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Why are herbicides an important forest management tool?

Category: Vegetation Management

Herbicides, such as glyphosate, play an important role in maintaining a viable wood supply for economic purposes and also contribute to an appropriate balance of conifer, deciduous, and mixed stands across the forest landscape.

White pine regeneration established 10 years after partial overstory removal (shelterwood harvest), without tending (top) and with tending (bottom). (Photos: Doug Pitt)

Herbicides are typically used in Canadian forest vegetation management only where conifer crops (e.g., spruce and pine species) are to be regenerated and grown for products such as lumber, paper and wildlife habitat. Following harvest, numerous pioneer plant species (e.g., Canada blue-joint grass, raspberry, trembling aspen) that are well-adapted to invading disturbed sites and open growing conditions, easily outcompete young conifer seedlings for nutrients, light, water and growing space (Wagner et al. 2001, Balandier et al. 2006). Reducing competition from adjacent plants is essential for crop-tree survival and growth, much the way that weeding insures success in the home garden. Of course, in contrast to the home garden, the scale at which forestry operations occur makes hand-weeding highly impractical. Herbicides allow effective, highly selective competition reduction in conifer crop production, at minimum cost (McDonald and Fiddler 1993, Wagner et al. 2006, Newton 2006, Dampier et al. 2006, Homagain et al. 2011). The use of herbicides in Canadian forest vegetation management is also heavily regulated and controlled in an effort to ensure environmental and human safety (Who decides whether a product is safe or not? How do they know?).

Balandier, P., Collet, C., Miller, J.H., Reynolds, P.E., Zedaker, S.M. 2006. Designing forest vegetation management strategies based on the mechanisms and dynamics of crop tree competition by neighboring vegetation. Forestry 79(1): 3-27.

Dampier, J.E.E., Bell, F.W., St-Armour, M., Pitt, D.G., Luckai, N. 2006. Cutting versus herbicides: Tenth-year volume and release cost-effectiveness of sub-boreal conifer plantations. Forestry Chronicle 82(4):521-528.

Homagain, K., Shahi, C.K., Luckai, N.J., Leitch, M., F.W. Bell. 2011. Benefit-cost analysis of vegetation management alternatives: An Ontario case study. Forestry Chronicle 87(2): 260-273.

McDonald, P.M., Fiddler, G.O. 1993. Feasibility of alternatives to herbicides in young conifer plantations in California. Canadian Journal of Forest Research 23:2015–2022.

Newton, M. 2006. Taking charge in forest vegetation management. Canadian Journal of Forest Research 36: 2357–2363.

Wagner, R.G., Bell, F.W., Campbel, R.A. 2001. Vegetation management. Pages 431-457 In: R.G. Wagner, and S.J. Colombo, eds. Regenerating the Canadian Forest: Principles and practice for Ontario. Fitzhenry & Whitside, Markham, ON.

Wagner, R.G., Little, K.M., Richardson, B., McNabb, K., 2006. The role of vegetation management for enhancing productivity of the world’s forests. Forestry 79 (1): 57–79.