Validate
2011-2012
NUMBER OF ROOMS USED
12
PROJECT DURATION
12 MONTHS
GOALS
Study and understand the impact of climate change and extreme weather events on a mid-mountain grassland ecosystem by continuously analysing its carbon and water cycles over a period of two years.
Événement climatique extrême estival dans le futur : impact sur les flux nets de CO2 et d’eau d’une prairie de montagne
Researchers
Jacques Roy ; Damien Landais ; Clément Piel ; Christophe Escape ; Sebastien Devidal ; Olivier Ravel ; Philippe Didier; Angela Augusti; Jean François Soussana; Catherine Picon Cochard; Florence Volaire; Michael Bahn
Publications
Roy, J., Picon-Cochard, C., … Soussana, J.-F. (2016). Elevated CO2 maintains grassland net carbon uptake under a future heat and drought extreme. PNAS, 113, 6224–6229.
Volaire, F., Morvan-Bertrand, A., … Picon-Cochard, C. (2020). The resilience of perennial grasses under two climate scenarios is correlated with carbohydrate metabolism in meristems. Journal of Experimental Botany, 71(1), 370–385.
Consequences
Extreme weather events are expected to become more frequent and intense in the coming decades, but they will also occur within a different climatic context than the current one. At the Ecotron in Montpellier, we studied the response of intact grassland monoliths (1 m², 60 cm deep) taken from a plateau grassland in the French Massif Central. In the first year, the grasslands were acclimatized to the average climatic conditions of the years around 2050 (+4°C and -56 mm for summer rainfall). In the second year, the same climate was maintained, but in half of the experimental units, we imposed a summer drought and heatwave (a 50% reduction in rainfall for one month, then a 100% reduction for two weeks with a 3.4°C increase in temperatures). A CO2 treatment was then applied.
(520 vs 380 µmol/mol/mol) was crossed with the climatic treatment.
Net CO2 flows were measured continuously during the second year of the experiment. The extreme weather event induced total canopy senescence regardless of the CO2 treatment. The interactive effect of rising CO2
The effect of drought treatment was significant at the beginning of the drought and particularly important in the autumn after the recovery period, with net photosynthesis twice as high in the treatment (extreme climate + CO2) as in the control. Integrated over the year, the high CO2 level
completely mitigated the impact of the extreme weather event on net CO2 exchanges. These results are discussed in conjunction with data on evapotranspiration and soil moisture.
