1. INTRODUCTION
1.1 Western Ghats: One of the 34 Biodiversity hot spots of the world, the Western Ghats, together with the west coast form an important ecological region, springing from the Arabian Sea coast to the montane heights of over 2,000 m. The Western Ghats form a practically unbroken relief dominating the western coast of the Indian peninsula for almost 1600 km from the mouth of the river Tapti (21o N) to the tip of South India (about 8o S), covering an area of approximately 160000 km2. The Ghats have an elevation range of 300-2700 m and a latitudinal spread from 8o N to 20o N. Palghat gap in Kerala is a major gap in this mountain range which was a part of the Indian plate of the Gondwanaland. The flow of Deccan lavas resulted in horizontally stratified mountains in the Deccan traps north of the river Krishna (Nayar, 1996). The origin of the of Peninsular India, particularly that of the Western Ghats and its complexity and diversity need to be viewed against the back drop of much-researched phenomenon of plate tectonics (Raven and Axelord 1974). India certainly appears to have remained connected to Madagascar and Africa until at least 100 m.y BP (million years before present) thereafter commencing its northward motion until it collided with Asia by mid-Eocene.
The Western Ghats straddle the states of Kerala, Tamil Nadu, Karnataka, Goa, Maharashtra, and southern Gujarat. Just as the Himalayas Preside over the biogeography of India, the Western Ghats to a large extent presides over the ecology and biogeography of Peninsular India (Subramanyam and Nayar, 1974). Its presence creates major precipitation gradients. This apparent unity in fact masks the great heterogeneity of the environmental conditions resulting from geographical, geological and demographic differences. The physiographic and geological diversity in the Deccan traps of basaltic rock north of the Krishna basin and of Precambrian crystallic rocks formed of granites, gneiss south of the Krishna basin are conspicuous. The soil consists of black soil, laterites and red loam and coastal alluvium. The annual rainfall varies from 2350 in the north to 7450 mm in the south which makes the Western Ghats the water shed of the Peninsula. (Nair and Daniel, 1986). Godavari, Krishna and Cauvery are the major east flowing rivers from Western Ghats. The West coast is intersected by over 80 rivers that run their shorter courses before joining the Arabian Sea.
The latitudinal and altitudinal gradients, rainfall patterns brought in by South-West and North-East Monsoons, the rapid decline in rainfall on the leeward side of the mountains, the Deccan Plateau, the presence of mosaic of soil types, variations in soil nutrients and over three millennia of vegetational changes caused by human impacts have resulted in a mosaic of ecological islands, niches and refugia which favour high degrees of endemism and relic species. According to Stebbins and Major (1965), in regions on the borderline between zones of adequate moisture and deficient moisture, even small climatic shifts will change local conditions beyond the limit of tolerance of the resident species, so that they may either migrate or evolve new ranges of tolerance. Over a distance of 20 km, the dry season ranges from 3 to 8 months due to relief, wind flow in the gradient on the leeward side, resulting in the formation of a unique flora in small ecological islands and the borderlines of wet evergreen moist deciduous dry evergreen and dry deciduous forests (Nayar, 1996).
1.2 The flora: The flora of Western Ghats comprises about 12,000 species from unicellular cyanobacteria to the flowering plants. In this spectrum of the flowering plants of Western Ghats comprises about 27 % of the Indian flora. Of the 4,000 species of flowering plants about 1,500 species are endemic species (Nayar, 1989). The presence of alpha diversity in Western Ghats depends on the four niches; habitat phenology, growth form and regeneration tactics. The species packing in the close evergreen forest is based on the growth form of the canopied trees, second storey species, lianas, epiphytes, shade tolerant shrubs, herbs and saprophytic ground flora. Of the 4,000 species of flowering plants about 3,100 species occur in the wet evergreen forests. The growth forms are result of plant segregation due to light requirements, and availability of space.
1.3 Endemism-Biodiversity hotspot: One of the main and easily identifiable components of biodiversity is endemism. While biodiversity is the biological capital of the Earth, endemic flora and fauna (which includes genes, species and ecosystems) of a region or nation are the exclusive biological capital of that region or nation (Nayar, 1996). Endemism encompasses taxonomic units of any rank or taxa (includes plants, animals and microorganisms), which occur in a biogeographical area usually isolated by geographical, ecological or temporal barriers. The areas of endemism may be large or small. The degree of endemism increases with increase in size of a homogenous biogeographical area having the same floristic history and ecological conditions. The distribution of endemics usually follows biogeographical provinces, patterns of unique ecological features, topographical and climatic interfaces. Endemic taxa restricted to a particular Peninsula, mountain range, an island or a mountain peak may be well remnants of an ancient flora which in the course of geological and climatic changes found refugium in isolated or restricted geographical region. Endemics once lost, it is an irretrievable loss for the region or nation (-ibid-)
The floral distribution in Western Ghats is not uniform; it varies between region to region. These distributional variations are clearly visible along the latitudinal gradient from southern tip to the northern part of the Western Ghats. More endemic species are occurring in the lower latitudes and decline drastically in higher latitude. The main contributory parameters for the changes in the vegetation in Western Ghats are the climatic gradients and the local topographic variations (Ramesh and Pascal, 1997). The reliefs of the Ghats act as a barrier to the eastward movement of the cloud masses brought by the summer monsoon winds. These masses bring prodigious amounts of rainfall over the reliefs of the Ghats causing diminished rainfall towards the east. This decrease results in the isolation of moist formations which are confined to the humid regions with a high rainfall (west east gradient). Lengthening of the dry season from low latitude to higher i.e., the duration of the dry season gradually increases from one month in the southern part of the Ghats to over eight months north of Mumbai. This gradient is determining richness of the biodiversity of a region and also endemism. (Ramesh and Pascal, 1997; Pascal, 1988).
