Biotic and abiotic drivers of biomass carbon storage in peri-urban forests in Burkina Faso.

Urban and peri-urban forests are vital nature-based climate solutions in urban centers undergoing rapid urbanization and rising temperatures. While their ecological role in carbon sequestration is documented in West Africa, how environmental factors affect aboveground carbon (AGC) storage in peri-urban forests remains poorly understood. This study investigates biotic and abiotic drivers of AGC storage across three peri-urban forests in Burkina Faso. Using inventory data of 4840 individuals across 158 plots, we investigated AGC variation patterns and drivers. We applied two-way analysis of variance to examine variations in AGC across forest sites and diameter size classes, and a structural equation model (SEM) to assess the direct and indirect effects of diversity, structural, climatic and topographic variables. Results showed significant main and interactive effects of site and diameter class on AGC (p value < 0.001), indicating that carbon allocation to diameter classes varies between forests. Twenty woody species accounted for 72.5 to 92.3% of total AGC stocks across forest sites, highlighting their high carbon storage potential. SEM results showed positive direct effects of tree size variation (β = 0.41) and density (β = 0.45) on AGC, while species diversity (β =  − 0.25) and elevation (β =  − 0.37) reduced AGC. Precipitation seasonality had no direct effect on AGC (β =  − 0.26) but positively influenced species diversity (β = 0.42). Tree density also indirectly reduced AGC (β =  − 0.11) via increased diversity (β = 0.47). These findings emphasize that enhanced carbon storage in peri-urban forests can be achieved by increasing tree density and size variation. Therefore, promoting high-carbon storing trees in planting campaigns can significantly enhance climate change mitigation efforts.