Putting a "Best Before" Date on Beetle Wood

Dr. Kathy Lewis
Kathy Lewis. Download the high-resolution image.

"We’re not saying that after two years the wood is of no value, but this kind of information is valuable..."

Millions of dead trees later, it’s almost pointless to talk of the mountain pine beetle outbreak as a new issue. But thanks to forestry professor Kathy Lewis, we’re closer to identifying a “best before” date for all of those red trees. 

From the forest industry’s perspective, shelf life is a big concern. What happens to the wood quality after a tree is attacked? How long can the dead trees stand in the forest before they’re of no use? UNBC professor Kathy Lewis is starting to answer those questions through her research on the shelf life of the trees left in the wake of the tiny bug with the voracious appetite.

The research has discovered that major changes do occur rapidly, but that after about two years, there is little additional decline in wood quality; at least until the tree falls down. Among the changes that occur almost immediately are the tell tale blue staining of the outer wood, a decline in moisture content, and an increased prevalence of cracking throughout the inside of the tree. 

Graph of tree shelf life.
Graph of tree shelf life. Download the high-resolution image.

“We’re not saying that after two years the wood is of no value, but this kind of information is valuable to determining the most appropriate products for this wood as well as the technologies we’ll require to process it,” says Dr. Lewis, who was named BC Forester of the Year in 1996 in recognition of contributions to forestry teaching and research. 

The research was carried out in the University’s I.K. Barber Enhanced Forestry Lab, which has state-of-the-art equipment for assessing wood quality and conducting experiments on forest genetics and growth patterns. Using a lab specially outfitted with equipment to analyze tree rings, the researchers were able to precisely identify time-since-death and match the dates to the data they gathered about wood quality.

For the study on shelf life, Dr. Lewis and her research team examined 450 trees from various locations to the southwest of Prince George, near the epicentre of the current pine beetle outbreak. This outbreak is believed to be the largest insect infestation in North American history. To date, the pine beetle has infected 87,000 square kilometres.

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Dr. Lewis's Bio

Dr. Lewis is a forest pathologist/microbial ecologist with research interests in the role of pathogenic fungi in natural ecosystem processes, and the long term effects of forest practices on forest health. In particular Kathy studies the relationship between biotic disturbance agents and stand dynamics, and the population genetics of forest pathogens as influenced by forest management practices. 

Kathy Lewis​
Associate Professor, Ecosystem, Science & Management (Forestry)

PhD Forest Pathology
(Oregon State University) 

(250) 960-6659

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