NWT RESEARCH DATABASE

Regions: Sahtu Settlement Area

Tags: physical sciences, permafrost, vegetation, hydrology

Objective(s): To assess changes in ice rich permafrost landforms and plant community composition across a treeline ecotone and relate those larger shifts to specific physically based estimates of energy-mass budget for such features.

Project Description: The objectives of this project are to assess changes in ice rich permafrost landforms and plant community composition across a treeline ecotone and relate those larger shifts to specific physically based estimates of energy-mass budget for such features. The distribution of permafrost and vegetation both vary through time and space across the treeline, and while changes in one will affect the other, variation in the local hydrology, soil, snow pack and other factors also play a key role in the distributions of permafrost and vegetation. This project will couple a spatially and temporally limited energy-mass balance assessment with broader surveys of changing permafrost and vegetation between 1945-present and ~1200-1600 metres above sea level. Climate stations installed during the 1990s are currently measuring air and permafrost temperatures at 5 permafrost features. These sites will be updated and adapted as necessary, including replacement of instrumentation, batteries, solar panels, etc. The research team will also measure active-layer thickness across a 1-2 m spaced grid at these 5 features each August using metal rods pressed into the ground until they hit the frost table. Another 85 ice rich permafrost features were identified from aerial photos taken in the 1940s. The research team will compare historical imagery with recent satellite imagery to determine regional aerial permafrost rates among these features. The research team will visit each feature identified on the imagery to confirm the presence of permafrost; document the extent, shape, and vegetation cover; and measure subsurface temperature, water pressure, and constituent materials of the soil. Tree life histories (date of colonization and growth rates) were surveyed along the Canol heritage trail and in isolated stands across tree line between Dechen Lá and MacMillan Pass. Tree life histories are assembled with careful measurement of annual growth rings, and the team intend to survey more trees off the Canol Road to establish if a similar rate of range expansion is occurring naturally, or if the trees are using the road as a colonization corridor. The method of sampling is non-destructive as only a pencil wide piece of tissue is taken from each stem to avoid mortality. Branch whorls and bud scars are counted as an alternative measure for younger saplings the team are concerned could die if cored. This summer’s work will begin with surveying the historically identified permafrost features and off disturbance tree density. This will inform site selection for two features appropriate for energy-mass balance assessment. A suite of equipment will be deployed at both stations to measure air and soil temperature, wind speed, snow depth, precipitation, solar radiation, and relative humidity at each location. These data can then inform a mass-energy balance equations accounting for the annual surplus of energy and how it is being partitioned between the plant community and ground thaw at the ground surface. For those in the community who are curious, or those responsible for land management that want to utilize this research or better inform the research team on the subject, the team welcome the opportunity to discuss ways to adapt the project to make it more valuable to the people of the Sahtu. While this research is focused on the physical sciences, the research team want to be mindful of human interests and find productive ways to engage regular citizens, and more importantly, local community members. Earthwatch for example is a non-profit that connects researchers with public participants. Earthwatch has supported previous research in the Mackenzies over the past 10 years and will also involve this research for a short time in August. Future recruitment for Earthwatch volunteers could focus on Sahtu land claims beneficiaries. A summary report of field activities will be prepared on an annual basis. Brief updates can also be given during the Sahtu Renewable Resource Board monthly teleconference calls. Meetings and presentations can be arranged in Tulita and/or Norman Wells at the conclusion of this project. Publications resulting from this research will be provided to the appropriate body as digital and/or paper copies. The fieldwork for this study will be conducted from July 12, 2017 to September 8, 2017.