The forests of Upper Guinea: gradients in large species composition.

Abstract

This chapter provides a forest gradient map for Upper Guinea, using forest inventory data of 40 large tree species. Variation in species composition is subsequently explained in terms of climate and soils. The area covered is confined to the forest zone of Sierra Leone, Liberia, Côte d'Ivoire and Ghana. A list of species that were inventoried from 176 forest sites (8 for Sierra Leone, 26 for Liberia, 37 for Côte d'Ivoire and 105 for Ghana), is given. Correspondence analysis for sites revealed that the forests belonging to the same country are clustered together. Ghana and Liberia have the most distinct forests, and Côte d'Ivore and Sierra Leone are in between. The vegetation types of the 176 sites were grouped as hyperwet evergreen, wet evergreen (with three subtypes), moist evergreen, moist semi-deciduous, and dry semi-deciduous. A clear decline in rainfall was observed from the hyperwet evergreen forest to the dry semi-deciduous forest. In contrast, soil fertility and water holding capacity increase along this forest gradient.