INTRODUCTION |
The Western Ghats is one among the 34 global hotspots of biodiversity and it lies in the western part of peninsular India in a series of hills stretching over a distance of 1,600 km from north to south and covering an area of about 1,60,000 sq.km. In the course of our ecological studies in the Uttara Kannada (formerly North Kanara) district of central Western Ghats, we came across two critically endangered tree species, far away from their home range much in the south. These trees viz., Madhuca bourdillonii (Gamble) Lam. and Syzygium travancoricum Gamble, were even considered almost extinct. Their rare presence in some of the relic evergreen forests of Uttara Kannada, over 700 km towards the north of their original home range, in southern Western Ghats, that too beyond the geographical barrier of the Palghat Gap, which halts the continuity of several sensitive endemics, throws up before us fresh questions regarding conventional approach to conservation, which has not given due merit to the ecological history of the region. These tree species occur in the vicinity of some of the Myristica swamps of the district, which are obviously part of the relic patches of primeval low altitude evergreen forests that survived human impacts to some degree. Historically, the overall forest disturbance in the Western Ghats increased in spatial extent as well as in intensity, during the post World war era, with the emphasis on industrialization and economic development. Forest based industries coupled with large scale hydroelectric projects and conversions of forest land for agriculture have contributed significantly in the decline of primeval forests. The Myristica swamps did not get enough attention until Chandran and Mesta [1] reported them as highly threatened relics of primeval forests of the Western Ghats. These swamps have high watershed value and are associated with perennial water courses. They also act as a treasure trove of endemic plants and animals of ancient lineage. These swamps are dominated by species of Myristicaceae (nutmeg family), one of the most ancient families of flowering plants. Myristica fatua var. magnifica (Bedd) Sinclair and Gymnacranthera canarica (King) Warburg, are tree species exclusive to the swamps. Recent discovery of Semecarpus kathalekanensis, an altogether new tree species of the mango family Anacardiaceae [2], in these swamps has created ripples in the conservation circles.
The micro-heterogeneity of these relic evergreen forests has several more endemic and interesting plant species, which include the trees Dipterocarpus indicus, Mastixia arborea, Agrostystachys longifolia and Myristica malabarica (Fig. 1); an undergrowth palm Pinanga dicksonii, a species of pepper Piper hookerii, a tree fern Cyathea nilgirica, etc. Lion-tailed macaque, an endemic endangered primate of the Western Ghats, has its northern-most range in the relic evergreen forests of southern Uttara Kannada, which also often harbour Myristica swamps. In addition are several other rare endemic animal species, which include amphibian genera like Nyctibatrachus and Micrixalus. The Myristica swamps of southern Uttara Kannada are found to harbour 29 species of amphibians of which 19 are Western Ghat endemics. Birds like Wyanad laughing thrush and Malabar pied hornbill associated with these swamp forests are also endemics. Phylloneura westersmanii, a damselfly of endemic monospecific genus Phylloneura was recently found in Myristica swamps of Siddapur (14.5° N), the northern range of which was earlier considered to be Coorg (12° N) district [3].
The Myristica swamps, which are sure indicators of relics of primeval forests of the Western Ghats, today occur in isolated patches; the southern-most swamps are found in Travancore region and the northern-most occur in Goa. Due to ever increasing human impacts, over the last few centuries, most of the primeval forests have given way to secondary forests, savannas, monoculture tree plantations, cash crops such as tea, coffee and rubber, rice fields, arecanut gardens, etc [4,5]. In addition, developmental projects such as hydel, and nuclear power plants, mining, etc., have mushroomed especially during the post-independence period. Nevertheless, the remains of numerous ancient sacred groves, specially preserved pepper forests of the past and many forest patches with difficult approach are serving as repositories of the endemic biodiversity of Western Ghats. Recent study of Western Ghats using WiFs (wide field sensor with spatial resolution of 70 m) remote sensing data mapped certain unique evergreen forest patches, which coincided with Myristica swamps, Ochlandra reed ecosystems and Nagea wallichiana facies [6], which are obviously relics of primary evergreen forests.
Myristica swamps are considered as priceless possessions for evolutionary biology. The swamp, with its entanglement of aerial roots, and canopy of dark green large leaves, and high degree of endemism, is doubtlessly, the relic of one of the most primeval ecosystems of the Western Ghats. As much remained undone regarding the diversity and ecology of these swamps, they are considered “virtually live museum of ancient life of great interest to biologists”[1,4]. With the presumption that the Myristica swamps and their immediate surroundings, studded with Dipterocarpus trees (Fig. 1), could shed some light on the nature of the primeval low altitude evergreen forests of Uttara Kannada district, we began surveying these forest relics more systematically. Our search resulted in the discovery of two critically endangered tree species viz., Madhuca bourdillonii (Gamble) Lam. and Syzygium travancoricum (Gamble). We consider the occurrence of these species in Uttara Kannada as very significant due to the following reasons:
