Carbon Exchange in Drained Peatlands undergoing Harvesting
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While our previous research has quantified the size of the C emissions in drained peatlands that are left unrestored and has demonstrated that active restoration is effective in returning the net C sink functioning in a relatively short period of time, very little is known about the GHG emissions during periods of active harvesting. This NSERC-CRD project in collaboration with Dr. Nigel Roulet (McGill), and Dr. Maria Strack (Waterloo) and members of the Canadian peat industry aims to describe the controls on GHG production and emission during the period when peat producers are actively harvesting peat from drained fields.
Students in the AERLab are focused on the processes controlling the production and emission of CO2 and methane. Measurements are being made on drained peat fields at a range of years of active harvesting (1 year through 30 years) in both eastern (QC) and western (AB) locations. A variety of techniques are being used including in situ gas exchange using portable IRGAs, eddy covariance, and laboratory incubation experiments. |
Results:
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We have found differences in GHG emissions with respect to years of peat extraction and position across the field. Emissions of CO2 are higher in the first few years following the initiation of peat extraction by vacuum harvesting. They then are relatively constant throughout the remaining lifetime of the active extraction. We measured emissions from peat fields that had been in active harvest for 3, 6, 9, 12 and 30 years. As the surface peat is extracted, more recalcitrant peat is exposed at the surface reducing CO2 emissions. The peat fields are contoured to help with surface drainage. This contouring results in the centre of the field having younger in age peat being exposed then surfaces towards the lateral drainage ditches. The centre position in the most recently opened peat fields was the highest emitter. Methane emissions were not significant from the fields of any age category. Ditches had methane emissions but the relative surface area represented by the ditches results in operations being a minor methane emitter. Results have implications for emission factors for this industry.
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Publications and theses: |
Hunter, M.L., Frei, R., Strachan, I.B., and Strack, M., Accepted. Environmental and management drivers of carbon dioxide and methane emissions from actively-extracted peatlands in Alberta, Canada. Journal of Geophysical Research - Biogeosciences
Clark, L., Strachan, I.B., Strack, M., Roulet, N.T., Knorr, K-H., and Teickner, H., 2023. Duration of extraction determines CO2 and CH4 emissions from an actively extracted peatland in eastern Québec, Canada. Biogeosciences 20: 737-751. He, H., Clark, L., Lai, O-Y., Kendall, R., Strachan, I.B. and Roulet, N.T., 2023. Simulating soil atmosphere exchanges and CO2 fluxes for an ongoing peat extraction site. Ecosystems, doi.org/10.1007/s10021-023-00836-2 Students currently involved in this study:
Completed theses: Laura Clark 2021 “Years of extraction determines CO2 and CH4 emissions from an actively extracted peatland in eastern Québec, Canada” MSc Thesis, McGill University Undergraduate Honours Thesis: Kaiyuan Wang 2021 "A further examination of peat stockpile emissions" Karina Volpato 2020 “Reducing production stage carbon emissions: A peat industry case study” Maria Gheta 2020 “CO2 and CH4 emissions from stockpiles of an exploited peatland in eastern Quebec” Laura Clark 2018-19 “Effects of age on CO2 emissions from in-production drained peatlands” Naomi Weinberg 2018 “Effects of extraction on CO2 emissions from an in-production drained peatland” |