Virunga Landscape

23. Virunga Landscape Th e Landscape in brief Coordinates: 1°1’29’’N – 1°44’21’’S – 28°56’11’’E – 30°5’2’’E. Area: 15,155 km2 Elevation: 680–5,119 m Terrestrial ecoregions: Ecoregion of the Afroalpine barrens of Ruwenzori-Virunga Ecoregion of the Afromontane forests of the Albertine Rift Ecoregion of the forest-savannah mosaic of Lake Victoria Aquatic ecoregions: Mountains of the Albertine Rift Lakes Kivu, Edward, George and Victoria Protected areas: Virunga National Park, DRC, 772,700 ha, 1925 Volcans National Park, Rwanda, 16,000 ha, 1925 Rutshuru Hunting Domain, 64,200 ha, 1946 added Bwindi-Impenetrable National Park situ- ated a short distance away from the volcanoes in southwest Uganda. Th is complex functions as a single ecosystem and many animals move across the borders, which permits restoration of the populations1. Physical environment Relief and altitude Th e Landscape is focused on the central trough of the Albertine Rift, occupied by Lake Figure 23.1. Map of Virunga Landscape (Sources: CARPE, Edward (916 m, 2,240 km²), and vast plains DFGFI, JRC, SRTM, WWF-EARPO). at an altitude of between 680 and 1,450 m. Its western edge stretches along the eastern bluff of Location and area the Mitumba Mountain Range forming the western ridge of the rift. In the northeast, it includes he Virunga Landscape covers 15,155 km² the western bluff of the Ruwenzori horst (fault Tand includes two contiguous national parks, block) with its active glaciers, whose peak reaches Virunga National Park in DRC and Volcans a height of 5,119 m and whose very steep relief National Park in Rwanda, the Rutshuru Hunting comprises numerous old glacial valleys (Figure Zone and a 10 km-wide strip at the edge of the 23.2). In the south, on the border between DRC national parks (Figure 23.1). It therefore contains and Rwanda, it contains the Virungas, a series of human populations who have a direct impact on eight large volcanoes surrounded by innumerable the protected areas. Although the more remote smaller volcanoes emerging from a vast plateau populations also have an infl uence, the conserva- of lava. Th e highest volcano, Karisimbi, rises to a tion program has chosen to work with the im- peak of 4,500 m (Figure 23.3). mediate peripheral communities because they use the savannahs and forests in the parks to obtain Geology and soils fi rewood and building materials or to clear land for agriculture and the construction of infrastruc- Th e mountains along the western fringe of ture. Outside the Landscape, the two national the Landscape consist of metamorphosed rocks parks are also contiguous with the national parks from the Protero zoic era. Th e Ruwenzori is a 1 In the fi rst half of the 1990s, following of Semuliki, Queen Elizabeth, Rwenzori and block of highly metamorphosed rocks (mainly years of war and troubles in Uganda, Mgahinga in Uganda. Together, these six national gneiss) which was pushed and driven upwards hundreds of elephants reoccupied parks constitute the largest transborder complex in the middle of the graben, splitting it into two Queen Elizabeth National Park, very of protected areas in Africa, to which must be branches: the Semliki along the line of the rift and probably coming from DRC. 216 Mitumba and the western slopes of Ruwenzori, and then on to the White Nile. Apart from Lake Edward, the Landscape also contains Lakes Bulera and Ruhondo in Rwanda, high-altitude lakes formed by the dam of high valleys following volcanic eruptions, together with the northern shore of Lake Kivu4 in DRC. Th ese lakes also belong to the Nile Basin via the Akagera River. Only the shores of Lake Kivu and the few streams that fl ow into this lake belong to the Congo Basin. Climate Th e climate is bimodal with two rainy sea- Figure 23.2. Th e high summits of the Rwenzori Range. sons around October-November and April-May and two dry seasons around January and July. However, rainfall and temperatures vary enor- mously according to altitude and relief5. Gradients are very steep in places. Th e plains to the south of Lake Edward are hot and receive less than 1,000 mm of precipitation a year on average, while the saddle between the Karisimbi, Mikeno and Bisoke volcanoes receives over 2,000 mm at an altitude of 3,000 m. Th e fl anks of the Ruwenzori are also very rainy, while the highest peaks, over 4,000 m, are dry6. Locally there are fog eff ects which ac- centuate rainfall. Above 3,500 m, night frost is frequent. Vegetation Th e main types of vegetation are (Figure 23.4): Figure 23.3. Th e Virunga. (1) grassy savannahs; bush and tree savannahs Lake George farther east. Th e plains to the north of Acacia and Combretum; savannahs with and south of Lake Edward consist of Quaternary xerophile thickets; and