The Western Ghats of southwestern India and the highlands of southwestern Sri Lanka, separated by 400 kilometers (km), are strikingly similar in their geology, climate and evolutionary history. The Western Ghats, known locally as the Sahyadri Hills, are formed by the Malabar Plains and the chain of mountains running parallel to India's western coast, about 30 to 50 km inland. They cover an area of about 160,000 square kilometeres (km2) and stretch for 1,600 km from the country's southern tip to Gujarat in the north, interrupted only by the 30 km Palghat Gap.
Sri Lanka is a continental island separated from southern India by the 20-meter-deep Palk Strait. The island, some 67,654 km2 in size, has been repeatedly connected with India between successive interglacials, most recently until about 7,000 years ago by a land bridge up to about 140 km wide.
The Western Ghats mediates the rainfall regime of peninsular India by intercepting the southwestern monsoon winds. The western slopes of the mountains experience heavy annual rainfall (with 80 percent of it falling during the southwest monsoon from June to September), while the eastern slopes are drier; rainfall also decreases from south to north. Dozens of rivers originate in these mountains, including the peninsula's three major eastward-flowing rivers. Thus, they are important sources of drinking water, irrigation, and power. The wide variation of rainfall patterns in the Western Ghats, coupled with the region's complex geography, produces a great variety of vegetation types. These include scrub forests in the low-lying rainshadow areas and the plains, deciduous and tropical rainforests up to about 1,500 meters (m), and a unique mosaic of montane forests and rolling grasslands above 1,500 m.
Precipitation across Sri Lanka is dependent on monsoonal winds, resulting in much of the island experiencing relatively low rainfall (less than 2,000 millimeters (mm) per year), except for the south-western 'wet zone' quarter, where precipitation ranges to as much as 5,000 mm per year. While dry evergreen forests occupy almost the entirety of the 'dry zone,' dipterocarp-dominated rainforests dominate the lowlands of the wet zone, and some 220 km2 of tropical montane cloud forest still persist in the central hills, which rise to a maximum altitude of 2,524 m.
Unique and Threatened Biodiversity
There are a minimum of 6,000 vascular plant species in the Western Ghats and Sri Lanka hotspot, of which more than 3,000 (52 percent) are endemic. There are also more than 80 endemic plant genera, many of which have only one species.
The Western Ghats harbors approximately 5,000 species of vascular plants belonging to nearly 2,200 genera; about 1,700 species (34 percent) are endemic. There are also 58 endemic plant genera, and, while some are remarkably speciose (like Niligrianthus, which has 20 species), nearly three-quarters of the endemic genera have only a single species.
Some prominent genera and families are represented by large numbers of endemic species, such as Impatiens with 76 of 86 species endemic, Dipterocarpus with 12 of 13 species endemic, and Calamus with 23 of 25 species endemic. Of the 490 tree species recorded from low- and mid-elevation forests, 308 species are endemic. The only gymnosperm tree, Podocarpus (=Nageia) wallichianus, is also endemic. Of the 267 species of orchids, 130 are endemic.
Similarly, plant diversity and endemism in Sri Lanka are quite high, with 3,210 flowering plant species in 1,052 genera, of which 916 species and 18 genera are endemic. Amazingly, all but one of the island’s more than 55 dipterocarp species are found nowhere else in the world. In addition, the island’s ferns (although not recently assessed) are estimated to number about 350 species. Approximately 433 plant species, and at least five genera, are confined to Sri Lanka and the Western Ghats combined.
In the Western Ghats, the Agasthyamalai Hills in the extreme south are believed to harbor the highest levels of plant diversity and endemism at the species level. Nearly 87 percent of the region’s flowering plants are found south of the Palghat Gap (37 percent being exclusive to this sub-region); these figures decrease to about 60 percent and 5 percent, respectively, in the Nilgiri Hills. In Sri Lanka, diversity, richness, and endemism across all taxa are much higher in the wet (including the montane) zone than in the dry zone. Indeed, the wet zone, which accounts for only a quarter of Sri Lanka’s territory, contains 88 percent of the flowering plants occurring in the island, and 95 percent of its angiosperm endemics.
