Methane in Zackenberg Valley, NE Greenland: multidecadal growing season fluxes of a high-Arctic tundra
<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-form...
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| Autores principales: | , , , |
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| Formato: | article |
| Lenguaje: | EN |
| Publicado: |
Copernicus Publications
2021
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| Materias: | |
| Acceso en línea: | https://doaj.org/article/af2e18a74fce481cacdfd0b8c5d34713 |
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| Sumario: | <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> |
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