We’ve been watching the Mountain Pine Beetle for a while as it’s feasted upon the pine forests of British Columbia, infecting nearly 710 million cubic meters of the “1.35 billion cubic meters of saleable pine in the province (CBC News).” It is difficult to imagine that a beetle, no bigger than a grain of rice, can cause so much damage. Then again, when that beetle has over a trillion friends, it is not so difficult to fathom. But new reports from the provincial Ministry of Forests and the Council of Forest Industries indicate that the infestation may have reached its peak, thanks in part to recent cold weather and a declining food supply.
It’s simply impossible to overstate how rapid—and devastating—the beetle’s spread has been. But it’s wrong to think of it as a “natural” phenomenon. Rather, it’s a regrettable—if not entirely unforeseeable—consequence of two entirely of human forces: timber management practices that have left unusually high concentrations of the precise sorts of trees that beetles like to feast on; and a climate-warming trend that’s been simply ideal for beetle reproduction. In other words, the pine beetle has enjoyed an all-you-can-eat buffet.
The result: ecological devastation on a truly massive scale.
A shocking visual: Clark cobbled together the following animation from this Canadian government report (pdf link) on the mountain pine beetle’s infestation of British Columbia’s interior forests. The beetle epidemic started with scattered, isolated outbreaks in 1999, and within 6 short years spread to cover an area about three times as large as Vancouver island. The red spots represent places affected by beetle outbreak. If your internet browser lets you view animated graphics, you should see the infestation spread like cancer.
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Good news about declining populations can’t begin to compensate for the damage done to date. But good news is good news.
The ministry’s annual survey on the pine beetle’s spread in 2007 seems to indicate that it is slowing, said Doug Routledge, COFI’s vice-president.
The survey shows that the pine beetle had infected 710 million cubic metres of lodgepole pine forests at the end of 2007, up from 582 million cubic metres at the end of 2006.
Routledge said that is an increase by a factor of 1.3, which is below the growth rate of 1.4 to 1.6 over the past five years leading officials to believe the beetle’s spread is past its peak “The primary reason is that it has pretty much eaten itself out of house and home,” Routledge added. ‘It’s running out of food.’ (Times Colonist).”
Maybe we’re just hungry for some sunny news amid the gloomy picture, but the peaking of the beetle infestation does represent a sliver of hope—not only for the industries and communities that rely upon timber, but for fragile salmon habitats as well.
Since the infestation began, forest cover along the salmon runs has decreased. Forest cover regulates the temperature and levels of streams and rivers home to the salmon runs. Boughs of the dead, beetle infected pine trees do not “intercept snow and rain, or shade the forest floor to slow the spring snow-melt (Times Colonist).” As a result, the snow packs are greater and melt faster, causing flash floods and higher river flows that erode the stream beds of the salmon runs. The lack of shade over these habitats also causes the water’s temperature to rise, decreasing the salmon’s food supply and creating a difficult environment for the salmon to thrive in. However, with the beetle’s declining population, efforts to protect and rebuild salmon habitats get a boost.
The beetles’ smorgasbord has run out – they’ve taken “all you can eat” to a new extreme and they’ve left the place in shambles. But it looks like the end of the Mountain Pine Beetle epidemic may be near – at least this phase of it.
Good news for British Columbia…bad news for coleopterologists (or do they get excited about anything beetles do? – beetle mania?).
Image courtesy of Allan L. Carroll, Ph.D.Research Scientist Natural Resources Canada, Canadian Forest Service, Pacific Forestry Centre, Victoria, BC.