Changes in soil characteristics and grass layer condition in relation to land management systems in the semi-arid savannas of Swaziland

摘要

The issue of sustainability and productivity of open communal rangelands compared to fenced range-lands is often subject to controversy. This study investigated differences in soil and grass layer variables between land management systems having high (communal land), low (government ranch) and medium (game reserve) stocking rates, and soil types (lithosol and vertisol or raw mineral). The results showed that differences in land management systems had caused considerable variations in most soil and vegetation variables. Soil from low or moderate stocking rate had highest K, Ca, P and N levels. Cenchrus ciliaris, Panicum maximum and Heteropogon contoitus were most abundant in the low stocking rate, while annuals Tragus berteronianus and Aristida bipartite were most frequent on high stocking rate. There were differences in frequency of these species between soil types. Significant variations for most vegetation and soil variables between land management systems suggested grazing pressure differences might be the primary cause. This supports the equilibrium model, which stresses the importance of livestock density on the soil and vegetation dynamics.