Globally-used forestry herbicides and their potential for impacts on soil and water resources
Résumé
Globally, land management activities can significantly alter ecosystem components on temporal and spatial scales. Alterations in wildlife habitat and potentially adverse impacts on soils and aquatic ecosystems are notable social concerns in the field of forest vegetation management (FVM. However studies have shown that FVM which usually occurs 1-3 times over a 20-100+ year-long crop rotation represents a minor impact compared to those resulting from population growth, forest harvest, or to agricultural activities which occur several times annually. FVM activities include plant protection, noxious weed control, conifer and hardwood culture restoration of semi-natural areas and improvement of recreational areas and wildlife habitat. FVM may be accomplished using a variety of tools including mechanical, manual, chemical, biological, and silvicultural methods. Among these tools, chemical herbicides combined with various silvicultural methods are often the preferred approach to FVM because they are the most cost efficient, reliable and effective means available. Herbicides may be spot applied, injected into single stems, applied in discreet bands, or broadcast applied either by aerial or ground-based equipment. More than 30 forest herbicide active ingredients are registered for use in various countries for FVM. The registration process usually includes exhaustive toxicological, environmental impact and environmental fate studies. Fewer than 10 of these active ingredients represent more than 85% of the total amount of forestry herbicide applied worldwide. This paper will review the evidence from published research which indicates that contrary to popular opinion there is little potential for long-term detrimental impacts on soil and water resources.
Un bilan à l`échelle internationale est fait sur l`emploi des herbicides à usage forestier et leur impact sur la qualité de l`eau et les micro-organismes du sol. La liste des principaux herbicides utilisés est établie. Une analyse bibliographique est ensuite réalisée permettant d`établir une comparaison de leurs principales caractéristiques écotoxicologiques. Le volume d`herbicide utilisé en forêt est faible puisqu`il est de l`ordre de 1 % du volume global utilisé alors que la surface forestière est beaucoup plus élevée proportionnellement. Les auteurs concluent à l`absence de risques écotoxicologiques pour le milieu aquatique et les micro-organismes du sol si les utilisateurs respectent les conditions d`application homologuées.