Vegetation influence and environmental controls on greenhouse gas fluxes from a drained thermokarst lake in the western Canadian Arctic
<p>Thermokarst features are widespread in ice-rich regions of the circumpolar Arctic. The rate of thermokarst lake formation and drainage is anticipated to accelerate as the climate warms. However, it is uncertain how these dynamic features impact the terrestrial Arctic carbon cycle. Methane (...
| Main Authors: | , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2020-09-01
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| Series: | Biogeosciences |
| Online Access: | https://bg.copernicus.org/articles/17/4421/2020/bg-17-4421-2020.pdf |
| _version_ | 1818476524794281984 |
|---|---|
| author | J. Skeeter A. Christen A.-A. Laforce E. Humphreys G. Henry |
| author_facet | J. Skeeter A. Christen A.-A. Laforce E. Humphreys G. Henry |
| author_sort | J. Skeeter |
| collection | DOAJ |
| description | <p>Thermokarst features are widespread in ice-rich regions of the
circumpolar Arctic. The rate of thermokarst lake formation and
drainage is anticipated to accelerate as the climate warms. However,
it is uncertain how these dynamic features impact the terrestrial
Arctic carbon cycle. Methane (<span class="inline-formula">CH<sub>4</sub></span>) and carbon dioxide
(<span class="inline-formula">CO<sub>2</sub></span>) fluxes were measured during peak growing season using
eddy covariance and chambers at Illisarvik, a 0.16 <span class="inline-formula">km<sup>2</sup></span>
thermokarst lake basin that was experimentally drained in 1978 on
Richards Island, Northwest Territories, Canada. Vegetation in the
basin differs markedly from the surrounding dwarf-shrub tundra and
included patches of tall shrubs, grasses, and sedges with some bare
ground and a small pond in the centre. During the peak growing season,
temperature and wind conditions were highly variable, and soil water
content decreased steadily. Basin-scaled net ecosystem <span class="inline-formula">CO<sub>2</sub></span>
exchange (NEE) measured by eddy covariance was
<span class="inline-formula">−</span>1.5 [CI<span class="inline-formula"><sub>95 %</sub>±0.2</span>] <span class="inline-formula">g</span> <span class="inline-formula">C−CO<sub>2</sub></span> <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M9" display="inline" overflow="scroll" dspmath="mathml"><mrow class="unit"><msup><mi mathvariant="normal">m</mi><mrow><mo>-</mo><mn mathvariant="normal">2</mn></mrow></msup><mspace linebreak="nobreak" width="0.125em"/><msup><mi mathvariant="normal">d</mi><mrow><mo>-</mo><mn mathvariant="normal">1</mn></mrow></msup></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="39pt" height="13pt" class="svg-formula" dspmath="mathimg" md5hash="f49fea5538a36980ffb2f1013d46d025"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="bg-17-4421-2020-ie00001.svg" width="39pt" height="13pt" src="bg-17-4421-2020-ie00001.png"/></svg:svg></span></span>; NEE followed
a marked diurnal pattern with no day-to-day trend during the study
period. Variations in half-hourly NEE were primarily controlled by
photosynthetic photon flux density and influenced by vapour pressure
deficit, volumetric water content, and the presence of shrubs within
the flux tower footprint, which varied with wind direction. Net
methane exchange (NME) was low (8.7 [CI<span class="inline-formula"><sub>95 %</sub>±0.4</span>] <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M11" display="inline" overflow="scroll" dspmath="mathml"><mrow class="unit"><mi mathvariant="normal">mg</mi><mspace linebreak="nobreak" width="0.125em"/><msub><mi mathvariant="normal">CH</mi><mn mathvariant="normal">4</mn></msub><mspace linebreak="nobreak" width="0.125em"/><msup><mi mathvariant="normal">m</mi><mrow><mo>-</mo><mn mathvariant="normal">2</mn></mrow></msup><mspace width="0.125em" linebreak="nobreak"/><msup><mi mathvariant="normal">d</mi><mrow><mo>-</mo><mn mathvariant="normal">1</mn></mrow></msup></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="78pt" height="16pt" class="svg-formula" dspmath="mathimg" md5hash="488a4208ed88168a6d2d19a7a7a45932"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="bg-17-4421-2020-ie00002.svg" width="78pt" height="16pt" src="bg-17-4421-2020-ie00002.png"/></svg:svg></span></span>) and had little impact on the
