The impact of two different grazing systems on arthropod and small mammal communities was investigated by comparing species diversity and abundance between Gellap Ost (S10) and Nabaos (S11) on two-hectare plots seasonally during the period 2001–2003. Assessing and monitoring of the small mammal populations was achieved using capture-mark-recapture methods. Arthropods were collected in pitfall traps. For both groups, species richness, total abundance and species diversity were lower in the overgrazed area. The most abundant small mammals were two gerbil species. The Bushveld Gerbil ( Gerbilliscus leucogaster) occurred frequently at Gellap Ost but did not occur at the overgrazed Nabaos site, while Gerbillurus vallinus, a species adapted to xeric conditions, favoured the degraded land. It is also obvious that uncontrolled grazing in the communal lands has led to land degradation, which has affected the biodiversity as indicated by the shift from “savannah communities” to “desert communities” of beetles and small mammals.