Effect of habitat transformation on dung beetle assemblages: A comparison between a South African nature reserve and neighboring farms

The effect of habitat transformation on dung beetle assemblages in the nort h-western Free State was investigated by comparing the fauna of a nature re serve with that on neighboring farms. Dung beetle sampling was done in four different localities within two different habitat types, a grassveld area and a bushveld (savanna) area. In these two habitat types, dung beetle asse mblages in Sandveld Nature Reserve (27 degrees 37 ' S, 25 degrees 46 ' E) a nd an farms were compared. Eighty-three species belonging to 26 genera were captured in the study area. Doube's classification was used to divide the dung beetles into functional groups according to the manner in which they u se and disturb dung. The grassveld habitats were dominated by larger dung b eetles belonging to functional groups I and LI, whereas in the bushveld hab itats smaller dung beetles belonging to functional groups TV and V were dom inant. There were definite habitat preferences, with the larger dung beetle s belonging to functional group I and II preferring the grassveld habitats and having higher abundance in the natural rather than the disturbed habita ts. The smaller dung beetles, belonging to functional group V, preferred th e bushveld habitats. The better competitors (the larger dung beetles) occur red more abundantly in the grassveld habitats and also more abundantly in t he natural grassveld habitat than in the disturbed habitat. None of the ind ices measuring species richness nor dominance showed significant difference s between the four habitats. The dung beetle assemblages in all four habita ts showed a lag series pattern, with high abundance of a few dominant, high ly effective competitors and a large number of 'rare' species, which were a ssumed to be less effective competitors. This does not, however, imply that the dung beetles were similarly affected by the different habitats, becaus e the biomass of dung beetles was higher in the grassveld than the bushveld habitats and also higher in the natural habitats. B change in vegetational ground cover caused by overgrazing and trampling has a greater effect on t he larger, more effective competitors in the assemblage, whereas the smalle r less effective competitors do not seem to be affected by this change.