Responses of the wetland grass, Beckmannia syzigachne, to salinity and soil wetness: Consequences for wetland reclamation in the oil sands area of Alberta, Canada

摘要

Reclamation of the boreal landscape, including both wetlands and uplands integrated into complex watersheds, has presented a challenge over the past decade with few attempts. Relevant today is wetland/peatland reclamation on reclaimed landscapes positioned on saline sand deposits left on ‘in-pits’ from open pit oil sands mining. Part of the reclamation challenge lies in choosing characteristic species that are tolerant of conditions present on the reclaimed landscape. Species need to both survive harsh environmental conditions and facilitate succession from mineral-based wetlands (marshes) to peat-based ones (fens). A two-by-six factorial experiment was implemented in a greenhouse under two moisture levels: saturation to 2.5 cm below the soil level (high) and saturation to 7.5 cm below the soil level (low) and six salinity treatments: 5 mg L−1 Na+, 400 mg L−1 Na+, 850 mg L−1 Na+, 1250 mg L−1 Na+, 1850 mg L−1 Na+, and 2700 mg L−1 Na+. Water level affected total biomass, with the low water level producing higher biomass. Sodium concentration affected biomass, root:shoot ratio, stomatal conductance, evapotranspiration, and photosynthetic rate; all responses were similar for the lower Na concentrations and declined after the 850 mg L−1 treatment. We conclude that B. syzigachne tolerates Na levels of 850 mg L−1 and survives with diminished performance at treatment of 850 mg L−1 up to 2700 mg L−1. With these salinity responses, along with broad tolerance to water levels, B. syzigachne has great potential as an early colonizing annual species for conditions predicted to occur in many of the in-pit reclamation designs.