Dryland

Drylands are defined by a scarcity of water. Drylands are zones where precipitation is balanced by evaporation from surfaces and by evapotranspiration by plants. The United Nations Environment Program defines drylands as tropical and temperate areas with an aridity index of less than 0.65. Drylands can be classified into four sub-types:Dry sub-humid lands Semi-arid lands Arid lands Hyper-arid lands