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| Titel |
Community shifts and carbon translocation within metabolically-active rhizosphere microorganisms in grasslands under elevated CO2 |
| VerfasserIn |
K. Denef, H. Bubenheim, K. Lenhart, J. Vermeulen, O. Cleemput, P. Boeckx, C. Müller |
| 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. 5 ; Nr. 4, no. 5 (2007-09-24), S.769-779 |
| Datensatznummer |
250001960
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| Publikation (Nr.) |
 copernicus.org/bg-4-769-2007.pdf |
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| Zusammenfassung |
| The aim of this study was to identify the microbial communities that are
actively involved in the assimilation of rhizosphere-C and are most
sensitive in their activity to elevated atmospheric CO2 in a temperate
semi-natural low-input grassland ecosystem. For this, we analyzed 13C
signatures in microbial biomarker phospholipid fatty acids (PLFA) from an
in-situ 13CO2 pulse-labeling experiment in the Giessen Free Air
Carbon dioxide Enrichment grasslands (GiFACE, Germany) exposed to ambient
and elevated (i.e. 50% above ambient) CO2 concentrations. Short-term
13C PLFA measurements at 3 h and 10 h after the pulse-labeling revealed
very little to no 13C enrichment after 3 h in biomarker PLFAs and a
much greater incorporation of new plant-C into fungal compared to bacterial
PLFAs after 10 h. After a period of 11 months following the pulse-labeling
experiment, the 13C enrichment of fungal PLFAs was still largely
present but had decreased, while bacterial PLFAs were much more enriched in
13C compared to a few hours after the pulse-labeling. These results
imply that new rhizodeposit-C is rapidly processed by fungal communities and
only much later by the bacterial communities, which we attributed to either
a fungal-mediated translocation of rhizosphere-C from the fungal to
bacterial biomass or a preferential bacterial use of dead root or fungal
necromass materials as C source over the direct utilization of fresh
root-exudate C in these N-limited grassland ecosystems. Elevated CO2
caused an increase in the proportional 13C enrichment (relative to the
universal biomarker 16:0) of the arbuscular mycorrhizal fungal biomarker
PLFA 16:1ω5 and one gram-positive bacterial biomarker PLFA i16:0,
but a decrease in the proportional 13C enrichment of 18:1ω9c, a
commonly used though questionable fungal biomarker PLFA. This suggests
enhanced fungal rhizodeposit-C assimilation only by arbuscular mycorrhizal
fungal species under elevated CO2. |
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