Deserts and xeric shrublands

Desertification in South Africa is a xeric shrubland that receives between of rain a year. The conversion of productive drylands to desert conditions, known as desertification, can occur from a variety of causes. One is human intervention, including intensive agricultural tillage or overgrazing in areas that cannot support such exploitation. Climatic shifts such as global warming or the Milankovitch cycle (which drives glacials and interglacials) also affect the pattern of deserts on Earth. Woody plant encroachment Xeric shrublands can experience woody plant encroachment, which is the thickening of bushes and shrubs at the expense of grasses. This process is often caused by unsustainable land management practices, such as overgrazing and fire suppression, but can also be a consequence of climate change. As a result, the shrublands' core ecosystem services are affected, including its biodiversity, productivity, and groundwater recharge. Woody plant encroachment can be an expression of land degradation. ==Ecoregions==

The World Wide Fund for Nature highlights a number of desert ecoregions that have a high degree of biodiversity and endemism: • The Carnarvon xeric shrublands of Australia are a regional center for endemism. • The Sonoran and Baja deserts of Mexico and the United States are unusual desert communities dominated by giant columnar cacti. • Madagascar spiny forests • Atacama Desert ==See also==