Floristic composition, structure and ecological drivers of woody stands of Detarium microcarpum Guill & Perr. and Detarium senegalense J.F.Gmel. in Benin

Abstract

contribute significantly to the livelihoods of local communities in sub-Saharan Africa. Exploration of the ecological patterns of their population structure is, therefore, necessary to ensure long-term management. The aims of this study were to: (i) determine the floristic composition of the habitats of D. microcarpum and D. senegalense, (ii) assess the population structure of both species, and (iii) assess the influence of biotic and abiotic drivers on the structural parameters of these species. A total of 177 plots were installed in eight sites in Benin. The data collected included the dbh1.30 m, the crown diameter, the total height, and the type of regeneration (generative, sprout, and sucker). The topographical and soil parameters of the plots were also recorded. A generalized linear model (binomial negative regression) and ANOVA were used for the analysis of density and morphological features data, respectively. The floristic composition of D. microcarpum habitats was found to be relatively distinct (p = 0.001) from one zone to another. A significant difference (p = 0.001) in heterospecific individuals was also observed between the habitats of both species. The density of individuals of D. microcarpum decreased significantly from the Sudanian zone (4594 ± 207 stems/ha) to the Guinean zone (93.60 ± 11.90 stems/ha; p < 0.001). In the Sudano-Guinean zone where both species were found, the density of D. senegalense was very low (19.07 ± 7.64 stems/ha). The density of adult individuals of D. microcarpum was significantly high on gravelly soils. The regeneration of the species was negatively correlated with the slope, soil texture and basal area of heterospecific individuals. In D. senegalense, its regeneration was negatively correlated with elevation and positively with the density of its adult individuals. The height of both species of Detarium was positively associated with altitude. This study showed the effect of biotic and abiotic factors determining the population dynamics of Detarium spp. species and could be considered in the sustainable management of these species.