Ethiopian highlands
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The Ethiopian Highlands are a rugged mass of mountains in Ethiopia and Eritrea in northeastern Africa. The Ethiopian Highlands form the largest continuous area of its altitude in the whole continent, with little of its surface falling below 1500 m (5000 ft), while the summits reach heights of 4600 m to 4900 m (15,000 to 16,000 ft). The Highlands are divided into northwestern and southeastern portions by the Great Rift Valley, which contains a number of salt lakes. The northwestern portion contains the Semien Mountains, part of which has been designated a national park. Its highest peak, Ras Dashan, is the highest peak in Ethiopia and the fourth-highest in Africa. Lake Tana, the source of the Blue Nile, also lies in the northwestern portion. The Southeastern portion's highest peaks are located in the former province of Bale. The Bale Mountains are nearly as high those of Semien, with peaks over 4000 m, such as Tullu Demtu (4337 m and the second-highest peak in Ethiopia) and Mount Batu (4307 m). The Bale mountains are also home to a national park of the same name.
The Ethiopian Highlands began to rise 75 million years ago, as magma from the earth's mantle uplifted a broad dome of the ancient rocks of the African Craton. The opening of the Great Rift Valley split the dome of the Ethiopian Highlands into three parts; the mountains of the southern Arabian Peninsula are geologically part of the ancient Ethiopian Highlands, separated by the rifting which created the Red Sea and Gulf of Aden and separated Africa from Arabia.
Ecology
The Ethiopian Highlands share a similar flora and fauna of other mountainous regions of Africa; this distinctive flora and fauna is known as Afromontane. The Highlands are home to a number of endemic species, such as the Walia Ibex and Ethiopian Wolf.
At lower elevations, the highlands are surrounded by tropical savannas and grasslands, including the Sahelian Acacia savanna to the northwest, the East Sudanian savanna to the west, and the Somali Acacia-Commiphora bushlands and thickets to the northeast, east, south, and through the Rift Valley.
The highlands themselves are divided into three distinct ecoregions, distinguished by elevation. The Ethiopian montane forests lie between 1,100 and 1,800 meters elevation, above the lowland grasslands and savannas. This woodland belt has several plant communities. Kolla, is an open woodland found at lower elevations, and dominated by species of Terminalia, Commiphora, Boswellia, and Acacia. Weyna dega is a woodland found in moister and higher locations, dominated by the conifers Podocarpus falcatus and Juniperus procera. The lower portion of the Harenna forest is a distinct woodland community, with an open canopy of Warburgia ugandensis, Croton macrostachyus, and Syzygium guineense, and Podocarpus falcatus, with wild coffee (Coffea arabica) as the dominant understory shrub.
The Ethiopian montane grasslands and woodlands occupies the area between 1800 and 3000 meters elevation. The natural vegetation was closed-canopy forest in moister areas, and grassland, bushland, and thicket in drier areas. A few areas of natural vegetation remain. Drier areas covered with forests of the forest consists of Podocarpus falcatus and Juniperus procera, often with Hagenia abyssinica. In the Harenna forest, pockets of moist, closed-canopy forest with Aningeria and Olea are draped with lianas and epiphytes, while above 2400 meters, a shrubby zone is home to Hagenia, Schefflera, and giant lobelias. The evergreen broadleaved forest of the Semien Mountains, between 2,300 and 2,700 meters elevation, is dominated by Syzygium guineense, Juniperus procera, and Olea africana.
Above 3000 meters elevation lie the Ethiopian montane moorlands, the largest afroalpine region in Africa. The montane moorlands lie above tree line, and consists of grassland and moorland with abundant herbs and some shrubs. The Ethiopian Wolf is endemic to the montane moorlands, and is critically endangered.
See also
External links
- [Ethiopian montane forests (World Wildlife Fund)]
- [Ethiopian montane grasslands and woodlands (World Wildlife Fund)]
- [Ethiopian montane moorlands (World Wildlife Fund)]
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