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Ecosystem Scale Implication of Soil CO 2 Concentration Dynamics During Soil Freezing in Alaskan Arctic Tundra Ecosystems
Author(s) -
Wilkman Eric,
Zona Donatella,
Arndt Kyle,
Gioli Beniamino,
Nakamoto Kyoko,
Lipson David A.,
Oechel Walter C.
Publication year - 2021
Publication title -
journal of geophysical research: biogeosciences
Language(s) - English
Resource type - Journals
eISSN - 2169-8961
pISSN - 2169-8953
DOI - 10.1029/2020jg005724
Subject(s) - environmental science , tundra , ecosystem , atmosphere (unit) , soil carbon , eddy covariance , atmospheric sciences , soil water , soil science , ecology , geology , geography , meteorology , biology
Abstract The rates, processes, and controls on Arctic cold period soil carbon loss are still poorly understood. To understand one component of winter CO 2 loss in the atmosphere, continuous measurements of soil (CO 2 ) were made and compared to ecosystem scale CO 2 fluxes. Measurements of soil (CO 2 ) were made near Utqiaġvik, Alaska from the beginning of soil thaw in summer 2005 to spring 2007. In the summer, soil (CO 2 ) rose with increased soil temperature, reaching value orders of magnitude higher than the atmospheric (CO 2 ). Soil (CO 2 ) initially decreased at the end of summer and beginning of fall but then increased subsequent to soil freezing. Due to complex changes in biological activity, storage, and transport processes, soil (CO 2 ) was then approximately doubled than that was observed in the summer. After reaching peak concentrations in November, soil (CO 2 ) steeply decreased over a couple of weeks, suggesting a substantial release of CO 2 into the atmosphere and movement within the soil column. Eddy covariance (EC) measurements showed variable but continued emissions of CO 2 to the atmosphere during freezeup. The disconnect between soil (CO 2 ) and landscape level fluxes may be attributed to the spatiotemporal heterogeneity in release of high concentrations of soil (CO 2 ) to the atmosphere during the fall; and when integrated over the area of the EC tower footprint, do not frequently result in detectable emission events. Continued monitoring of fall and winter soil (CO 2 ) and ecosystem fluxes will be vital for further understanding the variability of interannual Arctic CO 2 emissions.