1.4 Importance of Kans: As we go from southern part of the Western Ghats to northern region declining trend is observable in plant species richness. The existing evergreen forests are practically all localised in a narrow strip extending from the foot of the Ghats almost to summit (in south Kerala) and to about 10-20 km beyond the edge of the plateau (from Palghat, northwards). Towards the northern parts as well there are isolated patches of primary evergreen forest more or less similar to southern forests in floristic and faunal richness. On the Karnataka plateau some forests are about 20-40 km away from the present eastern limit of the evergreen continuum, and constitute evergreen or more often semi evergreen islets surrounded by moist deciduous formations. These islets may be considered as the relics of the past extent of the evergreen forests (Pascal, 1988). Even though many parts of the Western Ghats are subjected to severe anthropogenic pressures these types of relic formations keep their identity up to this period. These relic forests are known as kans in central Western Ghats of Uttara Kannada and Shimoga. The backdrop of the ecological history makes it clear that since time immemorial people preserved these forest patches as abodes of local deities. These kans are places where ancient vegetation is intertwined with the socio-cultural and religious practices. The kans are similar to Devarakadus of Coorg and Kavus in Kerala.
The genesis of sacred groves in the Western Ghats may go back to hunting gathering societies which attributed sacred values to patches of forest within their territories as they did to several other topographic or landscape features like mountain peaks, rocks, caves, springs and rivers. But practice of setting aside patches of forests as sacred groves would have strengthened with the spread of agriculture, when slashing and burning of forest on a massive scale caused decline in biodiversity and diminished water shed. The groves, in addition to their role as the abodes of gods, would have protected a range of landscape elements with their characteristic biodiversity (Chandran et al, 1998).
Kans ranging in area from part of a hectare to few hundred hectares and protected from time immemorial, may be considered as the best samples of climax forest of the region. Even when the protection has become less stringent these days any removal of live wood continuous to be taboo. Today these groves therefore serve critical function like sheltering rare plants, protection of the water resources, and being the only remnant of tree vegetation along the country are also the main sources of leaf litter Most of the Kan forest are endowed with faunal richness. They often serve as the last refuge for arboreal birds and mammals, especially monkeys (Chandran and Gadgil, 1993). The landscape heterogeneity and biodiversity are positively correlated within this ecosystem. These groves formed part of a landscape of well connected natural elements and functioned as refugia for many species of plants and animals. The medical plants from groves are known to cure many ailments according to traditional medicinal system (Devar 2008). Kan forest act as a seed banks for many important species and it would have ideally helped in forest regeneration and restoration around it through supply of seeding material.
The evergreen kan in traditional land use system acted as fire proof barriers protecting surrounding landscape elements from catching fire. Sacred groves operate as microwater sheds in local areas (Pushpangadan, et al, 1998). The grove increases the watershed value of the area by enhancing the recharging process of ground water by increased filtration. The non timber products obtained from the kan forests aided subsistence of local people. The produce included edible fruits, spices, honey, toddy, etc. The kans during the pre British time were well known centers for pepper (Chandran and Gadgil, 1993).
The British occupation of the Western Ghats, from early 19th century, set the tone for forestry operations to date (Chandran, 1997). Government reservation of kans following the Indian Forest Act of 1878, Uttara Kannada as state forests, followed by introduction of contract system for collection of non wood produce, which replaced the community management (Wingate, 1888). Reservation of the forest would have led to the villagers losing their hold over the kan.
Exploitation of the evergreen forests during 1940-1980 has affected the forest resources. During Second World war trees such as Calophyllum tomentosum, Artocarpus hirsutus and Tectona grandis were removed from the forests for ship building. Dipterocarpus indicus, an evergreen tree exclusively present in some kan forest was supplied to the railways and plywood companies (Shanmukhappa, 1977). Selective logging continued in these forests till it was banned in 1987. Despite anthropogenic influence of varied kinds continuously operating on the kan forests, many kans still harbour an enriched assemblage of flora and fauna compared to the adjoining forest patches.
1.5 Significance of Kathalekan: Kathalekan the focal area of this report was once, in all probability such a kanprotected by the peasant community in the past. What prompted this study is the fact that a good part of the sample area to this day retains features of a primeval forest. It is a homeland for various Western Ghats endemic species. In its species composition it shows similarity with Western Ghats southwards having Dipterocarpus indicus dominated forest than with north having Persea –Diospyros community. In addition to Dipterocarpus indicus are also found Palaquium ellipticum, Mesua ferrea, Myristica fatua, Gymnacranthera canarica, Pinanga dicksonii which are rather absent or rare in forest of northern latitude. The Myristica swamps of the Kathalekan are more similar to those of Travancore than anything such in the north. It is also almost the northern most range for distribution of the Lion Tailed Macaque.
It is unfortunate that such forest has not captured adequate attention of conservationists and forest management although some sporadic studies have been carried out here, especially in the Myristica swamp region. Selection felling and enormous incidental damages would not have taken place if there was more comprehensive ecological studies conducted earlier. At least today such opportunity has been used to conduct a co- ordinated and systematic ecological study of Kathalekan. This study with interesting findings hopefully may lead to more fruitful outcome in future, especially in the form of a more scientific management plan.
1.6 Objectives of the Study
Main objective of this study is to understand the ecology and conservation aspects of sacred kan forests in central Western Ghats. This involve:
- reconstruct forest history so as to understand the past of Kathalekan forest;
- decipher vegetational composition and structure (restricted to flowering plants) by using ecological survey methods;
- analysis of field data for diversity, evergreenness and endemism;
- exploring the regeneration related details of tree species of the region; and
- investigate anthropogenic threats operating in the study area and to formulate conservation plans.
