Assessing the effect of elevated carbon dioxide on soil carbon: A comparison of four meta-analyses

Bruce A Hungate, Kees Jan van Groenigen, Johan Six, Julie D. Jastrow, Yiqi Luo, Marie Anne de Graaff, Chris van Kessel, Craig W. Osenberg

Research output: Contribution to journalArticle

108 Citations (Scopus)

Abstract

Soil is the largest reservoir of organic carbon (C) in the terrestrial biosphere and soil C has a relatively long mean residence time. Rising atmospheric carbon dioxide (CO2) concentrations generally increase plant growth and C input to soil, suggesting that soil might help mitigate atmospheric CO2 rise and global warming. But to what extent mitigation will occur is unclear. The large size of the soil C pool not only makes it a potential buffer against rising atmospheric CO2, but also makes it difficult to measure changes amid the existing background. Meta-analysis is one tool that can overcome the limited power of single studies. Four recent meta-analyses addressed this issue but reached somewhat different conclusions about the effect of elevated CO2 on soil C accumulation, especially regarding the role of nitrogen (N) inputs. Here, we assess the extent of differences between these conclusions and propose a new analysis of the data. The four meta-analyses included different studies, derived different effect size estimates from common studies, used different weighting functions and metrics of effect size, and used different approaches to address nonindependence of effect sizes. Although all factors influenced the mean effect size estimates and subsequent inferences, the approach to independence had the largest influence. We recommend that meta-analysts critically assess and report choices about effect size metrics and weighting functions, and criteria for study selection and independence. Such decisions need to be justified carefully because they affect the basis for inference. Our new analysis, with a combined data set, confirms that the effect of elevated CO2 on net soil C accumulation increases with the addition of N fertilizers. Although the effect at low N inputs was not significant, statistical power to detect biogeochemically important effect sizes at low N is limited, even with meta-analysis, suggesting the continued need for long-term experiments.

Original languageEnglish (US)
Pages (from-to)2020-2034
Number of pages15
JournalGlobal Change Biology
Volume15
Issue number8
DOIs
StatePublished - 2009

Fingerprint

soil carbon
Carbon Dioxide
Carbon
carbon dioxide
Soils
soil
meta-analysis
Fertilizers
Global warming
Organic carbon
comparison
effect
Buffers
Nitrogen
biosphere
residence time
global warming
mitigation
organic carbon
fertilizer

Keywords

  • C sequestration
  • Effect size
  • Elevated CO
  • Meta-analysis
  • Soil C
  • Statistical power

ASJC Scopus subject areas

  • Ecology
  • Global and Planetary Change
  • Environmental Science(all)
  • Environmental Chemistry

Cite this

Hungate, B. A., van Groenigen, K. J., Six, J., Jastrow, J. D., Luo, Y., de Graaff, M. A., ... Osenberg, C. W. (2009). Assessing the effect of elevated carbon dioxide on soil carbon: A comparison of four meta-analyses. Global Change Biology, 15(8), 2020-2034. https://doi.org/10.1111/j.1365-2486.2009.01866.x

Assessing the effect of elevated carbon dioxide on soil carbon : A comparison of four meta-analyses. / Hungate, Bruce A; van Groenigen, Kees Jan; Six, Johan; Jastrow, Julie D.; Luo, Yiqi; de Graaff, Marie Anne; van Kessel, Chris; Osenberg, Craig W.

In: Global Change Biology, Vol. 15, No. 8, 2009, p. 2020-2034.

Research output: Contribution to journalArticle

Hungate, BA, van Groenigen, KJ, Six, J, Jastrow, JD, Luo, Y, de Graaff, MA, van Kessel, C & Osenberg, CW 2009, 'Assessing the effect of elevated carbon dioxide on soil carbon: A comparison of four meta-analyses', Global Change Biology, vol. 15, no. 8, pp. 2020-2034. https://doi.org/10.1111/j.1365-2486.2009.01866.x
Hungate, Bruce A ; van Groenigen, Kees Jan ; Six, Johan ; Jastrow, Julie D. ; Luo, Yiqi ; de Graaff, Marie Anne ; van Kessel, Chris ; Osenberg, Craig W. / Assessing the effect of elevated carbon dioxide on soil carbon : A comparison of four meta-analyses. In: Global Change Biology. 2009 ; Vol. 15, No. 8. pp. 2020-2034.
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