Past and future scenarios of the effect of carbon dioxide on plant growth and transpiration for three vegetation types of southwestern France
- ISSN: 1680-7316
The sensitivity of an operational CO2-responsive land surface model\n(the ISBA-A-gs model of Meteo-France) to the atmospheric CO2 concentration,\n(CO2), is investigated for 3 vegetation types (winter wheat, irrigated\nmaize, coniferous forest). Past (1960) and future (2050) scenarios\nof (CO2) corresponding to 320 ppm and 550 ppm, respectively, are\nexplored. The sensitivity study is performed for 4 annual cycles\npresenting contrasting conditions of precipitation regime and air\ntemperature, based on continuous measurements performed on the SMOSREX\nsite near Toulouse, in southwestern France. A significant CO2-driven\nreduction of canopy conductance is simulated for the irrigated maize\nand the coniferous forest. The reduction is particularly large for\nmaize, from 2000 to 2050 (-18%), and triggers a drop in optimum\nirrigation (-30 mm y(-1)). In the case of wheat, the response is\nmore complex, with an equal occurrence of enhanced or reduced canopy\nconductance.