"Drylands are characterized by a scarcity of water. For millennia, drylands have been shaped by a combination of low precipitation, droughts and heat waves, as well as human activities such as fire use, livestock grazing, the collection of wood and non-wood forest products (NWFPs), and soil cultivation. The United Nations Environment Programme (UNEP) defines drylands according to an aridity index (AI), which is the ratio between average annual precipitation and potential evapotranspiration; drylands are lands with an AI of less than 0.65. They constitute 41 percent of the global land area." (Food and Agriculture Organisation of the United Nations 2021)


Food and Agriculture Organisation of the United Nations. 2021. “Dryland Forestry.” 2021. http://www.fao.org/dryland-forestry/background/what-are-drylands/en/.