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Across-Habitat Comparison of Diazotroph Activity in the Subarctic
Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences. (Arcum)
2015 (English)In: Microbial Ecology, ISSN 0095-3628, E-ISSN 1432-184X, Vol. 69, no 4, 778-787 p.Article in journal (Refereed) Published
Abstract [en]

Nitrogen (N) fixation by N-2-fixing bacteria (diazotrophs) is the primary N input to pristine ecosystems like boreal forests and subarctic and arctic tundra. However, the contribution by the various diazotrophs to habitat N-2 fixation remains unclear. We present results from in situ assessments of N-2 fixation of five diazotroph associations (with a legume, lichen, feather moss, Sphagnum moss and free-living) incorporating the ground cover of the associations in five typical habitats in the subarctic (wet and dry heath, polygon-heath, birch forest, mire). Further, we assessed the importance of soil and air temperature, as well as moisture conditions for N-2 fixation. Across the growing season, the legume had the highest total as well as the highest fraction of N-2 fixation rates at habitat level in the heaths (> 85 % of habitat N-2 fixation), whereas the free-living diazotrophs had the highest N-2 fixation rates in the polygon heath (56 %), the lichen in the birch forest (87 %) and Sphagnum in the mire (100 %). The feather moss did not contribute more than 15 % to habitat N-2 fixation in any of the habitats despite its high ground cover. Moisture content seemed to be a major driver of N-2 fixation in the lichen, feather moss and free-living diazotrophs. Our results show that the range of N-2 fixers found in pristine habitats contribute differently to habitat N-2 fixation and that ground cover of the associates does not necessarily mirror contribution.

Place, publisher, year, edition, pages
2015. Vol. 69, no 4, 778-787 p.
Keyword [en]
Boreal forest, Cyanobacteria, Heterotrophs, Methanotrophs, N deposition, Nitrogen fixation, barctic tundra, Symbiosis
National Category
Environmental Sciences
URN: urn:nbn:se:umu:diva-103188DOI: 10.1007/s00248-014-0534-yISI: 000353295800006PubMedID: 25403111OAI: diva2:815288
Available from: 2015-05-29 Created: 2015-05-18 Last updated: 2016-05-20Bibliographically approved

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