Forest Zone - Extent

Extent

The forest zone of West Africa, in the strict sense, covers all of Liberia and Sierra Leone, most of Guinea, the southern halves of Côte d'Ivoire and Nigeria, and parts of Ghana, Togo and Guinea-Bissau.

The Dahomey Gap splits the forest zone into two halves by producing an area of much drier climate - Accra receives less than 760 millimetres (30 inches) of rainfall per year - between the wetter regions capable of supporting rainforest. The western forest zone is known as the Upper Guinea forests, and extends from Guinea to western Togo, and the eastern forest zone is known as the Lower Guinea forests, and extends from southeastern Benin through southern Nigeria and into Cameroon.

To the north, as the length for which the region is affected by the Intertropical Convergence Zone declines, the dry season becomes too long to support rainforest except in the wettest areas of the far west. Thus the forest fades out, except on some rivers, north of about 7° N in the east and 9° N in the west.

During the Last Glacial Maximum (and probably more severely during earlier glaciations), because the Atlantic Ocean was up to six degrees cooler, rainfall was dramatically reduced (by up to ninety percent in the area around Freetown) est all but vanished, probably surviving only in the extreme southeast of Nigeria and a few coastal areas of Côte d'Ivoire.

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