Dynamics of soil CO 2 efflux under varying atmospheric CO 2 concentrations reveal dominance of slow processes

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. Five-day intervals of exposure to elevated CO2 (eCO2) ranging 1.0–1.8 times ambient did not affect FCO2. FCO2 did not decrease until 4 months after termination of the long-term eCO2 treatment, longer than the 10 days observed for decrease of FCO2 after experimental blocking of C flow to belowground, but shorter than the ~13 months it took for increase of FCO2 following the initiation of eCO2. The reduction of FCO2 upon termination of enrichment (~35%) cannot be explained by the reduction of leaf area (~15%) and associated carbohydrate production and allocation, suggesting a dispropor-tionate contraction of the belowground ecosystem components; this was consistent with the reductions in base respiration and FCO2- temperature sensitivity. These asymmetric responses pose a tractable challenge to process-based models attempting to isolate the effect of individual processes on FCO2.

  • Citation: Kim, Dohyoung; Oren, Ram; Clark, James S.; Palmroth, Sari; Oishi, A. Christopher; McCarthy, Heather R.; Maier, Chris A.; Johnsen, Kurt 2017. Dynamics of soil CO 2 efflux under varying atmospheric CO 2 concentrations reveal dominance of slow processes . Global Change Biology. 10: 3501-.3512. 12 p. https://doi.org/10.1111/gcb.13713.
  • Keywords: Bayesian state space model, carbon dioxide, climate change, nitrogen fertilization, soil respiration
  • Posted Date: June 15, 2017
  • Modified Date: September 7, 2017
  • Requesting Print Publications

    Publication requests are subject to availability. Fiscal responsibility limits the hardcopies of publications we produce and distribute. Electronic versions of publications may be downloaded, distributed and printed.

    Please make any requests at pubrequest@fs.fed.us.

    Publication Notes

    • This article was written and prepared by U.S. Government employees on official time, and is therefore in the public domain.
    • Our online publications are scanned and captured using Adobe Acrobat. During the capture process some typographical errors may occur. Please contact the SRS webmaster if you notice any errors which make this publication unusable.
    • To view this article, download the latest version of Adobe Acrobat Reader.