Vulnerability of tropical moist forests to projected climate changes in Africa | Vulnérabilité des forêts tropicales humides aux changements climatiques prévus en Afrique

Climate is the main factor influencing tree species distribution. Across Africa global climate projections predict significant and rapid changes in the coming decades and these changes could affect the composition, structure and functioning of tropical African forests. Here, we used occurrence data from the RAINBIO database for native plants in Africa, combined with climatic layers, to infer the climatic tolerances of tropical forest tree and shrub species. This enabled us to assess the vulnerability of African tropical forests to changes in mean annual temperature, precipitation, and water deficit by 2080 under different climate scenarios. We formed communities (tree and shrub species coexisting in a pixel) using a multiple-resolution mask covering the tropical forests of the Congo Basin and West Africa. The climatic vulnerability was assessed using three parameters: the exposure (anomaly between current and future climate conditions), the safety margin (potential tolerance to changing climate conditions of species) and the risk (potential negative consequences of climate change on species). A total of 1009 communities were created, with resolutions ranging from 0.125 to 1°C, incorporating 3536 forest tree and shrub species. Under the RCP 4.5, a general warming trend is predicted in the tropical African forest, with over 73% of communities projected to be at risk from temperature increase by 2080. Around 11% of communities are projected to be at risk from increase in water deficit, while the risk from precipitation decrease is negligible. In terms of perspectives, we will include forest plot data in the vulnerability framework and investigate shifts in the floristic composition. This approach holds promise for understanding the complex dynamics of tropical African forests in the face of climate change and provide critical information for conservation and management strategies integrating future environmental challenges.