Mountain pine beetles across Alberta have varied in their survival rate this past year. A higher number outlived the winter in the province’s central and northwest areas while there has been a decrease in pine beetle population in the east and southwest.
Some scientists speculate a warming climate is to blame since pine beetles die off naturally after temperatures reach a continuous level around -40°C.
“Largely, the extreme cold that happened last winter (2009-10) wasn’t replicated this past winter (2010-11),” said Allan Carroll, associate professor of forestry at UBC.
Milder winter weather throughout most of the province’s forests this year is the likeliest cause of greater beetle survival, compared to the extreme temperature fluctuations the previous winter, which led to significant beetle mortality last year, according to Sustainable Resource Development.
“The likelihood of things improving for them in the coming years is fairly good,” said Carroll. “Where you’ve got lots of mature pine is where you have a large number of pine beetle.”
Pine beetles prefer mature, fully grown trees as opposed to baby or juvenile pines, and the only way to cull the beetle is sustained cold weather or the disappearance of mature pine trees, added Carroll.
“There are some small pockets of good news on the mountain pine beetle front lines this year, but overall, the infestations remain a challenge to Alberta and we must continue our aggressive action to protect forest health in the province,” said Sustainable Resource Development Minister Mel Knight.
Over-winter mortality survey results are used to help set priorities for control work in the coming year. This year’s results mean Alberta will continue to target specific areas for aggressive action against mountain pine beetle in 2011-12.
There are about 14.8 million acres of Alberta trees that are at risk from pine beetle attacks.
Pine beetles entered Alberta’s southwest in 2002 and again in 2006 in the west-central area. By 2009, another in-flight wave infiltrated the province. Carroll said the number of pine beetles in Alberta is immeasurable since each tree may contain 1,000 to 2,000 beetles and there are countless pine trees.
