Impact of land use and biophysical factors on natural populations of Senegalia macrostachya in Burkina Faso, West Africa

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Résumé

Senegalia macrostachya is a valuable shrub increasingly threatened in West Africa. The study aims to assess the impact of land use and biophysical factors on its population structure and diversity across Sudanian and Sudano-Sahelian climate zones in Burkina Faso. A total of 201 plots were sampled in three land use categories: farmlands, fallows and protected areas. In each plot, topographic variability, soil texture, woody species diversity and size of morphological traits of S. macrostachya were recorded. A significant difference (p < 0.0001) was found in woody species richness between climate zones and land use, with higher diversity in protected areas, as indicated by higher Hill index values. Population density of S. macrostachya was significantly higher in the Sudanian zone (245.06 ± 217.63 individuals/ha) than in the Sudano-Sahelian one (132.70 ± 96.03 individuals/ha). Density was also higher in protected areas (274.46 ± 186.60 individuals/ha) and fallows (190.17 ± 130.54 individuals/ha) than in farmlands (53.95 ± 47.17 individuals/ha). Stem diameter and height of S. macrostachya individuals varied significantly according to land use. Interaction and correlation analyses revealed strong influences of land use and biophysical factors (climate, topography, soil texture and stand parameters including other species density, diameter, height and basal area) on the morphological traits of S. macrostachya. The distribution of stem diameter classes revealed unstable populations in most land use categories. These findings suggest that S. macrostachya requires close attention to reduce the exploitation pressure it faces.

Mots-clés

Wild crop, Morphological parameters, Stand diversity, Resource availability, Climate drivers