Effects of seismic line reclamation on peatland carbon exchange
Boreal peatlands contain significant carbon (C) reserves. They contribute to the greenhouse gas (GHG) balance by serving as a long-term sink for carbon dioxide (CO2) and source of methane (CH4). Seismic lines built for geological exploration have damaged over 1900 km2 of peatlands in Alberta. On some of these paths, regeneration of trees is impeded, necessitating active reclamation treatments aiming to accelerate forest regrowth. One restoration technique is the creation of mounds to create drier microsites for tree growth. However, there remains a gap in knowledge regarding the effects of seismic lines on C and GHG exchange, ecological recovery pathways, and the benefits of mounded lines. We looked at variations in net ecosystem C exchange (NEE) and CH4 emissions using the chamber technique between mounted and un-mounded seismic lines to more accurately assess the C mitigation capability of mounded lines. The sites were contrasted with reference plots located nearby in the peatlands. Plant community composition, water table and soil temperature were also measured. Un-mounded seismic lines had low tree cover but were dominated by other common peat bog species e.g. Equisetum fluviatile, Carex aquatilis and Sphagnum species. Mounded lines resulted in larger, more frequently flooded depressions and less moss cover on the hummocks. CO2 flux varied between lines, with the mounded ones having higher CO2 emissions due to less vegetative cover and higher bulk density. Vegetation cover and water level had an influence on CH4 fluxes. These results provide important information on the effect of mounding on peatland C exchange.