A comparison between reclamation stockpile and boreal forest seed banks and plant communities

Abstract

Soil stockpiles are essential to the reclamation of large-and small-scale mining and other industrial sites. However, stockpiling soils can lead to the degradation of seed banks. This study examines the diversity, composition, depth of seed storage, and relationships between the aboveground and seed bank plant communities in stockpiles and compares them to the nearby boreal forest. The seed bank and aboveground vegetation sampled at eight stockpiles and six mature forest sites were near Fort McMurray (57.337 N, 111.755 W) and Cold Lake (54.695 N, 110.730 W), Alberta, Canada. Seed bank samples were taken from the forest floor (LFH) and depths of 0-5, 5-10, 10-20, 20-30, >50 cm. Aboveground vegetation cover was also estimated at these locations. The seed bank composition was determined using the seedling emergence method in a greenhouse. Stockpile seed banks had higher seedling abundance and species richness than nearby forested sites but were dominated by grasses and non-native forbs. Most seeds germinated from the surface layer, with 92% of seeds germinating from the LFH layers in the forested sites, and 68% from the 0 to 5 cm layer in the stockpiles. Mature forest sites had more similar aboveground and seed bank communities than the stockpiles. Overall, integrating information on seed bank and aboveground plant communities would improve reclamation decisions, rather than relying on aboveground vegetation alone.

Dominant drivers of plant community assembly vary by soil type and time in reclaimed forests

“…Non-native species are highly adaptable and have rapid expansion (MacDougall and Turkington 2005); thus, they dominate the initial plant community, accounting for [ 75% total proportional plant cover. Non-native forbs are generally found at low amounts within natural forest seed banks (Buss et al 2020;Bellairs and Bell 1993;Jauni et al 2015). Therefore, the non-native forbs in the seed bank likely originated after the donor site was cleared or from contamination during salvage and placement operations (Knapp et al 2016;Moore 1980).…”