Constructing fen peatlands in post-mining oil sands landscapes: Challenges and opportunities from a hydrological perspective

Peatland development occurs naturally over long periods of time in response to climate, geology, hydrology and vegetation. Open-pit oil sands mining activities in Northern Alberta result in large-scale removal of the surficial landscape, which comprises many (~ 50%) peatlands, approximately 90% of which are fens with a wide range of peat thicknesses (< 1 m to ~ 5 m). Recently, the concept of peatland creation was adapted into the regulatory framework. Two experimental fen peatlands have now been constructed on post-mining landscapes in order to test the design implications and implementation methods and to develop knowledge to advance the concept. These two systems were guided by different conceptual approaches: one utilized numerical modelling for landscape optimization, while the other attempted to mimic the landscape position of natural fen systems (and supported the design with numerical modelling). Both system designs attempt to accelerate succession by adding peat substrate (0.5 m and 2 m) and revegetating, with the belief that the system will stabilize within decades as opposed to millennia. This paper provides an overview of the feasibility of peatland creation, from a primarily hydrologic perspective, and addresses the complexity of determining whether these projects can be deemed a success. Future landscape design plans could benefit from a change of perception of the role of peatlands in the landscape. This change should involve a shift away from viewing wetlands as landforms constrained to low-lying areas within the reclaimed landscape, and towards recognizing that peatlands can function as both a sink and source of water to the remainder of the catchment. Wetland interconnectivity within the reconstructed landscape could increase water detention and storage during wet periods, which would benefit both the wetlands and the forestlands during dry periods. The assessment of the success of these constructed systems should be a reflection of our ability to correctly and accurately predict the influence of external forcings (e.g., climate) on the processes operating within a newly constructed system. Short timeframes (~ 5 years) are sufficient to characterize a range of processes operating in the constructed ecosystems; however, longer time periods will reduce uncertainty in the assessment of the system's successional pathway. The design of future constructed fen peatlands must employ an adaptive approach that assimilates the knowledge developed in the current research and the information attained over the longer-term to guide the design of future fen systems.