Document Type
Thesis
Degree Name
Master of Science (MSc)
Department
Geography & Environmental Studies
Faculty/School
Faculty of Science
First Advisor
Dr. William Quinton
Advisor Role
Supervisor
Abstract
The stability of permafrost in peatland-dominated regions of northwestern Canada is compromised by ongoing climate warming and increased wildfire activity. This study examines an 8-year record of changes to the surface and subsurface properties of a peat plateau following a low-severity wildfire that occurred in 2014 in a region of thawing, discontinuous permafrost. This is accomplished by comparing the burned portion of a peat plateau to two unburned control sites, one of which is the unburned portion of the same plateau that was affected by the fire. Net radiation was not significantly different one year following the wildfire but became increasingly larger at the Burn site in the following years, supplying a surplus of energy available for ground thaw. This increase in energy inputs coincided with the gradual collapse of the remaining standing dead trees, which is supported by a trend of increasing wind speeds. Soil moisture decreased at the Burn in the first 4 years post-fire before returning and maintaining similar moisture content as the adjacent control site. Ground temperatures were consistently warmer in the summer and colder in the winter compared to the adjacent control site. The cooler winter ground temperatures at the burn were attributed to the snowpack being thinner and denser, and thus less insulative, allowing for more energy to escape the subsurface during the winter seasons. This was not enough to offset the increased inputs of energy endured at the Burn over the summer seasons, as the depth to permafrost increased significantly over the study period and no trend was found for the control sites. The average annual rate of permafrost thaw was 9.6 cm/year at the Burn, compared to 5.6 cm/year at the nearby adjacent control site. The most notable finding was a near-continuous talik (perennially frozen) layer beneath the Burn, a feature known to further accelerate permafrost thaw. The thinner active layer at the Burn required less energy to thaw, leaving more energy available to drive other subsurface processes such as increasing ground temperatures and contributing to greater thaw. The combined impacts of the variables examined suggest that wildfire in this area exacerbates permafrost thaw.
Recommended Citation
Auclair, Maude, "Impacts of wildfire on subcanopy energy balance, thermal regime, and permafrost stability in peat plateaus at Scotty Creek, Canada" (2024). Theses and Dissertations (Comprehensive). 2682.
https://scholars.wlu.ca/etd/2682
Convocation Year
2024
Convocation Season
Fall