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| Titel |
Temperature response functions introduce high uncertainty in modelled carbon stocks in cold temperature regimes |
| VerfasserIn |
H. Portner, H. Bugmann, A. Wolf |
| 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. 11 ; Nr. 7, no. 11 (2010-11-15), S.3669-3684 |
| Datensatznummer |
250005063
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| Publikation (Nr.) |
 copernicus.org/bg-7-3669-2010.pdf |
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| Zusammenfassung |
Models of carbon cycling in terrestrial ecosystems contain formulations for
the dependence of respiration on temperature, but the sensitivity of
predicted carbon pools and fluxes to these formulations and their
parameterization is not well understood. Thus, we performed an uncertainty
analysis of soil organic matter decomposition with respect to its temperature
dependency using the ecosystem model LPJ-GUESS.
We used five temperature response functions (Exponential, Arrhenius,
Lloyd-Taylor, Gaussian, Van't Hoff). We determined the parameter confidence
ranges of the formulations by nonlinear regression analysis based on eight
experimental datasets from Northern Hemisphere ecosystems. We sampled over
the confidence ranges of the parameters and ran simulations for each pair of
temperature response function and calibration site. We analyzed both the
long-term and the short-term heterotrophic soil carbon dynamics over a
virtual elevation gradient in southern Switzerland.
The temperature relationship of Lloyd-Taylor fitted the overall data set best
as the other functions either resulted in poor fits (Exponential, Arrhenius)
or were not applicable for all datasets (Gaussian, Van't Hoff). There were
two main sources of uncertainty for model simulations: (1) the lack of
confidence in the parameter estimates of the temperature response, which
increased with increasing temperature, and (2) the size of the simulated soil
carbon pools, which increased with elevation, as slower turn-over times lead
to higher carbon stocks and higher associated uncertainties. Our results
therefore indicate that such projections are more uncertain for higher
elevations and hence also higher latitudes, which are of key importance for
the global terrestrial carbon budget. |
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