Impact of overgrazing on seed predation by rodents in the Thar desert,northwestern India

We compared the vegetation structure, rodent density and seed loss rate between protected and disturbed sites affected from grazing by cattle, goats and sheep, in the Thar desert of India. A perennial tussocky grassLasiurus sindicus Hent. was largely dominant in the protected site, whileL. sindicus was rare and replaced by undershrub speciesAerva pseudotomentosa Blatt. & Halb. andCrotalaria burbira Buch.-Ham. in the overgrazed site. In the grazed site, plant coverage was low, but the density of rodent burrows and the frequency of rodent captures were significantly high as compared to the protected site. Corresponding with the density of desert rodents, seed predation was significantly higher in the grazed site than in the protected site. These results suggest that overgrazing by large mammals has strong effects on plant succession by altering not only the species composition and abundance of plant community, but also the habitat suitability for seed-eating rodents.