The Sahara is the largest desert in the world and occupies approximately 10 percent of the African Continent. The ecoregion includes the hyper-arid central portion of the Sahara where rainfall is minimal and sporadic. Although species richness and endemism are low, some highly adapted species do survive with notable adaptations.
Only a few thousand years ago the Sahara was significantly wetter, and a large mammal fauna resided in this area. Climatic desiccation over the past 5000 years, and intense human hunting over the past 100 years, has obliterated these faunas. Now only rock, sand and sparse vegetation exist over huge areas. The remnant large mammal fauna is highly threatened by over-hunting.
Huge and Wild
The Sahara, with a size of 8.6 million km², is the world's largest desert, covering large parts of North Africa. Around 4 million people live here. Its maximum length is 4,800 km, running from west to east, and up to 1,200 km from north to south. Sahara covers most of Mauritania, Western Sahara, Algeria, Libya, Egypt, Sudan, Chad, Niger and Mali, and touches Morocco and Tunisia.
To the north, Sahara is bordered by the Atlas Mountains and the Mediterranean Sea; in the west by the Atlantic Ocean; in the south, the desert zone reaches 16º northern latitude; in the east it is bordered by the Nile. Still the desert continues to the east of the river until it reaches the Red Sea, but this is not considered a part of the Sahara.
Sahara is very dry but there is an annual rainfall in most regions, although just a few dozens of millimetre. Sahara has a subtropical climate in its northern parts, and a tropical one in the south. Winters in the north are cold to cool; in the south, mild. Summers are hot all over the desert. The highest temperature every recorded is 58ºC in Aziziyah, Libya. There is very little rain in the northern parts, virtually nothing in the east, although more in the south. Most rain falls throughout the summer, followed by some scarce winter rain.
About a quarter of Sahara consists of mountains. The highest peak reaches 3415, being Emi Koussi in Chad. Some mountain peaks may even have snow in the winter. The main mountain ranges are Hoggar in Algeria; Aïr/Azbine in Niger; and Tibesti in Chad. The Sahara's lowest point lies in the Qattara Depression in Egypt, at about 130 metres below sea level.
Sand sheets and dunes represent about 25% of the Sahara; the other parts are mountains, stoney steppes and oases. Pyramidal dunes can be as high as 150 metres, while mountainous sand ridges as high as 350 metres.
There are several rivers running through the Sahara, of which the Nile River and Niger River are the only permanent ones. The rest being seasonal, involves that most of the time, there is only a dry river bed, which may carry water for brief periods following uncommon rainfalls. There may be years in between this happening.
Metallic minerals are very important to most Saharan countries. Algeria and Mauritania have several major deposits of iron ore, while smaller deposits are found in Egypt, Tunisia, Morocco, Western Sahara and Niger. Copper is found in Mauritania and manganese in Algeria. Small deposits of uranium are widely distributed in the Sahara, while Niger has the largest deposits. Phosphates are found in great quantities in Morocco and Western Sahara, and are already well-exploited. Algeria's phosphate production is smaller, but large enough for exports. Oil is mainly found in Algeria, and is of great importance to the economy of the entire country. While the mineral exploitation has led to economic growth in Sahara, this has rarely helped the indigenous population, as skilled workers have been brought in to the different fields.
Of the Sahara's around 4 million people, most live in Mauritania, Western Sahara, Algeria, Libya and Egypt. Dominant groups of people are Sahrawis, Tuareg and Negroids. The largest city is Nouakchott, Mauritania's capital. Other important cities are Tamanrasset in Algeria, and Sebha and Ghat in Libya.
Biodiversity
The flora of the central Sahara Desert is very poor and estimated to include only 500 species. This is extremely low considering the huge extent of the area. It mainly consists of xerophytes and ephemeral plants (called also locally Acheb), with halophytes in moister areas. The flora has one near endemic family, a number of isolated monotypic genera of both wide and narrow distribution, and perhaps as many as 162 endemic species. The monotypic genera suggest a Tertiary origin with probable extinction of linking forms. Vegetation is very contracted along the wadis and the dayas with Acacia sp, Tamarix sp., and Calotropis procera., Where there is sufficient ground water, hammadas are covered by Anrthirrnum ramosissimuma and Ononis angustissima.
Considering the hyper-arid conditions, the fauna of the central Sahara is richer than is generally believed. Within this ecoregion there are 70 species of mammal, 20 of which are large mammals. There are also 90 species of resident birds, and around 100 species of reptiles. Arthropods are also numerous, especially ants. One of the bird species (Oenanthe monacha) is regarded as endemic to the ecoregion, and there is one strictly endemic currently undescribed worm snake (Leptotyphlops sp nov. "L"). However, given the vast size of the ecoregion, the number of endemic species is very small.
In the past the critically threatened addax (Addax nasomaculatus) would probably have occurred in this ecoregion, but this species is likely to be extirpated. Small numbers of scimiter-horned oryx (Oryx dammah, EX) may have also occurred in the past. Other desert antelopes may still be found in small numbers, such as slender-horned gazelle (Gazella leptoceros, EN), dama gazelle (Gazella dama, EN) and the red-fronted gazelle (Gazella rufifrons, VU).
The plants and animals of the Sahara are more threatened by desiccation than the fauna and flora in other areas. Plant leaves may dry out totally and then recover; animals may loose 30-60% of their body mass and are still able to recover. Many of the animals get their water only through metabolic processes. These kinds of adaptations have allowed them to survive in such an inhospitable environment.
