Implications of alternative herbicide-use policies for forest management in Ontario

Abstract

Public sentiment is against herbicide use on public forests in Ontario. Provincial policies are directing research into alternative vegetation management with only limited interaction or support with forest resource based industries. The initiative of this analysis was to substantiate or dismiss the hypothesis that a forest industry could feasibly regenerate a sound wood supply from a forest in Northwestern Ontario under various herbicide-use limitations. Forest-level simulation was used to produce 100-year forecast data for thirteen management scenarios, which covered current levels, reductions in area treated, restrictions on how and where it could be applied, no use of herbicides, and a shift to a flexible wood supply. Results of the wood-supply analysis revealed that the company's wood-fibre needs from the study forest could be maintained for all scenarios. Due to the age class structure of the forest and the reasonable harvest levels imposed by the company, the most important component of the forest model was its present volume. Thus, even under assumptions of decreased coniferous volume production resulting from non-herbicide silvicultural treatments, only slight increases in harvest area were necessary 70+ years into the forecasts. The wood supply, area treated with herbicides and silviculture cost response variables provided the information required for sound decisions to be made for a large array of potential herbicide policy changes. Any strategy derived would need to meet the new policy's requirements while minimizing impacts on wood supply and silviculture costs and maintaining a desirable level of flexibility. For the Seine River forest, a step-wise reduction in herbicide use was determined to be the most appropriate strategy. This timing conforms well with forecasts of low need for herbicide treatments and provides adequate time for research and development of environmentally sound, socially acceptable and economically feasible alternatives to herbicides. This strategy meets the 20% herbicide use reduction imposed in 1991 and sets the company in a position to meet further changes. Impacts on both wood supply and silvicultural costs were shown to be minor.