Effects of land tenure, geology and topography on vegetation and soils of two grassland types in South Africa

Abstract

A national degradation audit conducted in South Africa in the late 1990s found communal land tenure to be the strongest predictor of vegetation and soil degradation, while abiotic factors such as geology, slope and aspect were also correlated with degradation scores, but of secondary importance. This study compared the relative importance of land tenure, geology, slope angle and solar radiation index (calculated from aspect and slope angle) in influencing plant composition, basal cover, soil erosion and shrub encroachment in adjacent communal and commercial farming areas in two grassland types in South Africa. Sites under communal tenure had higher stocking rates and human population densities, different grass composition, lower basal cover, more bare ground, higher erosion scores and greater densities of unpalatable dwarf shrubs than commercial farms. Geology, slope angle and solar radiation had a secondary effect on some vegetation and soil variables, indicating the importance of controlling for these abiotic factors when comparing communal and commercial rangelands.

Keywords: basal cover, communal rangelands, degradation, erosion, shrub encroachment

African Journal of Range & Forage Science 2006, 23(1): 13–27