The avifauna of the Western Ghats and Sri Lanka is diverse, but endemism is not exceptional. There are more than 450 known bird species from the hotspot, of which about 35 are endemic. More than 20 species are endemic to Sri Lanka, mostly from the lowland rainforests and montane forests of the island's southwestern region. Both the Western Ghats and the island of Sri Lanka are considered as Endemic Bird Areas by BirdLife International.
Of the endemic species, 10 are considered threatened, including the green-billed coucal (Centropus chlororhynchos, VU), the Sri Lanka whistling thrush (Myiophonus blighi, EN) and rufous-breasted laughingthrush (Garrulax cachinnans, EN). The hotspot also holds several widespread threatened waterbird species, including the spot-billed pelican (Pelecanus philippensis, VU) and the lesser adjutant (Leptoptilos javanicus, VU). Another threatened species, the Kashmir flycatcher (Ficedula subrubra, VU), breeds in the Himalayas and winters in the Western Ghats and in Sri Lanka.
The hotspot is home to about 140 mammal species, although less than 20 are endemic. While mammal diversity is lower here than in some other tropical hotspots, the hotspot does support a significant diversity of bats, with nearly 50 species and one endemic genus, represented by the bat Latidens salimalii (CR), which is endemic to the High Wavy Mountains in the Western Ghats. In addition, there are three genera confined to Sri Lanka, each represented by single species: Pearson’s long-clawed shrew (Solisorex pearsoni, EN), Kelaart’s long-clawed shrew (Feroculus feroculus, EN), and the Ohiya rat (Srilankamys ohiensis).
Among flagship mammal species, the most prominent are the lion-tailed macaque (Macaca silenus, EN), found in highly fragmented tropical rain forests in the Western Ghats, and the endemic Nilgiri tahr (Hemitragus hylocrius, EN), which lives in the montane grasslands of the Western Ghats. One of the most threatened Indian mammals, the Malabar civet (Viverra civettina, CR), is known only from the Malabar Plains, which are densely populated and the focus of most development activities.
The hotspot also has important populations of the Asian elephant (Elephas maximus, EN). The Western Ghats is home to about 11,000 animals, while in Sri Lanka the species has been nearly extirpated from the wet zone and only about 2,500 survive elsewhere on the island.
The highest levels of vertebrate endemism in the Western Ghats and Sri Lanka hotspot are among reptiles and amphibians. Of the region's more than 260 reptile species, about 175 (66 percent) are endemic. One quarter of the nearly 90 reptile genera in the hotspot are endemic, and nine of these are represented by single species. Families such as Uropeltidae (47 of 48 species), Gekkonidae (18 of 30), and Agamidae (20 of 26) exhibit very high endemism.
Endemism is particularly marked among amphibians in this hotspot: of approximately 175 species, roughly 130 are endemic. In the case of Sri Lanka, amphibian diversity is only now becoming better known, and the country’s wet zone alone may contain as many as 140 endemic species. Across the hotspot, the genus Philautus is particularly well represented with over 50 species occurring, and nearly all of them are endemic.
Additionally, six genera (out of a total of 28) are endemic to the Western Ghats and Sri Lanka. Recently, a new amphibian family was discovered in Kerala in the Western Ghats; the burrowing anuran family, Nasikabatrachidae, with the single species Nasikabatrachus sahyadrensis (EN), represents the only endemic amphibian family in the hotspot. The closest living relatives of this family are the Sooglosside in the Seychelles.
Unfortunately, the amphibian fauna fare particularly high levels of threat, driven particularly by the continuing levels of habitat loss. Among the endemics, over 85 species are considered threatened. Amphibian extinctions are also relatively well documented, with some 20 historically recorded extinctions.
Many freshwater fish occupy very limited ranges in the Western Ghats and in Sri Lanka. Nearly 140 of more than 190 species of strictly freshwater fishes are endemic to the hotspot. There are also nine endemic genera, including one, Malpulutta, found only on Sri Lanka. In the Western Ghats, the southern region is known to be more diverse than the central and northern regions.
Although knowledge of invertebrate diversity in the Western Ghats and Sri Lanka is poor, the hotspot is believed to have significant levels of endemism within certain groups. For example, more than 100 of nearly 140 tiger beetle species are endemic. However, this may not hold true across groups: the number of butterfly species in this region is relatively low, with only 37 endemics of 330 in the Western Ghats, and 24 of 234 species endemic to Sri Lanka.
