ABSTRACT
A very large proportion of the earth’s land surface is unsuitable for cultivated crop production mainly because of a growing season limited by either insufficient rainfall or low temperatures or to a lesser extent because of steep slopes, shallow stony or inherently infertile soils. Agricultural use is hence limited to some form of pastoral farming, i.e. domestic livestock production on the basis of the natural or semi-natural (‘wild’) vegetation. Land used for this purpose – rangeland (in some cases termed ‘rough grazing’) – accounts for nearly 50 per cent of the total land area of the world today, half of which is in tropical/subtropical areas, and half in cool-temperate and cold climatic areas (Fig. 9.1). In both, however, pastoral farming is subject to comparable biophysical constraints and problems.
