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Freeze-thaw cycles simultaneously decrease peatland photosynthetic carbon uptake and ecosystem respiration

Freeze-thaw cycles simultaneously decrease peatland photosynthetic carbon uptake and ecosystem respiration
Freeze-thaw cycles simultaneously decrease peatland photosynthetic carbon uptake and ecosystem respiration

Decreasing snow cover in winter resulting from climate warming increases the incidence of freeze–thaw cycles (FTCs) in many ecosystems, including peatlands. As peatland ecosystems form a globally significant long-term carbon storage, understanding the effects of changing conditions in winter on carbon dynamics is essential. We studied how FTCs affect peatland carbon cycling by conducting mesocosm experiments with Sphagnum. Our results indicate an overall impeding effect of FTCs on Sphagnum photosynthesis, chlorophyll content, ecosystem respiration and enzymatic processes. A threefold reduction in photosynthesis in the FTC treatment was related to a decrease in chlorophyll content, showing that Sphagnum physiologically suffers from repeated FTCs. In the FTC treatment β-glucosidase and phosphatase enzymatic activities decreased by 50% and 30%, respectively, whilst alanine remained unaffected, indicating that in peat soils short-term FTCs affect the carbon and phosphorus cycles, but not the nitrogen cycle. Long-term effects of FTCs deserve further studies.

1239-6095
267-276
Küttim, Martin
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Hofsommer, Maaike L.
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Robroek, Bjorn J.M.
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Signarbieux, Constant
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Jassey, Vincent E.J.
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Laine, Anna M.
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Lamentowicz, Mariusz
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Buttler, Alexandre
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Ilomets, Mati
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Mills, Robert T.E.
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Küttim, Martin
7e6be476-dd0e-4d0f-9645-4b124de287ae
Hofsommer, Maaike L.
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Robroek, Bjorn J.M.
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Signarbieux, Constant
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Jassey, Vincent E.J.
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Laine, Anna M.
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Lamentowicz, Mariusz
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Buttler, Alexandre
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Ilomets, Mati
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Mills, Robert T.E.
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Küttim, Martin, Hofsommer, Maaike L., Robroek, Bjorn J.M., Signarbieux, Constant, Jassey, Vincent E.J., Laine, Anna M., Lamentowicz, Mariusz, Buttler, Alexandre, Ilomets, Mati and Mills, Robert T.E. (2017) Freeze-thaw cycles simultaneously decrease peatland photosynthetic carbon uptake and ecosystem respiration. Boreal Environment Research, 22, 267-276.

Record type: Article

Abstract

Decreasing snow cover in winter resulting from climate warming increases the incidence of freeze–thaw cycles (FTCs) in many ecosystems, including peatlands. As peatland ecosystems form a globally significant long-term carbon storage, understanding the effects of changing conditions in winter on carbon dynamics is essential. We studied how FTCs affect peatland carbon cycling by conducting mesocosm experiments with Sphagnum. Our results indicate an overall impeding effect of FTCs on Sphagnum photosynthesis, chlorophyll content, ecosystem respiration and enzymatic processes. A threefold reduction in photosynthesis in the FTC treatment was related to a decrease in chlorophyll content, showing that Sphagnum physiologically suffers from repeated FTCs. In the FTC treatment β-glucosidase and phosphatase enzymatic activities decreased by 50% and 30%, respectively, whilst alanine remained unaffected, indicating that in peat soils short-term FTCs affect the carbon and phosphorus cycles, but not the nitrogen cycle. Long-term effects of FTCs deserve further studies.

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2017_Kuttim et al Bor Env Res - Version of Record
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More information

Accepted/In Press date: 16 May 2017
e-pub ahead of print date: 29 May 2017
Organisations: University of Southampton, Biological Sciences

Identifiers

Local EPrints ID: 411953
URI: http://eprints.soton.ac.uk/id/eprint/411953
ISSN: 1239-6095
PURE UUID: fbe64d78-fd45-4a0e-833d-ecc8b0a2d5d9
ORCID for Bjorn J.M. Robroek: ORCID iD orcid.org/0000-0002-6714-0652

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Date deposited: 03 Jul 2017 16:31
Last modified: 07 Oct 2020 02:14

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