Threatened Ecosystem of Western Ghats (Review)
By Arnab Goon (Research Associate, Department of Ag. Chemicals, Bidhan Chandra Krishi Viswavidyalaya, West Bengal)
The Western Ghats constitute a mountain range along the western side of India. Their positioning makes the Western Ghats biologically rich and bio-geographically unique – a veritable treasure house of biodiversity.Though covering an area of 180,000 square kilometers or just under 6% of the land area of India, the Western Ghats contain more than 30% of all plant, fish, herpeto-fauna, bird and mammal species found in India. It is a UNESCO World Heritage Site and is one of the eight “Hottest biodiversity hotspots”.This region has over 5000 species of flowering plants, 139 mammal species, 508 bird species and 179 amphibian species; it is likely that many undiscovered species live in the Western Ghats. Many species, in fact 50% of India’s amphibians and 67% of fish species are endemic to this region. At least 325 globally threatened species occur in the Western Ghats.
The range runs north to south along the western edge of the Deccan Plateau and separates the plateau from a narrow coastal plain, called Konkan, along the Arabian Sea.The hill ranges of Western Ghats extend from the Satpura Range in the northto south through Maharashtra, Goa, Karnataka and into Kerala and Tamil Nadu. Major gaps in the range are the Goa Gap, between the Maharashtra and Karnataka sections and the Palghat Gap on the Tamil Nadu and Kerala border between the Nilgiri Hills and the Anaimalai Hills.The mountains intercept the rain-bearing westerly monsoon winds and are consequently an area of high rainfall, particularly on their western side. The dense forests also contribute to the precipitation of the area by acting as a substrate for condensation of moist rising orographic winds from the sea and releasing much of the moisture back into the air via transpiration, allowing it to later condense and fall again as rain.
The Western Ghats include a diversity of ecosystems ranging from tropical wet evergreen forests to montane grasslands containing numerous medicinal plants and important genetic resources such as the wild relatives of grains, fruit and spices. They also include the unique shola ecosystem which consists of montane grasslands interspersed with evergreen forest patches.
The Western Ghats have several manmade lakes and reservoirs. The well known lakes are the Ooty (2500m altitude) in Nilgiris and the Kodaikanal (2285m) and the Berijam in the Palani Hills. The majority of streams draining the Western Ghats and joining the Rivers Krishna and Kaveri carry water during monsoon months only and have been dammed for hydroelectric and irrigation purposes. The Western Ghats form one of the four watersheds of India, feeding the perennial rivers of India. Important rivers include theGodavari, Krishna, Kaveri, Mandovi and Zuari.Fast running rivers and steep slopes have provided sites for many large hydro-electric projects. There are about 50 major dams along the length of the Western Ghats.
The Western Ghats are home to thousands of animal species including at least 325 globally threatened species. Many areendemic species, especially in the amphibian and reptilian classes. Thirty two (32) threatened species of mammals live in the Western Ghatsamong which 16 endemic mammals, 13 are threatened.
There are at least 139 mammal species. The critically endangered mammals of the Western Ghats are the nocturnal Malabar large-spotted civet, Nilgiritahr, arboreal Lion-tailed macaque, asian elephants, tiger, Nilgirilangur, leopard, vulnerable sloth bears,Wroughton’sfreetailed bat, Theobald’s tomb bat, Lesser False Vampire bats etc.
The snake family Uropeltidae of the reptile class is almost entirely restricted to this region.
The amphibians of the Western Ghats are diverse and unique, with more than 80% of the 179 amphibian species being endemic to the region. Most of the endemic species have their distribution in the rainforests of these mountains. The endangered Purple frog was discovered in 2003 to be a living fossil. Four new species of Anurans belonging to the genus Rhacophorus,Polypedates, Philautus and Bufo have been described from the Western Ghats.
102 species of fish are listed for the Western Ghats water bodies. Western Ghats streams are home to several brilliantly coloured ornamental fishes like Red line torpedo barb, Red-tailed barb,Osteobramabakeri,Günther’s catfish and freshwater puffer fish Tetraodontravancoricus, Carinotetraodon imitator and marine forms likeChelonodonpatoca, mahseers such as Malabar mahseer.
