Resiliency of boreal forest tree species on a reclaimed oil sands mine and natural forest stands in northeastern Alberta

• Author / Creator

  Jean, Stephanie, A

• Disturbances in the boreal forest are common, so the species that comprise these forests must be resilient to them. This research examines the resiliency, here defined as the regeneration of boreal tree species following disturbance on both reclaimed and natural sites. The suckering response of seedling origin trembling aspen (Populus tremuloides) to cutting was first studied on an oil sands mine reclamation site. Aspen sucker regeneration varied from 0 to 47 suckers per cut tree. Soil, height, and competition all affected suckering. Sucker initiation was 7.8 times more likely on peat soil, 10% more likely per 10 cm increase in tree height, and 10% less likely per 10% increase in total competition. Competition hampered root suckering the most when cover of competing species was greater than 52.5%. Overall, trembling aspen responded vigorously to disturbances on mine reclamation sites which is a promising sign of resilience for these novel and young ecosystems. In natural forests, the regeneration of black spruce (Picea mariana) and trembling aspen in the first growing season after wildfire was examined. Regeneration of black spruce did not differ between bog and semi-upland habitats (x̅ = 11,979 stems ha-1). However, a high amount (x̅ = 10,916 stems ha-1) of aspen regeneration was observed in semi-upland habitats previously dominated by black spruce indicating a potential shift in successional trajectory. Black spruce regeneration densities were positively related with forb cover after wildfire, suggesting better available seedbeds. Aspen regeneration did not vary by fire severity (x̅low = 93,384, x̅mod = 122,909, x̅high = 104,000 stems ha-1), but aspen regeneration was reduced by competing vegetation. Overall, both tree species showed resiliency to wildfire. However, pure semi-upland black spruce stands may be at risk of changing successional trajectories, challenging the direct regeneration hypothesis as our current view of successional trajectory after wildfire.

• Subjects / Keywords

  • Picea mariana
  • resiliency
  • Populus tremuloides
  • boreal

• Graduation date

  Spring 2019

• Type of Item

  Thesis

• Degree

  Master of Science

• DOI

  https://doi.org/10.7939/r3-ssby-ac65

• License

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