Information on how abiotic and biotic factors affect species population structures and regeneration are critical for understanding plant growth in natural habitats. Here, we used the data from three spatially distinct populations of Afzelia africana Sm. in the Pendjari Biosphere Reserve in Benin, to determine how the species population structures respond to abiotic and biotic factors. Afzelia africana population structures were studied using several parameters including basal area, tree height, density of successive diameter classes, and size class slope. We tested for individual effects of abiotic (mound density, soil type, and terrain slope) and biotic (heterospecific tree density) factors on the species population structure. We also tested for similarity of species composition among studied A. africana population stands. Results revealed a tree density structure with mature individuals, and size class distribution indicating a recruitment bottleneck at the juvenile stage (10-20 cm diameter), possibly due to mammal browsing, natural and artificial fires. Heterospecific tree density was positively associated with A. africana adult density but negatively related to the species growth parameters (mean diameter, basal area, and tree height). These results indicate some degrees of niche overlap between A. africana and coexisting species but also partly reflect A. africana tolerance and adaptation to limited resources environment. Soil type significantly influenced both basal area and regeneration density, greater values being observed on silt-sand-rocky soils. Basal area was higher on steeper slope, probably a result of species conservative strategies. These findings were discussed in line with management and restoration action needs in the Pendjari Biosphere Reserve.

No abstract

No abstract

Background and aims – Understanding the spatial patterns and associations of tree species with their conspecific and heterospecific neighbours is critical for sustainable management of their stands. This study assessed the intra- and interspecific spatial structure of six life stages in Afzelia africana, a keystone multipurpose and endangered tree species in a tropical savanna of Benin.Material and methods – Three plots of 4 ha each were demarcated on three sites along a conservation gradient (hunting zone – core conservation zone). Individuals of A. africana (irrespective of their diameter at breast height) and heterospecific trees (dbh ≥ 5 cm) were mapped. Tree spatial patterns and associations were determined using univariate and bivariate pair correlation functions. The distance to the nearest neighbour was further used to assess tree-to-tree distance.Key results – We found variable spatial patterns across sites. In the core zone where wildlife density is high, most life stages had a random distribution. In contrast, in the hunting zone where wildlife density is low, the species spatial distribution changed from a predominantly aggregative pattern during early stages to a less aggregative or random spatial pattern for very large adults. Most pairs of life stages showed neutral associations, except for small and large adults, which had positive association between themselves on two sites. We also found that A. africana tree spatial distribution was unrelated to heterospecific trees.Conclusion – We suggest that bush fire, seed dispersion, predation, and local environment would have contributed to the observed patterns.