By Jim Hilton –
In a recent BC government press release, the spraying of forests to control deciduous plants that interfere with conifers was reduced from 16,000 hectares to 10,000. Most of the herbicide treatment was taking place between Prince George and Quesnel, and the main reason for the reduced use of herbicides was concern about the impacts on wildlife, particularly relative to ongoing declines in moose populations. There has also been a concern over the reduction of biodiversity in a variety of areas—for example, growing concerns about the possible impact of glyphosate (the main constituent of Roundup) on frogs and other plants and animals, especially species in adjacent wetlands contaminated from aerial spraying.
Personal communication with local silviculture specialists confirms that although herbicides are viewed as a quick, easy, cost-effective means of establishing conifer trees, more and more research seems to show otherwise.
Suzanne Simard, a forest science professor at the University of British Columbia (UBC) says coniferous forests don’t do better when the broadleaf plants are killed off using herbicides. After more than two decades of studying the impacts of spraying it turns out that nature is more complicated than a lot of people thought and herbicide application doesn’t help the conifers grow, which means amphibians and insects are being impacted needlessly.
Susan Woermke has many years of silviculture experience in the interior of the province and has arrived at the following conclusion: We do not need to use herbicides as there are other means of effective establishment: timely silviculture practices and site-specific prescriptions may be utilized as means of meeting legal obligations without undue cost. In her experience, conifers may also suffer growth defects contrary to the claims of herbicide manufacturers.
The photo below taken by Susan Woermke were from a site treated with Roundup and show deformation of pine leaders. While the pine were not killed, the damage will certainly impact the rate of growth and quality of the trees.
A study in eastern Canadian forests also described similar conclusions, noting that stocking commercial species without the use of herbicides is a superior solution. Another study recommended an end to government-funded herbicide use in Nova Scotia, and that the practice be banned on crown land.
The assumption that herbicides are the quick and easy way to increase production needs to be challenged as pointed out in a study done on canola production in the Peace River area. Author Mark Winston, in his book Bee Times, describes an experiment done by one of his graduate students comparing canola production on organic, conventional, and genetically modified fields. The conventional and genetically modified used insecticides, fungicides, and/or herbicides while the organic did not use any chemicals but maintained 30 percent of the surrounding land untreated to encourage wild bees. When all the costs were taken into account the organic area earned a profit of $65,000 compared to $27,000 in the 100% treated areas. The greater profit on the smaller land base was attributed to improved pollination and higher yields.
The complete elimination of herbicides may be a problem for some forest companies who are required to meet a minimum conifer stock as prescribed by government regulations. Some silviculture research specialists have been looking at the stocking standards that deal with the level of deciduous plants and the associated free growing levels of conifers so forest companies can meet their commitments.
Looking at recent wild fires, it has also been observed that aspen stands are much more resistant to wild fire spread and should be considered when implementing strategies for fire guards and fire prevention and control. With aspen being used for fibre in products like OSB, it is a good time to reconsider some so-called weed species as more useful in the mix of commercial forests.
Jim Hilton is a professional agrologist and forester who has lived and worked in the Cariboo Chilcotin for the past 40 years. Since his retirement he has been spending his time with a number of volunteer organizations, including community forests.