Morphological trait variation and relationships of Afzelia africana Sm. caused by climatic conditions and anthropogenic disturbance in Benin (West Africa)

Afzelia africana Sm. is a tree species found in different climatic conditions affected by chronic human disturbance. It is known that trees can respond to their environments by changing their morphological traits. Also, as plants store their reserves in fruits, seeds and leaves, long-lasting disturbance may impact morphological traits of fruits, seeds and leaves. Thus, in this study, we evaluated (1) the variation of morphological traits of A. africana according to climatic conditions and human disturbance, and (2) the relationships among morphological traits. Twelve morphological parameters based on fruits, seeds and leaflets were assessed across three climatic zones and compared for individuals in protected and disturbed landscapes. Univariate and multivariate analyses were used to evaluate the effects of climatic factors and disturbance. Highest values for fruit, seed and leaflet traits were observed in humid areas indicating for best performance under optimal conditions. Significant adverse effects of human disturbance were observed for traits in the humid and drier areas. The interaction between climatic conditions and disturbance was significant for most traits suggesting a climate-dependent effect of the disturbance on evaluated traits. Bioclimatic variables were thus identified as potential drivers of traits. Some significant and positive associations were observed among fruit and seed traits. These morphological trait variations are valuable insights to guide sustainable management and conservation of A. africana populations in different climatic zones and habitats types in Benin.