Carbon and Nitrogen Cycling Dynamics Following Permafrost Thaw in the Northwest Territories, Canada Journal Article uri icon

Overview

abstract

  • Rapid climate warming across northern high latitudes is leading to permafrost thaw and ecosystem carbon release while simultaneously impacting other biogeochemical cycles including nitrogen. We used a two-year laboratory incubation study to quantify concomitant changes in carbon and nitrogen pool quantity and quality as drivers of potential CO2 production in thawed permafrost soils from eight soil cores collected across the southern Northwest Territories (NWT), Canada. These data were contextualized via in situ annual thaw depth measurements from 2015 – 2019 at 40 study sites that varied in burn history. We found with increasing time since experimental thaw the dissolved carbon and nitrogen pool quality significantly declined, indicating sustained microbial processing and selective immobilization across both pools. Piecewise structural equation modeling revealed CO2 trends were predominantly predicted by initial soil carbon content with minimal influence of dissolved phase carbon. Using these results, we estimate near-surface permafrost soils have the potential to release up to 80 g C m-2 over one year in southern NWT, exceeding regional historic mean primary productivity rates in some areas. At recently burned sites, these thaw-mediated losses could contribute an additional 0.8 kg C m-2 of lagged carbon emissions in the decade following thaw, in addition to the ~3 kg C m-2 combusted during significant fire years in southern NWT. Taken together, this research provides first-order mechanistic knowledge needed to further constrain the permafrost-carbon feedback and parameterize Earth System Models, while building on empirical evidence that permafrost soils are at high risk of becoming weaker carbon sinks or even significant carbon sources under a changing climate.

publication date

  • January 1, 2022

Date in CU Experts

  • January 2, 2024 1:43 AM

Full Author List

  • Dieleman CM; Day NJ; Holloway JE; Baltzer J; Douglas TA; Turetsky M

author count

  • 6

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