West Saharan montane xeric woodlands
Encyclopedia
The West Saharan montane xeric woodlands is an ecoregion
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...

 that extends across several highland regions in 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...

. 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 humidity and lower temperatures of the highlands.

Setting

The Sahara is a vast desert, stretching across northern Africa from 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...

 to 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 mountains (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...

, Tibesti, Aïr) rise up from the desert and receive more rainfall and mostly present slightly cooler summer temperatures. These highlands support dry woodlands and shrublands distinct from the hot dry desert lowlands.

This ecoregion has an area of 258100 km² (99,653 sq mi). The boundaries for the largest part of this ecoregion, which includes the 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...

 Ahaggar and Aïr (or Azbine) massifs, follow the 'regs,' 'hamadas' and 'wadis' above the 1000 m contour. This covers a good part of southeast Algeria. These areas reach almost 3000 meters in altitude. Additional areas further south were included within this ecoregion, including the Aïr ou Azbine in northern Niger, Dhar Adrar in Mauritania, and Adrar des Iforas in Mali and Algeria, using the 500 m-elevation contour.

The mountains of the West Saharan Montane Xeric Woodland ecoregion are found within the Sahara Desert and are predominantly of volcanic origin. They rise from the surrounding flat desert landscape or sand dunes and create islands of moister habitat (guelta
Guelta
A guelta is a peculiar type of wetland, typical of desert regions. They are formed when underground water in lowland depressions spills to the surface and creates permanent pools and reservoirs....

) which support flora and fauna. The most important area is the 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...

 Plateau, an outlier of the Ahaggar Mountains in Algeria which supports some near-endemic species and some globally threatened antelopes. The highest point of these mountains is 3003 meters (Mount Tahat
Mount Tahat
Mount Tahat is the highest mountain peak in Algeria, at . Tahat is also the highest peak in the Ahaggar Mountains. Its nearest city is Tamanrasset which is located 56 km to its south.-Sources:*...

).

Winters are quite rigorous, with amplitude in temperature over 20°C. Day temperatures may be over 20°C while nights are freezing. In summer, days are very hot, though less than in central Sahara. Rainfall is rare and sporadic.

Flora and fauna

Vegetation varies greatly depending on altitude and landscape (in particular wind protection). It is often relict of mediterranean vegetation.

In gueltas, vegetation is very diverse and hosts many animals. Trees may be found at lower elevations, while higher mostly host bushes. It is however possible to find olive trees (the olive tree on the right hand picture was found at 2300 m). Endemic and rare species includes Saharan Cypress (“tarout”) (Cupressus dupreziana), wild olive (Olea lapperrini) and Saharan Myrtle (Myrtus nivellei), all of which are relict Saharan-Mediterranean species. Olive and myrtle trees grow at the bottom of wadi
Wadi
Wadi is the Arabic term traditionally referring to a valley. In some cases, it may refer to a dry riverbed that contains water only during times of heavy rain or simply an intermittent stream.-Variant names:...

s, intermittent stream valleys, or beside gueltas, permanent or temporary waterholes.

Other species with a preference for moist habitats are Trianthema pentandra, Lupinus pilosus, and Convolvulus fatmensis. Silene kiliani, Acacia laeta
Acacia laeta
Acacia laeta, commonly known as the Gay Acacia, is in the Acacia family.-Description:It is a perennial shrub or tree growing to a height of 4-10m...

, A. scorpiodes,
and Cordia rochii grow in wadis. Other representatives of the 28 national Algerian plant rarities found on Tassili n'Ajjer include Ficus ingens and Anticharis glandulosa.

Population and conservation

The human population of the ecoregion is very small, with less than 5 persons per km². Many people are nomadic though some small cities also exist (ideles). The vegetation remains fairly intact.
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