The Apparent Respiratory Quotient of Soils and Tree Stems and the Processes That Control It

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dc.citation.articleNumbere2021JG006676en_US
dc.citation.issueNumber3en_US
dc.citation.journalTitleJournal of Geophysical Research: Biogeosciencesen_US
dc.citation.volumeNumber127en_US
dc.contributor.authorHilman, Boazen_US
dc.contributor.authorWeiner, Talen_US
dc.contributor.authorHaran, Tomen_US
dc.contributor.authorMasiello, Caroline A.en_US
dc.contributor.authorGao, Xiaodongen_US
dc.contributor.authorAngert, Alonen_US
dc.date.accessioned2022-04-15T14:45:19Zen_US
dc.date.available2022-04-15T14:45:19Zen_US
dc.date.issued2022en_US
dc.description.abstractThe CO2/O2 fluxes ratio (apparent respiration quotient [ARQ]) measured in soils and plants contains valuable information about the respiratory-substrate stoichiometry and biotic and abiotic non-respiratory processes. We investigated ARQ variability by measurements in soil pore space air, and in headspace air from incubations of bulk-soil and tree stem tissues (both fresh and 24-hr stored tissues) in 10 measurement campaigns over 15 months in a Mediterranean oak forest. Mean (range) ARQ values were: soil air, 0.76 (0.60–0.92); bulk soil, 0.75 (0.53–0.90); fresh stem tissues, 0.39 (0.19–0.70); and stored stem tissues, 0.68 (0.42–1.08). The variability in tree stems was assumed to be controlled by CO2 re-fixation that lowered ARQ from 1.0, the value expected for carbohydrate respiration in plants. We estimate that the values of the stored tissues represent better stem metabolism since the fresh-tissue results contained a signal of wound-response O2 uptake that further lowered ARQ. The mean bulk-soil ARQ (0.75) was considerably lower than expected by soil organic matter (SOM) stoichiometry (0.95). This lower value might represent the stoichiometry of the SOM sub-pool that supports respiration, and/or oxidative depolymerization that increases O2 fluxes. Abiotic O2 uptake was demonstrated to reduce bulk-soil ARQ down to 0.37 and consume Fe2+, but estimated to have small effect under typical respiration rates. Soil-air ARQ was usually higher than bulk-soil ARQ and lower than root ARQ (which, when measured, ranged from 0.73 to 0.96), demonstrating the potential of ARQ to partition the autotrophic and heterotrophic sources of soil respiration. The limitations of this partitioning method are discussed.en_US
dc.identifier.citationHilman, Boaz, Weiner, Tal, Haran, Tom, et al.. "The Apparent Respiratory Quotient of Soils and Tree Stems and the Processes That Control It." <i>Journal of Geophysical Research: Biogeosciences,</i> 127, no. 3 (2022) Wiley: https://doi.org/10.1029/2021JG006676.en_US
dc.identifier.digitalHilman-TheApparentRespiratoryQuotienten_US
dc.identifier.doihttps://doi.org/10.1029/2021JG006676en_US
dc.identifier.urihttps://hdl.handle.net/1911/112073en_US
dc.language.isoengen_US
dc.publisherWileyen_US
dc.rightsThis is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.en_US
dc.rights.urihttps://creativecommons.org/licenses/by/4.0/en_US
dc.titleThe Apparent Respiratory Quotient of Soils and Tree Stems and the Processes That Control Iten_US
dc.typeJournal articleen_US
dc.type.dcmiTexten_US
dc.type.publicationpublisher versionen_US
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