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Contribution of soil respiration in tropical, temperate, and boreal forests to the ^(18)O enrichment of atmospheric O_2

Angert, Alon and Barkan, Eugeni and Barnett, Bruce and Brugnoli, Enrico and Davidson, Eric A. and Fessenden, Julianna and Maneepong, Somsak and Panapitukkul, Nipa and Randerson, James T. and Savage, Kathleen and Yakir, Dan and Luz, Boaz (2003) Contribution of soil respiration in tropical, temperate, and boreal forests to the ^(18)O enrichment of atmospheric O_2. Global Biogeochemical Cycles, 17 (3). Art. No. 1089. ISSN 0886-6236. doi:10.1029/2003gb002056. https://resolver.caltech.edu/CaltechAUTHORS:20181127-145121921

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Abstract

The ^(18)O content of atmospheric O_2 is an important tracer for past changes in the biosphere. Its quantitative use depends on knowledge of the discrimination against ^(18)O associated with the various O_2 consumption processes. Here we evaluated, for the first time, the in situ ^(18)O discrimination associated with soil respiration in natural ecosystems. The discrimination was estimated from the measured [O_2] and δ^(18)O of O_2 in the soil‐air. The discriminations that were found are 10.1 ± 1.5‰, 17.8 ± 1.0‰, and 22.5 ± 3.6‰, for tropical, temperate, and boreal forests, respectively, 17.9 ± 2.5‰ for Mediterranean woodland, and 15.4 ± 1.6‰ for tropical shrub land. Current understanding of the isotopic composition of atmospheric O_2 is based on the assumption that the magnitude of the fractionation in soil respiration is identical to that of dark respiration through the cytochrome pathway alone (∼18‰). The discrimination we found in the tropical sites is significantly lower, and is explained by slow diffusion in soil aggregates and root tissues that limits the O_2 concentration in the consumption sites. The high discrimination in the boreal sites may be the result of high engagement of the alternative oxidase pathway (AOX), which has high discrimination associated with it (∼27‰). The intermediate discrimination (∼18‰) in the temperate and Mediterranean sites can be explained by the opposing effects of AOX and diffusion limitation that cancel out. Since soil respiration is a major component of the global oxygen uptake, the contribution of large variations in the discrimination, observed here, to the global Dole Effect should be considered in global scale studies.


Item Type:Article
Related URLs:
URLURL TypeDescription
https://doi.org/10.1029/2003gb002056DOIArticle
ORCID:
AuthorORCID
Randerson, James T.0000-0001-6559-7387
Alternate Title:Contribution of soil respiration in tropical, temperate, and boreal forests to the 18O enrichment of atmospheric O2
Additional Information:© 2003 by the American Geophysical Union. Received 24 February 2003; accepted 30 July 2003; published 27 September 2003. We thank C. Nilnond from Prince of Songkla University for providing valuable help, and J.P. Severinghaus for advice on thermal diffusion calculations. B.L. greatly appreciates the support from the Israel Science Foundation, the USA‐Israel Binational Science Foundation, and the Moshe‐Shilo Minerva Center.
Funders:
Funding AgencyGrant Number
Israel Science FoundationUNSPECIFIED
Binational Science Foundation (USA-Israel)UNSPECIFIED
Moshe-Shilo Minerva CenterUNSPECIFIED
Subject Keywords:Dole Effect; oxygen isotopes; soil respiration
Issue or Number:3
DOI:10.1029/2003gb002056
Record Number:CaltechAUTHORS:20181127-145121921
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20181127-145121921
Official Citation:Angert, A., et al. (2003), Contribution of soil respiration in tropical, temperate, and boreal forests to the 18O enrichment of atmospheric O2, Global Biogeochem. Cycles, 17, 1089, doi: 10.1029/2003GB002056
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:91238
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:27 Nov 2018 23:11
Last Modified:16 Nov 2021 03:39

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