Historical changes in stocking rates of domestic livestock as a measure of semi-arid and arid rangeland degradation in the Cape Province, South Africa
Authors: W. R. J. Dean, and I. A. W. Macdonald
Journal: Journal of Arid Environments
Summary of Methods: Historical changes in stocking rates of domestic livestock on fenced ranches was used to determine if rangeland degradation has taken place in semi-arid and arid rangelands of Cape Province, South Africa (27° S, 23° E) South Africa. The numbers of all domestic livestock animals from agriculture censuses from 1840 through 1981 were converted to large stock units (LSU) (1 LSU = one bovid weighing 420 kg). Mean annual rainfall and stock-water points within each district were investigated and analyzed in relation to percent change of stocking rates and livestock units per 100 ha.
Article Summary / Main Points: Nearly all semi-arid and arid districts examined showed a 44% reduction in stocking rates between 1911 and 1981. For all savannah districts examined, stocking rates increased approximately 37% over the same period, with peak stocking rates during 1940-60. Certain districts in the eastern region showed both past and present stocking rates were correlated with mean annual rainfall. Other districts showed a minor correlation between rainfall variability and stocking rates suggesting that stocking rates were not directly influenced by variability of rainfall and higher probabilities of drought. The total number of stock-water points increased significantly over time across all districts and in some districts were highly correlated with increased stocking rates. The changes in stocking rates among semi-arid and arid rangelands were not found to be influenced by market forces or state policy, but rather by utilizable primary vegetation productivity.
Vegetation Types: Not Applicable
MLRA Ecoregions: Not Applicable
Article Review Type: Refereed
Article Type: Documented Case History
Keywords: arid rangelands, biome, degradation, grazing, livestock, primary productivity, savannah, semi-arid rangelands, south africa, stocking rates
Annotation: The findings of this study are limited in their application to many of our North American systems but may provide a useful reference for understanding the evolving correlation between stocking rates and semi-arid/arid ecosystems. Through this study significant error in reported livestock numbers on tax returns were found, suggesting the reported numbers highly conservative figures. This calls into question the significance on the findings from this study as census data has proved to be inaccurate, but long-term trends should be consistent.