Impacts of droughts and extreme-temperature events on gross primary production and ecosystem respiration: a systematic assessment across ecosystems and climate zones

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dc.contributor.authorvon Buttlar, Jannis
dc.contributor.authorZscheischler, Jakob
dc.contributor.authorRammig, Anja
dc.contributor.authorSippel, Sebastian
dc.contributor.authorReichstein, Markus
dc.contributor.authorKnohl, Alexander
dc.contributor.authorJung, Martin
dc.contributor.authorMenzer, Olaf
dc.contributor.authorArain, Altaf
dc.contributor.authorBuchmann, Nina
dc.contributor.authorCescatti, Alessandro
dc.contributor.authorGianelle, Damiano
dc.contributor.authorKiely, Gerard
dc.contributor.authorLaw, Beverly E.
dc.contributor.authorMagliulo, Vincenzo
dc.contributor.authorMargolis, Hank
dc.contributor.authorMcCaughey, Harry
dc.contributor.authorMerbold, Lutz
dc.contributor.authorMigliavacca, Mirco
dc.contributor.authorMontagnani, Leonardo
dc.contributor.authorOechel, Walter
dc.contributor.authorPavelka, Marian
dc.contributor.authorPeichl, Matthias
dc.contributor.authorRambal, Serge
dc.contributor.authorRaschi, Antonio
dc.contributor.authorScott, Russell L.
dc.contributor.authorVaccari, Francesco P.
dc.contributor.authorvan Gorsel, Eva
dc.contributor.authorVarlagin, Andrej
dc.contributor.authorWohlfahrt, Georg
dc.contributor.authorMahecha, Miguel D.
dc.contributor.funderHorizon 2020 Framework Programme
dc.contributor.funderCanadian Foundation for Climate and Atmospheric Sciences
dc.contributor.funderNatural Sciences and Engineering Research Council of Canada
dc.contributor.funderBIOCAP Canada
dc.contributor.funderEnvironment Canada
dc.contributor.funderNatural Resources Canada
dc.contributor.funderSixth Framework Programme
dc.contributor.funderUnited Nations
dc.contributor.funderMax-Planck-Institut für Biogeochemie
dc.contributor.funderNational Science Foundation
dc.contributor.funderTuscia University
dc.contributor.funderUniversité Laval
dc.contributor.funderU.S. Department of Energy
dc.contributor.funderFuture Earth
dc.date.accessioned2018-06-15T11:47:09Z
dc.date.available2018-06-15T11:47:09Z
dc.date.issued2018
dc.description.abstractExtreme climatic events, such as droughts and heat stress, induce anomalies in ecosystem-atmosphere CO2 fluxes, such as gross primary production (GPP) and ecosystem respiration (R-eco), and, hence, can change the net ecosystem carbon balance. However, despite our increasing understanding of the underlying mechanisms, the magnitudes of the impacts of different types of extremes on GPP and Reco within and between ecosystems remain poorly predicted. Here we aim to identify the major factors controlling the amplitude of extreme-event impacts on GPP, Reco, and the resulting net ecosystem production (NEP). We focus on the impacts of heat and drought and their combination. We identified hydrometeorological extreme events in consistently downscaled water availability and temperature measurements over a 30-year time period. We then used FLUXNET eddy covariance flux measurements to estimate the CO2 flux anomalies during these extreme events across dominant vegetation types and climate zones. Overall, our results indicate that short-term heat extremes increased respiration more strongly than they downregulated GPP, resulting in a moderate reduction in the ecosystem's carbon sink potential. In the absence of heat stress, droughts tended to have smaller and similarly dampening effects on both GPP and Reco and, hence, often resulted in neutral NEP responses. The combination of drought and heat typically led to a strong decrease in GPP, whereas heat and drought impacts on respiration partially offset each other. Taken together, compound heat and drought events led to the strongest C sink reduction compared to any single-factor extreme. A key insight of this paper, however, is that duration matters most: for heat stress during droughts, the magnitude of impacts systematically increased with duration, whereas under heat stress without drought, the response of Reco over time turned from an initial increase to a downregulation after about 2 weeks. This confirms earlier theories that not only the magnitude but also the duration of an extreme event determines its impact. Our study corroborates the results of several local site-level case studies but as a novelty generalizes these findings on the global scale. Specifically, we find that the different response functions of the two antipodal land-atmosphere fluxes GPP and Reco can also result in increasing NEP during certain extreme conditions. Apparently counterintuitive findings of this kind bear great potential for scrutinizing the mechanisms implemented in state-of-the-art terrestrial biosphere models and provide a benchmark for future model development and testing.en
dc.description.sponsorshipSixth Framework Programme (CarboEuropeIP); Future Earth (Food and Agriculture Organization-Global Terrestrial Observing System-Terrestrial and Atmospheric Carbon Observation)en
dc.description.statusPeer reviewed
dc.description.versionPublished Versionen
dc.format.mimetypeapplication/pdfen
dc.identifier.citationvon Buttlar, J., Zscheischler, J., Rammig, A., Sippel, S., Reichstein, M., Knohl, A., Jung, M., Menzer, O., Arain, M. A. and Buchmann, N. (2018) 'Impacts of droughts and extreme-temperature events on gross primary production and ecosystem respiration: a systematic assessment across ecosystems and climate zones', Biogeosciences, 15, pp. 1293-1318. doi: 10.5194/bg-15-1293-2018en
dc.identifier.doi10.5194/bg-15-1293-2018
dc.identifier.endpage1318
dc.identifier.issn1726-4170
dc.identifier.issued5
dc.identifier.journaltitleBiogeosciencesen
dc.identifier.startpage1293
dc.identifier.urihttps://hdl.handle.net/10468/6321
dc.identifier.volume15
dc.language.isoenen
dc.publisherCopernicus Publications on behalf of European Geosciences Unionen
dc.relation.projectinfo:eu-repo/grantAgreement/EC/H2020::RIA/640176/EU/Detecting changes in essential ecosystem and biodiversity properties – towards a Biosphere Atmosphere Change Index: BACI/BACI
dc.relation.urihttps://www.biogeosciences.net/15/1293/2018/
dc.rights© 2018, Authors. This work is distributed under the Creative Commons Attribution 4.0 License.en
dc.rights.urihttps://creativecommons.org/licenses/by/4.0/
dc.subjectCarbon-dioxide exchangeen
dc.subjectOrganic-matter decompositionen
dc.subjectNet primary productionen
dc.subjectWater-vapor exchangeen
dc.subjectBoreal aspen foresten
dc.subjectCanopy gas-exchangeen
dc.subjectSub-alpine foresten
dc.subjectSoil CO2 effluxen
dc.subjectInterannual variationen
dc.subjectPonderosa pineen
dc.titleImpacts of droughts and extreme-temperature events on gross primary production and ecosystem respiration: a systematic assessment across ecosystems and climate zonesen
dc.typeArticle (peer-reviewed)en
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