Sri Lanka has a number of unique endemics, including Aneuretus simoni, the only surviving representative of one of the world’s 14 ant subfamilies. It also hosts more than 50 known species of endemic freshwater crabs (all in the Parathelphusidae family), all of them endemic. These species are gravely threatened by habitat fragmentation and degradation, as well as by pesticide use in nearby areas. A preliminary assessment of their conservation status indicates that they are in dire straits: of the 51 species, 23 are listed as Critically Endangered, seven as Endangered, and another seven as Vulnerable.
Extremely high population pressure in both countries of this hotspot has seriously stressed the region's biodiversity. There are more than one billion people in India and almost 20 million in Sri Lanka. Nearly 50 million people occur in the hotspot overall, at a density of 260 people/km2 (one of the highest in hotspots). It is likely that no more than about 25 percent of the extent of original native vegetation remains in relatively pristine condition today.
The forests of the Western Ghats have been selectively logged and highly fragmented throughout their entire range. Forests have been converted to agricultural land for monoculture plantations of tea, coffee, rubber, oil palm, teak, eucalyptus, and wattle, and are also cleared for building reservoirs, roads, and railways. Encroachment into protected areas further reduces the extent of forests. Grazing by cattle and goats within and near protected areas causes severe erosion on previously forested slopes. Much of the remaining forest cover consists of timber plantations or disturbed secondary growth.
Today, approximately 20 percent of the original forest cover remains in more or less pristine state, with forest blocks larger than 200 km2 found in the Agasthyamala Hills, Cardamom Hills, Silent Valley-New Amarambalam Forests, and southern parts of the South Kannada District in Karnataka State. Remaining forest patches are subject to intense hunting pressure and the extraction of fuelwood and non-timber forest products. Uncontrolled tourism and forest fires are additional concerns.
The growth of populations around protected areas and other forests has led to increasing human-wildlife conflict. Raiding elephants cause crop loss, and leopards kill livestock. Compensation for farmers is generally inadequate, and wild animals are often killed or injured in an attempt to reduce further damage.
In Sri Lanka, two-thirds of the people live in the wet zone, which harbors greater endemism than the comparatively less populated and more extensive dry zone. Most of the island's rainforests were cleared originally for the cultivation of cinchona (a medicinal drug containing quinine and related compounds) and coffee, which gave way later to tea and rubber. The remaining forests cover only 4.6 percent of the wet zone. This remaining forest comprises some 140 fragments; the three largest are Peak Wilderness (250 km2), the Knuckles Hills (175 km2), and the Sinharaja World Heritage Site (90 km2), but the majority of these fragments are less than 10 km2 in extent.
One of the most prevalent threats to the remaining forests is encroachment into protected areas. Small-scale tea planters and farmers are increasingly utilizing protected forests, and cardamom cultivators in the Knuckles Range and Peak Wilderness areas clear the forest understory and extract firewood. In general, poaching and the extraction of forest products (timber, firewood, medicinal plants) are a problem in almost all forest reserves, and contribute to habitat fragmentation and significant edge effects. Also, the unrestricted use of agrochemicals by farmers and planters in these areas poses a serious threat to ecosystem services and groups such as amphibians. Finally, invasive species pose a growing threat, especially to aquatic habitats.
Conservation Action and Protected Areas
Both India and Sri Lanka have a long history of environmental protection and reverence for nature. What are perhaps the oldest reserves in the world were created in this region, with one in the dry zone of Sri Lanka dating to about 200 BC. In both nations, there is a strong civil society presence in conservation. In total, around 26,000 km2, or 13.8 percent of the hotspot area, is under official protection, about 11 percent of which is in categories I-IV.
India has a long history of conservation and environmental legislation, complimented by a protected area system that is more than a century old. In 1980, the Forest Conservation Act was enacted, providing an important means of biodiversity protection for the entire nation. This act states that forested land cannot be used for any purpose without approval by the central government. As a result, all legal logging operations in the hotspot were halted in the mid-1980s.
