Location and General Description
The ecoregion is located along the border between northeastern Nigeria and northwestern Cameroon (11° N, 14° E). Found in the semi-arid tropics, the ecoregion is within the Sudano-Sahelian belt, and is wetter and more vegetated than the Sahelian zone to the north. It can be divided into three altitudinally distinct zones: mountains, plateau and plains (FAO 2001). Most of the botanical value lies in those highly restricted plateau areas above 1,200 meters in elevation. All parts of this ecoregion are highly degraded.
The region has a six month wet season, from May to October. During this season, between 800 mm to 1,000 mm falls; the rest of the year is dry (FAO 2001). Mean temperature is moderated by altitude and ranges between 15° to 30 ° C. The Mandara range is composed of ancient granites (Morton 1986), unlike the volcanic rocks of the Cameroon mountains further to the southwest. The granites weather to produce an relatively infertile soil. However, there are also areas of more fertile clay soils. While agricultural activity is carried out most intensively on the plains, extensive areas of agriculture also affect the mountain slopes.
The area falls within White’s (1983) phytogeographical centre of Sudanian regional endemism. It is thought that Isoberlinia doka woodlands were once the dominant vegetation on Mount Mandara, which now supports only extremely degraded forms of this vegetation (Bellefontaine et al. 1997, MacKinnon and MacKinnon 1986). The trees here reach heights of 12 m to 18 m, and woody cover averages 50 percent or more (Bellefontaine et al. 1997). The herbaceous layer is largely dominated by hardy grasses (e.g. Andropogon spp. and Beckeropsis spp.) (Bellefontaine et al. 1997).
The ecoregion is, on the whole, heavily grazed and burnt. There are a few montane species and a number of submontane species in its flora. The highest points, from 1,200 m to 1,494 m, hold a mix of Sudanian and Afromontane species, such as the large succulent "tree" Euphorbia desmondi, Olea hochstetteri, and Pittosporum viridiflorum. The Mandara Plateau Mosaic, located at the northern limit of the Nigerian/Cameroon Mountain chain, has a long history of human settlement (Riddell and Campbell 1986). The region is one of the most environmentally, agriculturally and ethnically diverse areas of West Africa (FAO 2001).
The Mandara Mountains are known to be home to a number of rare and endemic plants (Stuart et al. 1990), with East African montane affinities, but they are little studied. Their ecological needs and major threats are thus poorly understood, and the conservation requirements of this area are not fully appreciated (Stuart et al. 1990). The current state of degradation of this ecosystem will certainly affect its prospects for future conservation action.
The dry forests of Mozogo-Gokoro National Park and the Mayo Louti Forest Reserves (Stuart et al. 1990) are areas only marginally associated with the Mandara ecoregion proper, however, being found at relatively low altitude in the saddle between two parts of the range. The mountains themselves may harbor a population of the endangered western subspecies of mountain reedbuck (Redunca fulvorufula adamauae) (Stuart et al. 1990, Hilton-Taylor 2000). This species lives in cool and dry mountainous regions, and this population may represent a remnant of its range during colder glacial periods (Kingdon 1997).
Scholte (1998) gives breeding records for Rüppel’s griffin (Gyps rupelli) and Egyptian vultures (Neophron percnopterus). These are the first breeding records for Egyptian vulture for this region of Africa (Scholte 1998). The region has three known endemic reptile species, Mount Lefo chameleon (Chamaeleo wiedersheimi), Mabuya langheldi, and African wall gecko (Tarentola ephippiata).
The distinctive plant communities associated with the Mandara Plateau receive no protection from the current network of protected areas in the region (MacKinnon and MacKinnon 1986). There is little available data on this ecoregion, and that which is available relates mainly to Cameroon’s 14 km2 Mozogo-Gokoro National Park, which is situated in the lower lying regions and is not fully representative of the ecoregion at large.
In 1998, Mozogo-Gokoro National Park had not been burnt for over 40 years (Culverwell, 1998), and as a result of this exclusion of fire, much of it has become far more densely wooded, with the establishment of dry thickets and the almost total elimination of grass cover. The woodland savanna is dominated by Acacia albida, with A. senegal, and A. nilotica also present. Other species include: Balanites aegyptiaca, Ziziphus spp., Crateva adansonii, Celtis integrifolia, Ficus spp., and Khaya senegalensis.
Recorded fauna include vervet monkey (Chlorocebus aethiops), patas monkey (Cercopithecus patas), olive baboon (Papio anubis), warthog (Phacochoerus aethiopicus), bushbuck (Tragelaphus scriptus), gray duiker, (Sylvicapra grimmia) and python (Python sebae). Although the park since its inception in 1932 has been treated effectively as a Strict Nature Reserve, with tourism prohibited, current plans are to open it for tourism.
Types and Severity of Threats
The Mandara Mountains are intensively used for cropping and livestock grazing (FAO 2001). Subsistence farmers also collect large amounts of fuelwood. Heavy grazing is probably detrimental to biodiversity in the area, although the farmers in the mountain region tend to stall feed their cattle during the growing season. Not only does this protect crops, but the manure from the stalls is also collected and used to fertilize areas under cultivation (FAO 2001). Thus agriculture and livestock production complement each other and benefit the human population of the ecoregion (FAO 2001). Firewood collection has added to the severe degradation of the indigenous woodlands.
Throughout all of Cameroon the major threat to biodiversity is posed by clearance of both lowland and montane forests (Stuart et al. 1990). This has already seemingly occurred on the Mandara Plateau with little natural forest vegetation remaining. Grazing and burning for clearing of new land are also extensive (Stuart et al. 1990). Illegal hunting, primarily for bushmeat, is on the rise in West Africa (Hearn 2001), with Cameroon being no exception. This endangers important mammal populations, even those in protected areas since policing is often under-resourced.
Climate change is likely to have serious consequences for vegetation found at higher (and therefore cooler) altitudes, for example the Mandara Plateau, as temperatures rise. The situation will be exacerbated through lack of information regarding the ecological needs of the plants and animals found here.
Justification of Ecoregion Delineation
The extent of this ecoregion is taken directly from the ‘Mandara plateau mosaic’ vegetation unit mapped by White (1983). The Mandara Mountains are known to be home to a number of rare and endemic plants (Stuart et al. 1990). This plateau was considered a distinct ecoregion due to its isolation from other highland areas, the modest amount of endemism present, and the unusual biogeographic affinities with other montane areas in eastern Africa.
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Culverwell, J. (1998) Long-term Recurrent Costs of Protected Area Management in Cameroon. Report to WWF-Cameroon and MINEF, Yaoundé.
Food and Agricultural Organization. 2001. Cattle stall-feeding in the Mandara Mountains Region. http://www.fao.org/wairdocs/ilri/x5511e/x5511e02.htm.
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Prepared by: Colleen Seymour
Reviewed by: In progress