title: Increasing atmospheric CO2 overrides the historical legacy of multiple stable biome states in Africa.
abstract: The dominant vegetation over much of the global land surface is not predetermined by contemporary climate, but also influenced by past environmental conditions. This confounds attempts to predict current and future biome distributions, because even a perfect model would project multiple possible biomes without knowledge of the historical vegetation state. Here we compare the distribution of tree- and grass-dominated biomes across Africa simulated using a dynamic global vegetation model (DGVM). We explicitly evaluate where and under what conditions multiple stable biome states are possible for current and projected future climates. Our simulation results show that multiple stable biomes states are possible for vast areas of tropical and subtropical Africa under current conditions. Widespread loss of the potential for multiple stable biomes states is projected in the 21st Century, driven by increasing atmospheric CO2 . Many sites where currently both tree-dominated and grass-dominated biomes are possible become deterministically tree-dominated. Regions with multiple stable biome states are widespread and require consideration when attempting to predict future vegetation changes. Testing for behaviour characteristic of systems with multiple stable equilibria, such as hysteresis and dependence on historical conditions, and the resulting uncertainty in simulated vegetation, will lead to improved projections of global change impacts.
authors.affiliation: Institute for Physical Geography, Goethe University Frankfurt am Main, Altenhöferallee 1, 60438, Frankfurt am Main, Germany.
authors.forename: Glenn R
authors.initials: GR
authors.lastname: Moncrieff
authors.affiliation: Biodiversity and Climate Research Centre, Senckenberg Research Institute and Natural History Museum, Senckenberganlage 25, 60325, Frankfurt am Main, Germany.
authors.forename: Simon
authors.initials: S
authors.lastname: Scheiter
authors.affiliation: Department of Biological Sciences, University of Cape Town, Private Bag, Rondebosch, 7701, Cape Town, South Africa.
authors.forename: William J
authors.initials: WJ
authors.lastname: Bond
authors.affiliation: Department of Botany, University of Otago, PO Box 56, Dunedin, 9054, New Zealand.
authors.forename: Steven I
authors.initials: SI
authors.lastname: Higgins
mesh_terms: D000349:Africa; D001272:Atmosphere / Q000737:chemistry*; D058448:Biota; D002245:Carbon Dioxide / Q000032:analysis*; D003198:Computer Simulation; D006109:Poaceae / Q000502:physiology; D011891:Rain; D013997:Time Factors; D014197:Trees / Q000502:physiology
chemical_list: D002245:Carbon Dioxide
keywords: adaptive dynamic global vegetation model (aDGVM); biome; climate change; dynamic vegetation model; forest; multiple stable states; savanna