Emily Peck, WWF-US, Conservation Science Program, Washington, DC, USA
Central African Republic
Democratic Republic of Congo
Luc De Vos, National Museum of Kenya, Nairobi, Kenya
Major Habitat Type
Tropical and subtropical upland rivers
Main rivers to other water bodies
The Uele River and its affluents, the Bili, Uere, and Bomokandi Rivers, drain woodland savannas in the north and east and mixed evergreen forests in the south and west. The Uele River begins in the Blue Mountains at an elevation of 1620 m, and then traverses the high plateau for 1170 km before joining the Ubangui River in Yakoma, below 500 m (Orange 1998). The Uele River’s catchment covers 139,700 km². The Bili is a blackwater river with a catchment area of 27,400 km². The Bili runs through more extensive areas of evergreen forests and carries a large amount of dissolved organic matter (Orange 1998).
The rivers and streams within the Uele ecoregion drain from a high plateau along the northeastern border of the Congo basin in the Democratic Republic of Congo. The basin of the Uele River, a major tributary to the Ubangui, determines the boundaries of this ecoregion.
The high plateau in the northeast of the ecoregion slopes west and south toward the central Congo basin. Numerous scarps and cliff faces break up the gently sloping landscape. As a result, waterfalls and rapids mark all rivers running off the plateau toward the central Congo basin.
A mosaic of afromontane forest, gallery forest, wooded savanna, and grassland blankets the northern highlands of the Uele ecoregion. Savannas range from dense woodland to virtually treeless grassland. Loudetia arundinacea and Hyparrhenia spp. dominate the grasslands of the far northeast. Numerous small rivers and papyrus swamps dissect these grasslands. Combretum spp. and Terminalia spp. dominate the savanna woodland vegetation. Other predominant species include Bauhinia thonningii, Dombeya quinqueseta, Hymenocardia acida and Acacia, Grewia and Bridelia spp. Gallery forest contains Irvingia smithii, Erythrophleum suaveolens, Chlorophora excelsa, and Klainedoxa and Ficus spp. (WCMC 1984).
The montane forests of the Blue Mountains exhibit an altitudinal zonation of plant species. Species such as Podocarpus, Prunus, and Ocotea occur at intermediate elevations. At higher altitudes these forests transition to elfin forests and communities of bamboo, tree ferns, and lobelias. At the highest altitudes, afro-alpine moorlands occur with a variety of shrubs and grasses (Sayer et al. 1992). Fire plays an important role in the maintenance of the vegetation cover and often sweeps across the savanna during the dry season. In the southern and western parts of the ecoregion, a closed canopy of broadleaf and needle leaf evergreen forest blankets the landscape. Evergreen forest covers 30% of the course of the Uele River, and 44% percent of the Bili River (Orange 1998).
Description of endemic fishes
Based on collected data, the ecoregion exhibits a low level of endemism in fish, although this may be due to low sampling effort. Nine fish species are considered endemic although seven of them are only reported from their type locality in the Uele system: Amphilius notatus, Distichodus langi, Clariallabes simeonsi, Chrysichthys uniformis, Barbus schoutedeni, Barbus urotaenia, Hippopotamyrus macroterops, Hippopotamyrus retrodorsalis,and Petrocephalus hutereaui. Further investigations in the Upper Congo River basin may reveal occurrences of these species outside the Uele system.
Level of taxonomic exploration
- Orange, D. (1998). "Matter transports in humid tropical watershed in a forested area: the Uele river in Zaïre"
- Sayer, J. A., Harcourt, C. S. and Collins, N. M. (1992). The conservation atlas of tropical forests: Africa London, UK: IUCN.
- Wcmc (1984) \World Heritage Sites: Garamba\ "<"http://www.wcmc.org.uk/protected_areas/data/wh/garamba.html ">" (2001)