Sahara Desert (ecoregion)

Sahara
Sand dunes in Tadrart Acacus, a desert area in western Libya
Ecology
Realm	Palearctic
Biome	Deserts and xeric shrublands
Geography
Area	4,619,260 km2 (1,783,510 sq mi)
Countries	Algeria, Chad, Egypt, Libya, Mali, Mauritania and Niger
Rivers	Nile River; intermittent rivers and streams
Climate type	hot desert and hyper-arid
Conservation
Conservation status	Vulnerable

The Sahara Desert ecoregion, as defined by the World Wide Fund for Nature (WWF), includes the hyper-arid center of the Sahara, between 18° and 30° N. It is one of several desert and xeric shrubland ecoregions that cover the northern portion of the African continent.

The Sahara Desert is the world's largest hot desert, located in North Africa. It stretches from the Red Sea to the Atlantic Ocean. The vast desert encompasses several ecologically distinct regions. The Sahara Desert ecoregion covers an area of 4,619,260 km² (1,783,510 sq mi) in the hot, hyper-arid center of the Sahara, surrounded on the north, south, east, and west by desert ecoregions with higher rainfall and more vegetation.

The North Saharan steppe and woodlands ecoregion lies to the north and west, bordering the Mediterranean climate regions of Africa's Mediterranean and North Atlantic coasts. The North Saharan steppe and woodlands receives more regular winter rainfall than the Sahara Desert ecoregion. The South Saharan steppe and woodlands ecoregion lies to the south, between the Sahara Desert ecoregion and the Sahel grasslands. The South Saharan steppe and woodlands receives most of its annual rainfall during the summer. The Red Sea coastal desert lies in the coastal strip between the Sahara Desert ecoregion and the Red Sea.

Some mountain ranges rise up from the desert and receive more rainfall and cooler temperatures. These Saharan mountains are home to two distinct ecoregions; the West Saharan montane xeric woodlands in the Ahaggar, Tassili n'Ajjer, Aïr, and other ranges in the western and central Sahara Desert, and the Tibesti-Jebel Uweinat montane xeric woodlands in the Tibesti and Jebel Uweinat of the eastern Sahara.