Responses of Raninforest Lizard Communities to Tea Plantation Edges in the Anamalai Hills of Southern Western Ghats India

Abstract

Human-made edges are an omnipresent form of altered habitats across the entire Western Ghats landscape. Furthermore a diverse range of edge types exist differing in the structure and composition of their altered surrounding habitat. Only a few attempts have been made to study the influence of the structure of this adjoining habitat or the 'matrix' on edge effects. Understanding the influence of different matrix habitats on edges will lead to the better understanding of the abiotic and biotic influences of the matrix on forest edges. Vegetation structure and composition has been the subject of several studies pertaining to fragmentation as well as effects of edges and both primary as well as secondary responses to edge effects have been documented. It has also been noted that while the reduction in plant species richness may occur as a result of decreasing forest area, it is more likely that this could be the result of increasing perimeter to area ratio resulting from fragmentation and increased proportion of area exposed to edge effects. The abiotic as well as biotic changes which affect vegetation not only bring about structural changes such as those in canopy cover, vertical stratification, density etc, but also affect functional aspects of plant communities such as pollination, seed dispersal and germination. Faunal communities respond in various ways to changes in their habitat; these may include changes in abundance, species richness, structure and composition of communities as well as behaviour of individual species. With respect to edge effect these changes or may vary in their magnitude and the distance or depth to which they penetrate into the interior. Magnitude and depth of influence are two complementary but distinct aspects of edge effects. Magnitl1de of influence is the degree to which a response value (a biotic or abiotic variable used to measure edge effects) differs between the edge and the interior while depth of influence if the maximum distance to which edge effects percolate into a habitat. However. A large amount of research on this topic has been restricted to birds and mammals and the responses shown by them might not be representative of the responses of other lesser known taxa.