The Upper Guinean forest of West Africa, identified over 20 years ago as a “global biodiversity hotspot” due to its exceptional concentrations of endemic species and exceptional loss of habitats, encompasses all of the lowland forests of West Africa (Mittermeier and others, 1999; Myers and others, 2000). The forest ecosystem extends from southern Guinea into eastern Sierra Leone, through Liberia, Côte d’Ivoire, southern Ghana, and across southwestern Togo. In southeastern Ghana, a savanna corridor known as the Dahomey Gap interrupts the Upper Guinean forest ecosystem (Salzmann and Hoelzmann, 2005). One outlier in the Dahomey Gap is the dense forest along the Ghana-Togo border highlands.
The maps of the Upper Guinean forest show two forest stages:
The forest class is characterized by West Africa’s dense tropical evergreen rain forest and moist deciduous forest, and a closed canopy cover (White, 1983). It occurs mainly along the coast where rainfall is higher. Of all the Upper Guinean countries, only Liberia lies entirely within the moist forest zone. About 50 percent of the remaining Upper Guinean dense forest is contained within Liberia.
Degraded forests were once dense, deciduous forests, now modified and fragmented by human activity. They occur mainly in the off-reserve areas and are particularly visible in Liberia, Côte d’Ivoire, and Ghana.
Originally, the Upper Guinean forest consisted of dense forest that covered an estimated 680,000 sq km (Mittermeier and others, 1999; Myers, 2000). Using the West Africa rainfall isohyets as a general reference, as well as the extent and pattern of the dense forest depicted on the 1975 map, the probable limits of the Upper Guinean dense forest (prior to 1900) have been delineated (see map below). In 1975, many remnant or relic patches of dense forest still remained. The assumption was that the forest patches seen in 1975 are remnants of an earlier, near continuous forest. With this approach, the estimate of the forest area prior to 1900 reaches about 360,650 sq km, which still represents a conservative assessment of the original extent of the Upper Guinean dense forest— the actual area may have been even greater. Furthermore, according to the data collected by Unwin (1920), the extent of dense forest in the Upper Guinean forest countries in 1920 was approximately 216,000 sq km, which supports the 1900 estimate.
The maps of the forest extent show that most of the forest removal seems to have occurred before 1975, with a loss of 84 percent of the original forest extent. The historical dense forest ecosystem has been transformed to a series of forest fragments separated by agricultural communities and degraded forested lands. Between 1975 and 2013, forest removal for wood products, plantations, farming and other uses was still ongoing, and resulted in the loss of 28 percent (65,000 sq km) of the forest (all classes considered). It is believed that Liberia is the only country in West Africa that was once entirely covered with rain forests, yet less than half remains today (Bakarr and others, 2004). Of the intact forest remaining in the Upper Guinean forest, Guinea contains 6 percent, Sierra Leone 4 percent, Liberia 49 percent, Côte d’Ivoire 21 percent, Ghana 18 percent, and Togo 2 percent. In 2013, the Upper Guinean forest countries retained only about 70,000 sq km of dense forest cover, and only 32,000 sq km are located in national parks, classified forests, nature reserves, and wildlife sanctuaries (IUCN and UNEP-WCMC, 2013). The remaining dense forest cover constitutes the last testimony to the species-rich forests that used to blanket most of the southern part of the region. While the IUCN has defined six protected area management categories based on primary management objectives, in practice protected area management differs greatly from country to country. Outside of the dense forest patches, degraded forest also continues to decrease in area, dropping from 120,192 to 94,836 sq km between 1975 and 2013, a loss of 21 percent of their area. Gallery forests, which form closed canopy corridors along rivers and intermittent drainage networks, are sparse and pretty rare across the Upper Guinean countries. They represent the most biologically rich habitats in the savanna zones of West Africa and are also threatened by degradation and deforestation.
Presently, the Upper Guinean forest is a highly fragmented system and remains one of the most severely threatened forest systems in the world. This region is a high global priority for biodiversity conservation, extractive industries, and other key global commodities such as rubber, cocoa, and oil palm. Intensified by increasing population, deforestation through unregulated logging and slash-and-burn agriculture is the major threat to the forest ecosystem. By 2013, 15 percent (33,748 sq km) of the 1975 dense and degraded forest had been converted to agriculture (including conversion to plantations). Other direct threats to the forest in this area include mining, bushmeat hunting, water pollution, and coastal development. Indirect threats to these ecosystems, such as poverty, migration and urbanization, political instability, unprotected borders (both land and water), inadequate and uneven policies, and lack of regional conservation planning, contribute to the continuous pressure on the Upper Guinean forest in both unprotected and protected areas. The largest blocks of forests now protected in Liberia, Côte d’Ivoire, and Ghana are still under considerable pressure from human encroachment that is continuing to fragment and degrade the remaining blocks of this high biodiversity ecosystem.