| Summary: | 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. M.Sc.
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