NWT RESEARCH DATABASE

Tags: physical sciences, water quality, permafrost, aquatic ecosystems, climate change, greenhouse gases, carbon fluxes, wildfire

Objective(s): To study carbon cycling in peatland catchments, to determine whether the interactions between wildfire and permafrost thaw causes increased release of greenhouse gases from peatlands and aquatic ecosystems to the atmosphere, and thus cause amplified climate change.

Project Description: The project team intends to study carbon cycling in peatland catchments, in order to determine whether the interactions between wildfire and permafrost thaw causes increased release of greenhouse gases from peatlands and aquatic ecosystems to the atmosphere, and thus cause amplified climate change. Given the overall objective of the project, the team intends to address 5 research questions: 1. How much greenhouse gases are produced in peatlands through combustion during wildfire? 2. To what degree does wildfire accelerate permafrost thaw in peatlands? 3. Does fire and permafrost thaw cause increased rates of soil respiration, and thus release of greenhouse gases to the atmosphere? 4. How large are greenhouse gas emissions to the atmosphere from lakes and how are emissions linked to terrestrial processes and disturbances such as fire and permafrost thaw? 5. How does fire and permafrost thaw affect downstream water quality and export of organic carbon? Combustion of organic matter in peatlands is assessed through Black spruce adventitious roots survey in recently burned sites. The research team will visit recently burned sites (burned in 2012-2014). The surveys take only a few hours in each location and are completely non-destructive. In order to assess the role of fire in causing accelerated permafrost thaw, the team will assess trajectories of vegetation composition, radiation balance and soil thermal regime in peatland sites that vary in time since fire between 1 and 40 years. At each location the research team will do vegetation surveys (non-destructive), measure thaw depth (done a few times per season, more often in road accessible sites), install soil temperature probes (4-6 probes at each site, probes will be deployed for three years and then removed). Soil respiration will be measured through static chamber measurements. For this purpose the team will install 48 collars (~40 cm in diameter, inserted ~25 cm into the peat) in total distributed across the road accessible sites. The collars will be installed for 3 years and then removed. Measurements are done using portable greenhouse gas analyzers. Boardwalks are likely to be installed at sites with high wetness, but will be removed at the end of the study. The measurements will be done ~10-15 times during the growing season each year. At each soil respiration collar, the team will also install 2 inch wells in order to sample pore water from specified depths. At each location the research team will measure peat depth and extract 3 peat cores of a 5 cm diameter – these peat samples will be transported back to the lab of Dr. Olefeldt at University of Alberta, where they will be used for incubation experiments. Lake greenhouse gas emissions will be measured using floating chambers at one site (61°10'N, 120° 5'W). Additional measurements will include lake temperature and water chemistry. The team will also extract lake sediments using a Russian corer to collect core samples, which will be transported to a lab in Edmonton where peat and sediment layers will be analyzed for radiocarbon age and carbon content. Two catchments of equal size (~200 km2) and with high peatland cover will be monitored for water chemistry, particularly organic matter characteristics at road culverts. The team will have continuous monitoring of water chemistry during the summers, including temperature, pH, electrical conductivity, dissolved organic carbon, and water color. Water samples will be collected for additional water analysis, including methyl mercury and fluorescence properties. The research team will make the resulting publications and the annual reports to the Aurora Research Institute available to local communities. The team will coordinate outreach to the local communities also through the other research groups who do work at Scotty Creek. The fieldwork for this study will be conducted from August 1, 2015 to August 31, 2015.