Establishing vegetation on a constructed fen in a post-mined landscape in Alberta’s oil sands region: A four-year evaluation after species introduction

Oil sands mining in Alberta has disturbed large areas of peatland, the dominant regional ecosystem type, and no formal strategies exist to reconstruct the landscape. Peatland reclamation is challenging, but approaches are now being tested to determine the feasibility of rebuilding these valuable ecosystems. To evaluate our design concept, a pilot reclamation fen and associated watershed was constructed in an oil sands mine near Fort McMurray, Alberta. We implemented a large-scale multifactorial field experiment to test the introduction of bryophytes and vascular plants by moss layer transfer (MLT), seeds, and nursery grown seedlings under wood-strand mulch and with a Typha latifolia removal treatment. Four years after planting, the MLT and Juncus balticus seedling treatment supported the highest bryophyte and vascular plant cover and species richness. Removal reduced T. latifolia cover but was not necessary in areas where seedlings or MLT were introduced as it may have been competitively excluded by the planted species. The most successful fen species to establish was Carex aquatilis that spread quickly but also reduced the cover and species richness of bryophytes and other vascular plants. Water level influenced species distributions, with near surface water tables supporting higher cover of T. latifolia and lower bryophyte and other vascular plant cover and species richness. Our research demonstrates that it is possible to establish and maintain fen bryophytes and vascular plants and limit T. latifolia invasion in a constructed fen. To prioritize fen plant species richness and bryophyte cover, future projects should design for lower water levels, select species tolerant of expected abiotic conditions, and introduce nurse plants such as J. balticus. This research is the first of its kind to evaluate a range of species introduction approaches and demonstrates that it is possible to establish fen plants in the post-mined landscape of Alberta.