The Victoria Basin forest–grassland mosaic is an ecoregion that lies mostly in Uganda 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 tropical lake, and the world's second-largest fresh water lake by surface area after ...

, with an outlier on the border of Ethiopia and South Sudan.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, , Bohairic , lg, Kiira , Nobiin: Áman Dawū is a major north-flowing river in northeastern Africa. It flows into the Mediterranean Sea. The Nile is the longest river in Africa and has historically been considered the longest rive ...

, 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 ...

forests of the Albertine Rift, which separate it from the Congolian rainforests of the

Congo Basin The Congo Basin (french: Bassin du Congo) 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 con ...

. It is bounded on the east by the highlands of Kenya's

Eastern Rift The Gregory Rift is the eastern branch of the East African Rift fracture system. The rift is being caused by the separation of the Somali plate from the Nubian plate, driven by a thermal plume. Although the term is sometimes used in the narrow s ...

, which are home to the Afromontane Eastern Arc forests. To the north, the forest-savanna mosaic transitions to the drier East Sudanian savanna. On the southwest, it transitions to the

Central Zambezian miombo woodlands The Central Zambezian miombo woodlands ecoregion spans southern central Africa. Miombo woodland is the predominant plant community. It is one of the largest ecoregions on the continent, and home to a great variety of wildlife, including many large ...

. 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, 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 The Ssese Islands are an archipelago of eighty-four islands in the northwestern part of Lake Victoria in Uganda. The islands are coterminous with the Kalangala District in southern Central Uganda, which does not have any territory on mainland Uga ...

in Lake Victoria, and in the northern enclave on the South Sudan-Ethiopia border, and is only 700 mm around Lake Edward 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 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'' 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 The Guineo-Congolian region is a biogeographical region in Africa straddling the Equator and stretching from the Atlantic Ocean through the Congo Basin to the Congo / Nile divide in Rwanda and Burundi. Formerly, this region was largely covered in ...

found further to the east in the

Congo basin The Congo Basin (french: Bassin du Congo) 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 con ...

. Characteristic trees include large-leaved albizia (''

Albizia grandibracteata ''Albizia'' is a genus of more than 160 species of mostly fast-growing subtropical and tropical trees and shrubs in the subfamily Mimosoideae of the family Fabaceae. The genus is pantropical, occurring in Asia, Africa, Madagascar, America ...

''), 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, widespread in warm temperate regions of the Northern Hemisphere. The genus is part of the extended hemp family (Cannabaceae). De ...

''), white stinkwood ('' Celtis africana''), bastard white stinkwood ('' Celtis gomphophylla''), red-fruited white stinkwood (''

Celtis mildbraedii ''Celtis mildbraedii'' is a species of forest tree in the family Cannabaceae. It was previously assigned to the family Ulmaceae. These trees grow in limited areas of South Africa, Mozambique and Zimbabwe. They are also found in forested areas fro ...

''), ''

Celtis philippensis ''Celtis philippensis'', is an Asian species of flowering plant in the family Cannabaceae Cannabaceae is a small family of flowering plants, known as the hemp family. As now circumscribed, the family includes about 170 species grouped in abo ...

'', ''

Celtis zenkeri ''Celtis zenkeri'' is a species of flowering plant native to sub-Saharan Africa. Description ''Celtis zenkeri'' is a large tree, growing up to 30 to 50 meters high. It is fast-growing, growing up to 15 cm in height per year, and in Côte d’Ivo ...

'', white star apple (''

Gambeya albida ''Gambeya albida'', commonly known as white star apple, is a forest fruit tree commonly found throughout tropical Africa. It is closely related to the African star apple (''Gambeya africana'') which is also common throughout West Africa. Some sc ...

''), Uganda ironwood (''

Cynometra alexandri ''Cynometra alexandri'', the Uganda ironwood or muhimbi, is a species of legume that occurs in tropical lowland forests of central and east Africa. They grow gregariously in drier forest types and as a constituent of swamp forests. They reach so ...

