Differences in pasture species composition as a consequence of grazing were used to develop a proposed classification of pasture species response to grazing, for both the Combretum apiculatum and the Acacia tortilis communities of the northern Transvaal mixed bushveld. The limited value of this approach is discussed in view of likely interactions with other driving forces.Woody vegetation changed in response to grazing in Acacia tortilis veld but not in Combretum apiculatum veld. Two thresholds of change were indicated, one of which coincided with soil change.The value of recognizing thresholds in pasture composition rahter than attempting to identify benchmarks is discussed. A different approach is required, using multivariate analysis to assess the effect of interacting driving forces and state variables. Advances in ecological knowledge are needed to complement the development of veld assessment techniques.Recommendations are made for veld measurement techniques.
Keywords: acacia tortilis; benchmarks; botany; bushveld; combretum apiculatum; driving forces; grass balance; grazing; interactions; mixed bushveld; multiple disturbance; multivariate analysis; northern transvaal; soil assessment; south africa; species classification; species composition; techniques; thresholds; vegetation; veld assessment