[en] Aim : In this study we identified large-scale variation in tree species composition across tropical African forests and determined the underlying environmental and historical factors.
Location : Tropical forests from Senegal to Mozambique.
Methods : Distribution data were gathered for 1175 tree species in 455 sample sites scattered across tropical Africa, including all types of tropical forests (wet, moist, dry, and lowland to moderate elevation montane forests). The value of elevation and 19 climatic variables extracted from the BIOCLIM data set were assigned to each sample site. We determined the variation in species composition using correspondence analysis and identified the environmental correlates.
We defined floristic clusters according to species composition and identified the characteristic species using indicator analysis.
Results : We identified a major floristic discontinuity located at the Albertine rift that separated the dry, moist and wet forests of West and Central Africa (the entire Guineo-Congolian Region) from the upland and coastal forests of East Africa. Except for the Albertine Rift, we found no evidence to support the other proposed floristic discontinuities (Dahomey Gap etc.). We detected two main environmental gradients across tropical African forests. The rainfall gradient
was strongly correlated with the variation in tree species composition in West and Central Africa. The elevation/temperature gradient highlighted the major floristic differences within East Africa and between East Africa and the Guineo-Congolian Region, the latter being most probably due to the geological disruption and associated climatic history of the East African uplift.
Main conclusions : We found floristic evidence for three main biogeographical regions across the tropical African forests, and described six floristic clusters with particular environmental conditions within these regions: Coastal and Upland for East Africa, Dry and Wet-Moist for West Africa, and Moist and Wet for Central Africa.
Fayolle, Adeline ; Université de Liège - ULiège > Forêts, Nature et Paysage > Gestion des ressources forestières et des milieux naturels
Swaine, Michael D.; University of Aberdeen - Aberdeen AB24 3UU - UK > Institute of Biological and Environmental Sciences
Bastin, Jean-François ; Université de Liège - ULiège > Forêts, Nature et Paysage > Biodiversité et Paysage
Bourland, Nils; Université de Liège - ULiège > Forêt, Nature et Paysages > Unité de Gestion des Ressources forestières et des Milieux naturels
Comiskey, James A.; National Park Service - USA > Inventory and Monitoring Program
Dauby, Gilles; Université Libre de Bruxelles - ULB > Faculté des Sciences > Evolutionary Biology and Ecology
Doucet, Jean-Louis ; Université de Liège - ULiège > Forêts, Nature et Paysage > Laboratoire de Foresterie des régions trop. et subtropicales
Gillet, Jean-François ; Université de Liège - ULiège > Forêt, Nature et Paysages > Gestion des Ressources forestières et des Milieux naturels
Gourlet-Fleury, Sylvie; CIRAD - Montpellier - France > Département Environnements et Sociétés > Unité de Recherche Biens et Services des Ecosystèmes Forestiers Tropicaux
Hardy, Olivier; Université Libre de Bruxelles - ULB > Faculté des Sciences > Evolutionary Biology and Ecology
Kirunda, Ben; Wildlife Conservation Society - Uganda > Albertine Rift Program
Kouamé, François N.; Université Félix Houphouët-Boigny - République de la Côte d'Ivoire > Laboratoire de Botanique
Plumptre, Andrew J.; Wildlife Conservation Society - Uganda > Albertine Rift Program
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