Amanda Schoonmaker, Northern Alberta Institute of Technology
The goal of this study was to evaluate the effect of different vegetation management solutions for forest reclamation. All tested treatments in this study share common overall objectives: (i) to overwhelm a reclamation site with desired herbaceous and woody species and (ii) to concurrently reduce vegetation cover of undesirable species. Five approaches were tested in different combinations:
1. Planting woody species: creating a forest cover with a higher density is expected to result in canopy cover decades sooner than low density cover. This approach acts by shading undesirable species, likely 5+ years after planting.
2. Pre-emergent herbicide: preventing establishment of agronomic species (clovers in particular) that grow from seed. This type of herbicide inhibits seedling establishment (targets radicle and cotyledon development). It is thought to be conducive to planting nursery stock within 1 day of application and should provide effective control in 18-24 months following application.
3. Post-emergent herbicide: aboveground killing of newly emerging vegetation and creation of growing space around target woody seedling to provide a less competitive first year of growth.
4. Native forbs (fireweed or goldenrod): aid in creating desirable vegetation cover to reduce dominance by undesirable species, likely to be more effective in the second and subsequent years.
5. Seeding native grasses: aid in creating desirable vegetation cover to reduce dominance by undesirable species, likely to be more effective in the second and subsequent years.
All treatments and treatment combinations have been deployed in the field. The key findings after the first growing season were: (1) herbicide applications do not significantly impair growth and development of the deployed target species and (2) herbicide treatments were successful in decreasing undesirable herbaceous species cover. With only a 3-month growing period from planting to survey (May to August), it was not expected to see the anticipated long-term treatment effects for the other approaches (such as woody and forb planting). These treatment combinations require 2-3 years to fully reach their expected potential. Therefore, it is strongly recommended to continue with annual vegetation surveys for the coming years to draw as much detailed information as possible from this experiment.