Elevated CO^sub 2^ maintains grassland net carbon uptake under a future heat and drought extreme

• Published in: Proceedings of the National Academy of Sciences - PNAS Vol. 113; no. 22; p. 6224
• Main Authors: Roy, Jacques, Picon-Cochard, Catherine, Augusti, Angela, Benot, Marie-Lise, Thiery, Lionel, Darsonville, Olivier, Landais, Damien, Piel, Clément, Defossez, Marc, Devidal, Sébastien, Escape, Christophe, Ravel, Olivier, Fromin, Nathalie, Volaire, Florence, Milcu, Alexandru, Bahn, Michael, Soussana, Jean-François
• Format: Journal Article
• Language: English
• Published: Washington National Academy of Sciences 31-05-2016
• Subjects: Carbon dioxide; Drought; Ecosystem studies; Grasslands; Heat; Plant growth; Terrestrial ecosystems
• ISSN: 0027-8424; 1091-6490

Extreme climatic events (ECEs) such as droughts and heat waves are predicted to increase in intensity and frequency and impact the terrestrial carbon balance. However, we lack direct experimental evidence of how the net carbon uptake of ecosystems is affected by ECEs under future elevated atmospheric CO^sub 2^ concentrations (eCO^sub 2^). Taking advantage of an advanced controlled environment facility for ecosystem research (Ecotron), we simulated eCO2 and extreme cooccurring heat and drought events as projected for the 2050s and analyzed their effects on the ecosystem-level carbon and water fluxes in a C3 grassland. Our results indicate that eCO^sub 2^ not only slows down the decline of ecosystem carbon uptake during the ECE but also enhances its recovery after the ECE, as mediated by increases of root growth and plant nitrogen uptake induced by the ECE. These findings indicate that, in the predicted near future climate, eCO^sub 2^ could mitigate the effects of extreme droughts and heat waves on ecosystem net carbon uptake.