Warming and elevated CO 2 intensify drought and recovery responses of grassland carbon allocation to soil respiration.

Autor: Meeran K; Department of Ecology, University of Innsbruck, Innsbruck, Austria., Ingrisch J; Department of Ecology, University of Innsbruck, Innsbruck, Austria., Reinthaler D; Department of Ecology, University of Innsbruck, Innsbruck, Austria., Canarini A; Centre for Microbiology and Environmental Systems Science, University of Vienna, Vienna, Austria., Müller L; Department of Ecology, University of Innsbruck, Innsbruck, Austria., Pötsch EM; Institute of Plant Production and Cultural Landscape, Agricultural Research and Education Centre, Raumberg-Gumpenstein, Austria., Richter A; Centre for Microbiology and Environmental Systems Science, University of Vienna, Vienna, Austria., Wanek W; Centre for Microbiology and Environmental Systems Science, University of Vienna, Vienna, Austria., Bahn M; Department of Ecology, University of Innsbruck, Innsbruck, Austria.
Jazyk: angličtina
Zdroj: Global change biology [Glob Chang Biol] 2021 Jul; Vol. 27 (14), pp. 3230-3243. Date of Electronic Publication: 2021 May 06.
DOI: 10.1111/gcb.15628
Abstrakt: Photosynthesis and soil respiration represent the two largest fluxes of CO 2 in terrestrial ecosystems and are tightly linked through belowground carbon (C) allocation. Drought has been suggested to impact the allocation of recently assimilated C to soil respiration; however, it is largely unknown how drought effects are altered by a future warmer climate under elevated atmospheric CO 2 (eT_eCO 2 ). In a multifactor experiment on managed C3 grassland, we studied the individual and interactive effects of drought and eT_eCO 2 (drought, eT_eCO 2 , drought × eT_eCO 2 ) on ecosystem C dynamics. We performed two in situ 13 CO 2 pulse-labeling campaigns to trace the fate of recent C during peak drought and recovery. eT_eCO 2 increased soil respiration and the fraction of recently assimilated C in soil respiration. During drought, plant C uptake was reduced by c. 50% in both ambient and eT_eCO 2 conditions. Soil respiration and the amount and proportion of 13 C respired from soil were reduced (by 32%, 70% and 30%, respectively), the effect being more pronounced under eT_eCO 2 (50%, 84%, 70%). Under drought, the diel coupling of photosynthesis and SR persisted only in the eT_eCO 2 scenario, likely caused by dynamic shifts in the use of freshly assimilated C between storage and respiration. Drought did not affect the fraction of recent C remaining in plant biomass under ambient and eT_eCO 2 , but reduced the small fraction remaining in soil under eT_eCO 2 . After rewetting, C uptake and the proportion of recent C in soil respiration recovered more rapidly under eT_eCO 2 compared to ambient conditions. Overall, our findings suggest that in a warmer climate under elevated CO 2 drought effects on the fate of recent C will be amplified and the coupling of photosynthesis and soil respiration will be sustained. To predict the future dynamics of terrestrial C cycling, such interactive effects of multiple global change factors should be considered.
(© 2021 The Authors. Global Change Biology published by John Wiley & Sons Ltd.)
Databáze: MEDLINE
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