Are chemical or mechanical treatments more sustainable for forest vegetation management in the context of the TRIAD?

Abstract

Chemical and mechanical forest vegetation management (FVM) treatments are analyzed and compared to assess which is the most sustainable in intensively managed plantations in the context of the TRIAD. At the biological and ecological level, herbicides have been found to have more impacts on flora and fauna compared to mechanical treatments, but the differences are of short duration. The effects of noise generated by manual or mechanical brushing on wildlife have not been investigated, however. Local application of herbicide at the base of the tree should further lower these impacts. At the social level, the general public has a negative perception of chemical treatments, while mechanical treatments are well perceived. However, in terms of worker safety, chemical treatments are less risky than manual brushing (brushsaw or chainsaw). At the economic level, herbicides globally cost less and are more effective at increasing fibre production than mechanical operations. We conclude that it is difficult to assess globally what is the most sustainable option to control competing vegetation. However, the careful use of herbicide may be the most sustainable option if the added productivity thus obtained is used to increase protected areas and ecosystem-based management, as is intended with the TRIAD concept. Key words: forest vegetation management, chemical release, mechanical release, functional zoning, plantations, ecological impacts, social impacts, economical impacts, intensive management, sustainable forestry