Agricultural land use reduces plant biodiversity and carbon storage in tropical West African savanna ecosystems: Implications for sustainability

Savanna ecosystems in tropical West Africa undergo severe land use pressure, resulting in ecosystem degradation and biogenic carbon emissions. In such context, highlighting the key ecological attributes of land degradation and the underlying processes are essential within the national adaptation and mitigation plans. This study analyzed the impacts of land use on plant biodiversity, stand structure and carbon storage. Inventories of ligneous species were conducted on 240 plots laid out along four levels of land disturbance in Burkina Faso. Dendrometric data collected from 6035 shrubs and trees were converted to aboveground biomass and carbon density. The results revealed a γ–diversity of 107 woody species belonging to 73 genera and 35 families. Significant effect of land use was found on species diversity, stand structure and carbon density (p < 0.001). Agricultural lands had the lowest diversity, density and carbon stocks, whereas protected areas held the highest values. Carbon density ranged from 10.362 ± 1.209 Mg C.ha−1 in fallows to 42.663 ± 1.982 Mg C.ha−1 in protected areas. Principal Component Analysis showed tight links between carbon storage, species diversity and stand structure. The multiple linear regression revealed that tree density explained 21.25% of the variation in the plot-level total carbon stocks (α = 19.301; p < 3.38e-14). Similarly, tree diameter and height together accounted for 45.43% of the variation in mean carbon stocks (α = 19.301; p < 2.2 e−16). This study demonstrated that the higher the land use pressure, the lower the species diversity and carbon storage in woody vegetation. The findings highlight the importance of accounting for improved or smart agricultural practices within the intended nationally determined contributions’ framework.