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INTRODUCTION
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INTRODUCTION |
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The Western Ghats of the Indian peninsula constitute one of the 34 global biodiversity hotspots along with Sri Lanka, on account of exceptional levels of plant endemism and by serious levels of habitat loss (Conservation International, 2005). The rugged range of hills stretching for about 1600 km along the west coast from south of Gujarat to the end of the peninsula (lat. 8° and 21° N and long. 73° and 78° E), is interrupted only by a 30 km break in Kerala, the Palghat Gap (Radhakrishna 2001). Covering a geographical area of about 160,000 km2, the Western Ghats have an average height of 900 m, with several cliffs rising over 1000 m. The Nilgiri Plateau to the north and Anamalais to the south of the Palghat Gap exceed 2000 m in many places. Towards the eastern side the Ghats merge with the Deccan Plateau which gradually slopes towards the Bay of Bengal. The northern half of the Western Ghats is covered with basaltic rocks of volcanic origin whereas the southern half is of Pre-Cambrian rocks of different kinds like the crystalline rocks, the peninsular gneisses and the charnokites. Nearly a hundred rivers originate from these mountains and most run their westward courses towards the Arabian Sea that is close-by. Only three major rivers, joined by many of their tributaries flow eastward, longer distances, towards the Bay of Bengal (Dikshit 2001; Radhakrishna, 2001). The Western Ghat rivers are very critical resources for peninsular India’s drinking water, irrigation and electricity (Subash Chandran et al., 2010, Ramachandra et al., 2007). The region has varied forest types from tropical evergreen to deciduous to high altitude sholas. It is also an important watershed for the peninsular India with as many as 37 west flowing rivers, three major east flowing rivers and innumerable tributaries. The richness and endemism in flora and fauna of this region is well established with over 4,000 species of flowering plants (38% endemics), 334 butterflies (11% endemics) [Kunte , in Press], 290 fishes (65% endemics) [Dhanukar, et al., 2011], 157 amphibians (86% endemics) [Biju et al., 2010], 157 reptiles (62% endemics) [Hegde, 2011, Ganesh et al., 2008a, Ganesh et al., 2009., Chandramouli and Ganesha, 2010, Dasa et al., 2006], 508 birds (4% endemics) [Molur et al., 2011] and 140 mammals (12% endemics) [Karanth et al., 2009]. This mountain stretch has influenced regional tropical climate, hydrology and vegetation and endemic plant species.
The entire region is reeling under tremendous pressure from human induced changes in terms of developmental projects like hydroelectric or thermal power plants, big dams, mining activities, unplanned agriculture practices, monoculture plantations, illegal timber logging, etc. This has led once contiguous forest habitats to fragmented patches, which intern led to shrinkage of original habitat for the wildlife, change in the hydrological regime of the catchment, decreased inflow in streams, human-animal conflicts, etc. Under such circumstances, a proper management practice is called for requiring suitable biological indicators to show the impact of these changes, set priority regions and in developing models for conservation planning.
Uttara Kannada district with a spatial extent of 10,291sq.km is the second largest district in south India with good vegetation cover (68%). Dandeli Anshi tiger reserve (814.89sq.km), which is about 8% of the total area is the only protected area in the district. It is a clear indication that a single large protected area is not sufficient for the conservation and management of biodiversity of this district. The rationale for protected area networks or any region to consider for conservation and management must be based on a well-defined functional unit. A river basin (catchment) is topographically and hydrologically well defined unit, which can be very well considered for conservation management. Across various spatial scales a river basin helps to understand the ecological processes and landscape influence on biodiversity. The current focus is to prioritise conservation regions in five river basins in Uttara Kannada district, using biological indicator - amphibians (surrogate for many other species). Objectives of the current research are: