Methane in Zackenberg Valley, NE Greenland: multidecadal growing season fluxes of a high-Arctic tundra

The carbon balance of high-latitude terrestrial ecosystems plays an essential role in the atmospheric concentration of trace gases, including carbon dioxide (CO2) and methane (CH<span class="inline-form...

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Autores principales:	J. H. Scheller, M. Mastepanov, H. H. Christiansen, T. R. Christensen
Formato:	article
Lenguaje:	EN
Publicado:	Copernicus Publications 2021
Materias:	Ecology QH540-549.5 Life QH501-531 Geology QE1-996.5
Acceso en línea:	https://doaj.org/article/af2e18a74fce481cacdfd0b8c5d34713
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spelling	oai:doaj.org-article:af2e18a74fce481cacdfd0b8c5d347132021-11-29T07:47:07ZMethane in Zackenberg Valley, NE Greenland: multidecadal growing season fluxes of a high-Arctic tundra10.5194/bg-18-6093-20211726-41701726-4189https://doaj.org/article/af2e18a74fce481cacdfd0b8c5d347132021-11-01T00:00:00Zhttps://bg.copernicus.org/articles/18/6093/2021/bg-18-6093-2021.pdfhttps://doaj.org/toc/1726-4170https://doaj.org/toc/1726-4189<p>The carbon balance of high-latitude terrestrial ecosystems plays an essential role in the atmospheric concentration of trace gases, including carbon dioxide (CO<span class="inline-formula"><sub>2</sub></span>) and methane (CH<span class="inline-formula"><sub>4</sub></span>). Increasing atmospheric methane levels have contributed to <span class="inline-formula">∼</span> 20 % of the observed global warming since the pre-industrial era. Rising temperatures in the Arctic are expected to promote the release of methane from Arctic ecosystems. Still, existing methane flux measurement efforts are sparse and highly scattered, and further attempts to assess the landscape fluxes over multiple years are needed.</p> <p>Here we combine multi-year July–August methane flux monitoring (2006–2019) from automated flux chambers in the central fens of Zackenberg Valley, northeast Greenland, with several flux measurement campaigns on the most common vegetation types in the valley to estimate the landscape fluxes over 14 years. Methane fluxes based on manual chamber measurements are available from campaigns in 1997, 1999–2000, and in shorter periods from 2007–2013 and were summarized in several published studies. The landscape fluxes are calculated for the entire valley floor and a smaller subsection of the valley floor, containing the productive fen area, Rylekærene.</p> <p>When integrated for the valley floor, the estimated July–August landscape fluxes were low compared to the single previous estimate, while the landscape fluxes for Rylekærene were comparable to previous estimates. The valley floor was a net methane source during July–August, with estimated mean methane fluxes ranging from 0.18 to 0.67 mg m<span class="inline-formula"><sup>−2</sup></span> h<span class="inline-formula"><sup>−1</sup></span>. The mean methane fluxes in the fen-rich Rylekærene were substantially higher, with fluxes ranging from 0.98 to 3.26 mg m<span class="inline-formula"><sup>−2</sup></span> h<span class="inline-formula"><sup>−1</sup></span>.</p> <p>A 2017–2018 erosion event indicates that some fen and grassland areas in the center of the valley are becoming unstable following pronounced fluvial erosion and a prolonged period of permafrost warming. Although such physical disturbance in the landscape can disrupt the current ecosystem–atmosphere flux patterns, even pronounced future erosion of ice-rich areas is unlikely to impact methane fluxes on a landscape scale significantly. Instead, projected changes in future climate in the valley play a more critical role. The results show that multi-year landscape methane fluxes are highly variable on a landscape scale and stress the need for long-term spatially distributed measurements in the Arctic.</p>J. H. SchellerJ. H. SchellerM. MastepanovM. MastepanovH. H. ChristiansenT. R. ChristensenT. R. ChristensenCopernicus PublicationsarticleEcologyQH540-549.5LifeQH501-531GeologyQE1-996.5ENBiogeosciences, Vol 18, Pp 6093-6114 (2021)
institution	DOAJ
collection	DOAJ
language	EN
topic	Ecology QH540-549.5 Life QH501-531 Geology QE1-996.5
