TY - JOUR

T1 - Correlations between substrate availability, dissolved CH4, and CH4 emissions in an arctic wetland subject to warming and plant removal

AU - Nielsen, Cecilie Skov

AU - Michelsen, Anders

AU - Strobel, Bjarne W.

AU - Wulff, Katrine

AU - Banyasz, Imre

AU - Elberling, Bo

N1 - CENPERM[2017]

PY - 2017

Y1 - 2017

N2 - The Arctic is warming which may potentially affect substrate availability, organic matter decomposition, plant growth, and plant species composition. This may lead to changes in the exchange of methane (CH4) and carbon dioxide (CO2) between the soil system and the atmosphere. Yet the correlations among substrate availability, CH4 production, and net emissions of CH4 have been scarcely studied in arctic wetlands. Presently, the impact of increasing temperatures on CH4 exchange is uncertain as the two existing reports on field warming in arctic wetlands present opposite results. We here report results on how summer warming and shrub removal affect soil water substrate (acetate, formate, oxalate, and dissolved organic carbon) concentrations as well as dissolved CH4 and CH4 emissions in a fen at Disko Island (West Greenland). The peak in dissolved CH4 followed the peak in acetate concentration, and appeared after the peak in CH4 emissions, which indicates a lack of correlation between CH4 production and emissions. The peak in CH4 emissions coincided with maximum gross ecosystem production suggesting that CH4 emissions are closely linked to photosynthesis. This was supported by an experiment with removal of the sedge Carex aquatilis ssp. stans which contributed with up to 77% of the CH4 emitted from the ecosystem. By contrast, shrub removal and summer warming did not significantly affect CH4 emissions, possibly due to the treatments impacting CH4 production more than emissions. This implies that such wetlands may be less sensitive to moderate warming and changes in shrub cover than previously assumed.

AB - The Arctic is warming which may potentially affect substrate availability, organic matter decomposition, plant growth, and plant species composition. This may lead to changes in the exchange of methane (CH4) and carbon dioxide (CO2) between the soil system and the atmosphere. Yet the correlations among substrate availability, CH4 production, and net emissions of CH4 have been scarcely studied in arctic wetlands. Presently, the impact of increasing temperatures on CH4 exchange is uncertain as the two existing reports on field warming in arctic wetlands present opposite results. We here report results on how summer warming and shrub removal affect soil water substrate (acetate, formate, oxalate, and dissolved organic carbon) concentrations as well as dissolved CH4 and CH4 emissions in a fen at Disko Island (West Greenland). The peak in dissolved CH4 followed the peak in acetate concentration, and appeared after the peak in CH4 emissions, which indicates a lack of correlation between CH4 production and emissions. The peak in CH4 emissions coincided with maximum gross ecosystem production suggesting that CH4 emissions are closely linked to photosynthesis. This was supported by an experiment with removal of the sedge Carex aquatilis ssp. stans which contributed with up to 77% of the CH4 emitted from the ecosystem. By contrast, shrub removal and summer warming did not significantly affect CH4 emissions, possibly due to the treatments impacting CH4 production more than emissions. This implies that such wetlands may be less sensitive to moderate warming and changes in shrub cover than previously assumed.

KW - Arctic

KW - Carex

KW - greenhouse gas

KW - methane

KW - warming

KW - wetland

U2 - 10.1002/2016JG003511

DO - 10.1002/2016JG003511

M3 - Journal article

AN - SCOPUS:85017319856

VL - 122

SP - 645

EP - 660

JO - Journal of Geophysical Research: Solid Earth

JF - Journal of Geophysical Research: Solid Earth

SN - 0148-0227

IS - 3

ER -