Only a few thousand years ago the Sahara was significantly wetter, and a large mammal fauna resided in this area. Climatic desiccation over the past 5000 years, and intense human hunting over the past 100 years, has obliterated these faunas. Now only rock, sand and sparse vegetation exist over huge areas. The remnant large mammal fauna is highly threatened by over-hunting.
Huge and Wild
The Sahara, with a size of 8.6 million km², is the world's largest desert, covering large parts of North Africa. Around 4 million people live here. Its maximum length is 4,800 km, running from west to east, and up to 1,200 km from north to south. Sahara covers most of Mauritania, Western Sahara, Algeria, Libya, Egypt, Sudan, Chad, Niger and Mali, and touches Morocco and Tunisia.
To the north, Sahara is bordered by the Atlas Mountains and the Mediterranean Sea; in the west by the Atlantic Ocean; in the south, the desert zone reaches 16º northern latitude; in the east it is bordered by the Nile. Still the desert continues to the east of the river until it reaches the Red Sea, but this is not considered a part of the Sahara.
Sahara is very dry but there is an annual rainfall in most regions, although just a few dozens of millimetre. Sahara has a subtropical climate in its northern parts, and a tropical one in the south. Winters in the north are cold to cool; in the south, mild. Summers are hot all over the desert. The highest temperature every recorded is 58ºC in Aziziyah, Libya. There is very little rain in the northern parts, virtually nothing in the east, although more in the south. Most rain falls throughout the summer, followed by some scarce winter rain.
About a quarter of Sahara consists of mountains. The highest peak reaches 3415, being Emi Koussi in Chad. Some mountain peaks may even have snow in the winter. The main mountain ranges are Hoggar in Algeria; Aïr/Azbine in Niger; and Tibesti in Chad. The Sahara's lowest point lies in the Qattara Depression in Egypt, at about 130 metres below sea level.
Sand sheets and dunes represent about 25% of the Sahara; the other parts are mountains, stoney steppes and oases. Pyramidal dunes can be as high as 150 metres, while mountainous sand ridges as high as 350 metres.
There are several rivers running through the Sahara, of which the Nile River and Niger River are the only permanent ones. The rest being seasonal, involves that most of the time, there is only a dry river bed, which may carry water for brief periods following uncommon rainfalls. There may be years in between this happening.
Metallic minerals are very important to most Saharan countries. Algeria and Mauritania have several major deposits of iron ore, while smaller deposits are found in Egypt, Tunisia, Morocco, Western Sahara and Niger. Copper is found in Mauritania and manganese in Algeria. Small deposits of uranium are widely distributed in the Sahara, while Niger has the largest deposits. Phosphates are found in great quantities in Morocco and Western Sahara, and are already well-exploited. Algeria's phosphate production is smaller, but large enough for exports. Oil is mainly found in Algeria, and is of great importance to the economy of the entire country. While the mineral exploitation has led to economic growth in Sahara, this has rarely helped the indigenous population, as skilled workers have been brought in to the different fields.
Of the Sahara's around 4 million people, most live in Mauritania, Western Sahara, Algeria, Libya and Egypt. Dominant groups of people are Sahrawis, Tuareg and Negroids. The largest city is Nouakchott, Mauritania's capital. Other important cities are Tamanrasset in Algeria, and Sebha and Ghat in Libya.
Biodiversity
The flora of the central Sahara Desert is very poor and estimated to include only 500 species. This is extremely low considering the huge extent of the area. It mainly consists of xerophytes and ephemeral plants (called also locally Acheb), with halophytes in moister areas. The flora has one near endemic family, a number of isolated monotypic genera of both wide and narrow distribution, and perhaps as many as 162 endemic species. The monotypic genera suggest a Tertiary origin with probable extinction of linking forms. Vegetation is very contracted along the wadis and the dayas with Acacia sp, Tamarix sp., and Calotropis procera., Where there is sufficient ground water, hammadas are covered by Anrthirrnum ramosissimuma and Ononis angustissima.
Considering the hyper-arid conditions, the fauna of the central Sahara is richer than is generally believed. Within this ecoregion there are 70 species of mammal, 20 of which are large mammals. There are also 90 species of resident birds, and around 100 species of reptiles. Arthropods are also numerous, especially ants. One of the bird species (Oenanthe monacha) is regarded as endemic to the ecoregion, and there is one strictly endemic currently undescribed worm snake (Leptotyphlops sp nov. "L"). However, given the vast size of the ecoregion, the number of endemic species is very small.
In the past the critically threatened addax (Addax nasomaculatus) would probably have occurred in this ecoregion, but this species is likely to be extirpated. Small numbers of scimiter-horned oryx (Oryx dammah, EX) may have also occurred in the past. Other desert antelopes may still be found in small numbers, such as slender-horned gazelle (Gazella leptoceros, EN), dama gazelle (Gazella dama, EN) and the red-fronted gazelle (Gazella rufifrons, VU).
The plants and animals of the Sahara are more threatened by desiccation than the fauna and flora in other areas. Plant leaves may dry out totally and then recover; animals may loose 30-60% of their body mass and are still able to recover. Many of the animals get their water only through metabolic processes. These kinds of adaptations have allowed them to survive in such an inhospitable environment.
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