The impact of livestock grazing on landscape biophysical attributes in privately and communally managed rangelands in Namaqualand

Abstract

This study's objectives were to compare the impact of livestock on vegetation characteristics (species richness and cover), landscape functional attributes (nutrient recycling, water infiltration/runoff, soil stability status) and other soil chemical and physical properties at different altitudes on privately and communally managed rangelands in the vicinities of Kougoedvlakte, Kuile and Paulskraal in Namaqualand. The applicability of contemporary methodology for quantifying underlying mechanisms contributing to landscape changes was also evaluated. Statistically significant differences in soil stability status and litter cover only were observed between the differently managed rangelands, these differences independent of altitude and attributed to greater substrate disturbance by livestock. However, on both the privately and communally managed range-lands, soil nutrient and water infiltration status, rock cover, soil alkalinity, salinity and total N content were significantly greater at low than high and/or medium altitudes. These differences reflected increased livestock grazing intensity with reduced rock cover, concomitant increase in soil alkalinity with increased faecal pellet density and reduced soil salinity due to greater erosion and active leaching of less organically rich soils at lower altitudes. It is concluded that contemporary methodology applied, which was originally developed for grassland ecosystems, was unsuitable for detecting changes in critical landscape functional attributes that drive vegetation change within the succulent karoo biome.