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| Titel |
An incubation system to trace carbon fluxes in soil - First experimental |
| VerfasserIn |
Stefany Thiessen, Gerd Gleixner, Markus Reichstein |
| Konferenz |
EGU General Assembly 2010
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 12 (2010) |
| Datensatznummer |
250043901
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| Zusammenfassung |
| Soils contain the largest carbon pool in terrestrial ecosystems and it is widely assumed
that a considerable fraction of this pool might be mobilized by global warming.
Numerous investigations have proven that soil respiration is a mixture of several source,
like root rhizosphere and soil organic matter (SOM) degradation. However, little
is still known about soil carbon dynamics and the influence of microbes on this
process.
We developed an incubation system to perform multitracer experiments to quantify the
contribution of microorganisms to carbon turnover from different carbon sources. A natural
13C label was used to mark carbon sources. The old carbon in the SOM held a depleted 13C3
signal and newly added C was enriched in 13C4. Accordingly, in the experiment we
quantified the relative respiration of carbon from added sugars and soil organic matter by
microbial groups, with additional application of fungicide (cycloheximide). A root
free arable soil was divided into three sets, all with depleted C3 soil, but varied
in terms of the added material: one with C4 glucose, a second with C4 glucose
combined with fungicide and the last one with water application only, as control. To
characterize microbial communities and estimate microbial biomass we extract
phospholipid fatty acids (PLFA). Furthermore, by measuring the isotopic ratio of the
PLFA it was also possible to identify microorganisms that metabolised the traced
material.
Preliminary results showed that the glucose application stimulated microbial growth in
the beginning, but afterwards the microbial biomass decreased again over time. However, a
change in the microbial community composition could not be observed, regardless to the kind
of added material. Nevertheless, the respiration response slowed down after the fungicide
application, and a second respiration pulse was induced by this application. This was
probably due to reactivation of the fungi, after the effect of the fungicide expired. |
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