Project overview

The restoration of forest ecosystems following bitumen mining is essential due to the significant disturbances caused by these activities that strip away all vegetation and soil. This study examines whether incorporating microtopographic features, such as small hills and ridges, can enhance seedling growth and survival compared to leveled soils, the business-as-usual reclamation practice.

The research seeks to understand whether mimicking the natural microvariations in the forest floor enhances the early development of native species (Populus tremuloides, Pinus banksiana, and Picea glauca). One-year-old seedlings were planted following a randomized block design in two slope-aspect sites in the Canadian Natural Resources Limited Albian Sands open-pit oil sands mine. To compare the three treatments, tree height and root collar diameter were measured for each individual between 2015 and 2018. 

Results indicated that microtopographic variation improved height and volume on the south-facing site, where conditions are harsher due to greater exposure to heat and drought. The hilled treatment had the most pronounced positive effect across species. In comparison, east-facing slopes showed non-significant results, potentially due to growth occurring in less stressful conditions, higher soil moisture, and lower heat exposure, which would not benefit from increased microtopography. Therefore, overall, height and volume were not boosted by hills or ridges in the east site. 

These findings highlight the site-dependent benefits of microtopography in reclamation. On drier sites, such as south-facing slopes, implementing a hilled treatment can significantly improve growth outcomes.  On milder sites, like east-facing slopes, microtopography, however, offers limited additional benefits, suggesting that a simple approach may suffice in less stressful environments.