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| Titel |
Oscillatory behavior of two nonlinear microbial models of soil carbon decomposition |
| VerfasserIn |
Y. P. Wang, B. C. Chen, W. R. Wieder, M. Leite, B. E. Medlyn, M. Rasmussen, M. J. Smith, F. B. Agusto, F. Hoffman, Y. Q. Luo |
| 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 ; 11, no. 7 ; Nr. 11, no. 7 (2014-04-07), S.1817-1831 |
| Datensatznummer |
250117343
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| Publikation (Nr.) |
 copernicus.org/bg-11-1817-2014.pdf |
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| Zusammenfassung |
| A number of nonlinear models have recently been proposed
for simulating soil carbon decomposition. Their predictions of soil carbon
responses to fresh litter input and warming differ significantly from
conventional linear models. Using both stability analysis and numerical
simulations, we showed that two of those nonlinear models (a two-pool model
and a three-pool model) exhibit damped oscillatory responses to small
perturbations. Stability analysis showed the frequency of oscillation is
proportional to √(ϵ−1−1) Ks/Vs in the two-pool model, and to √(ϵ−1−1) Kl/Vl in the three-pool model, where ϵ is
microbial growth efficiency, Ks and Kl are the half saturation
constants of soil and litter carbon, respectively, and /Vs and /Vl are
the maximal rates of carbon decomposition per unit of microbial biomass for
soil and litter carbon, respectively. For both models, the oscillation has a
period of between 5 and 15 years depending on other parameter values, and has
smaller amplitude at soil temperatures between 0 and 15 °C. In
addition, the equilibrium pool sizes of litter or soil carbon are
insensitive to carbon inputs in the nonlinear model, but are proportional to
carbon input in the conventional linear model. Under warming, the microbial
biomass and litter carbon pools simulated by the nonlinear models can
increase or decrease, depending whether ϵ varies with
temperature. In contrast, the conventional linear models always simulate a
decrease in both microbial and litter carbon pools with warming. Based on
the evidence available, we concluded that the oscillatory behavior and
insensitivity of soil carbon to carbon input are notable features in these
nonlinear models that are somewhat unrealistic. We recommend that a better
model for capturing the soil carbon dynamics over decadal to centennial
timescales would combine the sensitivity of the conventional models to
carbon influx with the flexible response to warming of the nonlinear model. |
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