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| Titel |
Temperature response of soil respiration is dependent on concentration of readily decomposable C |
| VerfasserIn |
A. A. Larionova, I. V. Yevdokimov, S. S. Bykhovets |
| 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 ; 4, no. 6 ; Nr. 4, no. 6 (2007-12-04), S.1073-1081 |
| Datensatznummer |
250001999
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| Publikation (Nr.) |
 copernicus.org/bg-4-1073-2007.pdf |
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| Zusammenfassung |
| Temperature acclimation of soil organic matter (SOM) decomposition is one of
the major uncertainties in predicting soil CO2 efflux associated with
the increase in global mean temperature. A reasonable explanation for an
apparent acclimation proposed by Davidson and colleagues (2006) based on
Michaelis-Menten kinetics suggests that temperature sensitivity decreases
when both maximal activity of respiratory enzymes (Vmax) and
half-saturation constant (Ks) cancel each other upon temperature increase. We
tested the hypothesis of the canceling effect by the mathematical simulation
of data obtained in incubation experiments with forest and arable soils. Our
data support the hypothesis and suggest that concentration of readily
decomposable C substrate (as glucose equivalents) and temperature dependent
substrate release are the important factors controlling temperature
sensitivity of soil respiration. The highest temperature sensitivity of soil
respiration was observed when substrate release was temperature dependent
and C substrate concentration was much lower than Ks. Increase of
substrate content to the half-saturation constant by glucose addition
resulted in temperature acclimation associated with the canceling effect.
Addition of the substrate to the level providing respiration at a maximal
rate Vmax leads to the acclimation of the whole microbial community as
such. However, growing microbial biomass was more sensitive to the
temperature alterations. This study improves our understanding of the
instability of temperature sensitivity of soil respiration under field
conditions, attributing this phenomenon to changes in concentration of
readily decomposable C substrate. |
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