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What alternatives to herbicides are available for forest vegetation management?

Category: Vegetation Management

Forest managers routinely design harvest and site preparation activities to minimize regrowth of undesirable vegetation, and rely on tools such as manual cutting, large nursery stock, and prescribed fire to maintain conifer growth, abundance, and dominance on areas where they choose not to use herbicides.

There are several cultural methods that forest managers routinely use to combat the competitive effects of non-crop vegetation in a preemptive fashion. For example, on sites capable of producing quality, high valued hardwoods, conifer regeneration (and the use of herbicides) is often avoided completely. Where conifer production is desired, stands can be harvested at times of the year, in a manner and with equipment designed to minimize the resprouting of non-crop vegetation (Myketa et al. 1998, Wagner and Columbo 2001). Site preparation timing, methods and equipment may similarly be tailored to specific site conditions for minimizing non-crop regrowth potential. Healthy, high quality conifer seedlings, with genetic selection for rapid growth are often planted to maximize their competitive advantage. On some sites, vegetation management methods are modified to promote the development of mixed stands of conifer and hardwoods (Pitt et al. 2004a, Pitt et al. 2004b, Pitt et al. 2010). Manual methods of weed control (e.g., cutting with brushsaws; Bell et al. 1997, Bell et al. 1999, Pitt and Bell 2004, Pitt and Bell 2005, Greifenhagen et al. 2005) are used where the use of herbicides is constrained, particularly to provide an extra measure of safety for humans or the environment, such as near human habitation or in riparian zones. Fire, one of nature’s key weed control measures, may be used as a tool for vegetation control in site preparation, under some very specific conditions.

Bell, F.W., Lautenschlager, R.A., Wagner, R.G., Pitt, D.G., Hawkins, J.W., Ride, K. 1997. Motor-manual, mechanical, and herbicide release affect early successional vegetation in northwestern Ontario. Forestry Chronicle 73(1): 61-68.

Bell, F.W., Pitt, D.G., Morneault, A., Pickering, S. 1999. Response of immature trembling aspen to season and height of cut. Northern Journal of Applied Forestry 16(2): 108-114.

Greifenhagen, S., Pitt, D.G., Wester, M.C., Bell, F.W. 2005. Juvenile response to conifer release alternatives on aspen-white spruce boreal mixedwood sites. Part II: Quality of aspen regeneration. Forestry Chronicle 81(4): 548-558.

Myketa, D., Polhill, B., Whaley, R. 1998. Harvesting practices and their implications for vegetation management. Northwest Sci. & Info. Technical Note TN-43. Pages 1-10 In: F.W Bell, M. McLaughlan and J. Kerley (compilers). Vegetation management alternatives - A guide to opportunities. Ontario Ministry of Natural Resources, Thunder Bay, ON.

Pitt, D.G., Mihajlovich, M., Proudfoot, L.M. 2004a. Juvenile stand responses and potential outcomes of conifer release efforts on Alberta’s spruce-aspen mixedwood sites. Forestry Chronicle 80(5): 583-597.

Pitt, D.G., Wagner, R.G., Towill, W.D. 2004b. Ten years of vegetation succession following ground-applied release treatments in young black spruce plantations. Northern Journal of Applied Forestry 21(3): 123-134.

Pitt, D.G., Bell, F.W. 2004. Effects of stand tending on the estimation of aboveground biomass of planted, juvenile white spruce. Canadian Journal of Forest Research 34: 649-658.

Pitt, D.G., and Bell, F.W. 2005. Juvenile response to conifer release alternatives on aspen-white spruce boreal mixedwood sites. Part I: Stand structure and composition. Forestry Chronicle 81(4): 538-547.

Pitt, D.G., Comeau, P.G., Parker, W.C., MacIsaac, D., McPherson, S., Hoepting, M., Stinson, A., Mihajlovich, M. 2010. Early vegetation control for the regeneration of a single-cohort, intimate mixture of white spruce and aspen on upland boreal sites. Canadian Journal of Forest Research 40: 549-564.

Wagner, R.G., Colombo, S.J., editors. 2001. Regenerating the Canadian Forest - Principles and practice for Ontario. Fitzhenry & Whiteside, Markham, ON.