The threat of mountain pine beetle to Canada’s boreal forest
Where is the beetle now?
The mountain pine beetle (MPB) is a native insect that attacks pines in western North American forests.
The current MPB outbreak started in British Columbia in the early 1990s. The insect has since killed about 50% of the total volume of commercial lodgepole pine in the province. While isolated records of MPB had been noted in Alberta before, it was the massive migration of beetles into that province from outbreaks in British Columbia during 2006 that fuelled the spread eastward.
Today the MPB occurs well beyond its historic range, extending into northern British Columbia and eastward in the boreal forest of north-central Alberta. Not just limiting itself to lodgepole pine any longer, the beetle is also reproducing in jack pine, the dominant pine species of the boreal forest.
Annual displacement vectors
Larger image [247 kb GIF]
What could influence the beetle’s continued spread?
Scientists expect the beetle to continue expanding its geographic range, moving into the boreal forest and Canada’s northern and eastern pine forests. Several factors will determine the extent to which this spread occurs:
- Dispersal ability – As a normal feature of their life history, adult beetles fly to new trees and colonize. The possibility of long-distance dispersal (greater than 100 km) under favourable weather conditions is well documented.
- Climatic suitability for infestation – Milder winters and warmer summers contribute to both higher recruitment and survival rates of the MPB.
- Susceptibility of boreal pine stands to infestation – Pine stands in the boreal forest are typically less dense and have smaller trees than British Columbia’s lodgepole pine forests. Such stand characteristics may not necessarily be optimal for beetle spread, but new evidence suggests they may be less of an impediment to the spread and establishment of the beetle in boreal stands than previously believed.
- Effectiveness of forest pest management efforts – Control efforts now underway are reducing MPB populations and helping to slow their spread, but the area of forest being attacked by the beetle continues to increase.
What are governments doing to slow the beetle’s spread?
The affected provinces and territories are leading their own beetle detection and control programs. Their efforts include detecting MPB in new areas and removing and burning infested trees to reduce further attack, or harvesting affected stands before the economic value of the wood is lost or diminished.
Still, the boreal forest is a novel environment for this beetle and many questions—such as how quickly populations will spread and what their impact will be on forest ecological, economic and social values—have yet to be answered. Research being conducted by the Canadian Forest Service and other agencies focuses on gaining greater understanding of the ecology and population dynamics of MPB in the insect’s new environment.
This information is being used in an ongoing risk analysis as part of the National Forest Pest Strategy, a collaboration of federal, provincial and territorial experts. The knowledge developed is assisting forest managers with assessing the threat to Canada’s forests posed by the beetle and identifying effective mitigation and adaptation options.