Why The World's Drylands Need Urgent Protection

Drylands are home to two billion people, many of whom are poor and depend directly on the land’s resources for food and energy. Drylands also generate crucial environmental services and contain 35% of the world’s biodiversity hotspots. The Food and Agriculture Organization of the United Nations explains the importance, and challenges, of conserving drylands.

Broadly speaking, drylands are characterised by a scarcity of water. The United Nations Environment Programme defines them as lands with an aridity index (AI) of less than 0,65. (The AI is the ratio between average annual precipitation and potential evapotranspiration; if the former is less than the latter, the climate is regarded as arid.). It further divides drylands into hyper-arid lands, arid lands, semiarid lands, and dry sub-humid lands.

Drylands cover about 41% of the Earth’s land surface, or about 6,1 billion hectares. They are distributed among all continents at tropical and temperate latitudes. Africa has the largest area of drylands (32% of the world’s total), followed by Asia, North America, Oceania, South America, and Europe.

An estimated two billion people live in drylands, about 90% of them in developing countries. The majority depend on forests and other wooded lands, grasslands, and trees on farms for their livelihoods and to meet basic needs for food, medicine, wood energy, and non-wood forest products.

Trees tend to be integral parts of traditional food systems in drylands, because crops and livestock thrive in their presence. Their leaves and fruits are sources of food and fodder.

Trees and forests in drylands generate a wealth of environmental services; they provide habitats for biodiversity, protect against water and wind erosion and desertification, provide shade for crops and animals, help water infiltrate soil, and contribute to soil fertility. They also increase the resilience of landscapes and communities in the face of global change. Drylands are home to 35% of global biodiversity hotspot areas, as well as one-third of all endemic and important bird areas. Drylands support half of the world’s livestock, a source of food security for the dryland population living in developing countries.

Climate Change