''), Budongo mahogany (''

Entandrophragma angolense ''Entandrophragma angolense'', called the ''tiama'', is a tree species with alternate, pinnately compound leaves that are clustered at the ends of branches. It is within the family Meliaceae and has a wide distribution area, occurring in moist sem ...

''), 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 ''sap ...

''), Budongo heavy mahogany (''

Entandrophragma utile ''Entandrophragma utile'', called the sipo or utile, is a species of large tree in the genus ''Entandrophragma'', native to nearly all of tropical Africa facing the Atlantic, from Guinea to Angola, and as far east as Uganda. The timber is traded ...

''), orange-barked terminalia (''

Holoptelea grandis ''Holoptelea'' is a genus of deciduous trees in the family Ulmaceae. Species , Plants of the World Online Plants of the World Online (POWO) is an online database published by the Royal Botanic Gardens, Kew. It was launched in March 2017 wit ...

''), smooth-barked mahogany ('' Khaya anthotheca''), big-leaf mahogany ('' Khaya grandifoliola''), umbrella tree (''

Maesopsis eminii ''Maesopsis eminii'', the umbrella tree, is a species of tree in the family Rhamnaceae found in India and Africa. It is the only species in the genus ''Maesopsis''. It is often grown as a plantation tree, and as a shade tree in coffee plantation ...

''), '' 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 African teak ...

''), Uganda mulberry (''

Morus mesozygia ''Morus mesozygia'', known as black mulberry or African mulberry, is a small- to medium-sized forest tree of Tropical Africa. Its leaves and fruit provide food for the mantled guereza, a colobus monkey native to much of Tropical Africa, and for t ...

''), African greenheart (''

Piptadeniastrum africanum ''Piptadeniastrum africanum'' is a tall deciduous tree within the Fabaceae family (subfamily Mimosaidae), also called ''Piptadenia africana'' its timber is traded under the names, Dabema or Dahoma. It commonly occurs in freshwater swamp forests b ...

''), aningeria (''

Pouteria altissima ''Pouteria altissima'' is a species of plant in the family Sapotaceae, and a source of anigre hardwood. It is found in Burundi, Cameroon, Central African Republic, the Republic of the Congo, the Democratic Republic of the Congo, Ivory Coast, E ...

''), and African nutmeg (''

Pycnanthus angolensis ''Pycnanthus angolensis'' is a species of tree in the nutmeg family, Myristicaceae. It is native to Tropical Africa. Its English language common names include African nutmeg, false nutmeg, boxboard, and cardboard. 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 re-grown after a timber harvest or clearing for agriculture, until a long enough period has passed so that the effects of the disturbance are no longer evident. ...

, 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 Kakamega is a town in western Kenya lying about 30 km north of the Equator. It is the headquarters of Kakamega County that has a population of 1,867,579 (2019 census). Kakamega is 52 km north of Kisumu, the tenth largest city in Ken ...

and South Nandi forests in western Kenya occur 1520 to 1680 meters elevation, west of the highlands that bound the

. Characteristic trees of the Kakamega and South Nandi forests include alangium (''

Alangium chinense ''Alangium chinense'' is a species of flowering plant in the Cornaceae family. It has the Chinese name (). Traditional uses It is one of the Chinese herbology#50 fundamental herbs, 50 fundamental herbs used in traditional Chinese medicine. In Hu ...

''), 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 ''Gambeya gorungosana'' is species of evergreen tree native to eastern and central Africa. Range and habitat ''Gambeya gorungosana'' ranges across eastern and central Africa, from Mozambique and Zimbabwe through Zambia, Malawi, Tanzania, Burundi ...

'', drum tree (''

Cordia millenii ''Cordia'' is a genus of flowering plants in the borage family, Boraginaceae. It contains about 300 species of shrubs and trees, that are found worldwide, mostly in warmer regions. Many of the species are commonly called manjack, while ''bocote' ...

''), ''

Ehretia cymosa ''Ehretia cymosa'' is a small tree belonging to the Boraginaceae or borage family. It occurs over a wide range of habitat throughout of western, central and eastern Africa, including Benin, Côte d'Ivoire, Cameroon, Ethiopia, Kenya, Comoros, Ma ...

