In forestry, vegetation management treatments are widely used to enhance establishment of young stands and achieve free growing requirements. In 1988, an operational herbicide monitoring trial was established in a 4-year-old white spruce (Picea glauca) and Douglas-fir (Pseudotsuga menziesii) plantation in the SBSdw3 biogeoclimatic zone to examine the effectiveness of glyphosate herbicide on a vegetation community. The study consists of two 1 ha treatment plots, one of which was treated with glyphosate once using a backpack sprayer at a rate of 1.8 kg a.i./ha. Ten years after treatment, glyphosate had increased basal diameter and crown radius, reduced height-to-diameter ratio, and improved vigour of white spruce. Fourteen years after planting, the glyphosate treated plot had significantly greater number of free growing spruce per ha. The treatment also increased conifer and herb percent cover, and reduced broadleaf and shrub percent cover. However, the treatment did not affect the plant species richness. Yield projections for conifers and broadleaves based on MGM suggest that treatment applied to control broadleaves and shrubs has the potential to increase conifer yield and reduce conifer rotation age.
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Updated April 19, 2007