Comparison of plant diversity in protected and communal lands in the Bushbuckridge lowveld savanna, South Africa

Patterns of higher plant species richness and beta diversity were assessed using standard Modified-Whittaker plots in relation to landuse, slope posit ion and mean annual rainfall across a rainfall gradient in the savanna area s of the Bushbuckridge lowveld, South Africa. In particular, comparison of communal areas with adjacent protected areas was important in showing the i mpacts of potential changes in landuse within an overarching catchment mana gement plan. Although most of the protected areas considered preservation o f biodiversity as their primary goal, they were characterised by significan tly fewer plant species than the adjacent, highly utilised, communal lands, at both the plot and point scale. Slope position also had a significant ef fect on plant species richness, with eutrophic bottomlands having c. 30% mo re species than the dystrophic toplands. This adds weight to the need for g reater public awareness for the judicious use and management of the sensiti ve bottomlands, which fringe the primary drainage lines that are vital for sustained supplies of good quality surface water in this semi-arid environm ent. The total number of species increased with increasing mean annual rain fall across the rainfall gradient. This suggests that, if the catchment man agement plan aims to identify additional areas for conservation, the higher rainfall areas should be the first to be assessed. Species turnover was gr eater along the rainfall gradient than the catenal gradient between topland s and bottomlands. (C) 2000 Elsevier Science ltd. All rights reserved.