The circumpolar Arctic is experiencing dramatic environmental changes that are already impacting tundra ecosystems and northern communities that are intimately linked to the land. Increasing permafrost degradation, shrub encroachment, larger and more frequent fires, and increasing human development have significant effects on biotic and abiotic conditions in the lower Peel River watershed, NT. To understand and respond to rapid environmental changes, diverse knowledge perspectives are needed, so my M.Sc. research uses scientific and social scientific approaches to investigate environmental change in the lower Peel River watershed. I investigated the impacts of the Dempster highway on plants, soils and permafrost in the Peel Plateau by conducting field surveys at sites dominated either by tall alder (Alnus crispa) shrubs or by dwarf shrubs, at 30 m and 500 m from the highway. At each site I measured vegetation composition, alder growth, soil nutrients, litter and organic layer thickness, active layer thickness, and snow depth. We found that alder growth and recruitment were enhanced adjacent to the Dempster Highway, and dramatic alterations to plant community composition, soil properties and ground temperatures were observed where alder shrubs had formed closed canopies. Tall shrub sites adjacent to the road exhibited lower abundance of understory vegetation including mosses, greater litter and organic soil thickness, higher nutrient availability, and deeper snowpack. Biotic and abiotic changes associated with road effects feedback with alder canopy development, and have important implications for permafrost conditions adjacent to the roadbed, and potentially on road bed performance. This research contributes to our understanding of environmental changes caused by the highway and their consequences for infrastructure stability and pan-Arctic changes in vegetation cover. In a separate but complementary effort, I worked with Teetl’it Gwich’in land users and youth from Fort McPherson, NT to map observations of environmental conditions and changes. In the pilot year of a community-based environmental monitoring program, we employed participatory multimedia mapping with Teetl’it Gwich’in land users and youth from Fort McPherson, NT. I accompanied Gwich’in monitors on trips on the land to document environmental conditions and changes. Observations made by land users were documented using photos, videos and audio taken by youth, and land users provided detailed information about each observation in follow-up interviews. I compiled observations (photo/video, GPS location, and interview audio and transcript) into a web-based map where the public will be able to see changes on the land in the images and words of Gwich’in land users. The online map will provide a medium for local residents to communicate their knowledge and concerns about the environment, and will be useful for land management and planning, environmental monitoring, and adaptation. / Graduate / 0768 / 0329 / 0326 / hkgill@uvic.ca

This thesis applies a novel method of change detection, the Landsat Image Stack Trend Analysis method to the monitoring of retrogressive thaw slumps in the Richardson Mountains, NWT. This method represents a significant improvement upon previous methods of thaw slump monitoring, which utilized air photos and high-resolution satellite imagery. This method applies Tasseled Cap brightness, wetness and greenness indices to Landsat TM/ETM images acquired between 1985 and 2011 and analyzes the temporal change of each pixel for the different indices values. This method is useful in retrogressive thaw slump monitoring in two ways. First, by creating a map showing the linear change over time from 1985 to 2011, retrogressive thaw slumps can be easily identified, as they are more dynamic than the surrounding tundra. In total, 251 thaw slumps were identified within an area of roughly 18 000km2. Second, thaw slump activity, from initiation, growth and stabilization can be studied by plotting the annual vegetation index pixel values of adjacent pixels in a thaw slump. This method allows for the efficient extraction of annual thaw slump headwall retreat rates, provided the availability of cloud-free imagery. The retreat rates of 16 slumps were extracted, which were found to have an average annual retreat rate of 11.8 m yr-1.

This thesis applies a novel method of change detection, the Landsat Image Stack Trend Analysis method to the monitoring of retrogressive thaw slumps in the Richardson Mountains, NWT. This method represents a significant improvement upon previous methods of thaw slump monitoring, which utilized air photos and high-resolution satellite imagery. This method applies Tasseled Cap brightness, wetness and greenness indices to Landsat TM/ETM images acquired between 1985 and 2011 and analyzes the temporal change of each pixel for the different indices values. This method is useful in retrogressive thaw slump monitoring in two ways. First, by creating a map showing the linear change over time from 1985 to 2011, retrogressive thaw slumps can be easily identified, as they are more dynamic than the surrounding tundra. In total, 251 thaw slumps were identified within an area of roughly 18 000km2. Second, thaw slump activity, from initiation, growth and stabilization can be studied by plotting the annual vegetation index pixel values of adjacent pixels in a thaw slump. This method allows for the efficient extraction of annual thaw slump headwall retreat rates, provided the availability of cloud-free imagery. The retreat rates of 16 slumps were extracted, which were found to have an average annual retreat rate of 11.8 m yr-1.