title: Elevated CO2 maintains grassland net carbon uptake under a future heat and drought extreme.
abstract: 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 CO2 concentrations (eCO2). 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 eCO2 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, eCO2 could mitigate the effects of extreme droughts and heat waves on ecosystem net carbon uptake.
authors.affiliation: Ecotron Européen de Montpellier, Unité Propre de Service 3248, Centre National de la Recherche Scientifique (CNRS), Campus Baillarguet, F-34980 Montferrier-sur-Lez, France; jacques.roy@ecotron.cnrs.fr.
authors.forename: Jacques
authors.initials: J
authors.lastname: Roy
authors.affiliation: Grassland Ecosystem Research, Unité de Recherche 874, Institut National de la Recherche Agronomique (INRA), F-63039 Clermont-Ferrand, France;
authors.forename: Catherine
authors.initials: C
authors.lastname: Picon-Cochard
authors.affiliation: Grassland Ecosystem Research, Unité de Recherche 874, Institut National de la Recherche Agronomique (INRA), F-63039 Clermont-Ferrand, France; Institute of Agroenvironmental and Forest Biology, Consiglio Nazionale delle Ricerche, 2-05010 Porano (TR), Italy;
authors.forename: Angela
authors.initials: A
authors.lastname: Augusti
authors.affiliation: Grassland Ecosystem Research, Unité de Recherche 874, Institut National de la Recherche Agronomique (INRA), F-63039 Clermont-Ferrand, France; Biodiversité Gènes et Communautés, INRA, Université de Bordeaux, F-33615 Pessac, France;
authors.forename: Marie-Lise
authors.initials: ML
authors.lastname: Benot
authors.affiliation: Grassland Ecosystem Research, Unité de Recherche 874, Institut National de la Recherche Agronomique (INRA), F-63039 Clermont-Ferrand, France;
authors.forename: Lionel
authors.initials: L
authors.lastname: Thiery
authors.affiliation: Grassland Ecosystem Research, Unité de Recherche 874, Institut National de la Recherche Agronomique (INRA), F-63039 Clermont-Ferrand, France;
authors.forename: Olivier
authors.initials: O
authors.lastname: Darsonville
authors.affiliation: Ecotron Européen de Montpellier, Unité Propre de Service 3248, Centre National de la Recherche Scientifique (CNRS), Campus Baillarguet, F-34980 Montferrier-sur-Lez, France;
authors.forename: Damien
authors.initials: D
authors.lastname: Landais
authors.affiliation: Ecotron Européen de Montpellier, Unité Propre de Service 3248, Centre National de la Recherche Scientifique (CNRS), Campus Baillarguet, F-34980 Montferrier-sur-Lez, France;
authors.forename: Clément
authors.initials: C
authors.lastname: Piel
authors.affiliation: Ecotron Européen de Montpellier, Unité Propre de Service 3248, Centre National de la Recherche Scientifique (CNRS), Campus Baillarguet, F-34980 Montferrier-sur-Lez, France;
authors.forename: Marc
authors.initials: M
authors.lastname: Defossez
authors.affiliation: Ecotron Européen de Montpellier, Unité Propre de Service 3248, Centre National de la Recherche Scientifique (CNRS), Campus Baillarguet, F-34980 Montferrier-sur-Lez, France;
authors.forename: Sébastien
authors.initials: S
authors.lastname: Devidal
authors.affiliation: Ecotron Européen de Montpellier, Unité Propre de Service 3248, Centre National de la Recherche Scientifique (CNRS), Campus Baillarguet, F-34980 Montferrier-sur-Lez, France;
authors.forename: Christophe
authors.initials: C
authors.lastname: Escape
authors.affiliation: Ecotron Européen de Montpellier, Unité Propre de Service 3248, Centre National de la Recherche Scientifique (CNRS), Campus Baillarguet, F-34980 Montferrier-sur-Lez, France;
authors.forename: Olivier
authors.initials: O
authors.lastname: Ravel
authors.affiliation: Centre d'Ecologie Fonctionnelle et Evolutive, CNRS, Unité Mixte de Recherche 5175, Université de Montpellier, Université Paul Valéry, École Pratique des Hautes Études, F-34293 Montpellier Cedex 5, France;
authors.forename: Nathalie
authors.initials: N
authors.lastname: Fromin
authors.affiliation: Centre d'Ecologie Fonctionnelle et Evolutive, CNRS, Unité Mixte de Recherche 5175, Université de Montpellier, Université Paul Valéry, École Pratique des Hautes Études, F-34293 Montpellier Cedex 5, France; Unité Sous Contrat 1338, INRA, Centre d'Ecologie Fonctionnelle et Evolutive F-34293 Montpellier Cedex 5, France;
authors.forename: Florence
authors.initials: F
authors.lastname: Volaire
authors.affiliation: Ecotron Européen de Montpellier, Unité Propre de Service 3248, Centre National de la Recherche Scientifique (CNRS), Campus Baillarguet, F-34980 Montferrier-sur-Lez, France; Centre d'Ecologie Fonctionnelle et Evolutive, CNRS, Unité Mixte de Recherche 5175, Université de Montpellier, Université Paul Valéry, École Pratique des Hautes Études, F-34293 Montpellier Cedex 5, France;
authors.forename: Alexandru
authors.initials: A
authors.lastname: Milcu
authors.affiliation: Institute of Ecology, University of Innsbruck, A-6020 Innsbruck, Austria.
authors.forename: Michael
authors.initials: M
authors.lastname: Bahn
authors.affiliation: Grassland Ecosystem Research, Unité de Recherche 874, Institut National de la Recherche Agronomique (INRA), F-63039 Clermont-Ferrand, France;
authors.forename: Jean-François
authors.initials: JF
authors.lastname: Soussana
mesh_terms: D002244:Carbon / Q000378:metabolism*; D057486:Carbon Cycle / Q000187:drug effects*; D002245:Carbon Dioxide / Q000494:pharmacology*; D057231:Climate Change; D055864:Droughts; D065948:Grassland; D006358:Hot Temperature; D018515:Plant Leaves / Q000187:drug effects / Q000254:growth & development*; D012987:Soil / Q000737:chemistry*
chemical_list: D012987:Soil; D002245:Carbon Dioxide; D002244:Carbon
keywords: carbon fluxes; climate change; elevated CO2; extreme events; grassland ecosystem