(Source: Groombridge and Jenkins 2002, Hoekstra and others 2005, Mayaux and others 2004 and WRI 2005)
The wide range of ecosystems – forests, savannahs, deserts, rivers, mountains, mangroves and seas – makes the sub-region rich in biodiversity. The Sahelian zone has several wetlands, including the Niger and Senegal rivers, Lake Chad and floodlands in Senegal and Niger which are very important for migratory birds. The inner Niger delta is a vast floodplain (more than 30,000 km2) situated in the middle of the Sahelian landscape, rich in natural resources and featuring varied ecosystems (lakes, forest floodplains, flooded grasslands and savannah) which supports the livelihoods of 1 million people. The delta is also well known as a wintering and staging area for million of migratory birds. Other important sub-regional biodiversity values include the west African manatee, a globally endangered species. The Guinea forest contains half the mammal species on the African continent, including the rare pygmy hippopotamus, the zebra duiker and the drill, the most threatened primate.
Challenges faced in realizing opportunities for development
Land degradation and desertification are major causes of biodiversity loss. Three factors contribute:
- A relatively dense and growing population with strong dependence on natural resources:
- Relatively easy access to resources; and
- Recurrent droughts.
These processes affect grasslands, steppes, savannahs and woodlands:
- They fragment forests and alter their structure and composition, especially when they are followed by recurrent forest and bush fires;
- They reduce surface water points and their associated plants;
- They strongly deplete animal populations and notably reduce a number of rare and vulnerable species through habitat degradation, sport hunting and especially through exploitation for bushmeat, which is exacerbated by drought-related food deficits.
Dust storms, forest fires, locust outbreaks and population displacement are all linked to the phenomenon of desertification, and have strongly negative consequences for people, in particular through the loss of livelihood and economic opportunities.
(Source: J. Gerholdt/Still Pictures)
Land degradation is a persistent reduction in the capacity to support life and supply ecosystem services. It affects biological diversity directly and indirectly. It may affect the survival of species and alter processes that support their life, or it may trigger socioeconomic phenomena that impact on living species and their ecosystems. Land degradation phenomena directly affecting biodiversity include water and wind erosion. Along major river basins siltation processes accumulate debris and materials that engulf natural vegetation, such as the Acacia nilotica riparian forests. Trees may survive for years, but the diverse understorey may not. Soil erosion contributes to moving the seed capital of the ground, uprooting grassy as well as woody species, and in accumulation areas it smothers valuable species. This occurs in the sand dune areas of countries such as Mauritania, Mali, Niger, Nigeria and Senegal.
(Source: Hamerlynck and Duvail 2003, IUCN 2003)
Indirect factors associated with land degradation that impact on biodiversity include the coping strategies people adopt to deal with environmental change. The movement of people south towards subhumid to humid tropical areas has resulted in depletion of natural resources: loss of primary forests and woodlands, repeated logging of the secondary vegetation, and depletion of a number of species. The influx of refugees from war-stricken areas also triggers severe land degradation in host regions and the overuse of wildlife resources. More diffuse degradation of land resources also occurs in the arid and sub-humid parts. These include the extraction of tree resources outside forests for charcoal making (about 150 million tonnes/year from the savannahs and woodland areas), and the use of high-value woods. Most affected are the Meliacaea family (Khaya species), Pterocarpus erinaceus, and Dalbergia melanoxylon.
The degradation and fragmentation of natural landscapes is caused by agricultural expansion. Agricultural expansion affects the survival and regeneration of animal populations, destroys the structure of wildlife habitat, and strongly contributes to reduction of wildlife populations. The number of species threatened continues to grow; these include lion, elephant, most of the greater antelopes, and waterdependent species such as manatees and crocodiles, which could form the basis of a tourism industry.
Strategies to enhaced the opportunities for development
(Source: Wetlands International, UNESCO 2006)
A number of conservation efforts, some involving communities, have been undertaken. An example of a successful conservation initiative involving local communities is shown in Box 1.
Table 2 shows international protected areas in Western Africa. An example of successful cooperative is the endeavour of Benin, Burkina Faso and Niger, supported by external partners such as France, to protect the extensive transboundary complex of the Pendjari and Arly national parks. Concerted efforts have succeeded in maintaining the overall system and resources in the protected areas in the three participating countries. Biodiversity is relatively well conserved in this area: avifauna is represented by around 378 species; fish species, amphibians and reptiles are prominently present; and the greater mammals of the savannahs and woodland areas are extensively featured (10,000 buffalo, 4,500 elephants, 7,500 roan antelopes, 2,000 bubals, 1,100 warthogs and 1,000 kobs). Lions, cheetahs, panthers and hyenas are also well represented. The habitat is also well conserved, and the overall trend of biological diversity is deemed very positive and on the rise.
- Beintema, A.J., Fofana, B. and Diallo, M., 2001. Gestion des forêts inondées dans le Delta Intérieur du Niger, Mali; Management of flood forests in the inner Niger Delta, Mali. Alterra-rapport 341,Alterra, Green World Research, Wageningen.
- Hamerlynck, O. and Duvail, S., 2003. The Rehabilitation of the Delta of the Senegal River in Mauritania. IUCN – The World Conservation Union, Gland and Cambridge.
- IUCN, 2003. Annual Report. IUCN – The World Conservation Union, Gland.
- UNEP and NESDA, 2004. Rapport sur l’Etat de l’Environnement en Afrique de l’Ouest. United Nations Environment Programme and Network for Environment and Sustainable Development in Africa, Nairobi.
- UNEP, 2006. Africa Environment Outlook 2.
- UNESCO, 2006a. Biosphere Reserves. Africa. United Nations Educational, Scientific and Cultural Organization.
- UNESCO, 2006b. World Heritage List. United Nations Educational, Scientific and Cultural Organization.
- Wetlands International.
This is a chapter from Africa Environment Outlook 2: Our Environment, Our Wealth (e-book).
Previous: Southern Africa and biodiversity | Table of Contents | Next: Western Indian Ocean Islands and biodiversity
Disclaimer: This article is taken wholly from, or contains information that was originally published by, the United Nations Environment Programme. Topic editors and authors for the Encyclopedia of Earth may have edited its content or added new information. The use of information from the United Nations Environment Programme should not be construed as support for or endorsement by that organization for any new information added by EoE personnel, or for any editing of the original content.