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Temperatures helping Alberta battle mountain pine beetle


The mountain pine beetle lives underneath the bark of pine trees, choking off the tree's water supply (Photo courtesy Alberta Sustainable Resource Development)
The mountain pine beetle lives underneath the bark of pine trees, choking off the tree's water supply (Photo courtesy Alberta Sustainable Resource Development)

Alexandra Pope, staff writer

March 14, 2011 — Wild swings between warm and frigid temperatures have officials in Alberta hoping for a major victory in their battle against a tiny threat to the province's pine forests: the mountain pine beetle.

Aerial surveys done in the fall clearly show which trees are dead and dying (Photo courtesy of Alberta Sustainable Resource Development)
Aerial surveys done in the fall clearly show which trees are dead and dying (Photo courtesy of Alberta Sustainable Resource Development)

Officials won't know for another couple of weeks how many beetles survived the winter, but weeks of deep cold punctuated by brief mild spells are an encouraging sign, according to Duncan MacDonnell with Alberta Sustainable Resource Development.

“That happened last year. We had extreme temperature fluctuations for a period of time, and that contributed to significant beetle mortality,” he said.

“This year has been the same, so we're hopeful we might see mortality like that again.”

Mountain pine beetles are a natural part of western Canada's forest ecosystem. They live under the bark of pine trees, laying their eggs inside the tree and cutting off its water flow.

In small numbers, the beetles help keep the forest healthy by killing off old, sick pine trees. But when there are too many beetles, they begin to attack healthy, mature pine trees.

In British Columbia, which has been battling a mountain pine beetle infestation since the 1990s, it's estimated that three-quarters of the province's lodgepole pine forests are dead or dying.

Southwestern Alberta, too, has had beetle infestations dating back to the 1940s, but in 2006, an in-flight of beetles from B.C. infested the province's northern pine forest for the first time. That poses a serious risk to communities that rely on the $10 billion forestry industry for their livelihood, MacDonnell said.

Crews will begin taking bark samples in April to determine how many beetles died over the winter (Photo courtesy Alberta Sustainable Resource Development)
Crews will begin taking bark samples in April to determine how many beetles died over the winter (Photo courtesy Alberta Sustainable Resource Development)

Fortunately, the climate is on the province's side.

Mountain pine beetles secrete a natural anti-freeze that protects them from the harsh northern winters, but an air temperature of -40°C for 24 hours or more will kill them.

That's not uncommon in northern Alberta in the winter. But recently, temperatures have been on a rollercoaster ride, and that's an even better sign, MacDonnell said.

“Extreme temperature fluctuations ... fool the beetle into thinking it's spring and time to convert that natural anti-freeze into energy,” he explained. “When that happens early in the life cycle of the beetle, there's a good chance you'll see some significant overwinter mortality.”

Crews will begin conducting ground surveys of the forest in April, at which point they'll have a better idea of the status of the infestation.

For now, MacDonnell said, the province is cautiously optimistic.

“(We) don’t take anything for granted ... because this is an insect that can turn around and bite you just when you think you’ve got it beat.”

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