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| Titel |
Disentangling residence time and temperature sensitivity of microbial decomposition in a global soil carbon model |
| VerfasserIn |
J.-F. Exbrayat, A. J. Pitman, G. Abramowitz |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1726-4170
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| Digitales Dokument |
URL |
| Erschienen |
In: Biogeosciences ; 11, no. 23 ; Nr. 11, no. 23 (2014-12-11), S.6999-7008 |
| Datensatznummer |
250117731
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| Publikation (Nr.) |
 copernicus.org/bg-11-6999-2014.pdf |
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| Zusammenfassung |
| Recent studies have identified the first-order representation of microbial
decomposition as a major source of uncertainty in simulations and
projections of the terrestrial carbon balance. Here, we use a reduced
complexity model representative of current state-of-the-art models of soil
organic carbon decomposition. We undertake a systematic sensitivity analysis
to disentangle the effect of the time-invariant baseline residence time
(k) and the sensitivity of microbial decomposition to temperature (Q10) on
soil carbon dynamics at regional and global scales. Our simulations produce
a range in total soil carbon at equilibrium of ~ 592 to 2745 Pg C, which is similar
to the ~ 561 to 2938 Pg C range in
pre-industrial soil carbon in models used in the fifth phase of the Coupled
Model Intercomparison Project (CMIP5). This range depends primarily on the value of
k, although the impact of Q10 is not trivial at regional scales. As
climate changes through the historical period, and into the future, k is
primarily responsible for the magnitude of the response in soil carbon,
whereas Q10 determines whether the soil remains a sink, or becomes a
source in the future mostly by its effect on mid-latitude carbon balance.
If we restrict our simulations to those simulating total soil carbon stocks
consistent with observations of current stocks, the projected range in total
soil carbon change is reduced by 42% for the historical simulations and
45% for the future projections. However, while this observation-based
selection dismisses outliers, it does not increase confidence in the future
sign of the soil carbon feedback. We conclude that despite this result,
future estimates of soil carbon and how soil carbon responds to climate
change should be more constrained by available data sets of carbon stocks. |
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