Dr. Ian Strachan, Professor, Department of Geography and Planning, Queen's University Understanding Carbon Cycling in Peatland Systems from Disturbance Through Restoration The operations of the Canadian Horticultural Peat Industry result in a disturbance to the natural carbon (C) functioning of selected peatlands. While the disturbed area is small in comparison to the total peatland area, nonetheless, during the years of active harvesting, these former peatlands are net C sources to the atmosphere. Following the cessation of harvesting operations, for any period left unrestored, the peatlands remain large sources of C to the atmosphere. Post-disturbance, the goal of active restoration is to return C functioning of the disturbed ecosystem to one resembling the pre-disturbance state. If the rewetting and revegetation process is successful in re-establishing conditions like that of an undrained peatland, this means a return to a sink for CO2 and a source of methane but an overall annual sink for carbon.
In this presentation, I provide examples of our Industry-partnered NSERC research where we have for the first time quantified the emissions from partially drained peatlands undergoing active production and have shown that restoration successfully returns the C sink function of peatlands. In the first example, several years of study in an eastern peatland indicated a decay in C emissions through years since harvesting began. We found that this resulted from the increasingly recalcitrant (older) C being exposed as years of harvest continued; a finding that was corroborated by C dating of the peat and measurements of humification. In the second example, the net ecosystem exchange (NEE) of C was continuously measured for multiple years in restored peatlands in eastern and western Canada using the eddy covariance method. We identified small but significant differences in respiration driven by temperature that were responsible for differences in cumulative NEE between years. In both locations, having the soil moisture consistently near the surface was linked to success. After ~15 years post-restoration, the eastern peatland had a mean net ecosystem uptake of 78 ± 17 g C m−2 year−1 which was similar to a reference undisturbed peatland. The more-newly restored western peatland showed greater spatial variation in NEE resulting from differences in soil moisture conditions across the site with wetter locations more closely resembled the NEE of an undisturbed peatland. Combined, all site years allow us to see the resulting restoration trajectory in terms of C function. Finally, through a radiative forcing model, we showed that restoration immediately following the cessation of harvesting operations would result in the restored ecosystem achieving a future net C sink status 7-8 times sooner than would a 20-year delay in restoration. Our results are currently being used to update emissions factors for Canada’s national C inventory. Comments are closed.
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