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Reduction of the temperature sensitivity of minerotrophic fen methane emissions by simulated glacial atmospheric carbon dioxide starvation

Boardman, Carl P.; Gauci, Vincent; Fox, Andrew; Blake, Stephen and Beerling, David J. (2013). Reduction of the temperature sensitivity of minerotrophic fen methane emissions by simulated glacial atmospheric carbon dioxide starvation. Journal of Geophysical Research: Biogeosciences, 118(2) pp. 462–470.

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DOI (Digital Object Identifier) Link: https://doi.org/10.1002/jgrg.20017
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Abstract

Variations to the global wetland CH4 source strength in response to changes in orbital insolation patterns and atmospheric CO2 concentration ([CO2]a) are hypothesized to play an important role in determining glacial-interglacial variations in atmospheric CH4 concentration ([CH4]a). Here the interactive effects of temperature, a major controlling variable determining wetland CH4 flux, and the low [CO2]a of glacial intervals are investigated for the first time. We measured the temperature dependence of CH4 emissions from replicated mesocosms (n = 8 per CO2 treatment) collected from a minerotrophic fen and an ombrotrophic bog incubated in either ambient (c. 400 ppm) or glacial (c. 200 ppm) [CO2]a located in the United Kingdom. CH4 fluxes were measured at 5°C, 10°C, 15°C, 20°C, and 25°C and then in reverse order over a 20 day period under each [CO2]a treatment. Results showed that the Q10 temperature response of CH4 emissions from the Carex/Juncus-dominated fen declined significantly by approximately 39% under glacial [CO2]a (ambient [CO2]a = 2.60, glacial [CO2]a = 1.60; P < 0.01). By contrast, the response of CH4 emissions from the Sphagnum-dominated bog remained unaltered (ambient [CO2]a = 3.67, glacial [CO2]a = 3.67; P > 0.05). This contrasting response may be linked to differences in plant species assemblage and the varying impact of CO2 starvation on plant productivity and carbon availability in the rhizosphere. Furthermore, our results provide empirical evidence to support recent model-based indications that glacial-interglacial variations in [CH4]a may be explained by changes in wetland CH4 source strength in response to orbitally forced changes in climate and [CO2]a.

Item Type: Journal Item
Copyright Holders: 2013 American Geophysical Union
ISSN: 2169-8961
Keywords: temperature response; Q10; peatlands; subambient CO2; Last Glacial Maximum; methane
Academic Unit/School: Faculty of Science, Technology, Engineering and Mathematics (STEM) > Engineering and Innovation
Faculty of Science, Technology, Engineering and Mathematics (STEM)
Faculty of Science, Technology, Engineering and Mathematics (STEM) > Environment, Earth and Ecosystem Sciences
Interdisciplinary Research Centre: Centre for Earth, Planetary, Space and Astronomical Research (CEPSAR)
OpenSpace Research Centre (OSRC)
International Development & Inclusive Innovation
Item ID: 37422
Depositing User: Vincent Gauci
Date Deposited: 16 Apr 2013 10:11
Last Modified: 15 Nov 2017 17:33
URI: http://oro.open.ac.uk/id/eprint/37422
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