Photo submitted by Alberta Agriculture & Forestry
Mountain Pine Beetle populations in the forests around Hinton have taken a beating this winter, says a top local scientist, but it will be months before researchers get a more accurate idea how much of a beating the MPB took in a recent extreme cold snap
News reports in the past week stated the cold temperatures caused 95 per cent MPB mortality. However, Keith McClain, program lead at the Mountain Pine Beetle Ecology Program at fRI Research, said that a comprehensive survey is required to be undertaken in the spring to confirm those numbers.
“Current mortality figures are only speculation based on our understanding of cause and effect,” said McClain.
At the very least, he said the current beetle populations were impacted by the recent cold temperatures, but obtaining a more accurate determination of mortality will have to wait until spring, explained McClain.
“In the words of a colleague of mine who is a lead researcher in MPB, ‘there will always be surprises.’ Trying to attach exact numbers to describe biophysical phenomena is always risky. I am comfortable in knowing that the beetle took a beating,” he concluded.
Years of research show that temperatures impact MPB development, but an understanding of beetle biology and how the beetle interacts with surrounding environmental conditions is required to know exactly how.
McClain explained that the various stages of development of the beetle from the egg to the pupae to the larvae and finally to an adult have inherent abilities to resist cold temperatures. The beetle adapt to colder temperatures by increasing their concentration of glycerol, a biological antifreeze.
“In general, larvae are the most cold-tolerant, followed by adult beetles, pupae, then eggs,” said McClain.
Due to this antifreeze overwintering adaptation, extremely cold temperatures for a prolonged period of time would be required to cause significant mortality of the larvae. This is especially true at the height of the beetle’s cold tolerance.
Larvae of MPB are most susceptible to the cold in the fall and in the spring when they either haven’t built up their antifreeze, or are already releasing it to resume feeding on the tree in the spring, explained Caroline Charbonneau, Area Information Coordinator of AB Agriculture & Forestry (AAF).
The beetle is also protected by the bark of the tree and depth of snow around the base of trees, added McClain.
“Temperatures of around -37 to -40 degrees C are required to cause mortality. However, in the early developmental stages at any point, cold tolerance is low and less extreme conditions are required to cause mortality,’ said McClain.
Regardless of circumstances, an excess of 97 per cent in population mortality is required to cause a decline in the spring population, he added. The cold temperatures, depending on duration and location, would have caused mortality, but the question remains how much.
Charbonneau said MPB in the Edson forest area have taken a significant hit the past two years, with high precipitation over the summer months and cold weather events at various stages of fall, winter and spring.
“It’s common for Mountain Pine Beetle to take a large hit and come back strong in certain areas, which is why the province takes advantage of these weather events to control the population,” she continued.
AAF’s Forest Health Department was busy conducting surveys during August and September to collect MPB red tree locations and determine priority locations.
Around 2,500 sites are planned to be ground surveyed by contractors and an estimated 13,920 trees are predicted to be controlled this season, according to Charbonneau.
“This number may change depending on production rates, budgeting and provincial priorities,” she said.
2,404 trees have been hand fallen and burned on site by three main contractors and approximately 90 fallers, ground surveyors, and quality checkers. Contractors will be working on this until the end of March, when wildfire season begins.
The province anticipates controlling approximately 100,000 infested trees this season in various Forest Areas, stated Charbonneau.
Local forestry companies such as Hinton Wood Products and Weyerhaeuser applied for funding to do MPB control in the area this season through a Forest Resource Improvement Association of Alberta (FRIAA) Grant, added Charbonneau.
Hinton Wood Products started ground surveys in early January and anticipate to control 1,000 trees near the Mountain Cree Community through the FRIAA and Forest Resource Improvement Program (FRIP) grant.
FRIP grant dollars will go towards training six Mountain Cree members for survey quality and control quality inspections.
The Mountain Cree Community is a small indigenous settlement located near the Cardinal River south of Cadomin.
The trained members are working with contractor, Simply Liv, to complete survey and control of MPB sites in and around their community.
Work is anticipated to be completed by the end of March.