Trembling Aspen Seedling and Plant Community Development on Reclaimed Sites

This research project investigates the effects of soil types and compaction levels commonly found in reclaimed oil sands surface soils on the natural regeneration of trembling aspen from seed. It aims to understand how different reclamation treatments influence tree establishment and plant community development, using both greenhouse and field experiments.

This research demonstrated that soil type was the most influential factor in trembling aspen seedling establishment and plant community development on reclaimed boreal oil sands sites. Forest floor–mineral mix (FFMM) supported the highest seedling establishment in greenhouse trials, while peat–mineral mix (PMM) performed best in field conditions due to greater moisture retention and reduced competition. Soil compaction negatively affected seedling establishment, whereas surface roughness and moisture availability were beneficial. Plant communities were clearly differentiated by soil type and time since reclamation, with natural and reclaimed soils exhibiting distinct compositions that gradually converged over time. Experimental treatments such as seeding and weeding had smaller effects compared to soil type, though FFMM consistently supported higher species richness. Additional studies at the RA1 site provided insights into soil hydrology, biogeochemistry, microbial activity, and aspen genetics, contributing to a more comprehensive understanding of factors influencing successful reclamation outcomes. The results offer a starting point for best practices to maximize potential natural seedling regeneration on boreal mixedwood reclamation sites with PMM and increased surface roughness being associated with increased deciduous tree seedling establishment.