Distribution and substrate specific studies on earthworms confined to Theni and Dindigul districts Tamilnadu

Abstract

India is a country of mega diversity with two biodiversity hotspots - Western Ghats and Eastern Himalaya. Although its area is only two percent of the world s landmass, it supports about 11 percent of the total known global earthworm diversity.They are designated as Ecosystem Engineers and play an important role in improvement of soil physical structure, organic matter dynamics and nutrient cycling rate through their feeding, burrowing and casting activities. They form one of the major macrofauna among soil biota to maintain dynamic equilibrium and regulate soil fertility. In the present study earthworm survey was undertaken in different habitats of four selected agricultural stations of Theni and Dindigul Districts, Tamilnadu, India. A total of 8 families and 35 species in Theni District and 6 families and 27 species in Dindigul District were sampled from different stations. The habitat and the density of earthworms of each station were noted. The ecological indices such as the earthworm abundance, diversity, species richness, evenness and percentage of distribution of earthworms of two districts were calculated and compared.The Shannon diversity, species richness and evenness indices were higher in Theni District when compared to Dindigul District. Population density of earthworms are negatively correlated with temperature and positively correlated with humidity and rainfall. As Earthworms are the major soil fauna may be regulating the physico-chemical properties of the soil and promote the soil fertility. The GIS map was used in the present investigation for soil suitability classification for saveing time and making ease the physicochemical parameters of soil and water. There existed a significant correlation (Pgt0.05) between the distribution of earthworms in two districts and mean value of temperature, physico chemical factors of soil (Ec, pH, N, P, K, Mg, and Fe)water (Ec, pH, HCO3, Cl, SO4, Ca, and Na). newline