Mountain pine beetles are a hardy bunch, it turns out.
While a deep freeze can prove deadly to the tree-killing critters, the latest cold snap hasn’t come close to packing a lethal punch.
Alberta Sustainable Resource spokesman Duncan MacDonnell said temperatures need to plummet to -40C to hit pine beetle killing range.
“That’s the first thing you look for when you’re assessing whether cold weather is going to cause significant pine beetle mortality,” he said. “You need -40C — and that’s ambient air, not wind chill — and you need that for 24 hours. And we haven’t hit that yet.”
There’s plenty of winter left, though, for a killing deep freeze. Typically, the coldest spells occur in late January and into February, so there’s still hope the beetles will meet their weather match.
However, even if the killer cold doesn’t show up, other weather patterns can also produce conditions that make life miserable for pine beetles.
Severe temperature fluctuations are not the pine beetle’s friend. As temperatures climb, the beetles convert their natural internal anti-freeze into energy because their bodies are fooled into thinking spring is afoot, MacDonnell said.
“When you get a subsequent cold snap, it doesn’t have to go to -40C because they are not as winter hardened once they’ve done that little bit of (anti-freeze) conversion,” he said.
“So if you’ve got a whole series of cold/warm, cold/warm, which looks like what we’re getting into here, that’s good.”
Alberta was first hit by mountain pine beetles in 2001. They arrived in the southwest corner of the province, south of Hwy 1. That area is now stable with no pine beetle expansion in recent years.
The leading edge of the province’s worst infestation is now in a triangle formed between Grande Prairie, Slave Lake and the Hinton-Edson area that was hit by two large inflights in 2006 and again in 2009.
“There are some heavy concentrations in there,” he said. About one million trees were killed last year or have been newly infected.
However, there is some good news. In the last two years, the number of newly infected trees has been reduced by 60 per cent through a combination of selective tree removal, targeted logging, and prescribed burns.
Natural factors, such as temperature fluctuations and the absence of any significant inflights in the last couple of years, have also played roles.
That doesn’t mean the province can rest easy. A freak wind could blow another inflight into Alberta from B.C. at any time, he said.
“The thing about the beetle is it can turn on a dime. If we got a big inflight into Alberta this summer, it’s a game changer again.”
Alberta has about six million hectares of pine forest. However, unlike B.C., where millions of hectares were devastated, the infestation in Alberta is not at a point where accurate measurements of damage can be estimated.
In Alberta there is a sprinkling of the telltale red-tinged dead trees, unlike the “red carpet effect” seen in B.C. where the red spreads as far as the eye can see.
pcowley@www.reddeeradvocate.com