Afrotropical realm
The Afrotropical realm is one of the Earth's eight biogeographic realms. It includes Sub-Saharan Africa, the southern Arabian Peninsula, the island of Madagascar, and the islands of the western Indian Ocean. It was formerly known as the Ethiopian Zone or Ethiopian Region.
Major ecological regions
Most of the Afrotropical realm, except for Africa's southern tip, has a tropical climate. A broad belt of deserts, including the Atlantic and Sahara deserts of northern Africa and the Arabian Desert of the Arabian Peninsula, separates the Afrotropic from the Palearctic realm, which includes northern Africa and temperate Eurasia.Sahel and Sudan
South of the Sahara, two belts of tropical grassland and savanna run east and west across the continent, from the Atlantic Ocean to the Ethiopian Highlands. Immediately south of the Sahara lies the Sahel belt, a transitional zone of semi-arid short grassland and vachellia savanna. Rainfall increases further south in the Sudanian Savanna, also known simply as the Sudan region, a belt of taller grasslands and savannas. The Sudanian Savanna is home to two great flooded grasslands: the Sudd wetland in South Sudan, and the Niger Inland Delta in Mali. The forest-savanna mosaic is a transitional zone between the grasslands and the belt of tropical moist broadleaf forests near the equator.Southern Arabian woodlands
South Arabia, which includes Yemen and parts of western Oman and southwestern Saudi Arabia, has few permanent forests. Some of the notable ones are Jabal Bura, Jabal Raymah, and Jabal Badaj in the Yemeni highland escarpment and the seasonal forests in eastern Yemen and the Dhofar region of Oman. Other woodlands that scatter the land are small, predominantly Juniperus or Vachellia forests.Forest zone
The forest zone, a belt of lowland tropical moist broadleaf forests, runs across most of equatorial Africa's Intertropical Convergence Zone. The Upper Guinean forests of West Africa extend along the coast from Guinea to Togo. The Dahomey Gap, a zone of forest-savanna mosaic that reaches to the coast, separates the Upper Guinean forests from the Lower Guinean forests, which extend along the Gulf of Guinea from eastern Benin through Cameroon and Gabon to the western Democratic Republic of the Congo. The largest tropical forest zone in Africa is the Congolian forests of the Congo Basin in Central Africa.A belt of tropical moist broadleaf forest also runs along the Indian Ocean coast, from southern Somalia to South Africa.
Somali–Masai region
In northeastern Africa, semi-arid Acacia-Commiphora woodlands, savannas, and bushlands are the dominant plant communities. This region is called the Somali-Masai center of endemism or Somali-Masai region. It extends from central Tanzania northwards through the Horn of Africa and covers portions of Tanzania, Kenya, Ethiopia, Somalia, Djibouti, and Eritrea. Thorny, dry-season deciduous species of Vachellia and Senegalia and Commiphora are the dominant trees, growing in open-canopied woodlands, open savannas, dense bushlands, and thickets. This region includes the Serengeti ecosystem, which is renowned for its wildlife.Eastern Africa's highlands
The Afromontane region extends from the Ethiopian Highlands to the Drakensberg Mountains of South Africa, including the East African Rift. This region is home to distinctive flora, including Podocarpus and Afrocarpus, as well as giant Lobelias and Senecios.- Ethiopian Highlands
- Albertine rift montane forests
- East African montane forests and Eastern Arc forests
Zambezian region
Deserts of Southern Africa
Southern Africa contains several deserts. The Namib Desert is one of the oldest deserts in the world and extends for over 2,000 kilometers along the Atlantic coasts of Angola, Namibia, and South Africa. It is characterized by towering dunes and a diversity of endemic wildlife. Further inland concerning the Namib Desert, the Kalahari Desert is a semi-arid savanna spanning Botswana, Namibia, and South Africa. The Kalahari is known for its diversity of mineral resources, particularly diamonds, as well as a variety of flora. South of the Namib and Kalahari deserts is the Karoo. A semi-desert natural region, the Karoo desert spans across parts of the Western and Eastern Cape in South Africa and contains vast open spaces and unique vegetation, such as certain species of Asteraceae flowering plants. Within the boundaries of the larger Karoo, the Tankwa Karoo is a more arid sub-region known for harsher conditions and starker landscapes. Further to the west, the Richtersveld, a mountainous desert in the northwestern corner of South Africa, presents a rugged landscape. It is celebrated as a UNESCO World Heritage Site for its unique biodiversity and cultural significance to the local Nama people.Cape floristic region
The Cape floristic region at Africa's southern tip is a Mediterranean climate region that is home to a significant number of endemic taxa, as well as to plant families like the proteas that are also found in the Australasian realm.Madagascar and the Indian Ocean islands
