Evolution of the potential distribution area of french mediterranean forests under global warming

Cédric Gaucherel (1) , Joel Guiot (2) , L. Misson (3)

1 UMR AMAP - Botanique et Modélisation de l'Architecture des Plantes et des Végétations
2 CEREGE - Centre européen de recherche et d'enseignement des géosciences de l'environnement
3 CEFE - Centre d’Ecologie Fonctionnelle et Evolutive

This work aims at understanding future spatial and temporal distributions of tree species in the Mediterranean region of France under various climates. We focused on two different species (Pinus Halepensis and Quercus Ilex) and compared their growth under the IPCC-B2 climate scenario in order to quantify significant changes between present and future. The influence of environmental factors such as atmospheric CO₂ increase and topography on the tree growth has also been quantified. We modeled species growths with the help of a process-based model (MAIDEN), previously calibrated over measured ecophysiological and dendrochronological series with a Bayesian scheme. The model was fed with the ARPEGE – MeteoFrance climate model, combined with an explicit increase in CO₂ atmospheric concentration. The main output of the model gives the carbon allocation in boles and thus tree production. Our results show that the MAIDEN model is correctly able to simulate pine and oak production in space and time, after detailed calibration and validation stages. Yet, these simulations, mainly based on climate, are indicative and not predictive. The comparison of simulated growth at end of 20 and 21 centuries, show a shift of the pine production optimum from about 650 to 950 m due to 2.5°K temperature increase, while no optimum has been found for oak. With the direct effect of CO₂ increase taken into account, both species show a significant increase in productivity (+26 and +43% for pine and oak, respectively) at the end of the 21 century. While both species have complementary growth mechanisms, they have a good chance to extend their spatial distribution and their elevation in the Alps during the 21 century under the IPCC-B2 climate scenario. This extension is mainly due to the CO₂ fertilization effect.

Domaines: Cosmologie et astrophysique extra-galactique [astro-ph.CO]; Astrophysique [astro-ph]; Interfaces continentales, environnement; Milieux et Changements globaux; Océan, Atmosphère; Sciences de la Terre

Cédric Gaucherel, Joel Guiot, L. Misson. Evolution of the potential distribution area of french mediterranean forests under global warming. Biogeosciences Discussions, 2008, 5 (1), pp.573-603. ⟨hal-00330283⟩