Radiocarbon analysis reveals that vegetation facilitates the release of old methane in a temperate raised bog

Garnett, M. H. , Hardie, S. M.L. and Murray, C. (2020) Radiocarbon analysis reveals that vegetation facilitates the release of old methane in a temperate raised bog. Biogeochemistry, 148(1), pp. 1-17. (doi: 10.1007/s10533-020-00638-x)

Abstract

Peatlands have accumulated vast quantities of organic carbon over thousands of years but it is unclear how these sensitive ecosystems will respond to future climate change. If emissions of methane from peatlands increase, then they may contribute increasingly towards climatic warming due to the higher greenhouse warming potential of this gas. We investigated the radiocarbon concentration of methane emissions from a temperate bog over 1.5 years, which we supported with measurements of the surface flux of methane and carbon dioxide. The radiocarbon content of methane emissions varied greatly, from modern (i.e. fixed from the atmosphere within recent decades) to ~ 1400 years BP. Flux rates of methane were spatially and temporally highly variable. A vegetation clipping experiment showed that plants had a great influence on the carbon isotope composition and flux of methane emitted from the peat surface, consistent with earlier studies showing the key role of plants in peatland methane emissions. When plants were absent, emission rates were 70–94% lower and the radiocarbon age of methane emissions was much younger and less variable. Our radiocarbon measurements show that at this peatland, plant-associated methane emissions contain carbon originally fixed from the atmosphere up to hundreds of years earlier, consistent with a contribution from plant mediated transport of methane sourced from sub-surface layers.

• Item Type: Articles
• Additional Information: We thank staff at the NERC Radiocarbon Facility and SUERC AMS Facility. The UK Natural Environment Research Council provided support for radiocarbon analyses. We are grateful to South Lanarkshire District Council for access to Langlands Moss. The manuscript was greatly improved thanks to comments received during the review process.
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Garnett, Dr Mark and Murray, Mr Callum
• Authors: Garnett, M. H., Hardie, S. M.L., and Murray, C.
• College/School: College of Science and Engineering > Scottish Universities Environmental Research Centre
• Journal Name: Biogeochemistry
• Publisher: Springer
• ISSN: 0168-2563
• ISSN (Online): 1573-515X
• Published Online: 14 February 2020
• Copyright Holders: Copyright © 2020 The Authors
• First Published: First published in Biogeochemistry 148(1): 1-17
• Publisher Policy: Reproduced under a Creative Commons License