and neighboring islands form a distinctive sub-region of the realm, with numerous endemic taxa, such as lemurs. Madagascar and the Granitic Seychelles are old pieces of the ancient supercontinent of Gondwana, and broke away from Africa millions of years ago. Other Indian Ocean islands, like the Comoros and Mascarene Islands, are volcanic islands that formed more recently. Madagascar contains various plant habitats, from rainforests to mountains and deserts, as its biodiversity and ratio of endemism are extremely high.Endemic plants and animals
Plants
The Afrotropical realm is home to several endemic plant families. Madagascar and the Indian Ocean Islands are home to ten endemic families of flowering plants; eight are endemic to Madagascar, one to Seychelles, and one to the Mascarene Islands. Twelve plant families are endemic or nearly endemic to South Africa of which five are endemic to the Cape floristic province. Other endemic Afrotropic families include Barbeyaceae, Dirachmaceae, Montiniaceae, Myrothamnaceae, and Oliniaceae.Animals
The East African Great Lakes are the center of biodiversity of many freshwater fishes, especially cichlids. The West African coastal rivers region covers only a fraction of West Africa, but harbors 322 of West Africa's fish species, with 247 restricted to this area and 129 restricted evento smaller ranges. The central rivers fauna comprise 194 fish species, with 119 endemics and only 33 restricted to small areas.
The Afrotropic has various endemic bird families, including ostriches, the secretary bird, guineafowl, and mousebirds. Several families of passerines are limited to the Afrotropics, including rock-jumpers and rockfowl.
Africa has three endemic orders of mammals, the Tubulidentata, Afrosoricida, and Macroscelidea. The East-African plains are well known for their diversity of large mammals.
Four species of great apes are endemic to Central Africa: both species of gorilla and both species of chimpanzee. Humans and their ancestors originated in Africa.
Habitats
The tropical environment is rich in terms of biodiversity. Tropical African forest is 18 percent of the world's total and covers over 3.6 million square kilometers of land in West, East, and Central Africa. This total area can be subdivided to 2.69 million square kilometers in Central Africa, 680,000 square kilometers in West Africa, and 250,000 square kilometers in East Africa. In West Africa, a chain of rain forests up to 350 km long extends from the eastern border of Sierra Leone to Ghana. In Ghana, the forest zone gradually dispels near the Volta River, following a 300 km stretch of Dahomey savanna gap. The rain forest of West Africa continues from east of Benin through southern Nigeria and officially ends at the border of Cameroon along the Sanaga River.Semi-deciduous rainforests in West Africa begin at the fringed coastline of Guinea Bissau and run through the coasts of Sierra Leone, Liberia, Ivory Coast, Ghana, continuing through Togo, Benin, Nigeria and Cameroon, and ending at the Congo Basin. Rainforests such as these are the richest, oldest, most prolific, and most complex systems on Earth, are dying, and in turn, are upsetting the delicate ecological balance. This may disturb global hydrological cycles, release vast amounts of greenhouse gases into the atmosphere, and lessen the planet's ability to store excess carbon.
The rainforest vegetation of the Guinea-Congolian transition area, extending from Senegal to western Uganda is constituted of two main types: The semi-deciduous rainforest is characterized by a large number of trees whose leaves are left during the dry season. It appears in areas where the dry period reaches three months. Then, the evergreen or the semi-evergreen rainforest climatically adapted to somewhat more humid conditions than the semi-deciduous type and is usually there in areas where the dry period is shorter than two months. This forest is usually richer in legumes and a variety of species and its maximum development is around the Bight of Biafra, from Eastern Nigeria to Gabon, and with some large patches leaning to the west from Ghana to Liberia and to the east of Zaïre-Congo basin.
Among rainforest areas in other continents, most of the African rainforest is comparatively dry and receives between 1600 and 2000 mm of rainfall per year. Areas receiving more rain than this mainly are in coastal areas. The circulation of rainfall throughout the year remains less than in other rainforest regions in the world. The average monthly rainfall in nearly the whole region remains under 100 mm throughout the year. The variety of the African rainforest flora is also less than the other rainforests. This lack of flora has been credited to several reasons such as the gradual infertility since the Miocene, severe dry periods during Quaternary, or the refuge theory of the cool and dry climate of tropical Africa during the last severe ice age of about 18,000 years ago.