Human and Environmental Factors Shape Tree Species Assemblages in West African Tropical Forests

Abstract

Human activities exert pronounced influence on forest ecosystems, impacting biodiversity and functions across multiple scales. However, the consequences of low-intensity human activities on tropical forest ecosystems are difficult to assess and remain poorly explored. The influence of human activities and other site-specific variables on forest tree assemblages in central-west Africa was investigated. The greatest impact of human activity was expected to be seen on edible tree species. Tree species in the forest were divided into edible (consumed by humans) and inedible species to assess the differential impacts of human resource use on species. Tree data from 66 plots in Nigeria and Cameroon (collected between 2002 and 2019) were analysed using Generalized Dissimilarity Models (GDMs) to assess pairwise beta-diversity between plots. Human activity significantly affected beta-diversity within the Nigeria-Cameroon forest region. Total beta-diversity was shaped by geographical distance between plots, plot elevation, stem density, proximity to human presence, and forest species composition. The forest species composition (monodominant or mixed forest) appeared to influence dissimilarity in beta-diversity for edible tree species only, likely linked to cultural practices in the region. Influence of elevation was significant for inedible species only, due to access restriction. These findings underscore the role of human influence in shaping tree species assemblages in African tropical forests and stress the necessity for further research in this area.