Bulkley Valley Research Centre - Science in the Public Interest

Conifer and Vegetation Responses to Pre-planting Applications of Glyphosate and Hexazinone on a Boreal Backlog Site

Project Reference Number: 2012-03

Project Status: Complete

Led by: Richard Kabzems, Research Silviculturist, BC Ministry of Forests, Lands and Natural Resource Operations

Funder: TransCanada Pipelines Ltd.

In 1982 an operational vegetation management trial (Sx82502G-2) was established to examine the effectiveness of treating a juvenile (11 years post wildfire) broadleaf dominated stand with herbicides (glyphosate, hexazinone) and/or mechanical shearing prior to conifer planting. Two complete blocks of three treatments (shearing alone, hexazinone plus shearing, glyphosate plus shearing) and a control (no shearing or chemical application) were established in each block. Application of hexazinone was done with “Velpar gridballs” at the rate of 4 kg/ha using a helicopter and aerial bucket in May 1983. Aerial application of glyphosate at the rate of 3 kg/ha using a spray system took place in June 1983. Winter shearing of existing vegetation on the chemical treatments was done in December 1983. Plots were operationally planted with PSB white spruce in May 1984. Broadleaf trees present on the site were spaced to 2000 stems per hectare in 1993.

Measurement of this study thirty years after establishment will support forest management objectives including stand development, vegetation community response, plant species diversity and stand growth and yield.  The following questions will be addressed by remeasuring this operational trial:

  1. How did the treatments influence white spruce growth, vigor and condition?
  2. How did the treatments influence broadleaf stand development?
  3. How did the treatments influence vegetation community composition?
  4. How did the treatments affect plant species diversity?
  5. How did the treatments influence future timber yields?