Vegetation gradients around cattleposts in the eastern mountains of Lesotho

Abstract

The grasslands of the mountains in eastern Lesotho support large numbers of sheep, angora goats and other livestock during the summer, during which they are corralled nightly by herders at cattleposts. Few studies, however, have quantified the impact of grazing on the composition and structure of the mountain grasslands. Gradients of grazing and trampling intensity related to distance from 23 cattleposts in the subalpine and alpine belts (2 650–3 175 m above sea level) were examined to describe the long-term effects of livestock on unpalatable dwarf shrubs, bare area and plant species composition. The potential for shrub invasion and bare areas (low herbaceous cover) to develop was highest near cattleposts. Species composition also changed significantly along the grazing gradient, accompanied by a shift in dominants from grazing-sensitive to grazing-resistant grasses and shrubs. Species either decreased or increased monotonically along the grazing gradient or had an intermediate, unimodal response. The relative positions of species’ centroids along the grazing gradient were used to quantify their grazing sensitivity on a scale from 10 (most sensitive) to 0 (most resistant), which confirmed and contradicted previous classifications of their grazing responses. Basic ecological research on this important mountain grazing and catchment system is recommended.

Keywords: grazing intensity, grazing sensitivity, piosphere, shrubs, species composition