University of Oulu

Lupascu, M., Czimczik, C. I., Welker, M. C., Ziolkowski, L. A., Cooper, E. J., & Welker, J. M. (2018). Winter ecosystem respiration and sources of CO2 from the High Arctic tundra of Svalbard: Response to a deeper snow experiment. Journal of Geophysical Research: Biogeosciences, 123, 2627–2642. https://doi.org/10.1029/2018JG004396

Winter ecosystem respiration and sources of CO₂ from the high arctic tundra of svalbard : response to a deeper snow experiment

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Author: Lupascu, M.1; Czimczik, C. I.2; Welker, M. C.3;
Organizations: 1Department of Geography, National University of Singapore, Singapore
2Department of Earth System Science, University of California, Irvine, CA, USA
3University Center on Svalbard, Longyearbyen, Norway
4School of the Earth, Ocean and the Environment, University of South Carolina, Columbia, SC, USA
5Department of Arctic and Marine Biology, Faculty of Biosciences, Fisheries and Economics, UiT-The Arctic University of Norway, Tromsø, Norway
6Department of Biological Sciences, University of Alaska Anchorage, Anchorage, AK, USA
7Department of Ecology and Genetics and UArctic, University of Oulu, Oulu, Finland
Format: article
Version: published version
Access: embargoed
Persistent link: http://urn.fi/urn:nbn:fi-fe2018110847664
Language: English
Published: John Wiley & Sons, 2018
Publish Date: 2019-02-17
Description:

Abstract

Currently, there is a lack of understanding on how the magnitude and sources of carbon (C) emissions from High Arctic tundra are impacted by changing snow cover duration and depth during winter. Here we investigated this issue in a graminoid tundra snow fence experiment on shale‐derived gelisols in Svalbard from the end of the growing season and throughout the winter. To characterize emissions, we measured ecosystem respiration (Reco) along with its radiocarbon (14C) content. We assessed the composition of soil organic matter (SOM) by measuring its bulk‐C and nitrogen (N), 14C content, and n‐alkane composition. Our findings reveal that greater snow depth increased soil temperatures and winter Reco (25 mg C m−2 d−1 under deeper snow compared to 13 mg C m−2 d−1 in ambient conditions). At the end of the growing season, Reco was dominated by plant respiration and microbial decomposition of C fixed within the past 60 years (Δ14C = 62 ± 8‰). During winter, emissions were significantly older (Δ14C = −64 ± 14‰), and likely sourced from microorganisms decomposing aged SOM formed during the Holocene mixed with biotic or abiotic mineralization of the carbonaceous, fossil parent material. Our findings imply that snow cover duration and depth is a key control on soil temperatures and thus the magnitude of Reco in winter. We also show that in shallow Arctic soils, mineralization of carbonaceous parent materials can contribute significant proportions of fossil C to Reco. Therefore, permafrost‐C inventories informing C emission projections must carefully distinguish between more vulnerable SOM from recently fixed biomass and more recalcitrant ancient sedimentary C sources.

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Series: Journal of geophysical research. Biogeosciences
ISSN: 2169-8953
ISSN-E: 2169-8961
ISSN-L: 2169-8953
Volume: 123
Issue: 8
Pages: 2627 - 2642
DOI: 10.1029/2018JG004396
OADOI: https://oadoi.org/10.1029/2018JG004396
Type of Publication: A1 Journal article – refereed
Field of Science: 1172 Environmental sciences
1171 Geosciences
Subjects:
Funding: This research was supported primarily by J.M.W.’s Fulbright Distinguished U.S. Arctic Chairship-Norway award in 2012. Additional support was provided by the Faculty of Biosciences, Fisheries, and Economics of the Department of Arctic and Marine Biology, University of Tromsø (UiT), and the National Science Foundation, OPP 0909538, awarded to J.M.W.
Copyright information: ©2018. American Geophysical Union. All Rights Reserved.