Modelling past and present distributions of tropical African biomes and species using a dynamic vegetation model.

Abstract

In the framework of the AFRIFORD project (Genetic and paleoecological signatures of African rainforest dynamics: pre-adapted to change?, http://www.ulb.ac.be/facs/sciences/afriford/), we used the CARAIB dynamic vegetation model to simulate past and present distributions of tropical African vegetation at the biome and species levels to better project and understand future dynamics. We studied individual species (e.g., Afzelia africana, Pericopsis elata, etc) for which we determined climatic requirements and gathered specific traits. To perform palaeovegetation reconstructions, we used outputs of snapshot climate simulations (e.g., CNRM-CM5, FGOALS-g2 and MRI-CGCM5 global climatic models) from the PaleoModelling Intercomparison Project (PMIP3, https://pmip3.lsce.ipsl.fr/) for the mid-Holocene (6 ka) and the Last Glacial Maximum (LGM, 21 ka). These global climatic outputs were downscaled at a 0.45° spatial resolution over Equatorial Africa using the MAR regional climate model (RCM). For current conditions, the RCM was nested in different historical climate datasets. We compared modelled species distributions with species occurrences from different databases for present and with palaeorecords for past periods. MAR regional climate simulations notably allow CARAIB to reproduce the Dahomey Gap separating the Upper and Lower Guinean forests in West Africa in present biome distribution. The vegetation model also simulates LGM rainforest distribution in agreement with hypothetical glacial rainforest refuge areas inferred from palaeorecords.AFRIFORD (Genetic and paleoecological signature of African rainforest dynamics: pre-adapted to change?