Closing the winter gap : year-round measurements of soil CO₂ emission sources in Arctic tundra
Pedron, Shawn A.; Welker, J. M.; Euskirchen, E. S.; Klein, E. S.; Walker, J. C.; Xu, X.; Czimczik, C. I. (2022-03-14)
Pedron, S. A., Welker, J. M., Euskirchen, E. S., Klein, E. S., Walker, J. C., Xu, X., & Czimczik, C. I. (2022). Closing the winter gap—Year-round measurements of soil CO2 emission sources in Arctic tundra. Geophysical Research Letters, 49, e2021GL097347. https://doi.org/10.1029/2021GL097347
© 2022. The Authors. This is an open access article under the terms of the Creative Commons Attribution-NonCommercial-NoDerivsLicense, which permits use and distribution in any medium, provided the original work is properly cited, the use is non-commercial and no modifications or adaptations are made.
https://creativecommons.org/licenses/by-nc-nd/4.0/
https://urn.fi/URN:NBN:fi-fe2022090857819
Tiivistelmä
Abstract
Non-growing season CO₂ emissions from Arctic tundra remain a major uncertainty in forecasting climate change consequences of permafrost thaw. We present the first time series of soil and microbial CO₂ emissions from a graminoid tundra based on year-round in situ measurements of the radiocarbon content of soil CO₂ (Δ¹⁴CO₂) and of bulk soil C (Δ¹⁴C), microbial activity, and temperature. Combining these data with land-atmosphere CO₂ exchange allows estimates of the proportion and mean age of microbial CO₂ emissions year-round. We observe a seasonal shift in emission sources from fresh carbon during the growing season (August Δ¹⁴CO₂ = 74 ± 4.7‰, 37% ± 3.4% microbial, mean ± se) to increasingly older soil carbon in fall and winter (March Δ¹⁴CO₂ = 22 ± 1.3‰, 47% ± 8% microbial). Thus, rising soil temperatures and emissions during fall and winter are depleting aged soil carbon pools in the active layer and thawing permafrost and further accelerating climate change.
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