The dog that didn’t Bark

May 18th, 2007
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Not long ago I attended a meeting of the B.C. Institute of Agrologists up in Prince George. The theme was an urgent one: “The Mountain Pine Beetle and Our Future: Life after Beetle Mania.” Nifty title. The pine beetle’s a huge issue throughout rural B.C. – and Alberta readers, you too have a dog in this fight, as it were because the pine beetle has crossed the provincial border.

On the field trip the words I was waiting for didn’t come: “global warming.” David Suzuki and others insist global warming is the cause of the  mountain pine beetle crisis, implying that all those SUVs spewing carbon dioxide have caused devastation in the bush.

Not so, said the real scientific specialists. The beetle is endemic to B.C.’s vast lodgepole pine forests, and normally plays its role in the ecology. The scientists have concluded that the most important reason the current outbreak, particularly its colossal size, is the skewed age distribution in the current lodgepole pine forest.

Mature and over-mature pine are the beetle’s preferred target. By the 1980s B.C.’s lodgepole pine forests were heavily skewed to mature and over-mature age classes. The situation was ripe for attack. A major outbreak in the Chilcotin early that decade was halted by the right weather – a severe cold snap in October, a time of year before the beetle has prepared its natural defences to extreme cold.

The reason most think that the “age-class distribution” became as skewed as it did is the success of fire suppression over decades. Fewer and smaller fires meant that the forest ceased to be fragmented into a variety of age classes, including large immature stands that are at lowest risk of attack. A demographically fragmented forest also helps prevent the build-up of extremely high beetle populations, limiting typical outbreaks to smaller forest areas (which can still appear huge to human eyes).

However, there are indications something else could be involved. In the Central Interior, the 140-year age class is distinctly over-represented. This demographic cohort predates effective fire protection by a good 60 to 80 years. Essentially, something really big happened on the landscape that resulted in large areas of new lodgepole pine stands establishing around 1860. There is one tantalizing record from a fur trader’s journal from around that time that refers to vast areas of “red forest”.

This tells us several things. First, that something huge could have happened before. Second, that a huge infestation can perhaps create its own long-term cycle. Third, if it happened before, then perhaps this infestation can’t be pinned on burning of fossil fuels.

It certainly appears that 15 years of moderate winters have reduced the probability of a killing event like that in the Chilcotin in 1984. But it certainly appears that global warming is not a primary cause, or likely even that significant a factor in the current enormous outbreak.
Don’t you think Suzuki, being a scientist himself, should have talked with the local folks before drawing such a conclusion? Maybe he didn’t because it might conflict with his agenda.

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