Plant species composition on two rock outcrops from the northern Western Ghats, Maharashtra, India

Abstract

The Western Ghats are full of high altitude plateaus/rock outcrops amidst mesic forests. Throughout the world, rock outcrops are isolated habitats and known for their uniqueness with respect to environmental variables and biodiversity and well known as centers of species endemism. In India such special habitats are geographically known but very less information is available about their floristic wealth. Available studies are occasional and limited to ecology. Due to a lack of appropriate information and errors in the study models of random sampling, important habitats may get misinterpreted and pose a threat to conservation. A comprehensive botanical study of two rock outcrops, Durgawadi Plateau (DP) and Naneghat Plateau (NP), on the escarpment of the northern Western Ghats revealed a very high within-site (360 taxa on DP and 249 taxa on NP) and between-site plant diversity totaling to 443 taxa of specific and infraspecific ranks. The individual outcrop areas are very small (2.8793km2 and 0.7524km2 respectively for DP and NP) but harbor a huge diversity of flowering plants. The commonly shared taxa are relatively low (37% of the taxa recorded) indicating that the two outcrops are floristically very distinct from each other. They are also distinct in terms of soil composition, though on the same crest line of Sahyadri and quite close to each other. The study emphasizes the need for micro-level inventories of smaller areas by taking intensive surveys for documentation of different aspects of the abiotic and biotic diversity as well as other environmental and anthropogenic variables.