spellingShingle	Ecology QH540-549.5 Life QH501-531 Geology QE1-996.5 J. H. Scheller J. H. Scheller M. Mastepanov M. Mastepanov H. H. Christiansen T. R. Christensen T. R. Christensen Methane in Zackenberg Valley, NE Greenland: multidecadal growing season fluxes of a high-Arctic tundra
description	<p>The carbon balance of high-latitude terrestrial ecosystems plays an essential role in the atmospheric concentration of trace gases, including carbon dioxide (CO<span class="inline-formula"><sub>2</sub></span>) and methane (CH<span class="inline-formula"><sub>4</sub></span>). Increasing atmospheric methane levels have contributed to <span class="inline-formula">∼</span> 20 % of the observed global warming since the pre-industrial era. Rising temperatures in the Arctic are expected to promote the release of methane from Arctic ecosystems. Still, existing methane flux measurement efforts are sparse and highly scattered, and further attempts to assess the landscape fluxes over multiple years are needed.</p> <p>Here we combine multi-year July–August methane flux monitoring (2006–2019) from automated flux chambers in the central fens of Zackenberg Valley, northeast Greenland, with several flux measurement campaigns on the most common vegetation types in the valley to estimate the landscape fluxes over 14 years. Methane fluxes based on manual chamber measurements are available from campaigns in 1997, 1999–2000, and in shorter periods from 2007–2013 and were summarized in several published studies. The landscape fluxes are calculated for the entire valley floor and a smaller subsection of the valley floor, containing the productive fen area, Rylekærene.</p> <p>When integrated for the valley floor, the estimated July–August landscape fluxes were low compared to the single previous estimate, while the landscape fluxes for Rylekærene were comparable to previous estimates. The valley floor was a net methane source during July–August, with estimated mean methane fluxes ranging from 0.18 to 0.67 mg m<span class="inline-formula"><sup>−2</sup></span> h<span class="inline-formula"><sup>−1</sup></span>. The mean methane fluxes in the fen-rich Rylekærene were substantially higher, with fluxes ranging from 0.98 to 3.26 mg m<span class="inline-formula"><sup>−2</sup></span> h<span class="inline-formula"><sup>−1</sup></span>.</p> <p>A 2017–2018 erosion event indicates that some fen and grassland areas in the center of the valley are becoming unstable following pronounced fluvial erosion and a prolonged period of permafrost warming. Although such physical disturbance in the landscape can disrupt the current ecosystem–atmosphere flux patterns, even pronounced future erosion of ice-rich areas is unlikely to impact methane fluxes on a landscape scale significantly. Instead, projected changes in future climate in the valley play a more critical role. The results show that multi-year landscape methane fluxes are highly variable on a landscape scale and stress the need for long-term spatially distributed measurements in the Arctic.</p>
format	article
author	J. H. Scheller J. H. Scheller M. Mastepanov M. Mastepanov H. H. Christiansen T. R. Christensen T. R. Christensen
author_facet	J. H. Scheller J. H. Scheller M. Mastepanov M. Mastepanov H. H. Christiansen T. R. Christensen T. R. Christensen
author_sort	J. H. Scheller
title	Methane in Zackenberg Valley, NE Greenland: multidecadal growing season fluxes of a high-Arctic tundra
title_short	Methane in Zackenberg Valley, NE Greenland: multidecadal growing season fluxes of a high-Arctic tundra
title_full	Methane in Zackenberg Valley, NE Greenland: multidecadal growing season fluxes of a high-Arctic tundra
title_fullStr	Methane in Zackenberg Valley, NE Greenland: multidecadal growing season fluxes of a high-Arctic tundra
title_full_unstemmed	Methane in Zackenberg Valley, NE Greenland: multidecadal growing season fluxes of a high-Arctic tundra
title_sort	methane in zackenberg valley, ne greenland: multidecadal growing season fluxes of a high-arctic tundra
publisher	Copernicus Publications
publishDate	2021
url	https://doaj.org/article/af2e18a74fce481cacdfd0b8c5d34713
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Methane in Zackenberg Valley, NE Greenland: multidecadal growing season fluxes of a high-Arctic tundra

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