growing season carbon balance of the basin. NME displayed high spatial
variability, and sedge areas in the basin were the strongest source of
<span class="inline-formula">CH<sub>4</sub></span> while upland areas outside the basin were a net
sink. Soil moisture and temperature were the main environmental
factors influencing NME. Presently, Illisarvik is a carbon sink during
the peak growing season. However, these results suggest that rates of
growing season <span class="inline-formula">CO<sub>2</sub></span> and <span class="inline-formula">CH<sub>4</sub></span> exchange rates may
change as the basin's vegetation community continues to evolve.</p> |
| first_indexed | 2024-12-10T09:26:51Z |
| format | Article |
| id | doaj.art-06ecd49453b4461c927b6dddaafd41dd |
| institution | Directory Open Access Journal |
| issn | 1726-4170 1726-4189 |
| language | English |
| last_indexed | 2024-12-10T09:26:51Z |
| publishDate | 2020-09-01 |
| publisher | Copernicus Publications |
| record_format | Article |
| series | Biogeosciences |
| spelling | doaj.art-06ecd49453b4461c927b6dddaafd41dd2022-12-22T01:54:29ZengCopernicus PublicationsBiogeosciences1726-41701726-41892020-09-01174421444110.5194/bg-17-4421-2020Vegetation influence and environmental controls on greenhouse gas fluxes from a drained thermokarst lake in the western Canadian ArcticJ. Skeeter0A. Christen1A.-A. Laforce2E. Humphreys3G. Henry4Department of Geography, The University of British Columbia, Vancouver, V6T1Z2, CanadaEnvironmental Meteorology, Faculty of Environment and Natural Resources, Albert-Ludwigs Universität Freiburg, Freiburg, GermanyDepartment of Geography and Environmental Studies, Carleton University, Ottawa, K1S5B6, CanadaDepartment of Geography and Environmental Studies, Carleton University, Ottawa, K1S5B6, CanadaDepartment of Geography, The University of British Columbia, Vancouver, V6T1Z2, Canada<p>Thermokarst features are widespread in ice-rich regions of the circumpolar Arctic. The rate of thermokarst lake formation and drainage is anticipated to accelerate as the climate warms. However, it is uncertain how these dynamic features impact the terrestrial Arctic carbon cycle. Methane (<span class="inline-formula">CH<sub>4</sub></span>) and carbon dioxide (<span class="inline-formula">CO<sub>2</sub></span>) fluxes were measured during peak growing season using eddy covariance and chambers at Illisarvik, a 0.16 <span class="inline-formula">km<sup>2</sup></span> thermokarst lake basin that was experimentally drained in 1978 on Richards Island, Northwest Territories, Canada. Vegetation in the basin differs markedly from the surrounding dwarf-shrub tundra and included patches of tall shrubs, grasses, and sedges with some bare ground and a small pond in the centre. During the peak growing season, temperature and wind conditions were highly variable, and soil water content decreased steadily. Basin-scaled net ecosystem <span class="inline-formula">CO<sub>2</sub></span> exchange (NEE) measured by eddy covariance was <span class="inline-formula">−</span>1.5 [CI<span class="inline-formula"><sub>95 %</sub>±0.2</span>] <span class="inline-formula">g</span> <span class="inline-formula">C−CO<sub>2</sub></span> <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M9" display="inline" overflow="scroll" dspmath="mathml"><mrow class="unit"><msup><mi mathvariant="normal">m</mi><mrow><mo>-</mo><mn