Species response to grazing in the Smaldeel area of the Eastern Cape

Abstract

Species composition of the grass layer was measured in plots selected to cover a wide spectrum of condition states in six range types. This was achieved by placing 257 sample plots along contrasting fence-lines in adjacent plots on either side of the fence, and in obviously degraded range. The response of important species to grazing in each range type was determined using detrended correspondence analysis. With few exceptions, the response of species was consistent across all range types and in most cases supports previous definitions of decreaser and increaser groups. Within range types, the influence of environment on species distribution in ordination space was identified using Spearman's rank correlation analysis. Significant correlations existed between ordination axes and soil characteristics such as soil depth, clay content and surface stone. In most cases grazing induced patterns of degradation in ordination space were predominantly influenced by soil depth. Understanding the influence of environmental characteristics on grazing patterns can assist in predicting species composition within range types.

Keywords: correspondence analysis; degradation; depth; detrended correspondence analysis; dry bedford grassveld; eastern cape; ecological classes; grasses; grazing gradients; grazing pattern; grazing patterns; moist bedford grassveld; ordination; range condition; range types; smaldeel; soil characteristics; soil depth; south africa; spearman's rank correlation; species; species composition; species distribution; species responses

African Journal of Range & Forage Science, 13(1): pp. 29-36