Preprints
https://doi.org/10.5194/bg-2016-105
https://doi.org/10.5194/bg-2016-105
06 Apr 2016
 | 06 Apr 2016
Status: this preprint has been withdrawn by the authors.

Ecosystem feedbacks from subarctic wetlands: vegetative and atmospheric CO2 controls on greenhouse gas emissions

Matthew J. Bridgman, Barry H. Lomax, and Sofie Sjogersten

Abstract. Wetland vegetation provide strong controls on greenhouse gas fluxes but impacts of elevated atmospheric carbon dioxide (CO2) levels on greenhouse gas emissions from wetlands are poorly understood. This study aims to investigate if elevated atmospheric CO2 enhance methane (CH4) emissions from subarctic wetlands and to determine if responses are comparable or species specific within the Cyperaceae, an important group of artic wetland plants. To achieve this we carried out a combined field and laboratory investigation to measure of CO2 and CH4 fluxes. The wetland was a CH4 source with comparable fluxes from areas with and without vegetation and across the different sedge communities. In contrast, the net ecosystem exchange of CO2 differed with sedge species. Within the laboratory experiment plants grown at double ambient (800 ppm) CO2, total biomass of Eriophorum vaginatum and Carex brunnescens increased, whereas the total biomass of E. angustifolium and C. acuta decreased, compared to the control (400 ppm CO2). These changes in biomass were associated with corresponding changes in CH4 flux. E. vaginatum and C. brunnescens mesocosms produced more CH4 when grown in 800 ppm atmospheric CO2 when compared to 400 ppm CO2 with E. angustifolium and C. acuta producing less. Additionally, redox potential and carbon substrate availability in the pore water differed among the plant treatments and in response to the elevated CO2 treatment. Together, this suggests species specific controls of CH4 emissions in response to elevated CO2, which facilitate differential plant growth responses and modification of the rhizosphere environments. Our study highlights species composition as an important control of greenhouse gas feedbacks in a CO2 rich future, which need to be considered in models aiming to predict how ecosystems respond to climate change.

This preprint has been withdrawn.

Matthew J. Bridgman, Barry H. Lomax, and Sofie Sjogersten

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Interactive discussion

Status: closed
Status: closed
AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment
Printer-friendly Version - Printer-friendly version Supplement - Supplement
Matthew J. Bridgman, Barry H. Lomax, and Sofie Sjogersten
Matthew J. Bridgman, Barry H. Lomax, and Sofie Sjogersten

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This preprint has been withdrawn.

Short summary
This study investigate if elevated atmospheric carbon dioxide enhance methane emissions from wetlands and if responses vary among different sedge species. Half of the species increased in biomass under elevated carbon dioxide compared to controls, resulting in greater soil methane emissions. In contrast, biomass and methane emissions of the other species was reduced under elevated carbon dioxide. This shows that species specific responses to elevated carbon dioxide impacted methane emissions.
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