Guinean forest-savanna mosaic

Guinean forest-savanna mosaic
Name	Guinean forest–savanna mosaic
Biome	Tropical and subtropical grasslands, savannas, and shrublands
Biogeographic realm	Afrotropical
Countries	Guinea; Sierra Leone; Liberia; Côte d'Ivoire; Ghana; Togo; Benin; Nigeria; Cameroon
Area km2	613000

Guinean forest-savanna mosaic is a transitional ecoregion in West Africa forming a broad belt between coastal Upper Guinean forests and interior Sudanian savanna regions. It spans multiple national borders including Guinea, Sierra Leone, Liberia, Côte d'Ivoire, Ghana, Togo, Benin, Nigeria, and Cameroon, and connects to conservation landscapes such as the Taï National Park buffer zones and the W National Park mosaic. The mosaic supports a complex patchwork of tropical rainforest fragments, savanna grasslands, gallery forests and wetlands, and has been shaped by climatic gradients, fluvial systems like the Volta River and the Niger River, and long-standing human land use linked to historical polities such as the Mali Empire and the Ashanti Empire.

Geography and extent

The ecoregion lies between coastal lowlands and the dry interiors, forming a discontinuous arc from the Sassandra River in Côte d'Ivoire through Ghana and Nigeria into western Cameroon. Major cities on its margins include Conakry, Freetown, Monrovia, Abidjan, Accra, Lagos, and Douala, while regional transport corridors such as the Lagos–Abidjan Highway and the Trans–Sahelian Highway intersect its landscape. Topography ranges from coastal plains to the inselbergs and plateaus of the Fouta Djallon and the Jos Plateau margins, and elevations influence river catchments feeding the Volta Basin and the Niger Basin. The area overlaps with administrative regions like Western Region (Ghana), Eastern Region (Nigeria), and Lagos State and includes protected areas such as Kakum National Park peripheries and the Gola Forest Reserve.

Climate and soils

The climate is tropical with a marked wet season controlled by the West African Monsoon and a dry season influenced by the Harmattan wind and subtropical high pressures. Rainfall gradients vary from more than 2,000 mm annually in western fragments near Sierra Leone and Liberia to under 1,000 mm toward northern Benin and Nigeria, producing ecotonal shifts documented in climatological studies by institutions like the International Institute of Tropical Agriculture and the World Meteorological Organization. Soils include ferralsols, acrisols, and varying alluvial deposits along rivers such as the Tano River and the Comoé River, with soil fertility influenced by weathering, erosion on slopes like the Gola Hills, and seasonal fire regimes historically used by groups such as the Akan people and the Yoruba.

Vegetation and habitats

Vegetation forms a patchwork of moist semideciduous forest fragments, wooded savanna, tall grasslands, and gallery forests along waterways such as the Upper Guinea Rainforest tributaries. Notable plant assemblages contain emergent trees like species used in trade and culture, historically exploited in markets of Kumasi and Lagos, and include genera prominent in floristic studies housed at the Royal Botanic Gardens, Kew and the Herbarium at the University of Ibadan. Mosaic habitats support liana-rich forest patches that buffer populations of endemic taxa recorded by the IUCN and surveyed in botanical inventories by the Muséum national d'Histoire naturelle and the Smithsonian Institution. Vegetation structure reflects influences from fire regimes, shifting cultivation by farmers in Eastern Region (Ghana) and Abia State, and landscape fragmentation near mining zones like those around Koidu and Obuasi.

Fauna and biodiversity

The region is home to a mix of forest and savanna fauna, including remnant populations of large mammals such as African elephants, leopards, and forest-adapted primates like the Western chimpanzee and the Patas monkey. Bird diversity includes species associated with ecotones recorded in checklists from the Audubon Society and the BirdLife International Important Bird Areas program, with notable records around sites like Kakum and the Gola Rainforest. Herpetofauna and invertebrates display high localized endemism cataloged by researchers from University of Ghana and University of Ibadan, while freshwater fauna in rivers like the Cavalla River reflect connectivity to Gulf of Guinea ichthyofauna studied by the IUCN SSC Freshwater Biodiversity Unit. Biodiversity values have been the subject of regional conservation assessments by agencies such as the World Wildlife Fund and the United Nations Environment Programme.

Human use and land cover change

Human societies within the mosaic rely on agroforestry, shifting cultivation, cocoa and oil palm plantations historically centered in districts near Kumasi and Abidjan, artisanal mining activities in places like Semafo concessions, and urban expansion of capitals including Accra and Abuja. Colonial-era commodity chains tied to ports like Freetown and Tema and institutions such as the Colonial Office reshaped land cover, while contemporary commodity markets and corporations based in London, Paris, and Lagos drive land-use change. Cultural landscapes shaped by ethnic groups such as the Akan, Mende, Kru, and Ewe include sacred groves, agroforestry systems, and managed fallows documented in ethnobotanical studies by scholars affiliated with the University of Cambridge and the London School of Economics. Remote sensing analyses by teams at the NASA and the European Space Agency show ongoing conversion of forest patches to cropland and pasture, fragmentation exacerbated by logging concessions and infrastructure projects like the West African Gas Pipeline.

Conservation and threats

Threats include deforestation for expansion of cocoa and oil palm plantations, illegal logging linked to supply chains transiting through hubs such as Abidjan and Lagos, artisanal and industrial mining impacts near Sierra Leone and Ghana, and climate-driven shifts in the West African Monsoon that alter fire regimes. Conservation efforts involve national parks and reserves including Kakum National Park, transboundary initiatives supported by the African Union, and NGO programs run by Conservation International, Fauna & Flora International, and The Nature Conservancy. Policy instruments such as the CITES listings for ivory and timber, donor-funded REDD+ projects overseen by the World Bank, and community forestry agreements negotiated with local councils and traditional authorities aim to balance livelihoods and biodiversity protection. Despite these measures, fragmentation, poaching, and unsustainable land conversion remain significant, prompting calls for integrated landscape approaches advocated at forums like the Convention on Biological Diversity meetings and regional strategies promoted by the Economic Community of West African States.

Category:Ecoregions of West Africa