The national and state governments provide the majority of conservation investment in India. For instance, the State Forest Departments work towards managing forests, conserving biodiversity, reforestation, and social forestry. The Ministry of Environment and Forests, the Planning Commission, and other agencies invest in environmental projects nationwide. Multilateral and bilateral donor agencies, including the World Bank, the Asian Development Bank, and the international development agencies of Japan, the United States, the United Kingdom, and other nations provide loans and grants to both the government and to research institutions and nongovernmental organizations (NGOs). Many national, regional, and local NGOs actively participate in biodiversity conservation, particularly through the involvement of communities in sustainable natural resource utilization. While research institutions and NGOs have access to much lower amounts of funding than the government agencies, their work tends to be more targeted towards biodiversity conservation.
Less than fifteen percent of the Western Ghats is protected in 20 national parks and 68 sanctuaries. Considering IUCN categories I-IV, which offer a higher level of protection, the figure drops to around 11percent, according to the World Database on Protected Areas. Thus, the protected area network is far from complete. One way of ensuring that the network of protected areas adequately conserves biodiversity is through the identification and conservation of 'Key Biodiversity Areas' (KBAs). These are globally important sites for biodiversity conservation, defined by the presence of irreplaceable and threatened biodiversity: globally threatened species, restricted-range species, and species that concentrate in globally significant numbers. KBAs are biologically meaningful units that can be potentially managed for conservation, defined in a bottom-up, data driven process.
The identification of KBAs in the Western Ghats was initiated in 2003, coordinated locally by Ashoka Trust for Research in Ecology and the Environment (ATREE), and in collaboration with The Wildlife Conservation Society-India and the University of Agricultural Sciences in Bangalore. Building from preliminary data on Important Bird Areas, compiled by the Bombay Natural History Society, data on globally threatened species of mammals, birds, amphibians, plants, and to a lesser extent, reptiles and fish, were synthesized to identify and delineate 126 KBAs in the Western Ghats. These sites are high priorities for conservation action. KBAs in the Western Ghats will be refined as new and better data become available. Landscape-scale action, through biodiversity conservation corridors, will be necessary for wide ranging species such as the Asian elephant (Elephas maximus, EN), tiger (Panthera tigris, EN), Asiatic wild dog (Cuon alpinus, EN), and greater spotted eagle (Aquila clanga, VU).
In the Sri Lankan portion of the hotspot, most of the remaining habitat is officially protected by the Forest Department (FD) and the Department of Wildlife Conservation (DWLC). These areas include national parks, strict nature reserves, jungle corridors, and sanctuaries. Approximately 30 percent of the nation's land area falls under some level of natural resource management.
One of the most important reserves in the hotspot is the Sinharaja Forest Reserve, which encompasses 50 percent of the remaining lowland rainforest vegetation in Sri Lanka. Portions of the reserve have been protected since 1875, and it was declared a World Heritage Site in 1989. Sixty-five percent of Sri Lanka's 220 endemic tree and woody climber species and 270 species of vertebrates have been recorded there. Although public awareness of Sinharaja's splendid biodiversity is growing, the reserve still faces threats. People from neighboring villages encroach on the reserve via logging roads to collect non-timber forest products.
In Sri Lanka, 92 Key Biodiversity Areas have been identified through a process coordinated by the Wildlife Heritage Trust of Sri Lanka and the University of Peradeniya, and involving a number of experts. Data on Important Bird Areas compiled by the Field Ornithology Group of Sri Lanka were incorporated into the analysis, along with published literature on species distributions, herbarium records, the 1996 National Conservation Review inventory of forest reserves, and other data for the remaining taxonomic groups. Nearly all of these KBAs are forest patches in the southwestern wet zone. All sites contain endemic species that are found nowhere else, and are therefore considered irreplaceable, with several sites having more than 100 globally threatened species. All of these sites technically have some form of protection, but there is a tremendous need to strengthen the management and monitoring of these areas. Additionally, landscape-scale conservation, particularly reforestation and conservation of biological corridors, will be required for biodiversity to persist in this severely fragmented region, even in the short term.
The flora and fauna of Sri Lanka are greatly understudied; for instance, in 2004 alone, a new species of owl, the Serendib scops owl (Otus thilohoffmanni), was described and nine other bird species added to the list of endemics. Thus, the number of endemic species is likely to be a gross underestimate, and the list of key biodiversity areas delineated will have to be modified as new data become available.
