Drylands

Drylands include such diverse ecosystems as true deserts, savannahs and tropical dry forest. According to the Millennium Ecosystem Assessment, drylands occupy some 40% of the Earth's terrestrial surface and are home to more than 2 billion people. Drylands include important centres of origin for agricultural crops and dryland ecosystems often harbour an extremely specialised community of animals and plants. Many dryland ecosystems are very vulnerable to pressures such as desertification (land degradation resulting from various factors, including climatic variations and human activities), overexploitation, pollution, introduction of invasive species and climate change

Dryland definitions in international policy vary, with the UN Convention to Combat Desertification having a more limited definition than the Convention on Biological Diversity (CBD). To help clarify this issue, UNEP-WCMC has produced A spatial analysis approach to the global delineation of dryland areas of relevance to the CBD Programme of Work on Dry and Subhumid Lands.

A global overview of the conservation status of tropical dry forests focuses on the status of and pressures upon these threatened dryland ecosystems.