West Central Alberta has so far been able to manage the infestation of mountain pine beetles (MPB), but many areas in Alberta were not as lucky.
Approximately 8,000 trees have been controlled – harvested or burned – in the Rocky Mountain House and Calgary forest areas since 2006, but only 646 had to be controlled in the last five years.
“In 2010, local beetle populations plummeted in the Eastern Slopes, thanks to aggressive control efforts and a cold winter in 2009,” said Mike Undershultz, a senior forest health officer for Alberta Agriculture and Forestry.
“Relatively speaking, there has been very little MPB activity in the areas ranging from Rocky Mountain House south to the Crowsnest Pass.”
MPB destroy trees by laying their eggs under the bark.
Once hatched, the larvae mine the phloem area beneath the bark, which eventually cuts off the tree’s supply of nutrients and kills it.
MPB also carries a fungus that causes dehydration and inhibits the tree’s natural defences. It also stains the wood blue or grey.
MPB had their first mass migration into Alberta in 2006.
The current range of MPB covers a majority of forested areas in Alberta, particularly areas in the northwest, with the infestation becoming less intense towards the east and south.
Cold winters are supposed to keep MPB at bay. However, the beetles are now able to thrive in areas once uninhabitable for them, and the MPB survival rate is much higher compared to the last two winters.
“This is likely the result of a mild winter and an unusually warm spring,” Undershultz said.
“It is agreed by many experts in the research community that climate change has played a role in promoting population growth and range expansion into previously climatically unsuitable areas.”
Annual population forecast surveys predict that some areas in Jasper National Park and south of Grande Prairie will be hit especially hard this year.
All mature pine trees in Alberta are susceptible to MPB infestation, especially large-diameter pines.
Lodgepole pine has been primarily impacted, with some Jack pine being killed in eastern Alberta.
While the Martin Hills area northeast of Slave Lake is the furthest east MPB are currently killing trees, Undershultz said Saskatchewan was at risk of infestation.
Over the past five years, the government of Saskatchewan has contributed over $4 million to the control of MPB in eastern Alberta as a preventive management strategy.
Since 2006, the Alberta government has controlled 1,391,378 trees.
They predicted these infested trees would have expanded to 47 million infested trees had they not intervened.
Left unmanaged, MPB could kill six million hectares of pine, valued at more than $8 billion, within Alberta.
“Aggressive action has been and will continue to be effective at reducing spread and minimizing losses,” Undershultz said.
According to the recently released 2016 MPB spring population forecast survey, “general MPB population success is predicted to be high to moderate over the majority of the beetle’s current range,” survey officials said.
“This is indicative of a static to increasing beetle population. Extremely high beetle success is predicted in some areas south of Grande Prairie and in Jasper National Park.”
Overall, MPB survival was better this winter (2015-16) compared to the previous two years, officials said.
“This is likely the result of a mild winter and unusually warm spring. With this continuing trend of increased beetle overwintering success throughout much of their current range, it is very unlikely that populations will naturally decline in the foreseeable future.
“Sustained and aggressive control action is the only current option to mitigate the environmental and economic impacts occurring in Alberta.”