Sniderhan, A. E., Spence, C., Kokelj, S. V., Baltzer, J. L. (2022) Land cover change an indicator of net permafrost aggradation in a Taiga Shield landscape. ArcticNet Annual Scientific Meeting, Dec 2022. https://event.fourwaves.com/asm2022/abstracts/7a19be59-e45e-4856-99b4-46fb62a52662

Warming has led to widespread impacts on the landscape in northern ecosystems. Areas underlain by discontinuous permafrost are as highly susceptible to significant change as a result of permafrost thaw leading to ground subsidence. The Baker Creek watershed is a typical Taiga Shield landscape on permafrost, just north of Yellowknife in the Northwest Territories. In this region, bedrock outcrops are interspersed with lakes, wetlands, soil-filled lowlands, and forests. Permafrost is discontinuous across the landscape – while bedrock and the terrain beneath lakes and streams are permafrost-free, permafrost can be found in forested parts of the landscape, usually associated with peatlands and glaciolacustrine sediments. Across this landscape, we took intensive ground-based measurements characterizing land cover types by their depth of organic soil and frost table. Using archival aerial photographs and recent satellite imagery, we assessed changes in land cover between 1972 and 2017. Strong associations between different land cover classes and the ground-based measurements in these sites allowed us to estimate change in permafrost extent using changes in land cover types as a proxy. While there is evidence of both development and thaw of permafrost within the Baker Creek watershed, our analysis suggests that there is net permafrost gain – a stark contrast with the patterns of change typically reported in discontinuous permafrost landscapes. We found that the aggradation we observed seems to be driven by a combination of local hydrology and climatic 'trigger years' that lead to colder, drier conditions favourable for the development of permafrost.

https://event.fourwaves.com/asm2022/abstracts/7a19be59-e45e-4856-99b4-46fb62a52662