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‘Uncertain times’ shadow spruce beetle outbreak

Mild winters and an accelerated life cycle are forcing government and scientists to look at the current spruce beetle infestation differently.
Jeanne Robert
Jeanne Robert is the regional forest entomologist for the Omineca and Northeast region.

Mild winters and an accelerated life cycle are forcing government and scientists to look at the current spruce beetle infestation differently.

"We are heading into uncertain times and those issues are on our minds and are certainly factors we are thinking about as we consider how to move forward," Jeanne Robert, the regional forest entomologist for the Omineca and Northeast region, said.

Since 2014, a total of 1.3 million hectares have been affected in the province by the spruce beetle, making it the largest outbreak ever recorded in B.C. A significant portion of the infestation has been seen in the Prince George, Fort St. James, Mackenzie, and Vanderhoof areas.

"Historically these massive cold snaps are what keeps the population under control," Robert said. "This is one of the things we need to pay attention to, I think, because bark beetles are not acting in a way they have historically and that can have implications in forestry. So we really want to make sure we keep track of these populations as we see them swing into the more extreme cases that we are seeing now."

Its life cycle has been one of those changes.

“Instead of taking two years to get from egg to an adult that flies to attack new trees it's actually just taking a year," Robert said. "So this isn't unusual for spruce beetles. It's quite common to have a portion of the population in a one-year life cycle but what we're seeing now is proportions are different from what we've seen historically. In the past, about 85 per cent of spruce beetles were in a two-year life cycle and now we're seeing an increase in the one-year life cycle."

The spruce beetle prefers to attack old growth trees and this latest infestation took place when a wind throw event - where trees are completely uprooted - took place north of Prince George and then again north of Mackenzie.

The impact varies from area to area and includes a light sprinkling of affected trees to severe infestation, which means 30 per cent of the trees in a particular stand are affected.

"That is characteristic of a spruce beetle infestation, it doesn't mean the whole area is red, it's very much patchy, very much rising and falling and there's a lot of overlap of Spruce beetle infestation year after year," Robert said."We will probably see this pattern continue for some time."

The concern about this particular outbreak is its size.

"It's large, it's widespread and it is exacerbated by the mild winter temperatures that we've had so if we are seeing minimum winter temperatures rise in this area of spruce beetle outbreak that is documented as well established, and we are very rarely seeing these very cold snaps early in the fall or early in the spring," Robert said.

The uncertainty isn’t all bad news, Robert stressed.

"There is a lot of resilience built into forest ecosystems to deal with these kinds of disturbances and hopefully as humans we can figure out a way to work with those mechanisms to create a forest that is going to work now and 50 years from now and 100 years from now," she said. "And that's why I get up in the morning."