Diurnal and seasonal variations of tundra CO2 emissions in a polygonal peatland near Salluit, Nunavik, Canada

• Main Authors: Gagnon, Samuel, Allard, Michel, Nicosia, Aurélien
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: NRC Research Press (a division of Canadian Science Publishing) 2017
• Subjects: Canada; Nunavik; Salluit; permafrost; Tundra
• Online Access: http://hdl.handle.net/1807/79486; http://www.nrcresearchpress.com/doi/abs/10.1139/AS-2016-0045

Polygonal peatlands are carbon-rich permafrost ecosystems that will likely be significantly affected by climate change. However, studies are often constrained to one measurement per day, which impedes assessments of the temporal variability in carbon fluxes. For this reason, we measured ecosystem respiration (ER) of CO2 in a polygonal peatland underlain by continuous permafrost over an entire growing season to determine the effects of temperature and water table depth on the temporal variability of ER. We used four automated closed chambers to measure ER under varying temperature and soil moisture regimes. Temporal variability was approximately the same for the four plots, both on a diurnal and seasonal scale. Both diurnal and seasonal variations in ER were strongly controlled by changes in soil surface temperature. Fluctuations of the water table depth associated with important rainfall events was also an important factor affecting ER on the seasonal scale. We found that water table level fluctuations below 20-25 cm did not significantly affect ER and that most soil respiration took place in the top 10 cm, likely in the surface 2 cm. Our results highlight the importance of monitoring future changes in tundra hydrology, which will determine the depth of organic matter available for aerobic decomposition. The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author.