Forest insect and disease pests have cost Canada hundreds of millions of dollars over the years in revenue losses, prevention and control investments, and environmental mitigation efforts.
The greatest direct economic impact of severe insect or disease outbreaks is reduced wood supply for the forestry sector. A drop in expected harvest levels costs forest companies heavily and the communities that rely on them. Other forest-based activities that can suffer include maple syrup production and outdoor recreation pursuits such as camping and wilderness wildlife viewing. In urban settings such as parks, plazas and boulevards, where trees are valued for the many benefits they provide (from shade and habitat for birds to aesthetic relief), large-scale loss through infection can result in high replacement costs.
Even before any of those economic losses are incurred, costly mitigation measures may have been taken in an effort to stop the pest’s spread.
Outbreaks also incur substantial costs for control and regulation. An example are the costs required for phytosanitary treatment of potentially infested or infected Canadian forest product exports, to ensure that pests are not inadvertently passed on to other countries.
Indirect economic impacts of forest pest outbreaks include a host of environmental and social costs when ecological damage has resulted from a severe infestation. These costs range from loss of water and air quality, wildlife habitat and genetic diversity to the degradation of aesthetic values of landscapes.
Forest insect and disease outbreaks in Canada have cost hundreds of millions of dollars in timber losses because of tree mortality or growth suppression. Examples:
- The native spruce budworm is a major defoliator of conifer forests, where it attacks mainly balsam fir and spruces and occasionally other conifer species. In the mid-1980s, the spruce budworm destroyed more than 10 million cubic metres of wood in Quebec alone.
- A relative of the above, the western spruce budworm feeds on Douglas-fir. It has defoliated more than half a million hectares of Canada’s forests annually for more than a decade, despite being the target of the largest annual spray program in Canada since the mid-1990s.
- The mountain pine beetle is is a native insect that periodically becomes a serious pest in mature pines in western North America. Lodgepole pine is its primary host in western Canada, although ponderosa pine and even jack pine are also attacked and killed. Between 1998 and 2009, mountain pine beetle killed an estimated 675 million cubic metres of pine in British Columbia—equal to about 50% of the province's commercial pine.
- White pine blister rust is an alien disease that was introduced into Canada in the early 1900s. It has caused significant annual losses of two white pine species, one in eastern and the other in western Canada. In the Maritime Provinces alone, for example, 84 000 cubic metres of wood supply was lost to the disease between 1982 and 1987. White pine blister rust is now one of several forest pests also endangering whitebark pine, a high-elevation species that grows in British Columbia and Alberta.
Valuating the costs
Researchers estimate the costs to Canada of the real and the potential impacts of forest pests to be in the order of hundreds of millions of dollars.
A 2009 report prepared for the Canadian Council of Forest Ministers concluded that Canada could have avoided a cost of $165 million annually by preventing the introduction and establishment of four high-profile invasive forest insects and diseases: Asian longhorn beetle, emerald ash borer, Sirex wood wasp and sudden oak death disease.
According to the same report:
- $34 million is the estimated average annual cost over the next 20 years if just one invasive species were to become established in Canada.
- For every $1 spent on coordinated multi-jurisdictional prevention activities, $3 in mitigation, regulatory and depletion costs can be avoided if only one such pest is prevented from establishing.
Such figures are generally considered to be conservative estimates of the full costs of forest pests. Many impacts cannot be accurately measured or valued in dollar terms, such as the aesthetic quality or biodiversity value of a forested landscape.