Drylands cover more than 40% of the Earth’s total land surface and are home to more than 2 billion people. Their biodiversity plays an important role in the global fight against climate change, poverty and desertification. According to the United Nations Convention to Combat Desertification (UNCCD), drylands are defined as: ‘areas where the potential amount of water that is transferred from the land to the atmosphere is at least 1.5 times greater than the mean precipitation: a calculation known as the aridity index. They are defined by water scarcity and characterized by seasonal climatic extremes and unpredictable rainfall patterns’.

Despite what many think, drylands contain a great variety of biodiversity. Many species and habitats found in drylands are not present in more humid ecosystems. Their biodiversity is also central to sustainable development and to the livelihoods of their inhabitants, many of whom are poor. For this reason the importance of biodiversity to poverty reduction and economic development may be greater in drylands than in many other ecosystems. Drylands also contribute a number of high-value products of global economic importance, at least 30% of the world’s cultivated plants and many livestock breeds originate in drylands. They, therefore constitute an important genetic reservoir that is becoming increasingly valuable for climate change adaptation.