Sahara Desert (ecoregion)
Encyclopedia
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.
, located in northern Africa
. It stretches from the Red Sea
to the Atlantic Ocean
. The vast Sahara encompasses several ecologically distinct regions. The Sahara desert ecoregion covers an area of 4619260 km² (1,783,506.3 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, and the Tibesti-Jebel Uweinat montane xeric woodlands
in the Tibesti and Jebel Uweinat
of the eastern Sahara.
The surface of the desert ranges from large areas of sand dunes (erg), to stone plateaus (hamadas), gravel plains (reg), dry valleys (wadis), and salt flats. The only permanent river that crosses the ecoregion is the Nile River, which originates in central Africa and empties northwards into the Mediterranean Sea. Some areas encompass vast underground aquifers resulting in oases
, while other regions severely lack water reserves.
(86 °F
). Daily variations may also be extreme: a swing from 37.5 to -0.5 °C (99.5 to 31.1 F) has been observed. The Sahara receives very little rain in the Inter-Tropical Convergence Zone which moves up from the south. Wind and sand storms occur as soon as early spring. Local inhabitants protect themselves from heat, cold and mostly wind and sand by covering their heads, such as the cheche
worn by Tuareg.
. Previous fauna may be recognised in stone carvings. However, desertification
set in around 3000 BCE, and the area became much like it is today.
The Sahara is largely undisturbed. The most degradation is found in areas where there is water, such as aquifer oases or along the desert margins where some rain usually falls most years. In these areas, animals such as addax
es, scimitar-horned oryxes, and bustard
s are over-hunted for their meat. Only one area of conservation
is recorded in the Sahara: the Zellaf Nature Reserve in Libya.
Ecoregion
An ecoregion , sometimes called a bioregion, is an ecologically and geographically defined area that is smaller than an ecozone and larger than an ecosystem. Ecoregions cover relatively large areas of land or water, and contain characteristic, geographically distinct assemblages of natural...
, as defined by the World Wide Fund for Nature
World Wide Fund for Nature
The World Wide Fund for Nature is an international non-governmental organization working on issues regarding the conservation, research and restoration of the environment, formerly named the World Wildlife Fund, which remains its official name in Canada and the United States...
(WWF), includes the hyper-arid center of the Sahara
Sahara
The Sahara is the world's second largest desert, after Antarctica. At over , it covers most of Northern Africa, making it almost as large as Europe or the United States. The Sahara stretches from the Red Sea, including parts of the Mediterranean coasts, to the outskirts of the Atlantic Ocean...
, between 18° and 30° N. It is one of several desert and xeric shrubland
Deserts and xeric shrublands
Deserts and xeric shrublands is a biome characterized by, relating to, or requiring only a small amount of moisture.-Definition and occurrence:...
ecoregions that cover the northern portion of the African continent.
Setting
The Sahara is the world's largest hot desertDesert
A desert is a landscape or region that receives an extremely low amount of precipitation, less than enough to support growth of most plants. Most deserts have an average annual precipitation of less than...
, located in northern Africa
Africa
Africa is the world's second largest and second most populous continent, after Asia. At about 30.2 million km² including adjacent islands, it covers 6% of the Earth's total surface area and 20.4% of the total land area...
. It stretches from the Red Sea
Red Sea
The Red Sea is a seawater inlet of the Indian Ocean, lying between Africa and Asia. The connection to the ocean is in the south through the Bab el Mandeb strait and the Gulf of Aden. In the north, there is the Sinai Peninsula, the Gulf of Aqaba, and the Gulf of Suez...
to the Atlantic Ocean
Atlantic Ocean
The Atlantic Ocean is the second-largest of the world's oceanic divisions. With a total area of about , it covers approximately 20% of the Earth's surface and about 26% of its water surface area...
. The vast Sahara encompasses several ecologically distinct regions. The Sahara desert ecoregion covers an area of 4619260 km² (1,783,506.3 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
Mediterranean climate
A Mediterranean climate is the climate typical of most of the lands in the Mediterranean Basin, and is a particular variety of subtropical climate...
regions of Africa's Mediterranean
Mediterranean Sea
The Mediterranean Sea is a sea connected to the Atlantic Ocean surrounded by the Mediterranean region and almost completely enclosed by land: on the north by Anatolia and Europe, on the south by North Africa, and on the east by the Levant...
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
South Saharan steppe and woodlands
The South Saharan steppe and woodlands is a deserts and xeric shrublands ecoregion of northern Africa.The ecoregion covers in Algeria, Chad, Mali, Mauritania, and Sudan...
ecoregion lies to the south, between the Sahara desert ecoregion and the Sahel
Sahel
The Sahel is the ecoclimatic and biogeographic zone of transition between the Sahara desert in the North and the Sudanian Savannas in the south.It stretches across the North African continent between the Atlantic Ocean and the Red Sea....
