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| Titel |
Examining soil carbon uncertainty in a global model: response of microbial decomposition to temperature, moisture and nutrient limitation |
| VerfasserIn |
J.-F. Exbrayat, A. J. Pitman, Q. Zhang, G. Abramowitz, Y.-P. Wang |
| 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 ; 10, no. 11 ; Nr. 10, no. 11 (2013-11-08), S.7095-7108 |
| Datensatznummer |
250085402
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| Publikation (Nr.) |
 copernicus.org/bg-10-7095-2013.pdf |
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| Zusammenfassung |
| Reliable projections of future climate require land–atmosphere carbon (C)
fluxes to be represented realistically in Earth system models (ESMs). There are
several sources of uncertainty in how carbon is parameterised in these
models. First, while interactions between the C, nitrogen (N) and phosphorus
(P) cycles have been implemented in some models, these lead to diverse
changes in land–atmosphere fluxes. Second, while the first-order
parameterisation of soil organic matter decomposition is similar between
models, formulations of the control of the soil physical state on microbial
activity vary widely. For the first time, we address these sources of
uncertainty simultaneously by implementing three soil moisture and three soil
temperature respiration functions in an ESM that can be run
with three degrees of biogeochemical nutrient limitation (C-only, C and N,
and C and N and P). All 27 possible combinations of response functions and
biogeochemical mode are equilibrated before transient historical (1850–2005)
simulations are performed. As expected, implementing N and P limitation
reduces the land carbon sink, transforming some regional sinks into net
sources over the historical period. Meanwhile, regardless of which nutrient
mode is used, various combinations of response functions imply a two-fold
difference in the net ecosystem accumulation and a four-fold difference in
equilibrated total soil C. We further show that regions with initially larger
pools are more likely to become carbon sources, especially when nutrient
availability limits the response of primary production to increasing
atmospheric CO2. Simulating changes in soil C content therefore
critically depends on both nutrient limitation and the choice of respiration
functions. |
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