Community structure and species composition along a disturbance gradient in a communally managed South African savanna

Abstract

The woody and herbaceous vegetation was investigated around four rural settlements in the savanna area of the eastern Transvaal Lowveld, South Africa. At each settlement three transects radiating out from the settlement, representing a gradient from high to low disturbance, were sampled for community structure and species composition. In general, attributes of woody community structure (density, height, biomass, basal area and diversity) were negatively related to increasing disturbance. Herbaceous cover responded positively. Although individual woody species exhibited a range of responses to disturbance, overall species compositional changes were not related directly to the intensity of disturbance. Individual woody species were classified into behavioural species response groups according to their response along the disturbance gradient. Local wood harvesters demonstrated marked selection for particular species and size classes, which should have disproportional impacts on community structure. However, proportional size class distributions were little altered along the gradient.