mathvariant="normal">2</mn></mrow></msup><mspace linebreak="nobreak" width="0.125em"/><msup><mi mathvariant="normal">d</mi><mrow><mo>-</mo><mn mathvariant="normal">1</mn></mrow></msup></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="39pt" height="13pt" class="svg-formula" dspmath="mathimg" md5hash="f49fea5538a36980ffb2f1013d46d025"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="bg-17-4421-2020-ie00001.svg" width="39pt" height="13pt" src="bg-17-4421-2020-ie00001.png"/></svg:svg></span></span>; NEE followed a marked diurnal pattern with no day-to-day trend during the study period. Variations in half-hourly NEE were primarily controlled by photosynthetic photon flux density and influenced by vapour pressure deficit, volumetric water content, and the presence of shrubs within the flux tower footprint, which varied with wind direction. Net methane exchange (NME) was low (8.7 [CI<span class="inline-formula"><sub>95 %</sub>±0.4</span>] <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M11" display="inline" overflow="scroll" dspmath="mathml"><mrow class="unit"><mi mathvariant="normal">mg</mi><mspace linebreak="nobreak" width="0.125em"/><msub><mi mathvariant="normal">CH</mi><mn mathvariant="normal">4</mn></msub><mspace linebreak="nobreak" width="0.125em"/><msup><mi mathvariant="normal">m</mi><mrow><mo>-</mo><mn mathvariant="normal">2</mn></mrow></msup><mspace width="0.125em" linebreak="nobreak"/><msup><mi mathvariant="normal">d</mi><mrow><mo>-</mo><mn mathvariant="normal">1</mn></mrow></msup></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="78pt" height="16pt" class="svg-formula" dspmath="mathimg" md5hash="488a4208ed88168a6d2d19a7a7a45932"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="bg-17-4421-2020-ie00002.svg" width="78pt" height="16pt" src="bg-17-4421-2020-ie00002.png"/></svg:svg></span></span>) and had little impact on the growing season carbon balance of the basin. NME displayed high spatial variability, and sedge areas in the basin were the strongest source of <span class="inline-formula">CH<sub>4</sub></span> while upland areas outside the basin were a net sink. Soil moisture and temperature were the main environmental factors influencing NME. Presently, Illisarvik is a carbon sink during the peak growing season. However, these results suggest that rates of growing season <span class="inline-formula">CO<sub>2</sub></span> and <span class="inline-formula">CH<sub>4</sub></span> exchange rates may change as the basin's vegetation community continues to evolve.</p>https://bg.copernicus.org/articles/17/4421/2020/bg-17-4421-2020.pdf |
| spellingShingle | J. Skeeter A. Christen A.-A. Laforce E. Humphreys G. Henry Vegetation influence and environmental controls on greenhouse gas fluxes from a drained thermokarst lake in the western Canadian Arctic Biogeosciences |
| title | Vegetation influence and environmental controls on greenhouse gas fluxes from a drained thermokarst lake in the western Canadian Arctic |
| title_full | Vegetation influence and environmental controls on greenhouse gas fluxes from a drained thermokarst lake in the western Canadian Arctic |
| title_fullStr | Vegetation influence and environmental controls on greenhouse gas fluxes from a drained thermokarst lake in the western Canadian Arctic |
| title_full_unstemmed | Vegetation influence and environmental controls on greenhouse gas fluxes from a drained thermokarst lake in the western Canadian Arctic |
| title_short | Vegetation influence and environmental controls on greenhouse gas fluxes from a drained thermokarst lake in the western Canadian Arctic |
| title_sort | vegetation influence and environmental controls on greenhouse gas fluxes from a drained thermokarst lake in the western canadian arctic |
| url | https://bg.copernicus.org/articles/17/4421/2020/bg-17-4421-2020.pdf |
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