Impact of peatland seismic line restoration on CO2 and CH4 fluxes

Abstract:

Peatlands account for over 134,000 km² in northern Alberta, Canada and are underlain by a vast network of oil and gas formations. Exploration of deposits results in long, linear clearings known as seismic lines. Seismic lines remove surface vegetation and compact peat, leading to long-term changes in water table depths and vegetation communities. At least 135,000 km of seismic lines currently cross peatlands in Alberta and have been shown to enhance carbon dioxide (CO₂) and methane (CH₄) emissions. Restoring these lines may facilitate tree growth on the lines, reduce habitat fragmentation, and restore carbon storage function. Mounding treatments have been applied to other peatland disturbances to recreate microforms and encourage tree regeneration, but little research has looked at treating seismic lines and no studies have addressed the impact on greenhouse gas exchange. We aim to quantify carbon fluxes from these treatments and determine which treatment facilitates the best recovery to carbon sink over time.

During summer 2019, we measured CO₂ and CH₄ fluxes and associated environmental variables across three restoration treatments applied in March 2019, alongside an untreated section and adjacent natural site. Mean seasonal CO₂ fluxes of treatments ranged from -8.0 to 1.6 gCO₂ m^-2 d^-1 compared to -12.4 gCO₂ m^-2 d^-1 in natural and -15.8 gCO₂ m^-2 d^-1 in untreated sections. CO₂ uptake increased with total vascular percent cover and varied with water table and temperature. Methane fluxes from treatments ranged from 193.6 to 630.3 mgCH₄ m^-2 d^-1 compared to 51.8 mgCH₄ m^-2 d^-1 in natural and 139.5 mgCH₄ m^-2 d^-1 in untreated sections. Treatment type and microform were significant influences. Overall, seismic line restoration seems to decrease CO₂ uptake and increase CH₄ emissions in the initial years post-restoration.