Synergy between traditional knowledge of use and tree population structure for sustainability of Cola nitida (Vent.) Schott. & Endl in Benin (West Africa)

Cola nitida is a West African tree, commonly used for pharmaceutical purposes. In Benin, the species is used for many purposes ranging from traditional rituals to domestic consumption. Nowadays, the species, as well as its offspring, are hardly encountered. So far, research on the species focused on a single domain such as ethnobotany and phytochemistry. The current paper used a holistic approach to explain the species scarcity in the natural habitats using (1) the rural knowledge pattern on C. nitida and (2) the tree population structure. Semi-structured interviews (n=170 respondents) were conducted and combined with ecological inventory (n=38 plots) in the phyto-geographical districts of Coast and Pobe in southern Benin. The indices of diversity, equitability, and consensus quantified the range, the evenness, and the relative reliability of rural communities' knowledge. Moreover, the plant part index gave the most used part of the tree. The knowledge on the species was unevenly distributed according to the gender, while the cofactor age did not have a statistically significant effect (P=0.902) on the pattern. In addition, seeds represented the most used plant part (PPI=0.59). C. nitida tree demographic structure showed a low density of seedling and sapling (1.05 +/- 0.47 treesha(-1)). Diameter size fitted with a two-parameter Weibull distribution indicated a threat of species extinction. The multiple uses of C. nitida seeds do not allow natural regeneration of the species. The domestication of C. nitida tree and the establishment of Cola garden/orchard in the surveyed districts are suggested for sustainable use of the species.