Influence of permafrost type and site history on losses of permafrost carbon after thaw

Journal of Geophysical Research-Biogeosciences
By: , and 



We quantified permafrost peat plateau and post-thaw carbon (C) stocks across a chronosequence in Interior Alaska to evaluate the amount of C lost with thaw. Macrofossil reconstructions revealed three stratigraphic layers of peat: (1) a base layer of fen/marsh peat, (2) peat from a forested peat plateau (with permafrost) and, (3) collapse-scar bog peat (at sites where permafrost thaw has occurred). Radiocarbon dating revealed that peat initiated within the last 2,500 years and that permafrost aggraded during the Little Ice Age (ca. 250 – 575 years ago) and degraded within the last several decades. The timing of permafrost thaw within each feature was not related to thaw bog size. Their rate of expansion may be more influenced by local factors, such as ground ice content and subsurface water inputs. We found C losses due to thaw over the past century were up to 46% of the C available, but the absolute amount of C lost (kg m-2) was over 50% lower than losses previously described in other Alaskan peatland chronosequences. We hypothesize that this difference stems from the process by which permafrost aggraded, with sites that formed permafrost epigenetically (significantly later than most peat accumulation) experiencing less absolute C loss with thaw than sites that formed syngenetically (simultaneously with peat accumulation). Epigenetic peat from our site had lower C:N ratios as compared to Alaskan sites that have syngenetic peat. This difference could help predict the magnitude of C loss with thaw across a range or permafrost types and histories.

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Publication type Article
Publication Subtype Journal Article
Title Influence of permafrost type and site history on losses of permafrost carbon after thaw
Series title Journal of Geophysical Research-Biogeosciences
DOI 10.1029/2021JG006396
Volume 126
Year Published 2021
Language English
Publisher American Geophysical Union
Contributing office(s) Geology, Minerals, Energy, and Geophysics Science Center, Volcano Science Center, Florence Bascom Geoscience Center
Description e2021JG006396, 17 p.
Country United States
State Alaska
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