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| Titel |
Modeling the vertical soil organic matter profile using Bayesian parameter estimation |
| VerfasserIn |
M. C. Braakhekke, T. Wutzler, C. Beer, J. Kattge, M. Schrumpf, B. Ahrens, I. Schöning, M. R. Hoosbeek, B. Kruijt, P. Kabat, M. Reichstein |
| 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. 1 ; Nr. 10, no. 1 (2013-01-24), S.399-420 |
| Datensatznummer |
250017479
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| Publikation (Nr.) |
 copernicus.org/bg-10-399-2013.pdf |
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| Zusammenfassung |
| The vertical distribution of soil organic matter (SOM) in the profile may
constitute an important factor for soil carbon cycling. However, the
formation of the SOM profile is currently poorly understood due to
equifinality, caused by the entanglement of several processes: input from
roots, mixing due to bioturbation, and organic matter leaching. In this study
we quantified the contribution of these three processes using Bayesian
parameter estimation for the mechanistic SOM profile model SOMPROF. Based on
organic carbon measurements, 13 parameters related to decomposition and
transport of organic matter were estimated for two temperate forest soils: an
Arenosol with a mor humus form (Loobos, the Netherlands), and a Cambisol with
mull-type humus (Hainich, Germany). Furthermore, the use of the radioisotope
210Pbex as tracer for vertical SOM transport was studied.
For Loobos, the calibration results demonstrate the importance of organic
matter transport with the liquid phase for shaping the vertical SOM profile,
while the effects of bioturbation are generally negligible. These results are
in good agreement with expectations given in situ conditions. For Hainich, the
calibration offered three distinct explanations for the observations (three
modes in the posterior distribution). With the addition of
210Pbex data and prior knowledge, as well as additional
information about in situ conditions, we were able to identify the most
likely explanation, which indicated that root litter input is a dominant
process for the SOM profile. For both sites the organic matter appears to
comprise mainly adsorbed but potentially leachable material, pointing to the
importance of organo-mineral interactions. Furthermore, organic matter in the
mineral soil appears to be mainly derived from root litter, supporting
previous studies that highlighted the importance of root input for soil
carbon sequestration. The 210Pbex measurements added only
slight additional constraint on the estimated parameters. However, with
sufficient replicate measurements and possibly in combination with other
tracers, this isotope may still hold value as tracer for SOM transport. |
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