Impacts of forest fire on discontinuous permafrost in the south-western Northwest Territories

Regions: Dehcho Region, North Slave Region, South Slave Region

Tags: physical sciences, permafrost, vegetation, climate change, carbon fluxes, fire ecology

Principal Investigator: Lewkowicz, Antoni G (12)
Licence Number: 15982
Organization: University of Ottawa
Licensed Year(s): 2018 2017 2016
Issued: Dec 12, 2016

Objective(s): To look at how permafrost is changing following forest fire over a range of environmental conditions.

Project Description: The goal of this project is to look at how permafrost is changing following forest fire over a range of environmental conditions, with the purpose of improving how change is modeled in the future. The fires of 2014 in the southwestern Northwest Territories (NWT) provide an opportunity to examine how discontinuous permafrost responds to disturbances. This work is being carried out in collaboration with an inter-university team of ecologists studying how vegetation responds to fire and the carbon cycle in the region.

Burnt and unburnt sites covering the regional range of climatic, ecological, and permafrost conditions were established in 2015 along a transect from Yellowknife to Kakisa. A total of 17 sites were set up in 2015, and a further three in 2016. Unburnt control sites were chosen to determine the baseline impacts of climate change in the area. Air and ground temperature sensors were installed at each site, and left in place to monitor temperatures year-round. A geophysical technique called direct current electrical resistivity tomography (ERT) was undertaken at each site in the spring and the fall and this will continue in future years. For this technique the research team pass a small amount of electrical energy into the ground (this has no negative impacts on the environment), which provides an image of where the ground is frozen and where it is unfrozen to a depth of at least 12 m. Small stainless steel rods called electrodes have been inserted into the ground and will stay there for the duration of the study so measurements can be taken at the same places each year to monitor changes. The team probe the depth of thaw at each of these electrodes at the end of summer. In 2016, permafrost cores were taken at each site using a two-person gasoline powered auger to understand the soil and ice conditions and for carbon stock assessments. In 2017, ERT resurveys will be completed at each site, and in historical burns of different ages to establish long term impacts on permafrost. In the long run, the research team expect that the ERT measurements will show permafrost disappearing entirely at some sites due to the effect of the 2014 forest fires whereas at others a deeper thaw at the surface may be observed.

The community researcher is organizing a unit on fire ecology in Kakisa which will be an on-the-land learning activity which will include a demonstration of ERT. Research will also be shared with other communities (Behchoko, Fort Providence, Yellowknife) by presenting a poster at a community event or in a school where possible.

Since part of the project will be undertaken during the school year, contact will be made in the field with local school teachers to give class presentations if desired in the schools. Information about ground temperature will be made available within the proposed NWT Permafrost Database Project.

The fieldwork for this study will be conducted from July 15, 2017 to September 15, 2017.