Diversity and composition of riparian vegetation across forest and agroecosystem landscapes of river Cauvery, southern India

摘要

The study aims to examine tree species richness, and composition and diversity of riparian forests across forest and agro-ecosystem landscapes observed along the river Cauvery of southern India. Riparian forest was sampled in a belt transect of size 100 à 50 m, at each of the 80 sampling plots scattered over a 318 km length along the river Cauvery. Total of 177 tree species belonging to 52 families, representing 2930 individuals, were recorded. Differences occurred between the forest and agro ecosystem landscape in terms of species richness, family richness and number of individuals observed, with a decrease in agro-ecosystem compared to forest landscape. Species similarity was low between the forest and agro-ecosystem landscapes. The Shannon-Wiener diversity index was higher for forest landscape (5.6) with more evenness in distribution. In the forest landscape, high importance value indices (IVI) were obtained for Terminalia arjuna, Pongamia pinnata, Hopea parviflora. In the agro-ecosystem, species Pongamia pinnata, Ficus benghalensis, Salix tetraspermae exhibited high IVI. Expansion of agricultural activities and other biotic pressures might have led to the variation in species composition between the forest and agro-ecosystem. Also, it has led to the decline in ripicole and evergreen species such as Hydnocarpus pentandra, Elaeocarpus tuberculatus, Madhuca neriifolia, Palaquium ellipticum, Myristica dactyloides, etc., consequently affecting the associated biodiversity of the river in the agro-ecosystem. Country needs to enact a permanent policy to protect and conserve riparian buffers to avoid further degradation and loss of biodiversity in the unregulated areas along the river. © International Society for Tropical Ecology.