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Why aren’t alternatives to herbicides being used in forest vegetation management?

Category: Vegetation Management

They are – most Forest managers use an integrated vegetation management approach that consists of a variety of preemptive techniques, in addition to direct tools such as herbicide treatments and manual cutting.

It is clear from the statistics, of the estimated 444,000 ha requiring tending each year in Canada, about 2/3 of these hectares are not treated using herbicides (http://nfdp.ccfm.org/). In fact, all well-managed forests employ what is referred to as an Integrated Vegetation Management (IVM) Program that includes herbicides, as well as a number of other techniques that are available to forest managers to reduce the competitive effects of non-crop vegetation (Little et al. 2006). Under an IVM program, a forest manager will use the most appropriate combination of tools that safely maximize the potential for regeneration success on a site-specific basis.

Generally speaking, however, there are no alternatives which are as cost-effective, efficient, safe, or reliable as modern chemical herbicides in forest regeneration scenarios and so herbicides, glyphosate-based herbicides in particular, naturally play a dominant role in most IVM programs (McDonald et al. 1993, Newton 2006). Herbicides also offer the only effective means of reducing competition from broadleaf herbaceous plants, which have been shown in several studies to significantly reduce conifer growth and survival (Zutter and Miller 1998, Man et al. 2008, Pitt et al. 2009, Parker et al. 2009, Pitt et al. 2011). Glyphosate-based herbicides also tend to kill plant root systems, preventing the resprouting that often occurs following manual cutting (Bell et al. 1999). Still, through IVM, non-chemical techniques are in fact employed on a significant portion of the forest land base.

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.

Little, K.M., Willoughby, I., Wagner, R.G., Adams, P., Frochot, H., Gava, J., Gous, S., Lautenschlager, R.A., Orlander, G., Sankaran, K.V., Wei, R.P. 2006. Towards reduced herbicide use in forest vegetation management. South African Forestry Journal 207: 63-80.

Man, C.D, Comeau, P.G., Pitt, D.G. 2008. Competitive effects of woody and herbaceous vegetation in a young boreal mixedwood stand. Canadian Journal of Forest Research 38: 1817-1828.

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.

Parker, W.C., Pitt, D.G., Morneault, A.E. 2009. Influence of woody and herbaceous competition on microclimate and growth of eastern white pine (Pinus strobus L.) seedlings planted in a central Ontario clearcut. Forest Ecology and Management 258: 2013-2025.

Pitt, D.G., Morneault, A., Parker, W.C., Stinson, A., Lanteigne, L. 2009. The effects of herbaceous and woody competition on planted white pine in a clearcut site. Forest Ecology and Management 257:1281-1291.

Pitt, D.G., Morneault, A., Parker, W.C., Lanteigne, L., Hoepting, M.K., and Stinson, A. 2011. Influence of herbaceous and woody competition on white pine regeneration in a uniform shelterwood. Forestry Chronicle 87(5): 653-668.

Wagner, R.G., Mohammed, G.H., Noland, T.L. 1999. Critical period of interspecific competition for northern conifers associated with herbaceous vegetation. Canadian Journal of Forest Research 29(7): 890–897.

Zutter, B.R., Miller, J.H., 1998. Eleventh-year response of loblolly pine and competing vegetation to woody and herbaceous plant control on a Georgia flatwood site. Southern Journal of Applied Forestry 22: 85–95.