NWT RESEARCH DATABASE

Regions: Dehcho Region

Tags: physical sciences, contaminants, mercury, climatology, wildlife, paleolimnology, ecology, remote sensing, dendrochronology, aerial photography

Objective(s): To examine change in lake area in this ecoregion; to assess amount of meadow habitat lost to rising water levels in core bison range; to investigate whether recent changes are part of a longer-term cycle and evaluate the causes of this change; to determine a way to document and integrate local and traditional knowledge of physical and biological habitat changes and how those changes are related to land use and wildlife populations; and, to determine if flooding has caused an increase in mercury levels in local waters.

Project Description: The objectives are to draw together multiple sources of information so that we may (1) examine change in lake area in this ecoregion, (2) assess amount of meadow habitat lost to rising water levels in core bison range, (3) investigate whether recent changes are part of a longer-term cycle and evaluate the causes of this change, (4) determine a way to document and integrate local and traditional knowledge of physical and biological habitat changes and how those changes are related to land use and wildlife populations, and (5) determine if flooding has caused an increase in mercury levels in local waters. Objective 1 has been largely accomplished in 2011 by examining historical Landsat satellite from the 1980’s to the present and digitizing historical aerial photographs from the 1950’s to the 1970’s, then calculating changes in lake area from those data. More lakes were added to the database in 2012. Objective 2 will be accomplished by an analysis of recent Landsat imagery to determine habitat changes over time. Objective 3 will be accomplished by first examining existing climate records from the region. These records will provide a snapshot of how climate has changed over the past 50 years or so. The research team will also collect tree cores from spruce/larch/jack pine trees in this region. It is expected that the team will be able to locate and sample trees at least 100 years old and perhaps as much as 200 years. The growth of the trees will be compared to climate data from the region to determine a potential climatic control on tree growth (e.g., early summer precipitation like we found in the Yellowknife region). After determining the climatic controls, the research team will use those relations to reconstruct the climatic parameter back in time allowing us to place recent climate trends in a much longer perspective. It will also allow the team the opportunity to examine the data for long-term trends and possible cycles related to climate in this region that could be driving some of the observed water level changes. Preliminary tree coring was done in 2010, and more extensive sampling was done in 2011 and 2012. For objective 4, the research team will work with the Fort Providence Resource Management Board to determine the potential and desire for a traditional knowledge study where the community would gather local knowledge documenting previous water level fluctuations and their impacts on wildlife. For objective 5, the research team propose to sample lake sediment cores from five lakes that expanded recently and compare those to cores from five lakes that have not expanded in recent years. Lake sediments are an archive of historical lake levels and past lake conditions (the field of paleolimnology) including mercury levels. Sediment cores can be analysed to examine mercury levels in the past. Advice and input on the project will be sought from the Fort Providence Resource Management Board and community members. The research team will seek direction on sampling locations as input from local knowledge holders on the history of water level changes in the study area. The research team will also hire local residents to guide and assist with field sampling. Environment and Natural Resources will continue to lead the study this year but the research team will determine the community's interest in longer-term environmental monitoring, which could be led by the community. A brief, plain language report on work done will be sent to the Fort Providence Resource Management Board, in March each year. The research team will also host a workshop in the community in March, where the team will share the findings, including maps showing the results of objectives 1 and 2, and preliminary data from objective 3. Maps are key focal points and will help facilitate discussion within the community. The fieldwork for this study will be conducted from January 6, 2014 to October 17, 2014.