Vegetation influence and environmental controls on greenhouse gas fluxes from a drained thermokarst lake in the western Canadian Arctic

• Published in: Biogeosciences
• Main Authors: J. Skeeter, A. Christen, A.-A. Laforce, E. Humphreys, G. Henry
• Format: Article in Journal/Newspaper
• Language: English
• Published: Copernicus Publications 2020
• Subjects: Ecology; QH540-549.5; Life; QH501-531; Geology; QE1-996.5; Arctic; Northwest Territories; Canada; Richards Island; Thermokarst; Tundra
• Online Access: https://doi.org/10.5194/bg-17-4421-2020; https://doaj.org/article/06ecd49453b4461c927b6dddaafd41dd

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 ( CH 4 ) and carbon dioxide ( CO 2 ) fluxes were measured during peak growing season using eddy covariance and chambers at Illisarvik, a 0.16 km 2 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 CO 2 exchange (NEE) measured by eddy covariance was − 1.5 [CI 95 % ±0.2 ] g C−CO 2 <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> <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> 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 ...