Hartley, I.P. and Hill, T.C. and Wade, T. and Clement, R.J. and Moncrieff, J.B. and Prieto-Blanco, A. and Disney, M.I. and Huntley, B. and Williams, M. and Howden, N.J.K. and Wookey, P.A. and Baxter, R. (2015) 'Quantifying landscape-level methane fluxes in subarctic Finland using a multi-scale approach.', Global change biology., 21 (10). pp. 3712-3725.
Quantifying landscape-scale methane (CH4) fluxes from boreal and arctic regions, and determining how they are controlled, is critical for predicting the magnitude of any CH4 emission feedback to climate change. Furthermore, there remains uncertainty regarding the relative importance of small areas of strong methanogenic activity, versus larger areas with net CH4 uptake, in controlling landscape-level fluxes. We measured CH4 fluxes from multiple microtopographical subunits (sedge-dominated lawns, interhummocks and hummocks) within an aapa mire in subarctic Finland, as well as in drier ecosystems present in the wider landscape; lichen heath and mountain birch forest. An inter-comparison was carried out between fluxes measured using static chambers, up-scaled using a high resolution landcover map derived from aerial photography, and eddy covariance. Strong agreement was observed between the two methodologies, with emission rates greatest in lawns. CH4 fluxes from lawns were strongly related to seasonal fluctuations in temperature, but their floating nature meant that water-table depth was not a key factor in controlling CH4 release. In contrast, chamber measurements identified net CH4 uptake in birch forest soils. An inter-comparison between the aerial photography and satellite remote sensing demonstrated that quantifying the distribution of the key CH4 emitting and consuming plant communities was possible from satellite, allowing fluxes to be scaled up to a 100 km2 area. For the full growing season (May to October), approximately 1.1 to 1.4 g CH4 m−2 was released across the 100 km2 area. This was based on up-scaled lawn emissions of 1.2 to 1.5 g CH4 m−2, versus an up-scaled uptake of 0.07 to 0.15 g CH4 m−2 by the wider landscape. Given the strong temperature sensitivity of the dominant lawn fluxes, and the fact that lawns are unlikely to dry out, climate warming may substantially increase CH4 emissions in northern Finland, and in aapa mire regions in general.
|Keywords:||Aapa mire, Arctic, Climate change, Eddy covariance, Methanogenesis, Methane oxidation, Remote sensing, Static chambers.|
|Full text:||(AM) Accepted Manuscript|
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|Full text:||(VoR) Version of Record|
Available under License - Creative Commons Attribution.
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|Publisher Web site:||http://dx.doi.org/10.1111/gcb.12975|
|Publisher statement:||© 2015 The Authors. Global Change Biology Published by John Wiley & Sons Ltd. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.|
|Date accepted:||27 April 2015|
|Date deposited:||27 May 2015|
|Date of first online publication:||27 June 2015|
|Date first made open access:||13 May 2016|
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