Switch of fungal to bacterial degradation in natura drained and rewetted oligotrophic peatlands reflected in delta N-15 and fatty acid composition

Gross-Schmölders, Miriam and von Sengbusch, Pascal and Krüger, Jan Paul and Klein, Kristy and Birkholz, Axel and Leifeld, Jens and Alewell, Christine. (2020) Switch of fungal to bacterial degradation in natura drained and rewetted oligotrophic peatlands reflected in delta N-15 and fatty acid composition. SOIL, 6 (2). pp. 299-313.

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Official URL: https://edoc.unibas.ch/80591/

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For centuries European peatlands have been degrading along with drainage, land use and climate changes. Increasing pressure on peatland ecosystems calls for a more cost-efficient method to indicate the current state of peatlands and the success of restoration efforts. Metabolic pathways in peatland soils are imprinted in stable isotope compositions due to differences in microorganism communities and their metabolic pathways. Therefore, we hypothesize that depth profiles of nitrogen stable isotope values provide a promising opportunity to detect peatland decomposition or restoration. We studied five peatlands, namely Degern Stormyr (northern Sweden), Lakkasuo (central Finland) and three mires in the Black Forest (southern Germany). At all locations, cores were taken from adjacent drained (or rewetted) and natural sites to identify delta N-15 trends that could indicate changes due to drainage and restoration. At all drained (and rewetted) sites we found a distinct peak ("turning point") of the delta N-15 values in the center of the drained horizon. We did a fatty acids (FAs) analysis to link our results to microbial community composition. As markers, we distinguished between one fungal-derived FA (C18:2 omega 9c) and four bacterial-derived FAs. For bacteria, we looked for one general bacterial-derived FA (C14:0), two FAs for gram-positive bacteria (i-C15:0; a-C15:0), and one FA for gram-negative bacteria (C16:1 omega 9c). In accordance with other studies, our results suggest that fungi dominate the microbial metabolism in the upper aerobic peat horizon. This is reflected by depleted delta N-15 values. Moving downwards, the drained horizon conditions slowly switch to oxygen limitation. Consequently, fungal-derived FAs decrease whereas bacterial-derived FAs rise. The highest diversity of microbial-derived FAs is indicated by the delta N-15 turning point. Below the delta N-15 turning point, oxygen is increasingly limited and concentrations of all microbial-derived FAs are decreasing down to the onset of the permanently waterlogged anaerobic horizon. Peatland cores with restoration successes again show, above the formerly drained horizon, no depth trend of the isotopic values. Hence, we conclude that delta N-15 stable isotope values reflect microbial community composition, which differs between drained and natural peatlands.
Faculties and Departments:05 Faculty of Science > Departement Umweltwissenschaften > Geowissenschaften > Umweltgeowissenschaften (Alewell)
UniBasel Contributors:Alewell, Christine and Gross-Schmölders, Miriam and Klein, Jennifer and Birkholz, Axel and Leifeld, Jens
Item Type:Article, refereed
Article Subtype:Research Article
Publisher:European Geosciences Union
Note:Publication type according to Uni Basel Research Database: Journal article
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Last Modified:20 Apr 2021 10:33
Deposited On:20 Apr 2021 10:33

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