Effects of land use types on the health status of Vitex doniana Sweet populations in Burkina Faso's Sudanian zone

Vitex doniana Sweet is a forest tree species of known socio-economic importance for its food, medicinal and cultural uses. It is currently threatened with extinction due to severe human pressure, so that measures need to be taken to ensure that its management is sustainable. The aim of this study was to assess the status of its populations in three types of land use situations corresponding to different intensities of human disturbance, namely protected areas, pastoral zones and cultivated areas. Based on stratified and oriented sampling, 82 plots of different sizes were set up according to the habitat under consideration. Data were collected for total tree height and trunk diameter at 1.30 m from the ground. Juveniles were counted and their heights measured. The regeneration mechanism was determined from excavation of the juveniles. The health of the trees was assessed on the basis of the presence/absence of infestation and traces left by their exploitation. The results show a significant influence (p < 0.05) of the type of land use on the density of individuals, the average diameter of the trunk and the health status of the trees. Adult tree density was 3.35 and 2.49 times higher in pastoral zones and protected areas respectively than in cultivated zones (5.44 +/- 2.80 trees/ha). Regeneration in protected areas (43.83 +/- 7.65 ind/ ha) was 1.27 and 2.61 times higher than in pastoral and cultivated areas respectively. The diameter class distributions were bell shaped in the pastoral zones, erratic in the cultivated zones and positively asymmetrical in the protected areas. Stump shoots and suckering are the main mechanisms of vegetative reproduction. More than 90% of the individuals found were affected by human uses: cut branches resulting in leaf removal and harvesting of bark and roots. Our results suggest that to ensure conservation of the species, protection measures need to be strengthened and use of its products better managed.