Temperature‐dependent shift from labile to recalcitrant carbon sources of arctic heterotrophs
Abstract Soils of high latitudes store approximately one‐third of the global soil carbon pool. Decomposition of soil organic matter (SOM) is expected to increase in response to global warming, which is most pronounced in northern latitudes. It is, however, unclear if microorganisms are able to utili...
| Published in: | Rapid Communications in Mass Spectrometry |
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| Main Authors: | , , , , , , , |
| Format: | Article in Journal/Newspaper |
| Language: | English |
| Published: |
Wiley
2005
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| Subjects: | |
| Online Access: | http://dx.doi.org/10.1002/rcm.1911 https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1002%2Frcm.1911 https://onlinelibrary.wiley.com/doi/full/10.1002/rcm.1911 |
| Summary: | Abstract Soils of high latitudes store approximately one‐third of the global soil carbon pool. Decomposition of soil organic matter (SOM) is expected to increase in response to global warming, which is most pronounced in northern latitudes. It is, however, unclear if microorganisms are able to utilize more stable, recalcitrant C pools, when labile soil carbon pools will be depleted due to increasing temperatures. Here we report on an incubation experiment with intact soil cores of a frost‐boil tundra ecosystem at three different temperatures (2°C, 12°C and 24°C). In order to assess which fractions of the SOM are available for decomposition at various temperatures, we analyzed the isotopic signature of respired CO 2 and of different SOM fractions. The δ 13 C values of CO 2 respired were negatively correlated with temperature, indicating the utilization of SOM fractions that were depleted in 13 C at higher temperatures. Chemical fractionation of SOM showed that the water‐soluble fraction (presumably the most easily available substrates for microbial respiration) was most enriched in 13 C, while the acid‐insoluble pool (recalcitrant substrates) was most depleted in 13 C. Our results therefore suggest that, at higher temperatures, recalcitrant compounds are preferentially respired by arctic microbes. When the isotopic signatures of respired CO 2 of soils which had been incubated at 24°C were measured at 12°C, the δ 13 C values shifted to values found in soils incubated at 12°C, indicating the reversible use of more easily available substrates. Analysis of phospholipid fatty acid profiles showed significant differences in microbial community structure at various incubation temperatures indicating that microorganisms with preference for more recalcitrant compounds establish as temperatures increase. In summary our results demonstrate that a large portion of tundra SOM is potentially mineralizable. Copyright © 2005 John Wiley & Sons, Ltd. |
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