Past and future scenarios of the effect of carbon dioxide on plant growth and transpiration for three vegetation types of southwestern France

J.-C. Calvet (1) , A.-L. Gibelin (1) , Jean-Louis Roujean (1) , E. Martin (1) , P. Le Moigne (1) , H. Douville (1) , J. Noilhan (1)

1 CNRM - Centre national de recherches météorologiques

The sensitivity of an operational CO₂-responsive land surface model (the ISBA-A-gs model of Météo-France) to the atmospheric CO₂ concentration, [CO₂], is investigated for 3 vegetation types (winter wheat, irrigated corn, coniferous forest). Past (1960) and future (2050) scenarios of [CO₂] corresponding to 320 ppm and 550 ppm, respectively, are explored. The sensitivity study is performed for 4 annual cycles presenting contrasting conditions of precipitation regime and air temperature, based on continuous measurements performed on the SMOSREX site near Toulouse, in southwestern France. A significant CO₂-driven reduction of canopy conductance is simulated for the irrigated corn and the coniferous forest. The reduction is particularly large for corn, from 2000 to 2050 (–18%), and triggers a drop in optimum irrigation (–30 mm y^-1). In the case of wheat, the response is more complex, with an equal occurrence of enhanced or reduced canopy conductance.

Domaines: Océan, Atmosphère

J.-C. Calvet, A.-L. Gibelin, Jean-Louis Roujean, E. Martin, P. Le Moigne, et al.. Past and future scenarios of the effect of carbon dioxide on plant growth and transpiration for three vegetation types of southwestern France. Atmospheric Chemistry and Physics Discussions, 2007, 7 (2), pp.4761-4779. ⟨hal-00328060⟩