Parks Canada says too soon to know

If upwards of 95 per cent of the mountain pine beetle perished over the winter, as predicted by a model developed by the Canadian Forest Service (CFS), this winter could have been the first time the mountain parks have caught a break in the fight against the beetle.

Barry Cooke, research scientist with CFS in Edmonton, said his team borrowed the prediction model from researchers studying mountain pine mortality in Idaho, and applied it to Alberta to see if it would work here as well.

“We put a research project together after the first two winters of validating the model and seeing that it was actually predicting correctly,” Cooke said.

This year, the model predicted upwards of 95 per cent mortality, especially at higher elevations and including Jasper. “That Dec. 14th and then the Christmas cold snaps, those were pretty serious cold events for mountain pine beetle,” Cooke said. “Since then it’s been cold but all the bang happened around Christmas.”

This is good news, he added, as experience shows that 97.5 per cent is the threshold that makes the difference between population growth or decline.

“When you get 95 per cent just from the winter you’re starting to get close to that unstable threshold,” Cooke said. “There’s a good chance in many locations you’ll go over that 97.5 per cent once you include all the mortality from March, April, May and June from things like woodpeckers and starvation.”

At a 95 per cent mortality rate, Cooke expects the beetles will come back with slightly reduced force. It should buy some time for control attempts, but without knowing exact numbers, it’s impossible to know how much time.

“The mountain parks were on a pretty devastating trajectory because they were getting only about 50 per cent mortality each winter, which is very good survival,” Cooke said. “So this is the first time in a long time they’ve caught a break.”

Because on-the-ground monitoring, which the province handles, is really the only way to know how the beetle populations are doing, official data won’t be available until the middle of May. “This model helps give them a good guess at what’s likely to happen,” Cooke said. “At the end of May we’ll compare the model predictions to the data and see how well it’s working.”

Dave Smith, vegetation specialist for Parks Canada, said only once crews get on the ground and “poke our heads under the various trees attacked” will they know the mortality rate. “Are they taking into account the beetles below the snow line? Snow acts as an insulator,” he said. “There’s a whole bunch of factors that exist.”

Parks starts doing aerial surveys in the spring. “At that time we can identify which have been hit,” Smith said. “We’ll get to as many sites as we can, actually look underneath the bark of the tree and determine if beetles have been successful.”

Only then, Smith said, will Parks be able to say if the cold winter helped.

The model provides a prediction based on weather, which Cooke said is the biggest factor. “This is all about climate change,” he said.

“The question that’s worth asking in the mountain parks is how has climate change contributed to the current situation and is it likely to contribute to further population growth? The environment’s getting warmer, the temperature’s getting better for mountain pine beetle everywhere in Alberta.”

An oft-repeated rule outlining temperatures needed to kill off the beetle is –40C for five days. “That is a useful rule of thumb in general but it doesn’t account for how beetles freeze,” Cooke said.

He said beetles adjust to the seasons slowly, so an early cold snap can do them in. As well, the day-to-day variation can throw them off, as they start equipping themselves physiologically the second it gets cold, and if the change is fast they can’t cope.

Since the weather may have done well to increase mortality rates, some may argue it’s time to relax on pine beetle control efforts, a notion Cooke said is completely false. “When this system’s going down, that’s when it makes sense to kick it because that’s when you have a chance of holding the line on spread and possibly driving it backwards,” he said.

“It’s a great time to really make a difference."