wooded savannahs alluvions providing sandy or clayey-sandy soils, having close fl oristic affi nities with East but there are also horizons of volcanic dust. Th e Africa, dominant in the central part of the oldest volcanic formations date from the Miocene Landscape between the towns of Rutshuru 2 Th e volcanoes are split into (12 million years); the most recent are present- and Beni and around Lake Edward three groups, of which the group day2. Th ese volcanic formations provide highly (2) sclerophyllous forests and thickets, as- lying farthest west, formed by the permeable soils that are unable to hold water sociated with the lava fi elds in the south Nyamulagira (3,058 m) and the but are extremely fertile3. Th e soils of the plains of the Landscape, in the Nyiragongo and Nyiragongo (3,470 m), is still active. around Lake Edward have also been infl uenced by Nyamulagira sectors Th e last major eruption in January 2002 the area of explosive volcanisms in Uganda, just (3) xerophile forests of Euphorbia dawei and seriously aff ected the city of Goma. to the east of the Landscape in Queen Elizabeth Olea europea, endemic to the piedmonts of 3 Before the colonial power installed National Park. the rift mountains water supplies, mainly in the 1950s, (4) Guinea-Congolese plain forests, limited to this volcanic region was very sparsely Hydrology the northern part of the Landscape along populated, however, it was used in the Semliki River and comprising mixed places as a pasture area by transhumant Th e volcano region has no or very few wa- formations and formations dominated by herdsmen. tercourses, but most of the southern part of the Cynometra alexandri 4 Lake Kivu is itself formed by the Landscape drains into Lake Edward through the (5) riparian forests damming of a river, which fl owed into Rwindi, Ishaha and Rutshuru rivers. From Lake (6) submontane and montane forests with forma- Lake Edward following the formation of Edward, the waters descend into Lake Albert via tions of Podocarpus, Hagenia and Hypericum the Virungas. the Semliki, which also receives the waters from and thickets of bamboo Synarundinaria alpi- 217 na, limited to the fl anks of Ruwenzori to the northeast and the volcanoes in the south ■ Inundatable forest (0.4%) (7) high-altitude barrens and thickets of ■ Dense forest 0-1000 m (10.4%) Ericaceae (Philippia benguelensis, Ph. john- ■ Dense forest 1000-1600 m (5.4%) stoni, Erica arborea, E. kingaensis) ■ Dense forest >1600 m (11.2%) (8) Afroalpine barrens with giant lobelia Lobelia ■ Forest-cultivation mosaic (26.5%) sp. and dendritic senecios Senecio sp., above ■ Savannah (15.1%) 7 3,500 m on the volcanoes and Ruwenzori ■ Water (14.6%) (Figure 23.5) (9) degraded forests and cultivated land, gener- ally outside the protected areas (10) swampy areas around Lake Edward. Figure 23.4. Main vegetation types the red-tufted sunbird Nectarinia johnstoni, while (Source: JRC). In Virunga National Park, 2,077 plant species one species, Grauer’s scrub-warbler Bradypterus have been recorded, of which 230 are endemic to graueri, only lives in high- altitude marshes with the mountains of the Albertine Rift (Plumptre et Cyperaceae. Th e papyrus gonolek Laniarius mu- al. 2003). fumbiri, which is specifi c to papyrus, is endemic to the Lake Victoria region8. Finally, the humid Fauna environments of the Landscape are also important for migratory populations of certain Palearctic 5 Th e average temperature falls by 0.6C° Mammals birds, particularly many shorebirds and the white- per 100 m rise in altitude. winged tern Chlidonias leucopterus. 6 Rainfall on the summit of Karisimbi is Over 210 species of mammals have been estimated at 800 mm/year on average. found in the Landscape. Of these, 21 are endemic Herpetofauna 7 Th e high-altitude environments of the to the Albertine Rift, particularly the Ruwenzori volcanoes and Ruwenzori have a similar, otter shrew Micropotamogale ruwenzori and the Reptiles are represented by 109 species of but not identical fl ora; many species are mountain gorilla Gorilla beringei beringei (Figure which 11 are endemic to the Albertine Rift (in- common, but others are limited to a 23.6); others are endemic to the northeast of the cluding the bush viper Atheris nitschei). Th e Nile single massif. Guinea-Congolese forests, especially Elliot’s red crocodile Crocodylus niloticus has recolonized 8 Of the 9 species connected with this colobus of Uganda Piliocolobus oustaleti and the Lake Edward after an absence of probably several region and known in the DRC, 6 have giant genet Genetta victoriae. Among the im- thousand years. Amphibians are represented by been found in the Landscape (Fishpool portant but widely distributed species, mention 78 species of which 21 are endemic.

Load more