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| Titel |
Temperature sensitivity of different soil carbon sources |
| VerfasserIn |
S. Thiessen, G. Gleixner, T. Wutzler, M. Reichstein |
| Konferenz |
EGU General Assembly 2012
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 14 (2012) |
| Datensatznummer |
250066203
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| Zusammenfassung |
| Soils contain the largest carbon pool in terrestrial ecosystems and it is widely assumed that
even if a small fraction of this pool is mobilized due to global warming, this might affect the
CO2 concentration in atmosphere. The effect of temperature and the influence of fresh
substrate on soil organic matter decomposition are two key issues, which we need to
understand in order to forecast soil carbon dynamics under climate change. The
objective of this study was to investigate the temperature sensitivity of freshly added
organic matter and bulk soil carbon to test the kinetic assumption of substrate quality.
Further we were able to investigate if the addition of fresh organic matter accelerates
decomposition of soil organic matter (“priming effect (PE)”) and does this effect depends on
temperature.
We performed a laboratory incubation experiment in a newly developed through-flow soil
incubation system and incubated sieved soil samples with and without 13C labeled litter for
199 days. The soils were incubated with two temperature treatments, one with diurnally
temperature cycle between 5 and 15Ë C, the other between 15 and 25Ë C. Soil CO2
production was continuously monitored with an infrared gas analyzer, while the 13C signal
was determined for -1, 2, 15, 42, 70, 93, 135, 158 and 199 days after litter addition. We
observed that the instantaneous temperature sensitivity does not differ between the
original and the amended soil. However, in the amended treatment the temperature
sensitivity increased during the incubation time, along with increasing microbial
biomass. Further, we found in both temperature treatments a stimulation of the
soil organic matter decomposition by the freshly add organic matter. This relative
stimulation was smaller in the warm treatment (46%) and in the cold treatment
(54%). Overall we conclude that there is no simple substrate-temperature sensitivity
relationship, but complex interactions governing the emergent temperature sensitivity. |
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