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Across Canada's boreal forest, disturbances from in situ oil sands mining, including well‐pads, significantly impact vast areas of the landscape. The creation of well‐pads requires removal of vegetation and placement of mineral fill, which essentially stops any carbon (C) sequestration on the once peatland ecosystem. It is important that, once no longer in use, these well‐pads are restored as long‐term C (peat) accumulation is what defines peatland ecosystem. However, little is known about the recovery of greenhouse gas exchange post‐restoration of these features. We studied a decommissioned well‐pad located in a treed poor fen that was restored using three soil adjustment treatments (SATs): (1) complete mineral fill removal (Peat‐Dec); (2) partial pad removal and burial under peat layer (BUPL); and (3) mixing mineral and peat by inversion (Mixed‐P‐M). The recreated peat surface was revegetated with donor peatland species using the moss layer transfer technique (MLTT). The objectives of this paper were to (1) quantify plot‐scale seasonal carbon dioxide (CO2) and methane (CH4) exchange of the SATs, 2–4 years post‐restoration compared to reference sites and (2) determine the influence of several environmental variables on CO2 and CH4 exchange. All SATs proved effective in recreating a soil surface needed to support peatland vegetation as shown by similar rates of net ecosystem exchange (NEE). Equally, both types of vegetation reintroduced led this site on a trajectory toward functioning as a net C sink. [ABSTRACT FROM AUTHOR]

Many raised bogs in Central Europe are in an unfavorable state: drainage causes high emissions of carbon dioxide (CO2) and nitrous oxide (N2O), while rewetting may result in high methane (CH4) emissions. Also, the establishment of typical bog species is often hampered during restoration. Measures like topsoil removal (TSR) or introduction of target vegetation are known to improve restoration success in other systems, but experiences on bogs after long‐term agricultural use are scarce and their climate effects including carbon losses from TSR are unknown. In a field trial in north‐western Germany, consisting of seven plots (intensive grassland, IG, and six restoration approaches), we explored the effects of rewetting, TSR and Sphagnum introduction on greenhouse gas (GHG) emissions. We measured GHG fluxes to obtain two‐year GHG budgets and applied a radiative forcing model to assess the time‐dependent climate effects. Existing uncertainty of decomposition processes in the translocated topsoil has been incorporated by different topsoil accounting scenarios. According to our data, rewetting alone reduced CO2 emissions by approximately 75% compared to IG, but substantially increased CH4 emissions. After TSR and rewetting, on‐site CO2 emissions were close to zero or, with Sphagnum introduction, net negative while CH4 emissions remained very low. The climatic warming effect of TSR including C export becomes less climate warming than rewetting nutrient‐rich peatlands after a few decades. For raised bog restoration, we therefore recommend a TSR sufficient to achieve nutrient‐poor and acidic conditions needed for rapid Sphagnum establishment. [ABSTRACT FROM AUTHOR]