Characterizing dominant controls governing evapotranspiration within a natural saline fen in the Athabasca Oil Sands of Alberta, Canada

Natural Boreal saline fens provide analogues for reclaimed wetland systems constructed with sodium-rich tailings materials. These natural analogues can improve our understanding of vegetative controls on dominant ecohydrological processes (i.e. evapotranspiration (ET)) in constructed landscapes. Therefore, the objective of this study is to characterize ET within a natural boreal saline fen over a growing season to determine the primary hydro-climatic controls using community-scale ET measurements targeting dominant vegetation communities within different microforms along with environmental controls. ET rates were highest during periods of peak vegetation growth and temperatures between June and August, with rates decreasing slightly in July. Vegetation species' physiology was the dominant variable governing ET. The more salt tolerant species maintained higher ET rates despite the lower leaf area index and water table levels found within these species. The lower ET rates measured in July can be attributed to high water tables from above average precipitation causing soil inundation and salt stress, increasing stomatal closure. However, community plots containing Triglochin maritima maintained transpiration rates under the coupled stress conditions. Therefore, this is a potentially important species for use in boreal reclamation planting schemes. Last, the findings emphasize that the dominant vegetation selected for reclamation projects must coincide with the materials used (peat and subsurface materials), as results within this study demonstrate that some native boreal fen species (Calamagrostis inexpansa, Hordeum jubatum, and Juncus balticus) were unable to maintain transpiration rates during flood and saline conditions that can occur within the mining area of this region. Copyright (C) 2015 John Wiley & Sons, Ltd.