Herbaceous biomass, species composition and soil properties of keygrazing patches in coastal forest thornveld and two grassland types of theEastern Cape province, South Africa

Abstract

In spite of predictions of communal rangeland collapse due to continuous grazing and increased livestock populations, this grazing system remains prevalent in communal areas, suggesting animals utilise heterogeneity found in these areas. A study was conducted to compare biomass and herbaceous species composition in patches frequently grazed by cattle to randomly selected control sites in three communal areas located in Lesotho Highland Basalt Grassland (Magwiji), Bhisho Thornveld (Mnyameni) and Tsomo Grassland (Cala). The relationship of vegetation parameters in frequently selected patches to the corresponding soil properties, topography and human impact was also examined. Biomass of frequently selected patches was significantly (p < 0.05) higher in the dry season (June) at Magwiji (528 kg ha⁻¹) than in less frequently selected patches (130 kg ha⁻¹). There was an association between sites selected in winter and soil organic carbon, and these sites were dominated by Cynodon dactylon and Pennisetum clandestinum. The floristic patterns observed in Magwiji were associated with soil organic carbon content. Low-lying swampy patches had high soil pH in Cala, while mountain top soils in Magwiji had low electrical conductivity and these areas selected in winter were associated with grass species such as Eragrostis superba and Heteropogon contortus.

Keywords:

• cattle
• graze
• key resource areas
• livestock