Dynamics of soil CO2 efflux under varying atmospheric CO2 concentrations reveal dominance of slow processes.

Journal Article

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 disproportionate 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 .

Full Text

Duke Authors

Cited Authors

  • Kim, D; Oren, R; Clark, JS; Palmroth, S; Oishi, AC; McCarthy, HR; Maier, CA; Johnsen, K

Published Date

  • September 2017

Published In

Volume / Issue

  • 23 / 9

Start / End Page

  • 3501 - 3512

PubMed ID

  • 28380283

Electronic International Standard Serial Number (EISSN)

  • 1365-2486

International Standard Serial Number (ISSN)

  • 1354-1013

Digital Object Identifier (DOI)

  • 10.1111/gcb.13713

Language

  • eng