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Making the best of beetle wood

By HANNAH HOAG | DEC 03 2007
Making the best of beetle wood
Instruments installed at the top of a 33-metre tower measure the levels of carbon dioxide in the atmosphere above beetle-infected forests. Photo: University of Northern British Columbia

When you’re given lemons, the old saying goes, make lemonade. That’s the situation at the University of Northern British Columbia, where at least a dozen researchers are working on 28 different projects to understand and mitigate the devastating impact of the mountain pine beetle.

Over the past several years, large swaths of the normally green pine forests of northern and central British Columbia have been painted rust-orange and grey. The pine beetle has killed more than 58 percent of the pine trees in the region and the province estimates that by 2018 nearly three-quarters of the pines will be dead. The epidemic is thought to have peaked in Prince George, the epicenter of the outbreak, leaving researchers at UNBC to focus on the future and address the aftermath of the beetle’s rampage.

Wood drives the economy in Prince George. About 15 percent of the population logs, transports, cuts or processes the region’s wood. The pine beetle’s spread threatens the future of that industry and the region’s well-being.

In the short term, the infestation has led to a harvesting boom, as companies rush to cut the still-standing dead trees before they lose their value as lumber. However, it would be better for the industry economically if it could stretch out the timber supply for as long as possible.

Kathy Lewis, a professor in the forestry department at UNBC, has been studying the shelf life of the dead trees by measuring the changes to the trees’ biophysical properties over time. Normally, trees are harvested when they are alive and their wood is still moist. As the dead trees lose moisture, they become more brittle and prone to breaks during handling, cutting and processing.

Her group studied 450 trees from locations southwest of Prince George that had been killed within the last five years. Their first challenge was determining the time since death. Other studies used external indicators, including needle colour, to determine the length of time since the tree had died. Dr. Lewis’s group aimed to be more accurate. They lined up the tree rings from beetle-killed trees with a live-tree chronology to figure out the year the trees died. They then matched tree quality with time since death.

Dr. Lewis found most of the changes occur rapidly – within the first two years – as the tree loses its moisture. Dry trees crack more, but they are also less susceptible to decay. Dr. Lewis suspects more changes occur six to 10 years after the tree has died, and she has received funding from the federal Mountain Pine Beetle Program to continue the project. She says forest managers will be able to use the information to plan salvage harvests to recover the greatest value from the wood and maintain a wood supply for the future.

In one of many related projects, Dr. Lewis is collaborating with UNBC wood product specialist Ian Hartley and graduate student Sorin Pasca, who have developed an eye-pleasing concrete made of cement and wood chips from the trees infected by the mountain pine beetle. The material can be cut into boards, moulded, sanded and polished. It could be used for everything from wallboards to countertops to flooring, says Mr. Pasca, and it has an “outstanding external appearance.”

The novelty behind the product is the fortunate compatibility of dead pine wood with cement, explains Mr. Pasca. The sugars and resins in most woods make them incompatible with cement, “but most of these are gone in the dead beetle wood,” he says.

Mr. Pasca’s product offers an application for dead trees that no longer make the cut for lumber. Only small chips of wood or sawdust are needed to make the wood-cement mixture, so trees of almost any age can be used, as long as they aren’t in the advanced stages of decay.

Meanwhile, Art Fredeen, a forest ecophysiologist at UNBC, is looking at the effects the pine beetle infestation will have on atmospheric greenhouse gases. “The forest is a huge carbon-dioxide bank account with its savings stored in the trunks of the trees,” he says. But when trees die, they stop photosynthesizing, begin to decompose and release carbon dioxide into the air, becoming carbon sources.

Dr. Fredeen is measuring carbon dioxide emissions from standing forests killed by the pine beetle and forests that have already been logged. He wants to find out what effect the logging activity is having on carbon dioxide levels in the atmosphere. “It’s possible the beetle is going to result in a large pulse of carbon dioxide into the atmosphere after it is all done,” he says.

Other UNBC researchers, including entomologist Staffan Lindgren and ecosystem scientist Dezene Huber, are looking at the pine beetle’s spread to spruce trees, a major concern. Another researcher, environmental engineering professor Steve Helle, is investigating ways to convert beetle wood into ethanol. Still others are looking at pine beetle genetics and beetle flight patterns to predict how the infestation may cross east into Alberta.

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