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| Titel |
Microbial responses to multifactorial climate change factors in heathland soil revealed by 13C tracing of added glycine and FACE CO2 |
| VerfasserIn |
Louise Andresen, Jennifer Dungait, Roland Bol, Merete Selsted, Per Ambus, Anders Michelsen |
| Konferenz |
EGU General Assembly 2013
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 15 (2013) |
| Datensatznummer |
250074646
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| Zusammenfassung |
| Understanding microbial responses in soils is the key to understand the potential impacts of predicted climate changes on soil C dynamics. Microbial utilization of carbon sources represents a gateway in the routing of carbon incorporation and respirational release.
After one year of accumulated ecosystem effects from multifactorial climate change treatments (‘CLIMAITE’), microbial activity was investigated by addition of the 13C labelled amino acid (13C2-glycine; 99 at.%) to a factorial design of: elevated temperature (T), summer drought (D) and elevated atmospheric carbon dioxide (510 ppm [CO2]), and combined treatments (TD, TCO2, DCO2 and TDCO2) at an undisturbed temperate heathland dominated by Calluna vulgaris.
The integrated microbial long-term responses to treatments were identified by analysis of PLFA in full concentrations in the top soil and the accumulative indirect labelling by the 13C-depleted FACE CO2 air. The short-term microbial response was directly assessed by quantification of incorporation of 13C-glycine into biomarker PLFA of specific microbial groups one day after injection, using gas chromatography-combustion-stable isotope ratio mass spectrometry (GC-C-IRMS). Bacteria were more opportunistic in utilization of the added glycine substrate: i.e. 13C from the labelled glycine was incorporated into Gram positive bacteria (i15:0, i17:0) in all treatments, whereas in contrast the fungi had minor or no glycine derived 13C-enrichment.
The direct short-term response was a more active microbial biomass both incorporating and respiring 13C from the added glycine in treatments with elevated CO2. However, as response to the long-term climate treatment, warming decreased the concentration of PLFAs in general.
The integrated 13C-depleted labelling obtained via plant use of 13C-depleted CO2 and subsequent root exudation of 13C-depleted labile carbon, illustrated the intimate links between microbial incorporation of carbon and plant CO2 assimilation. Hence, the response suggests future climatic conditions may increase bacterial utilization of free amino acids from labile root exudates. |
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