The Guinean forest-savanna, also known as the Guinean forest-savanna transition, is a distinctive ecological region located in West Africa. It stretches across several countries, including the Gambia, Senegal, Guinea, Sierra Leone, Liberia, Ivory Coast, Ghana, Togo, Benin, Nigeria, and Cameroon. This region is characterized by a unique blend of forested areas and savannas, creating a diverse and dynamic landscape.
It is an ecoregion of West Africa, a band of interlaced forest, savanna, and grassland running east to west and dividing the tropical moist forests near the coast from the West Sudanian savanna of the interior.
Setting The Guinean forest–savanna mosaic covers an area of , extending from western Senegal to eastern Nigeria, and including portions of Gambia, Guinea Bissau, Guinea, Sierra Leone, Côte d'Ivoire, Ghana, Togo, Benin and Cameroon. The Cameroon Highlands of eastern Nigeria and Cameroon separate the Guinean forest–savanna mosaic from the Northern Congolian forest–savanna mosaic, which lies to the east.Fjeldsaå, J., & Lovett, J. C. (1997). Geographical patterns of old and young species in African forest biota: the significance of specific montane areas as evolutionary centres. Biodiversity & Conservation, 6, 325-346. The Dahomey Gap is a region of Togo and Benin where the forest-savanna mosaic extends to the coast, and separates the Upper Guinean forests of Guinea, Sierra Leone, Liberia, Côte d'Ivoire, and Ghana from the Lower Guinean forests of Nigeria and Cameroon.
Climate The climate in this region varies depending on the specific location, but it generally experiences a tropical climate with distinct wet and dry seasons.Goetze, D., Hörsch, B., & Porembski, S. (2006). Dynamics of forest–savanna mosaics in north‐eastern Ivory Coast from 1954 to 2002. Journal of biogeography, 33(4), 653-664. The wet season brings heavy rainfall, while the dry season is characterized by lower precipitation and drier conditions. This ecoregion is situated in the humid tropical savanna zone, where the average yearly high temperatures range from 30 to 33 °C and the lows range from 14 to 21 °C. The annual rainfall typically falls between 1,600 and 2,000 mm, although there are areas in the Dahomey Gap that receive 1,000 mm or less annually.
The Guinean savanna mosaic represents a critical ecological transition zone between the dense, evergreen rainforests to the south and the more open, tree-dotted savannas to the north. This transition creates a unique mix of plant and animal species adapted to varying ecological conditions. Like many ecosystems worldwide, the Guinean forest–savanna mosaic is susceptible to the impacts of climate change. Altered rainfall patterns, increased temperatures, and more frequent extreme weather events have affected the health and composition of this biome.
Biodiversity The Guinean forest–savanna mosaic is known for its high biological diversity.Christiana Ndidi, E., & Adeniyi Suleiman, G. (2009). Species diversity patterns along the forest savanna boundary in Nigeria. Management of Environmental Quality: An International Journal, 20(1), 64-72. It is home to a wide range of plant and animal species, including many endemic species that are found nowhere else in the world. Some iconic species found here include chimpanzees, pygmy hippos, forest elephants, and various species of primates and birds. They also include several species of primates, reptiles, amphibians, and plants that have evolved in isolation within this region.
Vegetation
Forest: The forested areas in this mosaic are primarily composed of tropical rainforests, characterized by high rainfall, high humidity, and diverse flora and fauna. These forests are home to a wide variety of plant species, including towering hardwood trees, lianas, epiphytes, and a rich understory of shrubs and herbs. Savanna: The savanna component consists of grasslands interspersed with scattered trees, which are adapted to periodic fires. The savanna ecosystem supports a different set of plant species, including various grasses, shrubs, and acacia trees.
Flora
This biome is characterized by a mix of forested areas and open savannas. It is often referred to as a mosaic because it consists of a patchwork of different vegetation types.Whittaker, R. H., & Levin, S. (1977). The role of mosaic phenomena in natural communities. Theoretical population biology, 12(2), 117-139. In the forested areas, you can find a mix of evergreen and deciduous trees, while the savanna regions feature grasslands and scattered trees.Liu, Z., Wimberly, M. C., & Dwomoh, F. K. (2016). Vegetation dynamics in the upper guinean forest region of West Africa from 2001 to 2015. Remote Sensing, 9(1), 5. In terms of plant life, it contains a mix of tree species such as mahogany, iroko, and various species of acacia, alongside grasses and shrubs common to savannas. The region is mainly grassland crossed with trees growing alongside streams and on hillsides, with the constantly occurring fires keeping back the growth of trees in open country. Lophira lanceolata is one of the tree species found that is more resistant to fire than many others.Fairhead, J., & Leach, M. (1996). Misreading the African landscape: society and ecology in a forest-savanna mosaic (No. 90). Cambridge University Press.
Fauna
The mixture of forest and grassland provide habitat for a range of species from large mammalsAndrews, P. (2006). Taphonomic effects of faunal impoverishment and faunal mixing. Palaeogeography, Palaeoclimatology, Palaeoecology, 241(3-4), 572-589. such as African leopard, forest elephants, hippopotamus and antelopes such as the red-flanked duiker to the common tortoise as well as more localised species including patas monkeys and Ghana worm lizards (Amphisbaenia).Brockerhoff, E. G., Barbaro, L., Castagneyrol, B., Forrester, D. I., Gardiner, B., González-Olabarria, J. R., ... & Jactel, H. (2017). Forest biodiversity, ecosystem functioning and the provision of ecosystem services. Biodiversity and Conservation, 26, 3005-3035. The wetlands in the region are rich in birdlife, including iris glossy starling and black crowned crane.
