Key microbial processes that control organic matter decomposition in high Arctic peatlands

 

In high Arctic peatlands organic matter is slowly decomposed by large and complex microbial communities. In the upper few centimeters of soil, aerobic microorganisms are degrading fresh organic matter deposited by mosses, grasses, and other vascular plants to form CO2. The organic matter that is not decomposed in the top layer is transformed and to some extent mineralized through anaerobic decomposition to methane and CO2 in the deeper layers.

We study the effect of altered plant vegetation on the microbiota responsible for aerobic decomposition in high Arctic peatlands. Plant populations are driven by changes in herbivore populations and our preliminary results suggest that the microbial food web in the upper soil layer is substantially affected by changes in the plant cover. Thus, our studies link above- and below-ground ecology. Our main objective is to identify how above-ground ecology alters microbial food webs and which consequences this has to aerobic carbon cycling in high-Arctic peatlands.  

In the deeper layers our emphasis is on syntrophic fermentation and methanogenesis. These are the terminal processes in anaerobic mineralization of organic matter and driven by a few specialist bacteria and archaea. These are also the lifestyles that provide the least energy. Syntrophy and methanogenesis are key processes in greenhouse gas production, but sensitive to environmental change as they represent difficult microbial lifestyles. Our objective is to understand how these sensitive and important microbial processes react to changes in temperature and other environmental conditions. By this, we hope to uncover how the climate controls microbial production of greenhouse gases in high Arctic peatlands.

 

OUT NOW! Yang, Liebner, Svenning & Tveit. Decoupling of microbial community dynamics and functions in Arctic peat soil exposed to short term warming. Molecular Ecology

 

Publications:

Bender et al., 2021. Microbial responses to herbivory‑induced vegetation changes in a high‑Arctic peatlandPolar Biology

Tveit et al., 2020. Environmental patterns of brown moss- and Sphagnum-associated microbial communitiesScientific Reports

 

Further reading:

Tveit et al., 2012. Organic carbon transformations in high-Arctic peat soils: key functions and microorganisms. The ISME Journal

Tveit et al., 2015. Metabolic and trophic interactions modulate methane production by Arctic peat microbiota in response to warming. PNAS

Geisen et al. 2015. Metatranscriptomic census of active protists in soilsThe ISME Journal

 

Contact:

Kathrin M. Bender (PhD candidate)
Yngvild Bjørdal (master student)

  

 

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last update: 27.08.2021

Bender et al. Microbial responses to herbivory‑induced vegetation changes in a high‑Arctic peatland. Polar Biology
Tveit et al., 2020.  Environmental patterns of brown moss- and Sphagnum-associated microbial communities. Scientific Reports
Ny Ålesund. Soil samples of grazing enclosures. From left to right: 14 y enclosure, 4 y enclosure, grazed sample. Foto: Mette M. Svenning 
Kathi's Cells in the Cold. Anaerobic lab work.

 

 

 

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