In West Africa, the forest zone is the southern part of the region that was once covered by tropical rainforest. This area is sometimes called Guinea to help distinguish it from the grassland-covered Sudan, the drier Sahel, and the very dry Sahara. This area includes vegetation mainly made of trees and has the following types of plant communities: -mangrove swamp forest (salt and fresh water swamp) -tropical rain forest.
Extent
The forest zone of West Africa, specifically, includes all of Liberia and Sierra Leone, most of Guinea, the southern parts of Côte d'Ivoire and Nigeria, and sections of Ghana, Togo, and Guinea-Bissau.
The Dahomey Gap divides the forest zone into two parts by creating a region with much drier weather. For example, Accra receives less than 760 millimetres (30 inches) of rainfall each year, which is not enough to support rainforests in that area. The western part of the forest zone is called the Upper Guinea forests, stretching from Guinea to western Togo. The eastern part is called the Lower Guinea forests, extending from southeastern Benin through southern Nigeria to Cameroon.
To the north, as the time the region is influenced by the Intertropical Convergence Zone decreases, the dry season becomes too long to support rainforests except in the wettest areas of the far west. Because of this, the forest area ends, except along some rivers, north of about 7° N in the east and 9° N in the west.
Geography
Most of the forest zone is covered by Precambrian cratons and has not experienced tectonic activity during the Phanerozoic periods. These cratons are believed to have joined together toward the end of the Precambrian era. The area is mostly flat or has gentle hills and valleys, with mountains only along the northern edge, reaching up to 1948 meters in the Loma Massif. Many rivers flow through the forest zone, including the Niger and the Volta rivers, which are the most significant.
Climate
The forest zone is very close to the equator, so temperatures change very little throughout the year. The climate is hot all year, with the highest temperatures usually around 31 °C and the lowest around 24 °C. In areas such as Fouta Djallon and near Mont Nimba, the highest temperatures are about 27 °C, but the lowest can drop to about 16 °C.
Rainfall is the main factor that influences the climate of the forest zone. During the northern summer, a large area of low pressure centered over India creates a long, low-pressure area that extends across the region. This low-pressure area moves farthest north between July and September, bringing very moist winds from the Atlantic Ocean to the coast. These winds cause heavy rainfall, sometimes as much as thirty inches per month, in lowland areas of Guinea, Sierra Leone, and Liberia. As this low-pressure area moves north and south, it causes two rainy seasons on the southern coast: one heavy season from May to July and a lighter season from October to November.
During the northern winter, a high-pressure system forms over the Sahara Desert, pushing dry winds from the northeast across the region. This creates a dry season, except in the far southeast, where a weather pattern over southern Africa brings westerly winds to the north of the equator. This effect is common enough that the driest months, January and February, are not completely dry along the coast, even though rainfall is very low—about 1 inch per month in places like Abidjan.
Total rainfall each year decreases as distance from the coast increases. The shape of the coastline also affects rainfall amounts. In the wettest areas of Guinea, Sierra Leone, and Liberia, yearly rainfall averages between 3000 to 5000 millimeters (120 to 200 inches). In Abidjan, it averages about 2050 millimeters (81 inches), in Lagos about 1800 millimeters (71 inches), and near the northern edge of the forest, about 1400 millimeters (55 inches).
Land use and demographics
In the eastern part of the forest zone, the presence of Mount Cameroon makes the soil fertile, allowing for large areas of subsistence farming. Major crops grown here include millet, yams, and rice. On the richest soils, plantation agriculture is widespread, with cocoa being the main crop. Further west, the soil is less fertile due to the region’s ancient geology, and farming focuses more on growing perennial crops, with cocoa still being the most important. However, deforestation has greatly reduced natural rainforests in countries like Côte d'Ivoire and Liberia. As a result, many farmers without land have been forced to use areas with poor soil for farming, even though population growth remains very high despite frequent conflicts.
The eastern part of the forest zone is one of Africa’s most densely populated regions because of its reliable rainfall and fertile alluvial soils. While the area includes many large cities, such as Lagos, Ibadan, and Port Harcourt, which have grown into mega-cities since the 1970s, most people still live in rural areas and rely on subsistence farming. Major ethnic groups in this region include the Igbo and Yoruba. The western part has fewer people but shares similar demographics, with many African tribes living there. Major cities in this region are Abidjan and Conakry.
Flora, fauna and conservation
The West African forest zone has fewer types of plants compared to other tropical forests because of long periods of ice and rainfall that changes a lot with the seasons. However, many plants found there are unique to the area, and some are valuable, such as the iroko tree (Chlorophora excelsa).
The region is home to many animal species that live nowhere else, but most are now in danger of disappearing because of forest loss. One well-known example is the pygmy hippopotamus (Hexaprotodon liberiensis). Another is the royal antelope (Neotragus pygmaeus), which is one of the smallest hoofed mammals in the world and can jump up to ten times its body size.
Although many national parks and protected areas exist to help save the remaining forests, most lack enough money to be properly managed. Because of this, the future of these forests is uncertain.