Western Forests Highly Susceptible to Extensive Outbreaks of Bark Beetle (4/24/2008)

Adult mountain pine beetle - Dendroctonus ponderosae

Lodgepole pine forests have characteristics that could lead to large bark beetle outbreaks in the western U.S., according to a University of Idaho researcher.

Jeffrey Hicke, assistant professor of geography, says that a large percentage of these forests have sizes, ages and densities of lodgepole pines that leave them susceptible to mountain pine beetle attack, potentially resulting in significant losses to these forests in Idaho and Washington. Mountain pine beetles thrive in warm, dry forests and attack lodgepole pines that grow on roughly 15 million acres of western forestlands.

"Our results show that a large proportion of lodgepole pine forest is in a condition susceptible to outbreak," said Hicke. "The combination of increasingly suitable climate and large amount of susceptible host trees will lead to severe and frequent outbreaks in the future."

Hicke's research concludes that roughly 46 percent, or seven million acres, of lodgepole pine forest is highly susceptible to mountain pine beetle attack. This could lead to at least a 34 percent loss in forest biomass should an outbreak occur. The research further shows that the highest level of vulnerability is in the Rocky Mountain and Cascade Mountain ranges.

This research is an important contribution to the U.S. Geological Survey's Western Mountain Initiative, which aims to understand and predict the responses of Western mountain ecosystems - emphasizing sensitivities, thresholds, resistance and resilience - to climatic variability and change.

Hicke's research paper, "Mapping lodgepole pine stand structure susceptibility to mountain pine beetle attack across the western United States," was published April 5 in the scientific journal Forest Ecology and Management.

His research is supported by grants from the USDA Forest Service, the U.S. Geological Survey Western Mountain Initiative and the National Science Foundation.

Note: This story has been adapted from a news release issued by the University of Idaho

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