Lands classified as desert (length of growing period = 0), arid (lgp <90), and semi-arid (90<lgp<180) occupy approximately half of total emerged lands. These areas receive between 100 and 600 mm of rainfall annually, in a very erratic and inconsistent regime, the main feature of their “dryness” being the negative balance between the annual rainfall and evapo-transpiration. Many of world’s drylands are grazed natural pastures. The specificity of these rangelands lies in their lack of biomass stability. Drylands are widely spread over the globe, hosting an important share of the global population in fragile ecosystems. They therefore represent an important focus area for the LEAD Initiative.

Livestock production has been the main activity developed to sustain livelihoods in these low productivity and unstable environments. Nomadic pastoralism fully exploits these characteristics, however, the more traditional practices have been modified in recent years and pastoralists are adopting a variety of agricultural practices, including cropping. In pastoral areas, livestock are often one of the few assets owned by the poor and as such play a significant role in their livelihoods. One of the main interactions between the poor and the environment in drylands is through their high dependence on common property grassland resources.

There are several environmental problems which affect drylands and the human populations which they support. Overgrazing and land degradation has increased as a result of reduced mobility of pastoral herds and increases in cropping and livestock numbers. In addition, competition for resources between wildlife and livestock interactions is increasing, resulting in increased marginalisation of the poor and game poaching. Finally, declining biodiversity is a critical issue in drylands where the number of flora and fauna species is high, for example, the presence of large mammals is important in the ecology of African grasslands but dry savannah areas and deserts host 13% and 15%, respectively, of mammals threatened by extinction, In Africa, the average plant genetic diversity for savannah land (1,750 species) is not far below that of rainforests (2,202 species). Drylands are also important for their contribution to carbon sequestration, despite their low biomass production rates.