The Victoria Basin forest–grassland mosaic is an

ecoregion An ecoregion (ecological region) is an ecological and geographic area that exists on multiple different levels, defined by type, quality, and quantity of environmental resources. Ecoregions cover relatively large areas of land or water, and c ...

that lies mostly in

Uganda Uganda, officially the Republic of Uganda, is a landlocked country in East Africa. It is bordered to the east by Kenya, to the north by South Sudan, to the west by the Democratic Republic of the Congo, to the south-west by Rwanda, and to the ...

and extends into neighboring countries. The ecoregion is centered north and west of

Lake Victoria Lake Victoria is one of the African Great Lakes. With a surface area of approximately , Lake Victoria is Africa's largest lake by area, the world's largest tropics, tropical lake, and the world's second-largest fresh water lake by surface are ...

, with an outlier on the border of

Ethiopia Ethiopia, officially the Federal Democratic Republic of Ethiopia, is a landlocked country located in the Horn of Africa region of East Africa. It shares borders with Eritrea to the north, Djibouti to the northeast, Somalia to the east, Ken ...

and

South Sudan South Sudan (), officially the Republic of South Sudan, is a landlocked country in East Africa. It is bordered on the north by Sudan; on the east by Ethiopia; on the south by the Democratic Republic of the Congo, Uganda and Kenya; and on the ...

.Burgess, Neil, Jennifer D'Amico Hales, Emma Underwood, et al. (2004). "Terrestrial Ecoregions of Africa and Madagascar: A Conservation Assessment". World Wildlife Fund. Island Press, 2004, pp. 291-292.

Geography

The ecoregion covers an area of 165,800 km² (64,000 sq mi). It lies in the upper basin of the

Nile River The Nile (also known as the Nile River or River Nile) is a major north-flowing river in northeastern Africa. It flows into the Mediterranean Sea. The Nile is the longest river in Africa. It has historically been considered the longest river i ...

, between 800 and 1500 meters elevation. It is bounded on the west by the higher-elevation

Afromontane The Afromontane regions are subregions of the Afrotropical realm, one of the Earth's eight biogeographic realms, covering the plant and animal species found in the mountains of Africa and the southern Arabian Peninsula. The Afromontane regions o ...

forests of the

Albertine Rift The Albertine Rift is the western branch of the East African Rift, covering parts of Uganda, the Democratic Republic of the Congo (DRC), Rwanda, Burundi and Tanzania. It extends from the northern end of Lake Albert to the southern end of Lake Tan ...

, which separate it from the

Congolian rainforests The Congolian rainforests (French language, French: ''Forêts tropicales congolaises'') are a broad belt of lowland tropical and subtropical moist broadleaf forests, tropical moist broadleaf forests which extend across the Congo Basin, basin of th ...

of the

Congo Basin The Congo Basin () is the sedimentary basin of the Congo River. The Congo Basin is located in Central Africa, in a region known as west equatorial Africa. The Congo Basin region is sometimes known simply as the Congo. It contains some of the larg ...

. It is bounded on the east by the highlands of Kenya's Eastern Rift, which are home to the Afromontane Eastern Arc forests. To the north, the forest-savanna mosaic transitions to the drier

East Sudanian savanna The East Sudanian savanna is a hot, seasonally dry tropical savanna ecoregion of Central and East Africa. Geography The East Sudanian savanna is the eastern half of the Sudanian savanna belt which runs east and west across Africa. The easte ...

. On the southwest, it transitions to the Central Zambezian miombo woodlands. The ecoregion's smaller northern outlier lies on the border of Ethiopia and South Sudan. It is bounded on the east by the

Ethiopian Highlands The Ethiopian Highlands (also called the Abyssinian Highlands) is a rugged mass of mountains in Ethiopia in Northeast Africa. It forms the largest continuous area of its elevation in the continent, with little of its surface falling below , whil ...

, on the west by the East Sudanian savanna, and on the south by the Northern Acacia–Commiphora bushlands and thickets.

Climate

The ecoregion's climate is tropical. Annual maximum mean temperatures range from 24º to 27º, and mean minimum temperatures range from 15 °C to 18 °C. Rainfall generally ranges from 1000 to 1400 mm annually, but exceeds 2000 mm on the Ssese Islands in Lake Victoria, and in the northern enclave on the South Sudan-Ethiopia border, and is only 700 mm around

Lake Edward Lake Edward (locally Rwitanzigye or Rweru) is one of the smaller African Great Lakes. It is located in the Albertine Rift, the western branch of the East African Rift, on the border between the Democratic Republic of the Congo (DRC) and Uganda, ...

in the Western Rift. Most rain falls in the two rainy seasons, from March to May and from August to November.