Mammals: The Guinean forest–savanna mosaic is home to a wide variety of mammalian species. This includes iconic species such as African elephants, western chimpanzees, and western lowland gorillas. Other notable mammals include leopards, various species of antelope (such as duikers and bushbucks), and a diverse range of primates (like guenons, colobus monkeys, and baboons). Birds: The avifauna of this region is highly diverse, with hundreds of species recorded. This includes a mix of forest-dwelling birds like turacos, hornbills, and various species of parrots, as well as savanna-adapted species like raptors, bustards, and various types of weavers. Reptiles and Amphibians: The mosaic is also home to a variety of reptiles and amphibians, including numerous snake species, chameleons, crocodiles, and an array of frogs and toads. Invertebrates: The biodiversity of invertebrates, including insects and arachnids, is extremely high, with countless species contributing to the overall ecological balance.
Human settlement The ecoregion covers large areas of many West African nations including: Senegal - much of the southern Casamance arm of the country including the city of Ziguinchor. All of inland Guinea-Bissau The Gambia - in particular, south of the River Gambia Guinea - the band of lowland areas parallel to the coast and then running south-east of the central mountains, including the towns of Fria, Kindia and Kissidougou. Northern Sierra Leone including the towns of Makeni and Kabala. Côte d'Ivoire - a swathe across the middle east from Touba through the country's second-largest city Bouaké. A wide strip across Ghana including the country east of Lake Volta, where the main town is Ho. Togo - the southern plateau. Benin - the southern areas including the city of Bohicon. Nigeria - a large area including the cities of Ibadan, which means where the forest meets the savanna, the country's capital Abuja, Lokoja where the River Niger and River Benue meet, Enugu, and Makurdi.
Threats and Conservation Like many tropical ecosystems, this mosaic is under threat from various human activities.Atsri, H. K., Konko, Y., Cuni-Sanchez, A., Abotsi, K. E., & Kokou, K. (2018). Changes in the West African forest-savanna mosaic, insights from central Togo. PloS one, 13(10), e0203999. Deforestation due to logging, agriculture expansion, and mining operations pose significant challenges to its conservation. Additionally, infrastructure development and road construction can fragment habitats, making it difficult for wildlife to move between different areas.
Deforestation and Habitat Loss: One of the most significant threats to the biodiversity of the Guinean forest–savanna mosaic is deforestation. This occurs due to agriculture expansion, logging, and infrastructure development. Hunting and Poaching: Unsustainable hunting and poaching for bushmeat and the pet trade can put immense pressure on the local wildlife populations. Climate Change: Changes in rainfall patterns, temperature, and other climatic factors can disrupt the delicate ecological balance of the region. Conservation Efforts: Several conservation organizations and government agencies are working to protect and restore the biodiversity of this mosaic. This includes the establishment of protected areas, community-based conservation initiatives, and sustainable land-use planning.
Conservation Initiatives Conservation organizations and governments in the region have recognized the importance of preserving the Guinean forest–savanna mosaic. Efforts have been made to establish protected areas and national parks, such as Taï National Park in Ivory Coast and Gola Rainforest National Park in Sierra Leone and Liberia.Chatelain, C., Dao, H., Gautier, L., & Spichiger, R. (2004). Forest cover changes in Côte d'Ivoire and Upper Guinea. In Biodiversity of West African forests: an ecological atlas of woody plant species (pp. 15-32). Wallingford UK: CABI Publishing.Curry-Lindahl, K. (1974). Conservation problems and progress in equatorial African countries. Environmental Conservation, 1(2), 111-122.
Protected areas The Guinean forest–savanna mosaic is a biologically diverse and ecologically significant region in West Africa. Its unique blend of forest and savanna habitats, along with its endemic species, make it an area of global importance for conservation efforts.Poorter, L. (Ed.). (2004). Biodiversity of West African forests: an ecological atlas of woody plant species. CABI. A 2017 assessment found that 107,116 km2, or 16%, of the ecoregion is in protected areas.Eric Dinerstein, David Olson, et al. (2017). An Ecoregion-Based Approach to Protecting Half the Terrestrial Realm, BioScience, Volume 67, Issue 6, June 2017, Pages 534–545; Supplemental material 2 table S1b. Protected areas include Upper Niger National Park in Guinea, Dulombi-Boe National Park in Guinea-Bissau, Outamba-Kilimi National Park in Sierra Leone, Mont Sangbé National Park in Ivory Coast, Bui National Park and Digya National Park in Ghana, and Old Oyo National Park and Gashaka-Gumti National Park in Nigeria.
Research and Monitoring Scientists and researchers are actively studying this region to better understand its ecological dynamics, species distribution, and responses to environmental changes. Some key aspects of this research and monitoring initiative includes:
Ecosystem Description Biodiversity: The Guinean forest–savanna mosaic is renowned for its high biodiversity, supporting a wide variety of plant and animal species. This region is home to several endangered and endemic species, such as chimpanzees, pygmy hippos, and various rare plants.