Soil Properties and Trace Gas Fluxes in a Chronosequence of Permafrost Disturbances, Cape Bounty, Melville Island, Nunavut
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Authors
Stanton, Thomas D.
Date
Type
thesis
Language
eng
Keyword
Soil Science , Greenhouse Gas
Alternative Title
Abstract
Permafrost thaw is accelerating in the Arctic, likely leading to the widespread formation of active
layer detachments (ALDs), a disturbance event that takes the form of a shallow landslide in areas
underlain by permafrost. Despite a growing body of literature concerning thermokarst effects on
ecosystem function, there remains a considerable knowledge gap regarding the long-term effects
that ALDs exert on tundra ecosystems. Without an understanding of how these features affect
tundra nutrient distribution and availability over time, projections of carbon feedback loops in
the Arctic cannot be made. This research addresses how ALDs affect soil nutrient distribution
(carbon, nitrogen, and trace elements) and greenhouse gas fluxes across a chronosequence of
ALDs.
In summer 2022, we characterized nine ALDs of varying ages (0-2 years, 15-16 years, and 60+
years) since disturbance at the Cape Bounty Arctic Watershed Observatory (CBAWO), Melville
Island, Nunavut. Each age was replicated three times, and an undisturbed site was established
close to each age ALD. At each of the plots, we measured surface trace gas emissions, bulk soil
element depth distribution to 50 cm, and soil physical factors. For most properties, control sites
differed across the landscape. We therefore assessed the impact of age by subtracting the
disturbance values from control values. ALDs elevated soil total carbon and nitrogen values for
at least 15 years, while soil physical properties remained largely unaffected. Gas fluxes were
highly variable across the landscape and not ultimately linked to ALD age. Surprisingly, no
trends with soil depth were noted. This research will provide landscape and temporal scale
information on soil element distribution and gas flux in disturbed tundra environments, assisting
in efforts to characterize how the Arctic will respond to a changing climate.