Vegetation of inland endorheic pans in the North-West Province, South Africa
Cilliers, Sarel S.; Bredenkamp, George J.
Wetlands in South Africa are often small and ephemeral because of low rainfall and high evaporation. Endorheic pans are well defined, natural, shallow, circular to oval depressions with no outlet, which are semi-permanently or periodically filled with water and occur in areas of less than 500 mm mean annual precipitation. Many of these pans dry up seasonally, mainly through loss of water by evaporation and they often have highly saline soils and contain high concentrations of sodium chloride and sulphates of sodium, calcium and magnesium. Although few vegetation studies have been done on pans, they are of ecological importance as part of the broader landscape of arid regions and of further ecological interest for their own biota, specifically during the periods that they hold water, and because of the briefness of those periods and the limited availability of water. This paper reports on a vegetation analysis of a number of representative pans in the arid North-West Province of South Africa. A total of 8 plant communities and 13 subcommunities are described in this study. Soil salinity, clay contents of the soil, the degree of soil dispergation, and anthropogenic influences, such as trampling and grazing, are the most important determining factors for the different plant communities.