Base de données de recherche des TNO

étiquettes: physical sciences, revegetation, landscape disturbance, community based monitoring, cumulative effects, satellite imagery

Objectif(s): To use satellite imagery (Landsat, QuickBird, InSAR, etc.) to document the rate and extent of landscape change (slumps, subsidence, vegetation change, drained lakes, etc.) in the northern Mackenzie Basin.

Description du projet: Objective 1: To use satellite imagery (Landsat, QuickBird, InSAR, etc.) to document the rate and extent of landscape change (slumps, subsidence, vegetation change, etc.) in the northern Mackenzie Basin. To quantify landscape disturbances and vegetation regeneration patterns since 1985 the research team will obtain Landsat satellite images that will provide reflectance measurements covering a 10000 km2 study area at 5 year intervals. The goal is to discriminate among landscape disturbances (thaw slumping, seismic tracks, roads, fires, drained lakes, etc.) that can impact water quality, fish habitat, and caribou forage. The research team will assess ground deformation and annual subsidence in upland tundra north of Inuvik and in the Peel Plateau using advanced Interferometric Synthetic Aperture Radar (InSAR). Ground subsidence caused by: 1) seasonal thawing of the active-layer, and 2) long- term subsidence caused by changes in climate and land cover disturbances will be measured. Mapping of annual and cumulative ground deformation, will allow the team to identify thaw sensitive sediments, areas of high moisture content, and locations where permafrost is actively degrading. To identify the drivers of the observed changes the research team will compare disturbance maps from satellite imagery with existing data sets on: 1) natural disturbances, 2) human-caused disturbances, and 3) other biogeophysical variables. Linking broad-scale change detection with field studies and fine-scale mapping. Objective 2: To examine the causes and effects of tundra disturbances and the differences among lakes in the Mackenzie Delta using detailed field investigations. The research team will assess the impacts of human-caused and natural disturbances by measuring biotic and abiotic response variables at a range of disturbed and undisturbed sites. During the field season, research will focus on polygonal terrain, drained lakes, and all weather road sites, as well as Delta lakes. Plot-level studies in polygonal terrain and drained lake basins will explore the interactions of plant community composition and permafrost soil conditions. Plot-level studies in the Peel Plateau and Tuktoyaktuk coastlands will focus on the vegetation and soil conditions adjacent to all weather roads. Both projects will measure vegetation composition, soil characteristics (pH, moisture, and nutrient availability), permafrost characteristics, and snow conditions using plot and transect based methods. Lake-level studies will measure physical parameters (depth, sill height), characterize water quality (pH, temperature, turbidity, conductivity, and solute chemistry), and examine macrophyte productivity and community composition in lakes of different closure classes (flooding frequencies). This work is part of a larger initiative investigating muskrat ecology in the Delta. The research team will continue to maintain a network of ground temperature loggers established in polyonal peatlands and tundra sites near Tuktoyaktuk (N69.366, W 133.035), Inuvik (N68.315, W133.434), and Jimmy Lake (N68.648, W133.626). To examine the influence of snow depth of ground temperatures at these sites the research team have sought to experimentally increase snow cover using snow fences. Ongoing analysis will indicate the level to which snow cover is increased by these fences and the impacts of increased snow depth on ground temperatures and soil moisture. Fieldwork will have negligible impacts on the sampling sites. Objective 3: To build local capacity for monitoring vegetation and permafrost in the region by implementing a community-based monitoring protocol. For the past five years the research team have been working in the Mackenzie Delta and Peel Plateau regions to develop a vegetation and permafrost monitoring protocol that can be implemented by a range of participants (community members, university and government scientists, government inspectors, etc.). Between 2010 and 2013, the team have established 81 environmental monitoring sites to characterize baseline variation in vegetation, snow, and permafrost. Throughout this project the research team will continue to work with local monitors, the Inuvialuit Hunters and Trappers Committees and the Gwich’in Renewable Resource Councils to expand this network using a community-based sampling protocol. Key variables in the community-based sampling protocol include: vegetation structure, ground temperatures, berry productivity, shrub growth and abundance, soils, ground temperatures, thaw depth, and snow conditions. At core sites the research team will maintain meteorological stations, frost tubes, and ground temperature cables. Field sampling from 2014-2016 will focus on the following site types: tussock tundra, spruce forest, and sedge wetlands. Comparing biotic and abiotic conditions at these sites with the range of variability at undisturbed sites will allow the team to evaluate the relative impacts of different forms of disturbances. Combined with the work using satellite images to quantify broad-scale changes of associated disturbances, this fieldwork will provide data that can be used to develop a regional model of cumulative impacts. Re-sampling baseline sites on an ongoing basis will also allow us to determine if vegetation and permafrost conditions are responding to increased air temperatures at undisturbed sites. This project will involve the participation of Inuvialuit and Gwich’in land-users and community youth who will assist with data collection and work as wildlife monitors. Wildlife monitors will also assist with site selection based on their knowledge and expertise. Spatial Datasets on the timing, distribution, and magnitude, of landscape scale disturbances, and vegetation change will be added to the NWT Discovery Portal and the NWT Spatial Data Warehouse online map viewer. Field data on vegetation structure, community composition, berry production, active layer depth, and soils will be uploaded to the NWT Discovery Portal. The fieldwork for this study will be conducted from March 16, 2016 to September 16, 2015.