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
Red Sea
The Red Sea is a seawater inlet of the Indian Ocean, lying between Africa and Asia. The connection to the ocean is in the south through the Bab el Mandeb strait and the Gulf of Aden. In the north, there is the Sinai Peninsula, the Gulf of Aqaba, and the Gulf of Suez...
.
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
West Saharan montane xeric woodlands
The West Saharan montane xeric woodlands is an ecoregion that extends across several highland regions in the Sahara. Surrounded at lower elevations by the largely barren Sahara, the West Saharan montane xeric woodlands are isolated refuges of plants and animals that can survive in the higher...
in the Ahaggar, Tassili n'Ajjer
Tassili n'Ajjer
Tassili n'Ajjer is a mountain range in the Algerian section of the Sahara Desert. It is a vast plateau in south-east Algeria at the borders of Libya, Niger and Mali, covering an area of 72,000 sq...
, Aïr, and other ranges in the western and central Sahara, and the Tibesti-Jebel Uweinat montane xeric woodlands
Tibesti-Jebel Uweinat montane xeric woodlands
The Tibesti-Jebel Uweinat montane xeric woodlands ecoregion, in the deserts and xeric shrublands Biome, is located in the Maghreb of North Africa...
in the Tibesti and Jebel Uweinat
Jebel Uweinat
Jebel Uweinat is a mountain range in the area of the Egyptian-Libyan-Sudanese border. The mountain lies about 40 km S-SE of Jabal Arkanu...
of the eastern Sahara.
Oasis
In geography, an oasis or cienega is an isolated area of vegetation in a desert, typically surrounding a spring or similar water source...
, while other regions severely lack water reserves.
Climate
The Sahara desert generally features an arid climate. The Sahara desert is one of the hottest regions of the world, with a mean temperature over 30 °CCelsius
Celsius is a scale and unit of measurement for temperature. It is named after the Swedish astronomer Anders Celsius , who developed a similar temperature scale two years before his death...
(86 °F
Fahrenheit
Fahrenheit is the temperature scale proposed in 1724 by, and named after, the German physicist Daniel Gabriel Fahrenheit . Within this scale, the freezing of water into ice is defined at 32 degrees, while the boiling point of water is defined to be 212 degrees...
). Daily variations may also be extreme: a swing from 37.5 to -0.5 °C (99.5 to 31.1 F) has been observed. The Sahara receives very little rain in the Inter-Tropical Convergence Zone which moves up from the south. Wind and sand storms occur as soon as early spring. Local inhabitants protect themselves from heat, cold and mostly wind and sand by covering their heads, such as the cheche
Chéché
Chéché or Ché Ché is a village in the Gabú Region of northeastern Guinea-Bissau. It lies on the south of the Corubal River, to the south of Canjadude....
worn by Tuareg.
History and conservation
The Sahara was one of the first regions of Africa to be farmed. Some 5,000 years ago, the area was not so arid and the vegetation might have been closer to a savannaSavanna
A savanna, or savannah, is a grassland ecosystem characterized by the trees being sufficiently small or widely spaced so that the canopy does not close. The open canopy allows sufficient light to reach the ground to support an unbroken herbaceous layer consisting primarily of C4 grasses.Some...
. Previous fauna may be recognised in stone carvings. However, desertification
Desertification
Desertification is the degradation of land in drylands. Caused by a variety of factors, such as climate change and human activities, desertification is one of the most significant global environmental problems.-Definitions:...
set in around 3000 BCE, and the area became much like it is today.
The Sahara is largely undisturbed. The most degradation is found in areas where there is water, such as aquifer oases or along the desert margins where some rain usually falls most years. In these areas, animals such as addax
Addax
The Addax , also known as the screwhorn antelope, is a critically endangered species of antelope that lives in the Sahara desert. As suggested by its alternative name, this pale antelope has long, twisted horns. It is closely related to the oryx, but differs from other antelopes by having large...
es, scimitar-horned oryxes, and bustard
Bustard
Bustards, including floricans and korhaans, are large terrestrial birds mainly associated with dry open country and steppes in the Old World...
s are over-hunted for their meat. Only one area of conservation
Conservation ethic
Conservation is an ethic of resource use, allocation, and protection. Its primary focus is upon maintaining the health of the natural world: its, fisheries, habitats, and biological diversity. Secondary focus is on materials conservation and energy conservation, which are seen as important to...
is recorded in the Sahara: the Zellaf Nature Reserve in Libya.