As in India, the bulk of conservation investment is by the government. In general, conservation investment by the government has focused on law enforcement, resulting in the alienation of some communities in the vicinity of protected areas. More recent projects have aimed to rectify this by involving and aiding communities in the vicinity of protected areas. Other current projects target capacity building. Multilateral and bilateral donors include the governments of the Netherlands and the United States, and the Global Environment Facility. The only international conservation organization with a base in Sri Lanka is the World Conservation Union (IUCN), which has worked with the government to develop a national Red List of threatened species, and helped to develop a national strategy for biodiversity conservation. Investment by civil society institutions has largely focused on environmental education and advocacy.
- Arachchi, K. M. & Pethiyagoda, R. In press. The Sri Lankan Shrub Frogs of the Genus Philautus Gistel, 1848. Rhacophorinae: Ranidae.
- Ashton, P.S. & Gunatilleke, C.V.S. 1987. New light on the plant geography of Ceylon I: Historical plant geography. Journal of Biogeography 14: 249-285.
- Bahir, M. M., Ng, P.K.L., Crandall, K. & Pethiyagoda, R. In Press. Conservation assessment of the freshwater crabs (Crustacea: Bracyura: Parathelphusidae) of Sri Lanka. In D.C.J Yeo, P. K. L. Ng & R. Pethiyagoda. (Eds.), Contributions to Biodiversity Exploration and Research in Sri Lanka. The Raffles Bulletin of Zoology.
- Biju, S.D. & Bossuyt, F. 2003. New frog family from India reveals an ancient biogeographical link with the Seychelles. Nature 425:711-714.
- BirdLife International. 2003. Saving Asia's Threatened Birds: A Guide for Government and Civil Society. Cambridge: Birdlife International.
- Collins, N.M., Sayer, J.A. & Whitmore, T.C. 1991. The Conservation Atlas of Tropical Forest: Asia and the Pacific. IUCN. ISBN: 0756790794.
- Conti, E., Rutschmann, F. & Eriksson, T. 2003. Testing the out-of-India origin of crypteroniaceae with molecular dating methods [abstract]. In Proceedings of the Annual Meeting of the Association for Tropical Biology and Conservation. p. 37. Aberdeen, U.K.: University of Aberdeen.
- D'Abrera, B. 1998. The Butterflies of Ceylon. Colombo: WHT Publications. ISBN: 094735235X.
- Dahanukar, N., Raut, R. & Bhat, A. 2004. Distribution, endemism and threat status of freshwater fishes in the Western Ghats of India. Journal of Biogeography 31: 123-136.
- Daniels, R.J.R. 2001. Endemic fishes of the Western Ghats and the satpura hypothesis. Current Science 81:241-244.
- Das, I. 1996. Biogeography of the Reptiles of South Asia. Malabar: Krieger Publ. Co. ISBN: 0894649353.
- Dassanayake, M.D. & Fossberg, F.R. 1980-2002. A Revised Handbook to the Flora of Ceylon. Vols. 1-9 edited by M.D. Dassanayake, F.R. Fossberg, & W.D. Clayton; Vols. 10-14 edited by M.D. Dassanayake & W.D. Clayton. New Delhi: Oxford & IBH Publishing Co. ISBN: 9054102705.
- Ganeshaiah, K.N. 2003. Sasya Sahyadri: Distribution, Taxonomy and Diversity of Plants of Western Ghats. Bangalore, India: University of Agricultural Sciences.
- Gimaret-Carpentier, C., Dray, S. & Pascal, J.P. 2003. Broad-scale biodiversity pattern of the endemic tree flora of the Western Ghats (India) using canonical correlation analysis of herbarium records. Ecography 26: 429-444.
- Gunasekera, N.S. & Dayanandan, S. 2003. Dipterocarpaceae as a model for understanding evolution in tropical trees. In Proceedings of the Annual Meeting of the Association for Tropical Biology and Conservation. Aberdeen, U.K.: University of Aberdeen.
- Inger, R. F.1999. Distribution of amphibians in Southern Asia and adjacent islands. In W.E. Duellman. (Ed.), Patterns of Distribution of Amphibians: A Global Perspective. Baltimore: Johns Hopkins University Press. ISBN: 0801861152.
- Jayasuriya, A.K. & Traniello, J.F.A. 1985. The biology of the primitive ant Aneuretus simoni (Emery), 1: Distribution, abundance, colony structure and foraging ecology. Insectes Sociaux 32:363-374.
- Jha, C. S., Dutt, C. B. S. & Bawa, K. S. 2000. Deforestation and land use changes in Western Ghats, India. Current Science 79:231-238.
