Mapping the Ecological Niche of a Key West African Species: Terminalia leiocarpa

ABSTRACTTerminalia leiocarpa (DC.) Baill is a tree species widely used in ethnoveterinary practices, human medicine, furniture and charcoal making. Our study aimed to (i) map the favourable areas for the species in Benin, both currently and in the future, and (ii) analyse the biotic and abiotic factors affecting the structure and availability of T. leiocarpa. To achieve this goal, a dendrometric inventory of 141 plots across the three climate zones of Benin was carried out. This included the collection of soil type and insect attack data at the plot level, as well as climate data downloaded from the WorldClim 2 platform. Dendrometry parameters, such as basal area, tree height and diameter, Lorey height and importance value index (IVI) were calculated, and generalised linear mixed models, were established to determine the effects of biotic (diameter of heterospecific trees, density and diameter of conspecific trees) and abiotic (mean of daily temperature variation (bio2) and annual precipitation (bio12)) factors on these parameters. The future distribution areas of T. leiocarpa in Benin were projected under SSP 2–4.5 and SSP 5–8.5 scenarios using Maximum Entropy (MaxEnt). The results predicted a decrease in the suitable areas of 22% and 33% under the SSP 2–4.5 and SSP 5–8.5 scenarios, respectively. Our results also showed that conspecific tree diameter (β = 0.34; p = 0.000) and conspecific tree density (β = 0.02; p = 0.036) were positively associated with the tree height, while bio2 (β = −0.32; p = 0.039) and bio12 (β = −0.01; p = 0.004) had a negative effect on T. leiocarpa diameter. These results should help us to understand the ecological niche and to take the necessary steps upstream to contribute to the conservation and sustainable use of T. leiocarpa. Future studies could focus on analysing the impact of environmental factors on juvenile growth and survival.