The role of microhabitat for bryophyte establishment in reclamation of boreal wetlands

Abstract

Abstract Minerogenous peatlands that accumulate deep deposits of organic matter (fens) were an important part of the pre-disturbance landscape across Alberta’s oil sand mining area. Bryophytes occupy 80–100% of the ground layer in these site types and form an important part of the accumulated organic matter. Bryophytes are small plants that occur in microhabitats influenced by surrounding vascular plants and substrate features. The objective of this paper is to evaluate the resilience of bryophytes and initial success of an experimental wetland (Sandhill Wetland-SHW) by assessing the changing vegetation and substrate regimes over eight years after wet-up. Included in this analysis is an account of the ground layer flora between 2014 and 2021 along with evaluation of associated environmental factors. At SHW, a number of peatland bryophytes initially established in numerous areas across the wetland. However, in subsequent years increasing water tables with expanding Typha-dominating areas, high sedge productivity and fluctuating water tables, increasing vascular plant cover, and increasing sodicity have reduced the microhabitats available for bryophytes, with the result being a much-diminished set of peatland bryophyte species. We suggest that future reclamation designs for fens should include microhabitats for bryophytes, as bryophytes are foundational species and integral to fen development. In comparison, reclamation designs for non-peat forming ecosystems that do not have abundant bryophytes, such as marshes and saline wetlands, do not require these microhabitat conditions. Installing a recently harvested peat substrate appears to provide suitable conditions for early establishment of bryophytes.