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Will tropical forests face slow down with ongoing climate changes? [O-2215-04]

Hérault B., Aubry-Kientz M., Rossi V., Wagner F.. 2015. In : Our Common Future under Climate Change. International scientific conference Abstract Book 7-10 July 2015. Paris, France. Paris : CFCC15, p. 262-262. Our Common Future under Climate Change, 2015-07-07/2015-07-10, Paris (France).

In the context of climate changes, identifying and then predicting the impacts of climatic drivers on tropical forest dynamics is becoming a matter of urgency. We used a coupled model of tropical tree growth and mortality, calibrated with forest dynamic data from the 20 year study site of Paracou, French Guiana, in order to introduce and test a set of climatic variables. Three major climatic drivers of the tropical forest dynamics were identified through the variable selection procedure: drought, water saturation and temperature. Drought decreased annual growth and mortality rates, high precipitation increased mortality rates and high temperature decreased growth. Interactions between key functional traits, stature and climatic variables were investigated, showing best resistance to drought for trees with high wood density and for trees with small current diameters. We then used SELVA, an individual-based model to run forest dynamic simulations for the next century using predictions from the IPCC 5AR with 3 different scenarios corresponding to 3 relative concentration pathways. Basal area, above-ground fresh biomass, quadratic diameter, growth and mortality rates exhibited decreasing values as long as the scenario became pessimistic. Temperature is the strongest driver highlighting a drop of 40% in average forest growth for the RCP8.5. Our results highlights the potential slowdown danger that tropical forests will face during the next century. (Texte intégral)

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