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| Titel |
Microbial carbon recycling – an underestimated process controlling soil carbon dynamics – Part 1: A long-term laboratory incubation experiment |
| VerfasserIn |
A. Basler, M. Dippold, M. Helfrich, J. Dyckmans |
| 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 ; 12, no. 20 ; Nr. 12, no. 20 (2015-10-19), S.5929-5940 |
| Datensatznummer |
250118129
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| Publikation (Nr.) |
 copernicus.org/bg-12-5929-2015.pdf |
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| Zusammenfassung |
Independent of its chemical structure carbon (C) persists in soil for
several decades, controlled by stabilization and recycling. To disentangle
the importance of the two factors on the turnover dynamics of soil sugars,
an important compound of soil organic matter (SOM), a 3-year incubation
experiment was conducted on a silty loam soil under different types of land
use (arable land, grassland and forest) by adding 13C-labelled glucose.
The compound-specific isotope analysis of soil sugars was used to examine
the dynamics of different sugars during incubation.
Sugar dynamics were dominated by a pool of high mean residence times (MRT)
indicating that recycling plays an important role for sugars. However, this
was not substantially affected by soil C content. Six months after label
addition the contribution of the label was much higher for microbial biomass
than for CO2 production for all examined land use types, corroborating
that substrate recycling was very effective within the microbial biomass.
Two different patterns of tracer dynamics could be identified for different
sugars: while fucose and mannose showed highest label contribution at the
beginning of the incubation with a subsequent slow decline, galactose and
rhamnose were characterized by slow label incorporation with subsequently
constant levels, which indicates that recycling is dominating the dynamics
of these sugars. This may correspond to (a) different microbial growing
strategies (r and K-strategist) or (b) location within or outside the cell
membrane (lipopolysaccharides vs. exopolysaccharides) and thus be subject of
different re-use within the microbial food web. Our results show how the
microbial community recycles substrate very effectively and that high losses
of substrate only occur during initial stages after substrate addition. This
study indicates that recycling is one of the major processes explaining the
high MRT observed for many SOM fractions and thus is crucial for
understanding the global soil C cycle. |
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