Identifying Limiting Factors For Tree Growth On Reclaimed Sites In The Athabasca Oil Sands Region

Reclaimed oil sands sites often face challenging conditions for tree growth due to factors like salinity, soil compaction, and low nutrient and water availability. These limitations can significantly reduce ecosystem productivity and cause visible symptoms in plants, such as foliar discoloration. Affected areas, like Suncor Lease 86-17 near Fort McMurray, currently lack a comprehensive field assessment program for growth limitations. This project aimed to identify growth-limiting factors using forest nutrition techniques, including soil and foliar analyses. It also explored how these factors relate to tree growth metrics, with the goal of recommending management practices to improve tree productivity.

From 2011 to 2012, tree growth studies at Suncor Lease 86-17 identified soil compaction, salinity, and nutrient deficiencies—especially nitrogen for white spruce and potassium for lodgepole pine—as key limitations in reclaimed oil sands sites. Growth was higher in medium and high productivity areas, with soil organic carbon and plant available water positively influencing tree performance. Foliar and soil analyses confirmed nutrient stress, and water stress was more evident in 2011 due to lower rainfall. Plant communities varied by substrate but not by productivity level. A 2012 fertilization trial showed early positive responses, suggesting nutrient additions could enhance growth. Further large-scale studies are recommended to evaluate long-term impacts and improve reclamation strategies.