Earthworm Biodiversity in an Arid Region of Rajasthan, India

Among the soil fauna, earthworms have an important role to improve soil texture. The soil texture plays an important role in water holding capacity. Earthworms have an ability to enhance soil characteristics. It contributes to the breakdown of organic matter and release plant nutrients (Edwards and Bohlen, 1996). Earthworms are also considered as useful indicator of the health of soil ecosystem (Edwards and Bohlen, 1992) as to their role in soil fertility through fragmentation and mixed up the soil with mineral particle, enhancing microbial activity to breakdown plant organic matter. The contribution of earthworms in soil turnover, structure formation and serve as a fertility enhancer in different way. Earthworms are useful in land improvement and organic waste management (Edwards and Baker, 1992; Lavelle and Martin, 1992; Johnson, 1997; Villenave et al., 1999). The distribution and population density of various earthworm species have been correlated with soil type and agriculture land use (Haynes et al., 2003; Sbrina et al., 2009). The biodiversity of earthworms is influenced by physical, chemical and biological properties of soil and climatic conditions of habitats. Earthworm’s biodiversity is directly affected by soil characteristics (Edwards and Lofty, 1977). These community influencing factors are soil pH, organic matter, nitrogen, C/N ratio, soil moisture and soil texture. Biodiversity is counted as human resources (Heywood, 1996). Recently, many biologists studied the biodiversity and distribution of earthworms in the different parts of the world (Blakemore, 2000, 2002, 2003; Change and Chen, 2004,2005; Blakemore et al.,2006; Sautter et al., 2006; Ghafoor et al., 2008). Present study was done in Bikaner district, which is located in Thar desert of Rajasthan ranging 28.01° N 73.19° E.
. The average rain fall in this area is 10” to 15” only. Therefore, climatic conditions are adverse for organisms. Most of its area is irrigated