How livestock grazing affects vegetation structures and small mammal distribution in the semi-arid Karoo

In this study we investigated vegetation changes superimposed by grazing and their effect on small mammals in the Karoo (South Africa) on grazed farmland and an adjacent, 10-year livestock enclosure. Plains and drainage line habitats were compared by monitoring vegetation height and cover, and small mammal species composition and abundance along transects. Animals were captured by live trapping. Vegetation cover was low on the grazed compared to the ungrazed study site, but vegetation height did not differ. The number of small mammal individuals and the number of species captured was higher at the ungrazed study site. Two species of climbing rodents captured in the ungrazed drainage line were absent from the grazed drainage line. Numbers of small mammals captured on the plains were similar for grazed and ungrazed land, but grazed plains were dominated by a single species of gerbil. (C) 2000 Academic Press.