Dynamics of soil CO2 efflux under varying atmospheric CO2 concentrations reveal dominance of slow processes. (10th May 2017)

• Record Type: Journal Article
• Authors: Kim, Dohyoung; Oren, Ram; Clark, James S.; Palmroth, Sari; Oishi, A. Christopher; McCarthy, Heather R.; Maier, Chris A.; Johnsen, Kurt
• Is Part Of: Global change biology. Volume 23:Number 9(2017)
• Page Start: 3501
• Page End: 3512
• Publication Date: 2017-05-10
• Subjects: Bayesian state space model -- carbon dioxide -- climate change -- nitrogen fertilization -- soil respiration; Climatic changes -- Environmental aspects -- Periodicals; Troposphere -- Environmental aspects -- Periodicals; Biodiversity conservation -- Periodicals; Eutrophication -- Periodicals; 551.5
• DOI: 10.1111/gcb.13713
• Languages: English
• ISSNs: 1354-1013

Abstract

Abstract: We evaluated the effect on soil CO2 efflux (FCO 2 ) of sudden changes in photosynthetic rates by altering CO2 concentration in plots subjected to +200 ppmv for 15 years. Five‐day intervals of exposure to elevated CO2 (eCO2 ) ranging 1.0–1.8 times ambient did not affect FCO 2 . FCO 2 did not decrease until 4 months after termination of the long‐term eCO2 treatment, longer than the 10 days observed for decrease of FCO 2 after experimental blocking of C flow to belowground, but shorter than the ~13 months it took for increase of FCO 2 following the initiation of eCO2 . The reduction of FCO 2 upon termination of enrichment (~35%) cannot be explained by the reduction of leaf area (~15%) and associated carbohydrate production and allocation, suggesting a disproportionate contraction of the belowground ecosystem components; this was consistent with the reductions in base respiration and FCO 2 ‐temperature sensitivity. These asymmetric responses pose a tractable challenge to process‐based models attempting to isolate the effect of individual processes on FCO2 . Abstract : We evaluated the effect on soil CO2 efflux (FCO2 ) of sudden changes in photosynthetic rates by altering CO2 concentration in plots subjected to +200 ppmv for 15 years. FCO2 in elevated CO2 (eCO2 ) plots was not affected by short‐term (five‐day) manipulation of atmospheric CO2 concentration ranging from ambient to 300 ppmv above ambient. However, prolonged exposure to ambient CO2 (aCO2 ) after the termination of the long‐term CO2 enrichment reduced FCO2 in previously eCO2 plots to lower than that in aCO2 plots for at least 2 years.