Long term dynamics and structure of woody vegetation in the Ferlo (Senegal)

This study analyzes the evolution of the woody vegetation structure in the Ferlo (Senegal) from 1976 to 1995 on a site not much influenced by human pressure (Fété-Olé), to characterize the long-term effects of drought. In 1995, we measured ecological indicators related to the woody population, differentiating species, and we compared them with data collected on the same site in 1976 and 1983. To document the combined effects of drought and anthropogenic factors on the woody plant vegetation, we measured the same indicators at increasing distances from a borehole and we compared them with the Fété-Olé data. The two study sites confirmed the degradation of the woody cover and highlighted the importance of soil quality in the resilience of these ecosystems: in both sites, the topographic elements significantly influenced density, diversity, regeneration and mortality, with a contraction of the vegetation in depressions. Results at Fété-Olé showed a decline of the woody cover over the 1976–1995 period coupled with an increase of Sahelian species like Boscia senegalensis, Balanites aegyptiaca and Calotropis procera. The floristic richness, density and regeneration showed an average increase with distance to borehole, confirming the anthropogenic pressure on the woody plant population.