 10 June 2010.
Kumara,
H.N. & M. Singh (2004). Distribution and abundance of
primates in rain forests of the Western Ghats, Karnataka, India and the
conservation of Macaca
silenus. International
Journal of Primatology 25: 1001-1018.
Molur, S., D. Bbrandon-Jones,
W. Dittus, A. Eudey, A. Kumar, M. Singh, M.M. Feeroz, M. Chalise, P. Priya
& S. Walker (2003). Status of South Asian Primates:
Conservation Assessment and Management Plan (C.A.M.P.) Workshop Report, 2003,
Zoo Outreach Organization/CBSG-South Asia, Coimbatore, India, viii+432pp.
Myers,
N., R.A. Mittermeier, C.G. Mittermeier, G.A.B. da Fonseca & J. Kent (2000).Biodiversity hotspots for conservation priorities. Nature 403:
853-858.
Paine,
R.T. (1966). Food web complexity and species diversity. American
Naturalist 100: 65-75.
Paine,
R.T. (1969). A note on trophic complexity and community stability. American
Naturalist 1003: 91-93.
Pascal,
J.P. (1988). Wet Evergreen Forests of the Western Ghats of India: Ecology,
Structure, Floristic Composition and Structure, Institut Francais de
Pondichery, Pondicherry, India, 345pp.
Pascal,
J.P. & B.R. Ramesh (1997). A Field Key to the Trees and Lianas of the
Evergreen Forests of the Western Ghats (India). Pondicherry, Institut
Francais de Pondicherry, Pondicherry, India, 238pp.
Ramachandran,
K.K. & G.K. Joseph (2000). Habitat utilization of Lion-tailed
Macaque (Macaca
silenus) in Silent Valley National Park, Kerala, India. Primate Report58: 17-25.
Ramachandran,
K.K. & G. Joseph (2001). Distribution and demography of
diurnal primates in Silent Valley National Park and adjacent areas, Kerala,
India. Journal
of Bombay Natural History Society 98: 191-196.
Singh,
M., M. Singh, M.A. Kumar, H.N. Kumara & L.D’ Souza (1997).Distribution and research potential of non-human primates in the
Aliyar-Valparai sector of Indira Gandhi Wildlife Sanctuary, Tamilnadu, India. Tropical
Biodiversity 4: 187-208.
Stiling,
P. (2004). Ecology: Theories and Applications. Prentice-Hall of
India Pvt. Ltd, New Delhi, 403pp.
Sushma,
H.S. & M. Singh (2006). Resource partitioning and
interspecific interaction among sympatric rain forest arboreal mammals of the
Western Ghats, India. Behavioral Ecology 17: 479-490.
Terborgh,
J. (1983). Five New World Primates. Princeton University Press, Princeton,
260pp.