Post-Wildfire CO2 Exchange in Peatlands in Ontario's Rock Barrens Landscape

Abstract:

Wildfire disturbance in peatlands affects peat accumulation, respiration and primary production rates, thereby influencing the net carbon uptake of the ecosystem. An unprecedented 11,000 hectare wildfire burned in the rock barrens landscape of Ontario, Canada in 2018 and there is a substantial knowledge gap regarding the impacts on ecosystem function and peatland biogeochemistry. Ecosystem-scale CO₂ fluxes of burned and unburned peatlands are compared using eddy covariance collected throughout 2019 and 2020. To compare the effect of spatial location on plot-scale CO₂ fluxes post-wildfire, static surface chambers are used to measure and compare CO₂ fluxes between edge and middle zones of the largest peatlands within the tower footprints. Environmental conditions including temperature, moisture, photosynthetically active radiation and canopy openness are measured to determine dominant abiotic controls over CO₂ flux. Further, peat depth measurements and vegetation surveys to identify dominant functional groups are conducted within the edge and middle zones of the peatland for assessment of biotic controls. Burn severity was greater in the peatland edge than middle, therefore it is hypothesized that differential burn severity and changes in environmental conditions will make the middle of the burned peatland a net CO₂ sink and the edge zone a net CO₂ source following wildfire. With limited research on wildfire and ecosystem resilience to disturbance in the rock barrens landscape, this project will increase our understanding of how biogeochemical processes are impacted and will recover following wildfire. This could have major implications for the landscape carbon balance and for various species at risk that inhabit peatlands on this landscape.