Advancing Understory Redevelopment in Forest Reclamation and the Role of Seedling Quality

This study investigated the feasibility of restoring forest understories by outplanting nursery-grown native shrub species in reclaimed sites within the Athabasca Oil Sands region of Alberta. This was accomplished by: (1) testing whether attributes used to evaluate the quality of tree seedlings can be applied to shrubs; and (2) a field trial where nine native boreal shrub species were outplanted onto seven different sites and monitored for performance. To test which conditions led to improved shrub growth, the study sites varied in age since reclamation, canopy tree species, and soil characteristics.

The attributes used to evaluate the quality of tree seedlings largely did not correlate with performance of shrub seedlings grown under no-stress conditions and outplanted to reclamation sites, which suggests that nursery protocols need to change in order to produce better planting stock. The field study found that outplanted seedlings grew best on young reclamation sites that had no tree canopy and lacked competitive vegetation – which shows success in early establishment, but may not reflect the ability of plants to maintain growth as competitive conditions develop. Site conditions had the greatest influence on seedling performance, and larger seedlings typically performed better in reclamation site conditions.