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| Titel |
Convergent modelling of past soil organic carbon stocks but divergent projections |
| VerfasserIn |
Z. Luo, E. Wang, H. Zheng, J. A. Baldock, O. J. Sun, Q. Shao |
| 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 ; 12, no. 14 ; Nr. 12, no. 14 (2015-07-28), S.4373-4383 |
| Datensatznummer |
250118035
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| Publikation (Nr.) |
 copernicus.org/bg-12-4373-2015.pdf |
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| Zusammenfassung |
| Soil carbon (C) models are important tools for understanding soil C balance and
projecting C stocks in terrestrial ecosystems, particularly under global
change. The initialization and/or parameterization of soil C models can vary
among studies even when the same model and data set are used, causing
potential uncertainties in projections. Although a few studies have assessed
such uncertainties, it is yet unclear what these uncertainties are
correlated with and how they change across varying environmental and
management conditions. Here, applying a process-based biogeochemical model
to 90 individual field experiments (ranging from 5 to 82 years of
experimental duration) across the Australian cereal-growing regions, we
demonstrated that well-designed optimization procedures enabled the model to
accurately simulate changes in measured C stocks, but did not guarantee
convergent forward projections (100 years). Major causes of the projection
uncertainty were due to insufficient understanding of how microbial
processes and soil C pool change to modulate C turnover. For a given site,
the uncertainty significantly increased with the magnitude of future C input
and years of the projection. Across sites, the uncertainty correlated
positively with temperature but negatively with rainfall. On average, a
331 % uncertainty in projected C sequestration ability can be inferred in
Australian agricultural soils. This uncertainty would increase further if
projections were made for future warming and drying conditions. Future
improvement in soil C modelling should focus on how the microbial community and
its C use efficiency change in response to environmental changes, and better
conceptualization of heterogeneous soil C pools and the C transformation
among those pools. |
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