Climate change, genetics, and the beetle

Douglas fir beetle, or mountain pine beetle: take your pick. Infestations of either can result in catastrophic loss of forest.

Beetles are a natural part of the ecological cycle and they tend to attack weak and dying trees. But when numbers spiral out of control, any tree of that species becomes a target, and the beetles have a kill rate of up to 90%.

Canadian forests, particularly in British Columbia and Alberta, have seen a major infestation of mountain pine beetle in recent decades. The massive outbreak that started in 1996 has been a problem ever since. Bark beetles are tiny, just 5 mm in size, and attack a variety of different pine trees including lodgepole, Ponderosa, whitebark, jack and Scotch. Of the 55 million forested hectares in British Columbia, the mountain pine beetle has decimated 16 million hectares.

Fortunately, mountain pine beetle is not considered a threat to the Revelstoke area.

Douglas fir beetle is another story.

In an early 2017 article for the Revelstoke Review, Alex Cooper notes that a Douglas fir beetle infestation has resulted in mass clearcuts on Boulder Mountain. He writes that Mount Macpherson has been diagnosed with Douglas fir beetles. If it becomes an outbreak where healthy mature trees are affected, Mount Macpherson will need massive logging to try and curtail infestation. Logging in this zone will affect a popular network of biking, hiking, skiing and recreation trails.

Does climate change play a role in the beetles’ persistence? The Government of Canada Natural Resources information site thinks so. It notes milder winters and warmer summers are conducive to the survival rates and dispersal of beetles.

In an interview with Yale Environment 360, entomologist Diana Six explains the beetle outbreak is happening worldwide, though B.C. has been hit particularly hard. Six explains that returns to colder, wetter weather manage infestations because the beetles are cold blooded, but that these die offs have not been occurring as the temperature trends upwards. Dry summers are also leaving trees more stressed and susceptible to infection. More northern trees, like white pole pines, are usually able to resist beetles but are now dying within a couple years of infestation. Six expects Douglas fir beetle infestations to explode in coming years as well as beetles continue to expand their known territory.

What can we do? Limiting greenhouse gas emissions and doing our best to fix the mess the planet currently finds itself in is a start. An intriguing idea that Six floats is that trees are some of the most genetically diverse species on the planet, and that our current methods of pest management are not the answer. She notes forests are not naturally homogenous (while replanting usually is), and that evolution may be the forests’ saving grace.

“We don’t replant with stock that may not be genetically correct and we don’t thin or cut down trees that may have been selected by beetles or drought to survive,” Six tells the e360 as a possible solution. “And we have to get smart about how we are treating our forests if we’re going to help nature’s process of adaption to proceed.”

Revelstoke take notice, the beetle has come our way.

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