- Kostermans, A. J. G. H. 1992. A Handbook of the Dipterocarpaceae of Sri Lanka. Colombo: Wildlife Heritage Trust of Sri Lanka. ISBN: 9559114050.
- Krombein, K.V. & Norden, B.B. 1997. Bizarre nesting behavior of Krombeinictus nordenae Leclercq (Hymenoptera: Sphecidae, Crabroninae). J. South Asian Nat. Hist. 2(2): 145-154.
- Kunte, K., Joglekar, A., Ghate, U., & Pramod, P. 1999. Patterns of butterfly, birds and tree diversity in the Western Ghats. Current Science 77(4): 577-586.
- Meegaskumbura, M., Bossuyt, F., Pethiyagoda, R., Manamendra-Arachchi, K., Milinkovitch, M. C. & Schneider, C. J. 2002. Sri Lanka: An amphibian hotspot. Science 298:379.
- Mittermeier, R. A., Carr, J. L., Swingland, I. R. et al. 1992. Conservation of amphibians and reptiles. In K. Adler. (Ed.), Herpetology: Current Research on the Biology of Amphibians and Reptiles. Ithaca: Society for the Study of Amphibians and Reptiles. ISBN: 0916984273.
- Naggs, F. & Raheem, D. In press. The Darwin Initiative Project on Sri Lankan land snails: Patterns of diversity in Sri Lankan forests. In I. Killeen & M. Seddon. (Eds.), Molluscan Conservation and Biodiversity. London: Conchological Society.
- Naggs, F. & Raheem, D. 2000. Land Snail Diversity in Sri Lanka. CD ROM. London: Natural History Museum.
- Ng, P. K. L. & Tay, F. W. M. 2001. The freshwater crabs of Sri Lanka (Decapoda: Brachyura: Parathelphusidae). Zeylanica 6(2): 113:199.
- Pascal, J. P. 1988. Wet Evergreen Forests of the Western Ghats of India: Ecology, Structure, Floristic Composition and Succession. Pondicherry, India: French Institute. ISBN: 2010117905.
- Pethiyagoda, R. & Manamendra-Arachchi, K. 1998. Evaluating Sri Lanka's amphibian diversity. Occasional Papers of the Wildlife Heritage Trust of Sri Lanka 2: 1-12.
- Pethiyagoda, R. 1991. Freshwater Fishes of Sri Lanka. Colombo: Wildlife Heritage Trust. ISBN: 955911400X.
- Pethiyagoda, R. 1994. Threats to the indigenous freshwater fishes of Sri Lanka and remarks on their conservation. Hydrobiologia 285: 189-201.
- Ramesh, B.R. & Pascal, J.P. 1991. Distribution of Endemic, arbsorescent Evergreen Species in the Western Ghats. Proceedings of Symposium on Rare and Endangered Plants of the Western Ghats Kerala Forest Department. Trivandrum.
- Rodgers, W.A., Panwar, H.S. & Mathur. V.B. 2002. Wildlife Protected Area Network in India: A review . Dehradun: Wildlife Institute of India. ISBN: 8185496137.
- Roelants, K., Jiang, J. & Bossuyt, F. In press. Endemic ranid (Amphibia: Anura) genera in southern mountain ranges of the Indian subcontinent. Represent ancient frog lineages: Evidence from molecular data. Molecular Phylogenetics and Evolution.
- Siddall, M., Rohling, E.J. Almogi-Labin, A. et al. 2003. Sea-level fluctuations during the last glacial cycle. Nature 423:853-858.
- Sukumar, R. 2003. The Living Elephants: Evolutionary Ecology, Behaviour, and Conservation. New York: Oxford University Press. ISBN: 0195107780.
- Wikramanayake, E., Dinerstein, E., Loucks, C. J. et al., 2002. Terrestrial Ecoregions of the Indo-Pacific: A Conservation Assessment. Washington, D.C.: Island Press. ISBN: 1559639237.
Disclaimer: This article is taken wholly from, or contains information that was originally published by, the Conservation International. Topic editors and authors for the Encyclopedia of Earth may have edited its content or added new information. The use of information from the Conservation International should not be construed as support for or endorsement by that organization for any new information added by EoE personnel, or for any editing of the original content.