La problématique de l’utilisation des herbicides en foresterie: le cas du Québec

Herbicide use in forestry is analysed from an historical and environmental perspective. First chemical herbicides were developed during the Second World War. Organochloride herbicides were widely used in the past but they are now classified as very harmful for human and the environment. However, recently developed herbicides like glyphosate present the same efficiency and a much lower toxicity. In general, the public opinion about herbicides is strongly negative. In Québec, all herbicides were banned from use in public forest after some environmental assessments. This decision seems to be more politically than scientifically based. In the case of intensive managed forest, mechanical treatments with forest tractors can present similar or even lower environmental impacts than glyphosate, but few studies exist to make an objective comparison. Furthermore, in terms of tree growth, low toxicity herbicides seem to present higher effectiveness than mechanical treatments. This possible growth gain can then be used to reduce pressure on natural forest by increasing protected areas and the use of ecosystem forest management. Nevertheless, the use of herbicides must be strictly monitored to reduce environmental risks