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Dynamics of soil CO 2 efflux under varying atmospheric CO 2 concentrations reveal dominance of slow processes
Author(s) -
Kim Dohyoung,
Oren Ram,
Clark James S.,
Palmroth Sari,
Oishi A. Christopher,
McCarthy Heather R.,
Maier Chris A.,
Johnsen Kurt
Publication year - 2017
Publication title -
global change biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 4.146
H-Index - 255
eISSN - 1365-2486
pISSN - 1354-1013
DOI - 10.1111/gcb.13713
Subject(s) - photosynthesis , ecosystem , respiration , chemistry , dominance (genetics) , zoology , environmental chemistry , co occurrence , environmental science , ecology , biology , botany , biochemistry , gene , artificial intelligence , computer science
We evaluated the effect on soil CO 2 efflux ( F CO 2 ) of sudden changes in photosynthetic rates by altering CO 2 concentration in plots subjected to +200 ppmv for 15 years. Five‐day intervals of exposure to elevated CO 2 ( eCO 2 ) ranging 1.0–1.8 times ambient did not affect F CO 2 . F CO 2 did not decrease until 4 months after termination of the long‐term eCO 2 treatment, longer than the 10 days observed for decrease of F CO 2 after experimental blocking of C flow to belowground, but shorter than the ~13 months it took for increase of F CO 2 following the initiation of eCO 2 . The reduction of F CO 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 F CO 2 ‐temperature sensitivity. These asymmetric responses pose a tractable challenge to process‐based models attempting to isolate the effect of individual processes on F CO2 .