Abstract

This study analyses the effects of anthropogenic disturbance on trees and shrubs floristic α-diversity in two protected rain forests in southwestern Côte d’Ivoire. These forests have been under timber harvesting since their protection in 1929. The forestry service had developed plantations of indigenous timber species and teak since 1996 to increase their productivities for timbers. Additionally, they host many plantations of cash crop among which coffee, cocoa and rubber are the most important. To understand how these plantations affect the local flora, the diversity of shrubs and trees with DBH ≥ 10 cm was analyzed through the species number and diversity indices. Plots were of 20 m x 50 m size and a total of 10 per vegetation type. Highest species numbers, Shannon-Wiener’s index, Hill’s index and Pielou’s index, in both plots and vegetation types were found in natural forest and undergrowth cleared forest which had similar values of these parameters. Plot richness was ranked between 1 and 7 species whilst vegetation type richness varied from 4 to 12 species for all plantations. Yet Simpson’s diversity index showed highest values in plantations. Richness in plantation was influenced by the location of plantation site and the nature of crop but no influence was found with the combination site and crop nature.

Key words: Forest protection, cash crops, agroforestry, flora and diversity, South-West Côte d’Ivoire.