Year of Publication: 2013
Abstract:
A major barrier to reclamation after oil sands mining is lack of commercially available, diverse native plant seeds and propagules for revegetation. Potential of LFH (forest floor material) developed on coarse textured soil for establishing native plants and how salvage, placement and storage affect plant establishment and soils were studied. Abundance and composition of vascular plants in the soil propagule bank were determined in a growth chamber. In large field experiments, LFH salvage (10, 25 cm) and placement (10, 20 cm) depths were compared to standard peat-mineral mix used in oil sands reclamation. On a smaller scale, LFH developed from fine and coarse textured soil was salvaged (10, 30, 60 cm) and replaced (2, 5, 10 cm) on mineral and peat-mineral mix substrates. Storage effects were determined on soil chemical and physical properties, seed germination and viability, root viability and plant emergence, considering length of stockpiling, stockpile size, construction season and soil texture. Effects of plant derived smoke water and potassium nitrate on germination of cold stratified and non stratified seed from 18 native boreal plant species were determined in a growth chamber. LFH placement increased species richness, density and canopy cover of total, native, woody, herbaceous and non native plant species on most substrates. Shallow salvaged LFH resulted in greater species richness, canopy cover and plant density than deeper salvaged LFH. Greater placement depths resulted in increased canopy cover. Stockpiling LFH resulted in a significant decline (up to 100 %) in seed viability for 24 of 27 boreal species in small and large stockpiles at depths below 1.0 m. Anaerobic soil conditions developed soon after construction and persisted below 1.0 m in large stockpiles; anaerobic conditions developed in smaller stockpiles. Native boreal plant seeds responded to smoke water and potassium nitrate. Vaccinium myrtilloides had the largest increased germination using smoke water, and the most reduced germination using potassium nitrate. LFH conservation is critical for development of diverse, self-sustaining forested ecosystems on mined lands. Direct placement is better than stockpiling because seed viability, nutrients, organic matter and soil biota are difficult and costly to replenish once degradation occurs in stockpiles.