There are at least 508 bird species. Most of Karnataka’s 500 species of birds are from the Western Ghats region.There are at least 16 species of birds endemic to the western Ghats including the endangered Rufous-breasted Laughingthrush, the vulnerable Nilgiri Wood-pigeon, White-bellied Shortwing and Broad-tailed Grassbird, the near threatened Grey-breasted Laughingthrush, Black-and- Irufous Flycatcher, Nilgiri Flycatcher, and Nilgiri Pipit and theleast concern Malabar Parakeet, Malabar Grey Hornbill, White-belliedTreepie, Grey-headed Bulbul, Rufous Babbler,WynaadLaughingthrush, White-bellied Blue-flycatchers and the Crimson-backed Sunbird. The management status of the wildlife sanctuaries in this part of India varies enormously. Almost one-third of all the flowering plant species in India are found in this region. Of the 450-odd plants found in this region, 40% are endemic (these are species that have adapted to thisparticular area and the conditions existing in it.) There is an equal diversity of animal and bird life. A few of the indigenous and exotic tree and plant species in the Western Ghats are the teak, jamun, cashew, hog plum, coral tree, jasmine and crossandra.
During the past 40 to 50 years the plant and animal life has as a whole suffered due to so-called development and urbanization, which has led to the extinction of many species and more are in danger of becoming extinct.
Western Ghats is a significant ecosystem with a large expanse through several state boundaries, so its management as such is guided by the state policies and economic gains that the states might earn through various projects. Being a very significant ecosystem, the Western Ghats is shadowed by two proximate threats which are localised threats and landscape level threats. The main problems of the Western Ghats region are the pressure of increasing population on land and vegetation, undesirable agricultural practices etc. These factors have contributed to ecological and environmental problems in the region. The fragile eco-system of the hills has come under severe pressure because of submersion of large areas under river valley projects, damage to areas due to mining, denudation of forest, clear felling of natural forests for raising commercial plantation, soil erosion leading to silting of reservoirs and reduction in their life span and the adverse effects of floods and landslides, encroachment of forest land and poaching of wild life etc. As per estimates, only about 24.8% of the forests in Western Ghats landscape are unfragmented, the rest either destroyed or fragmented by allowing mining, infrastructure projects of varying intensity. With the rich natural resources sitting in the lap of Western Ghats, the development or growth model wants to exploit the resources at a much larger pace than ever. Only in the last two years about 118 new mining leases have been granted in the forest areas of Goa, thermal plants in Konkan region, massive tunneling and hill cutting for highways and railways in the Sahyadris in Karnataka and Tamil Nadu presents a cumulative threat to such a rich ecosystem and unless there is a systematic, informed and coordinated as well as participatory action to deal at the landscape level, the current wave of development and its ill perceived impacts would take its toll on this rich ecosystem. Government introduced a large number of Acts, Rules and Regulations which can be utilized for this purpose. The Government of India established many protected areas including 2 biosphere reserves, 13 National parks to restrict human access, several wildlife sanctuaries to protect specific endangered species and many Reserve Forests, which are all managed by the forest departments of their respective state to preserve some of the ecoregions still undeveloped. A total of thirty nine areas including national parks, wildlife sanctuaries and reserve forests were designated as world heritage sites – twenty in Kerala, ten in Karnataka, five in Tamil Nadu and four in Maharashtra. Different groups are actively working in the Western Ghats to help the forest department in conserving the Protected Areas and also secure critical corridors in these landscapes.
Thus combinations of several factors facilitate or deter specific species from retaining a healthy breeding population in the Western Ghats. These factors include habitat quality, reduced fragment size, increased edge effects and extent of isolation. Ecorestoration using a carefully designed strategy that creates room for recovery requires both corridoring as well as managing patch habitat quality. The Ecologically Sensitive Areas (ESA) would have to be managed through scientific ecorestoration programs. This will essentially require detailed habitat studies so that populations of habitat specific species are able to recover in the ESAs