Flora and fauna

The predominant vegetation includes extensive areas of savanna and woodland, interspersed with smaller areas of forest.

Papyrus Papyrus ( ) is a material similar to thick paper that was used in ancient times as a writing surface. It was made from the pith of the papyrus plant, ''Cyperus papyrus'', a wetland sedge. ''Papyrus'' (plural: ''papyri'' or ''papyruses'') can a ...

swamps are common in river lowlands.

Plant communities

The principal plant communities include Lake Victoria drier peripheral semi-evergreen Guineo-Congolian rain forest, Lake Victoria transitional rain forest, moist ''

Combretum ''Combretum'', the bushwillows or combretums, make up the type genus of the family Combretaceae. The genus comprises about 272 species of trees and shrubs, most of which are native to Tropics, tropical and southern Africa, about 5 to Madagascar ...

'' wooded grassland, dry ''Combretum'' wooded grassland, Evergreen and semi-evergreen bushland and thicket, Edaphic wooded grassland on drainage-impeded or seasonally flooded soils, and swamp forest.

Semi-evergreen rainforest

Semi-evergreen rainforest was the predominant vegetation type on the north shore of Lake Victoria and southeast of Lake Albert. Botanist Frank White designated it as "Lake Victoria drier peripheral semi-evergreen Guineo-Congolian rain forest", a floristically-impoverished variant of the species-rich Guineo-Congolian forests found further to the east in the

. Characteristic trees include large-leaved albizia ('' Albizia grandibracteata''), cheesewood ('' Alstonia boonei''), false mvule ('' Antiaris toxicaria''), African ita (''

Celtis adolfi-friderici ''Celtis'' is a genus of about 60–70 species of deciduous trees, commonly known as hackberries or nettle trees, in the hemp family Cannabaceae. It has a cosmopolitan distribution. Description ''Celtis'' species are generally medium-sized tree ...

''), white stinkwood (''

Celtis africana ''Celtis africana'', the white stinkwood, is a deciduous tree in the family Cannabaceae. Its habit ranges from a tall tree in forest to a medium-sized tree in bushveld and open country, and a shrub on rocky soil. It occurs in Yemen and Somalil ...

''), bastard white stinkwood ('' Celtis gomphophylla''), red-fruited white stinkwood ('' Celtis mildbraedii''), '' Celtis philippensis'', '' Celtis zenkeri'', white star apple ('' Gambeya albida''), Uganda ironwood ('' Cynometra alexandri''), Budongo mahogany ('' Entandrophragma angolense''), Sapelli mahogany (''

Entandrophragma cylindricum ''Entandrophragma cylindricum'' is a tree of the genus ''Entandrophragma'' of the family ''Meliaceae''. It is commonly known as sapele or sapelli ( ) or sapele mahogany, as well as aboudikro, assi, and muyovu. Origin of the name The name ''sape ...

''), Budongo heavy mahogany ('' Entandrophragma utile''), orange-barked terminalia ('' Holoptelea grandis''), smooth-barked mahogany ('' Khaya anthotheca''), big-leaf mahogany ('' Khaya grandifoliola''), umbrella tree ('' Maesopsis eminii''), '' Mildbraediodendron excelsum'', mvule (''

Milicia excelsa ''Milicia excelsa'' is a tree species from the genus '' Milicia'' of the family '' Moraceae''. Distributed across tropical Central Africa, it is one of two species (the other being '' Milicia regia'') yielding timber commonly known as ọjị, Af ...

''), Uganda mulberry ('' Morus mesozygia''), African greenheart ('' Piptadeniastrum africanum''), aningeria ('' Aningeria altissima''), and African nutmeg ('' Pycnanthus angolensis'').Kindt R, van Breugel P, Orwa C, Lillesø JPB, Jamnadass R and Graudal L (2015)"Lake Victoria drier peripheral semi-evergreen Guineo-Congolian rain forest". ''Useful tree species for Eastern Africa: a species selection tool based on the VECEA map.'' Version 2.0. World Agroforestry Centre (ICRAF) and Forest & Landscape Denmark. http://vegetationmap4africa.org. Accessed 19 March 2020. This vegetation type covers an area of 48,223 km², of which 4.6% is in protected areas explicitly designated for biodiversity, species or landscape protection (

IUCN protected area categories IUCN protected area categories, or IUCN protected area management categories, are categories used to classify protected areas in a system developed by the International Union for Conservation of Nature (IUCN). The enlisting of such areas is part ...

I - IV), and another 4.9% is in areas designated for both protection and sustainable use (IUCN categories V - VI). Human activity has transformed most of the original rainforest area to various types of savanna, or to agriculture and tree plantations. Mabira Forest is the largest remaining block of semi-evergreen forest. The reserve is

secondary forest A secondary forest (or second-growth forest) is a forest or woodland area which has regenerated through largely natural processes after human-caused Disturbance (ecology), disturbances, such as Logging, timber harvest or agriculture clearing, or ...

