Impacts of donor-peat management practices on the functional characteristics of a constructed fen

The reclamation of fen peatlands on post-oil sand development landscapes involves the transfer of peat from a donor fen to form the upper 2 m of a sediments-filled pit resulting from open-pit mining. The placed peat serves two major functions of attenuating the upwelling of dissolved solutes from the underlying tailing sediments to the rooting zone, and as fen vegetation establishment substrate. However, the modifications (e.g., decomposition and fragmentation) resulting from salvage and transfer practices (e.g., dewatering and loading/placement with earth-moving equipment) could impact the potentials of the placed peat to support ecohydrological functions in the constructed fen. Thus, we conducted a study to evaluate the impact of these practices on the biogeochemical and hydrologic functioning of a constructed fen. Peat cores were extracted along transects in the donor fen before peat transfer, and after placement in the constructed fen. Cores were also taken from a natural reference site to serve as the nearest possible comparison to donor site conditions prior to dewatering. The cores were subsampled and analyzed for selected physicochemical and hydrophysical properties. Relative to the reference site, our results indicates a higher surface bulk density, and accelerated mineralization of organic-bound nutrients in the dewatered donor peat. Following transfer of peat to the constructed fen, changes in hydrophysical properties were reflected in a reduction of the horizontal/vertical anisotropy ratio from 1.5 to 1, which could impact the vertical fluxes of water. However this impact is likely less than that of the heterogeneity associated with the fragmentation of the placed peat. Hence, we recommend some management practices that can alleviate the modifications resulting from contemporary operational practices.