Deserts and xeric shrublands

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Worldwide, Deserts and Xeric Shrublands vary greatly in the amount of annual rainfall they receive; generally, however, evaporation exceeds rainfall in these ecoregions, usually less than 10 inches annually. Temperature variability is also extremely diverse in these remarkable lands. Many deserts, such as the Sahara, are hot year-round but others, such as Asia's Gobi, become quite cold in winter.


Temperature extremes are a characteristic of most deserts. Searing daytime heat gives way to cold nights because there is no insulation provided by humidity and cloud cover. Not surprisingly, the diversity of climatic conditions - though quite harsh - supports a rich array of habitats. Many of these habitats are ephemeral in nature - reflecting the paucity and seasonality of available water.

Woody-stemmed shrubs and plants characterize vegetation in these regions. Above all, these plants have evolved to minimize water loss. Animal biodiversity is equally well adapted and quite diverse.

The Namib-Karoo deserts of southwestern Africa support the world’s richest desert floras, while the Chihuahuan Desert and central Mexican deserts are a close second and are the richest Neotropical deserts. Australian deserts support the richest reptile faunas. The Carnavon Xeric Scrub of western Australia is a regional center of endemism for a range of taxa.

Unusual desert communities dominated by giant columnar cacti occur in the Sonoran and Baja deserts of North America, while the spiny deserts and shrublands of southwestern Madagascar are globally unique in terms of structure and taxa (although some Baja California communities are partially convergent in structure).

The Atacama Desert ecoregion of western South America (as well as the adjacent transition area of the Monte / Puna / Yungas) and the Horn of Africa deserts were recognized as some of the more outstanding regional centers of richness and endemism. The Central Asian deserts, while not nearly as rich as Afrotropical or Neotropical deserts, are representative of the region’s deserts.

Biodiversity Patterns
Deserts and xeric shrublands may have extraordinarily rich floras with very high alpha and beta diversity; reptile faunas may also be very diverse; local endemism may be quite pronounced in some regions.

Minimum Requirements
Many species track seasonally variable and patchy resources and require large natural landscapes to persist; water sources and riparian habitats are critical for the persistence of many species.

Sensitivity to Disturbance
Highly sensitive to grazing, soil disturbance, burning, plowing, and other cover alteration; restoration potential can be very low and regeneration very slow; exotic species may be a serious problem.

Australasia

Western Australia
Southern central Australia
Eastern central Australia
Western Australia
Southern Australia
Southern Australia
Northwestern Australia
Western central Australia
Central Australia
Western coast of Australia

Afrotropical

Southern Africa: Southern Namibia into South Africa
Arabian Peninsula: Yemen and Saudi Arabia
Arabian Peninsula: Yemen, Saudi Arabia, and Oman
Somali montane xeric woodlands
Islands east of the Horn of Africa and south of Yemen
Red Sea coastal desert
Africa: Namibia
Africa: Namibia
Nama Karoo
Masai xeric grasslands and shrublands
Madagascar succulent woodlands
Madagascar spiny thickets
Africa: Coastal Namibia and Angola
Kalahari xeric savanna
Southern Africa: Islands about half-way between southern Madagascar and southern Mozambique
Eastern Africa: Somalia
Arabian Peninsula: Oman and United Arab Emirates
Ethiopian xeric grasslands and shrublands
Eritrean coastal desert
North central Africa: Eastern Chad and small area of western Sudan
Western Asia: Oman, Yemen, and Saudi Arabia
Aldabra Island xeric scrub

Indo-Malayan

Southern Asia: Western India into Pakistan
Southern Asia: Eastern India and western Pakistan
Southern Asia: Eastern central Pakistan
Southern Asia: Southern India into the island of Sri Lanka

Nearctic

Wyoming Basin shrub steppe
Southern North America: Southern United States into northeastern Mexico
Southern North America: Northeastern Mexico
Southern North America: Southwestern United States into northwestern Mexico
Snake-Columbia shrub steppe
Mojave desert
Southern North America: Central Mexico
Southern North America: Baja California Peninsula in western Mexico
Great Basin shrub steppe
Colorado Plateau shrublands
Southern North America: Northern Mexico into southwestern United States
Central Mexican matorral
Southern North America: Baja California Peninsula in Mexico
California montane chaparral and woodlands
California interior chaparral and woodlands
Western North America: Southwestern United States into northwestern Mexico

Neotropical

Islands in the Atlantic Ocean about halfway between South America and Africa
Island group in the southeast Caribbean
Southern North America: Southern Mexico
Southern North America: Southern Baja California in western Mexico
Northern South America: Northernwestern Venezuela
Guatemala
South America: Island off the coast of Colombia in the Pacific Ocean
Islands of the Lesser Antilles in the Caribbean
Northern South America: North-central and coastal Venezuela
Northern South America: Northern Colombia and northwest Venezuela
Galápagos Islands, off the coast of Ecuador
Southeastern Cuba
Cayman Islands in the Caribbean
Northern South America: Northeastern Brazil
Western South America: Northwestern Chile
Caribbean Islands off the coast of Venezuela
Northern South America: Northern Venezuela

Palearctic

Northern Africa: Southeastern Algeria, northern Niger, Mali, and Mauritania
Tibesti-Jebel Uweinat montane xeric woodlands
Central Asia: Western China
Africa--Mauritania, Mali, Algeria, Niger, Chad, Sudan
Southern Iran, eastern Iraq, and western Pakistan
Northern Africa
Southern Asia: Southern Afghanistan into Pakistan and Iran
Red Sea Nubo-Sindian tropical desert and semi-desert
Central Asia: Central China
South central Asia: Northern Afghanistan
North Saharan steppe and woodlands
Western Asia: Northern Iraq into Syria and Jordan
Central Asia: Iran and Turkmenistan
Central Asia: Kazakhstan
Junggar Basin semi-desert
Central Asia: Western Mongolia into southern Russia
Eastern Asia: Central Mongolia
Eastern Gobi desert steppe
Southwestern Asia: Central and eastern Iran into western Afghanistan
Central Asia: Central Turkmenistan stretching into Uzbekistan and Kazakhstan
Asia: Southeastern Kazakhstan
Central Asia: Southern Kazakhstan into Uzbekistan
Southern central Asia: Southeastern Afganistan
Western Asia: Along the coast of the Caspian Sea in Russia, Kazakhstan, Turkmenistan, and Iran
Indian subcontinent--Pakistan, Afghanistan
Central Asia: Northern Afghanistan, southern Turkmenistan, southern Uzbekistan, extending into Iran and Tajikistan
Southwestern Asia: Azerbaijan, into Georgia and Iran
Atlantic coastal desert
Southwestern Asia: Most of Saudi Arabia, extending into Oman, United Arab Emirates, Yemen, Egypt, Iraq, Jordan, and Syria
Asia: China and Mongolia
Afghanistan
Southern Europe: Portions of the southern Italian mainland and parts of the islands of Corsica, Sardinia, and Sicily