Land use dictates diversity, density and regeneration of woody species in southwestern Mali, West Africa

Abstract

Despite the progression of land degradation and deforestation leading to vegetation fragmentation, most of the population in Mali are still strongly dependent on trees. The current study aimed at exploring how woody species diversity, density and regeneration varies with land use types (farmland, fallow and forest). The study also puts a particular focus on abundance, regeneration and distribution of Parkia biglobosa, a high value tree crop. Data were gathered through systematic vegetation surveys in 48 quadrat plots of 50 × 50 m distributed in three land use types. Ninety one woody species belonging to 72 genera and 30 families were recorded. Land use affected woody species regeneration, density and diversity and the structure of P. biglobosa. The highest mean number of species per plot was recorded in fallow (11.1 ± 1.5) and forest (10.8 ± 0.7) compared with farmland (6.9 ± 1.0). The most abundant regeneration individuals were recorded in the fallow (1998 ± 333 ha−1), followed by forest (1532 ± 167 ha−1) and farmland (897 ± 264 ha−1). For trees, the mean density of 99 ± 26 ind. ha−1 recorded in farmland is similar to fallow (156 ± 46 ha−1) but lower than forest (559 ± 133 ha−1). The lower Shannon’s diversity index H′ was also observed in the farmland (1.3 ± 0.1) compared with fallows (1.7 ± 0.2) and forests (1.9 ± 0.1). Spatial distribution of regeneration individuals for each species obtained from Morisita’s index showed aggregated patterns for most of the species while Canonical Correspondance Analysis showed more common species between fallow and forest. P. biglobosa trees growing in farmland had the greatest value (57.6 ± 7.0 cm) for collar diameter compared to that of forest (33.7 ± 4.6 cm) and fallow (31.2 ± 4.7 cm).