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| Titel |
Information content of incubation experiments for inverse estimation of pools in the Rothamsted carbon model: a Bayesian perspective |
| VerfasserIn |
B. Scharnagl, J. A. Vrugt, H. Vereecken, M. Herbst |
| 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 ; 7, no. 2 ; Nr. 7, no. 2 (2010-02-25), S.763-776 |
| Datensatznummer |
250004501
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| Publikation (Nr.) |
 copernicus.org/bg-7-763-2010.pdf |
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| Zusammenfassung |
| A major drawback of current soil organic carbon (SOC) models is that their
conceptually defined pools do not necessarily correspond to measurable SOC
fractions in real practice. This not only impairs our ability to rigorously
evaluate SOC models but also makes it difficult to derive accurate initial
states of the individual carbon pools. In this study, we tested the
feasibility of inverse modelling for estimating pools in the Rothamsted
carbon model (ROTHC) using mineralization rates observed during incubation
experiments. This inverse approach may provide an alternative to existing SOC
fractionation methods. To illustrate our approach, we used a time series of
synthetically generated mineralization rates using the ROTHC model. We
adopted a Bayesian approach using the recently developed DiffeRential
Evolution Adaptive Metropolis (DREAM) algorithm to infer probability density
functions of the various carbon pools at the start of incubation. The
Kullback-Leibler divergence was used to quantify the information content of
the mineralization rate data. Our results indicate that measured
mineralization rates generally provided sufficient information to reliably
estimate all carbon pools in the ROTHC model. The incubation time necessary
to appropriately constrain all pools was about 900 days. The use of prior
information on microbial biomass carbon significantly reduced the uncertainty
of the initial carbon pools, decreasing the required incubation time to about
600 days. Simultaneous estimation of initial carbon pools and decomposition
rate constants significantly increased the uncertainty of the carbon pools.
This effect was most pronounced for the intermediate and slow pools.
Altogether, our results demonstrate that it is particularly difficult to
derive reasonable estimates of the humified organic matter pool and the inert
organic matter pool from inverse modelling of mineralization rates observed
during incubation experiments. |
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