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, A.-L. Gibelin, J.-L. Roujean, E. Martin, P. Le Moigne, H. Douville, and J. Noilhan CNRM/GAME (Météo-France, CNRS), Toulouse, France
Abstract. 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 maize, 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 maize and the
coniferous forest. The reduction is particularly large for maize, 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.
Citation: Calvet, J.-C., Gibelin, A.-L., Roujean, J.-L., Martin, E., Le Moigne, P., Douville, H., and Noilhan, J.: Past and future scenarios of the effect of carbon dioxide on plant growth and transpiration for three vegetation types of southwestern France, Atmos. Chem. Phys., 8, 397-406, doi:10.5194/acp-8-397-2008, 2008.