'', Budongo mahogany (''

''), orange-milk tree (''

Harungana madagascariensis ''Harungana madagascariensis'' is a flowering plant found in Madagascar that is commonly known as the dragon's blood tree, orange-milk tree or haronga. Description The haronga is a small, bushy tree that usually ranges from 4 m to 7 ...

''), river macaranga (''

Macaranga capensis ''Macaranga'' is a large genus of Old World tropical trees of the family Euphorbiaceae and the only genus in the subtribe Macaranginae (tribe Acalypheae). Native to Africa, Australasia, Asia and various islands of the Indian and Pacific Oceans, ...

''), umbrella tree (''

''), calabash nutmeg (''

Monodora myristica ''Monodora myristica'', the calabash nutmeg, is a tropical tree of the family Annonaceae or custard apple family of flowering plants. It is native to Angola, Benin, Cameroon, the Central African Republic, the Democratic Republic of the Congo, Eq ...

''), ''

Neoboutonia macrocalyx ''Neoboutonia'' is a plant genus of the family Euphorbiaceae first described as a genus in 1864. It is the only genus in subtribe Neoboutoniinae, and native to tropical Africa. It is dioecious. ;Species # ''Neoboutonia macrocalyx '' Pax - Burund ...

'', East African newtonia ('' Newtonia buchananii''), aningeria (''

''), red stinkwood ('' Prunus africana''), jumping seed tree (''

Shirakiopsis elliptica ''Shirakiopsis'' is a genus of flowering plants in the family Euphorbiaceae first described as a genus in 1999. There are six known species, 3 native to tropical Asia and 3 to tropical Africa.Strombosia scheffleri ''Strombosia'' is a plant genus of about 10 species in the family Olacaceae. It has also been classified in the family Strombosiaceae. The generic name is from the Greek ', meaning "pear-shaped", referring to the fruit. Description ''Strombosia'' ...

'', Guinea waterberry (''

Syzygium guineense ''Syzygium guineense'' ( bm, Kokisa) is a leafy forest tree of the family Myrtaceae, found in many parts of Africa both wild and domesticated. Both its fruits and leaves are edible; the pulp and the fruit skin are sucked and the seed discarded. I ...

''), '' Turraea holstii'', and lemonwood (''

Xymalos monospora ''Xymalos monospora'' (plant family Monimiaceae), commonly known as lemonwood, is a species of evergreen tree native to Africa, the only species in the genus ''Xymalos''. It is an Afromontane endemic, and can be found from 900 to 2700 meters elev ...

'').

Swamp forest

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

, on the border of Tanzania and Uganda. The Tanzanian portion is known as the

Minziro Forest The Minziro (Nature) Forest Reserve is a conservation area along the Kagera River in Bukoba district of northwestern Tanzania. It protects one of the largest forests in Tanzania, of a forest type that is unique in the country. It was gazetted in 1 ...

, and the Ugandan portion as the

Sango Bay forests The Sango Bay forests are distinctive forests found in southwestern Uganda, near the border with Tanzania. The Sango Bay forests grow on seasonally-flooded lowlands near on the lower reaches of the Kagera River, just west of where it empties into ...

. ''Baikieaea insignis'' subsp. ''minor'' and ''

Afrocarpus dawei ''Afrocarpus dawei'' is a species of conifer in the family Podocarpaceae. It is native to Africa, where it occurs in the Democratic Republic of the Congo, Tanzania, and Uganda. This species is a tree that grows in swampy forest habitat that is ...

'' 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 and the Democratic Republic of the Congo's Virunga National Park lie in the basin of Lake Edward, in the western portion of the ecoregion. Other protected areas include Murchison Falls National Park,

Lake Mburo National Park Lake Mburo National Park is a national park located in Nyabushozi County, Kiruhura District near Mbarara in Uganda. Location Lake Mburo National Park is located in Kiruhura District in the Western Region of Uganda, about east of Mbarara and ab ...

, and Mabira Forest Reserve in Uganda, Akagera National Park 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