, and has been subject to long-term human influence, including logging since the early 20th century and encroachment by banana and coffee plantations in the 1970s and 80s.

Lake Victoria transitional rain forest

Transitional rainforests are evergreen rain forests found at the eastern and western ends of the ecoregion. They are transitional between lowland forests which are mostly made up of Guineo-Congolian species, and higher-elevation

forests, and the transitional forests include both characteristic lowland and highland species. The Kakamega and South Nandi forests in western Kenya occur 1520 to 1680 meters elevation, west of the highlands that bound the Eastern Rift. Characteristic trees of the Kakamega and South Nandi forests include alangium ('' Alangium chinense''), peacock flower ('' Albizia gummifera''), pear wood (''

Apodytes dimidiata ''Apodytes dimidiata'' (white pear or umDakane) is a bushy tree with white flowers bearing a fragrance reminiscent of fresh coconut, and small black and red fruits. It is usually about 5 m tall (but reaches a height of 20 m when growing ...

''), bastard white stinkwood ('' Celtis gomphophylla''), '' Gambeya gorungosana'', drum tree ('' Cordia millenii''), '' Ehretia cymosa'', Budongo mahogany ('' Entandrophragma angolense''), orange-milk tree ('' Harungana madagascariensis''), river macaranga ('' Macaranga capensis''), umbrella tree ('' Maesopsis eminii''), calabash nutmeg ('' Monodora myristica''), '' Neoboutonia macrocalyx'', East African newtonia ('' Newtonia buchananii''), aningeria ('' Pouteria altissima''), red stinkwood (''

Prunus africana ''Prunus africana'', the African cherry, has a wide distribution in Africa, occurring in montane regions of central and southern Africa and on the islands of Bioko, São-Tomé, Grande Comore, and Madagascar. It can be found at above sea level. I ...

''), jumping seed tree ('' Shirakiopsis elliptica''), '' Strombosia scheffleri'', Guinea waterberry ('' Syzygium guineense''), '' Turraea holstii'', and lemonwood ('' Xymalos monospora'').

Swamp forest

A distinctive swamp forest community is found along the lower reaches of the

Kagera River The Kagera River, also known as Akagera River, or Alexandra Nile, is an East African river, forming part of the upper headwaters of the Nile and carrying water from its most distant source.Stanley, H.M., 1899, Through the Dark Continent, London: ...

west of

, on the border of Tanzania and Uganda. The Tanzanian portion is known as the Minziro Forest, and the Ugandan portion as the Sango Bay forests. ''Baikieaea insignis'' subsp. ''minor'' and '' Afrocarpus dawei'' are the dominant canopy trees.Kamukala, G. L., and S. A. Crafter, eds. (1993). ''Wetlands of Tanzania: Proceedings of a Seminar on the Wetlands of Tanzania, Morogoro, Tanzania, 27–29 November 1991''. Volume 10 of The IUCN Wetlands Programme. IUCN, 1993.

Protected areas

14% of the ecoregion is in protected areas, including national parks and forest reserves. Uganda's

Queen Elizabeth National Park Queen Elizabeth National Park is a national park in the Western Region, Uganda, Western Region of Uganda. Location Queen Elizabeth National Park (QENP) spans the districts of Kasese District, Kasese, Kamwenge District, Kamwenge, Rubirizi Distri ...

and the Democratic Republic of the Congo's

Virunga National Park Virunga National Park is a national park in the Albertine Rift Valley in the eastern part of the Democratic Republic of the Congo. It was created in 1925. In elevation, it ranges from in the Semliki River valley to in the Rwenzori Mountains. ...

lie in the basin of

, in the western portion of the ecoregion. Other protected areas include Murchison Falls National Park, Lake Mburo National Park, and Mabira Forest Reserve in Uganda,

Akagera National Park Akagera National Park is a protected area in eastern Rwanda covering along the international border with Tanzania. It was founded in 1934 and includes savannah, montane and swamp habitats. The park is named for the Kagera River which flows along ...

in Rwanda, Minziro Forest Nature Reserve in Tanzania, and Kakamega Forest Reserve in Kenya.

References

{{DEFAULTSORT:Victoria Basin forest-savanna mosaic Afrotropical ecoregions Ecoregions of Burundi Ecoregions of the Democratic Republic of the Congo Ecoregions of Ethiopia Ecoregions of Kenya Ecoregions of Rwanda Ecoregions of South Sudan Ecoregions of Tanzania Ecoregions of Uganda Tropical and subtropical grasslands, savannas, and shrublands