Rangeland Ecology: Managing Change in Biodiversity

Abstract

The rangelands of the world are those semi-arid regions where reliance on rain-fed cropping, on its own, is not a viable form of land use. In their natural state they consist of a vegetation mixture of grasses and woody plants, in various proportions. The extremes of pure grassland (e.g., prairies) and pure shrubland are included, but the focus is on the semi-arid savanna lands. The primary use of rangelands is for livestock production. The management systems vary from nomadic pastoralism through mixed subsistence farming (relying mainly on livestock) to commercial ranching. Some have been used in much the same way for thousands of years and others, mainly in the New World, have had only a relatively short history (around a hundred years) of use. Some were quite radically altered through their management a long time ago [Noy-Meir and Seligman, 1979], and we can only make intelligent guesses as to how their biological diversity has been changed. In virtually all rangelands, however, advances in technology (water development, disease control, improved breeds, etc.) have led to concern over extensive degradation — epitomised by the well-publicised changes in the Sahel, but perceived to be of similar degree and extent in many other areas.

I wish to thank Paul Risser and Bill Lauenroth for helpful referees’ comments, which improved the paper considerably.