Grasslands are mostly found in arid and semi-arid zones where rainfall is sparse and unpredictable, or in humid zones where topography is steep or temperatures low. Their existence is also determined by cultural factors, distance to markets or the presence of low fertility or stony soils, salinity or seasonal flooding.

...Worldwide, there are at least 40 million pastoralists who depend on natural grazing for their livelihood; most are subsistence herders and more than half are in Africa. Rapid increases in human and livestock populations this century have contributed to increasing grazing pressures, particularly in arid and semi-arid environments.

...Extensive grazing lands are not only important for livestock; they are often major catchments and wildlife habitats, as well as sites for the in situ conservation of plant genetic resources. Their proper management is, therefore, of great concern to the whole community. It is hoped that this publication will assist in their conservation and sustainable use.