A degradation gradient for the assessment of rangeland condition of a semi-arid sourveld in southern Africa

Abstract

Data collected between 1986/87 and 1999/2000 from a long-term rangeland monitoring project on three different sites were used to construct a degradation gradient in a semi-arid sour grassland of southern Africa. The degradation gradient was then used to quantify rangeland condition of areas ranging from poor (trampled areas close to watering points) to well-managed areas and areas that degraded as a result of selective grazing due to under-utilisation. Changes in the proportion of species composition over the degradation gradient were determined using a nearest plant point technique. Indicator species for the purpose of rangeland condition assessment were identified. Elionurus muticus was identified as a indicator species for rangeland that degraded as a result of selective grazing, while species such as Eragrostis chloromelas, Eragrostis plana and Cynodon hirsutus were indicators for rangeland that degraded due to long-term overgrazing. As computer equipment can limit the use of the degradation gradient, easier alternative methods were investigated, and the accuracy of these methods was tested against the degradation gradient. The advantage of this technique lies in its simplicity and ease of use. Another advantage is that only the most important indicator and the dominant species can be used to determine rangeland condition.