B.C. and Western Boreal will feel climate change effects
By Cindy Macdonald
Climate change is happening quickly, but forests adapt slowly. That’s the root of the problem that will challenge Canada’s forest industry for the next hundred years.
The effects of climate change will vary by region. It is believed that Canada will experience a greater rise in temperature than the predicted global average. During a webinar called Tracking Indicators of Change in January 2016, Dr. Catherine Ste-Marie of Natural Resources Canada noted that under a moderate climate change scenario, where global temperatures are expected to rise 3.2 degrees, Canada’s average is predicted to rise 5.6 degrees. Temperature increases are forecast to be greatest in the high Arctic, and greater in the central portions of the country than along the east and west coasts.
Some results of climate change are already evident; the mountain pine beetle infestation is the most obvious consequence, but there are others. More frequent forest fires, covering a larger range. Aspen dieback in Alberta.
The Canadian Forest Service has been doing research on climate change for decades. In recent years, much of this work has been channeled into a program called Forest Change. Dr. Ste-Marie explained that the goals of the Forest Change program were: tracking the effects of climate change, creating a suite of tools to support decision-making, and performing assessments that could guide policy and future investments.
Which trees are vulnerable?
The Canadian Council of Forest Ministers has also supported research into climate change. In one of its early reports, Vulnerability of Canada’s tree species to climate change and management options for adaptation (2009), the lead author, M. Johnson, summarized: “Over the next several decades, the climate in Canadian forests will shift northward at a rate that will likely exceed the ability of individual tree species to migrate. While most tree species can migrate naturally up to a few hundred metres per year via seed dispersal, the climatic conditions in which each species thrives may move north by several thousand metres per year.”
“Tree species and genotypes will acclimatize, adapt, and migrate; however, in many cases, the rate and magnitude of future climate change may significantly exceed the ability of tree species to naturally adjust,” he continued.
The vulnerability report outlines the following expected trends in species ranges:
British Columbia: There is likely to be a decline in spruce-dominated forests in the central and southern interior of British Columbia. Losses of sites suitable for interior Douglas fir are likely in the south beyond 2080.
Western boreal: According to most climate model projections, this region will undergo the greatest warming. In the north, warming will lead to the expansion of zones that are suitable for pine species over the short term, but by 2050, total areas suitable for pines will likely be less than present day. In the southern forest-grassland transition zone, warming and drying are likely to result in progressive stages of dieback. Drought-prone spruce will be lost first, followed by pines and then aspen, to be replaced by some form of prairie grassland.
Eastern boreal: There is likely to be an increase in productivity and relatively little species loss, although spruces and birch may be out-competed by pine and aspen on drier sites. However, one study projects major losses of area suitable for black spruce and jack pine in central Ontario.
Southern Ontario, Québec, and the Maritimes: Species diversity in this region is high, and models project that by 2100, northward shifts of 250–600 km will occur in climate zones that are suitable for many hardwood species. Some of these species presently occur naturally only south of the U.S. border. Balsam fir is likely to disappear from Nova Scotia and most of New Brunswick, and shift north into northeastern Québec and Labrador.
There are efforts being made by foresters and researchers regarding selective breeding and assisted migration of tree species to counter the effects of climate change on Canada’s forests, but these do carry some ecological risk and are the subject of some ethical debate. Whether by nature’s hand or man’s, the forest landscape in Canada will change dramatically in the next 100 years.
For more information:
Natural Resources Canada–Canadian Forest Service’s Forest Change initiative reports on indicators that reflect past trends in, and future projections of, changes across Canada. It also provides adaptation tools and resources for forest managers: www.cfs.nrcan.gc.ca/forestchange