GRANTS PASS, Ore. – Logging is not very effective at controlling insect outbreaks, and can leave a forest less able to withstand another infestation of tree-killing bugs, according to a new study by the Xerces Society for Invertebrate Conservation.
“There is no evidence that once an infestation has started we can log our way out of it,” the report said. “Even thinning, which is widely promoted as a solution, has mixed results. Caution should be used when thinning for long-term pest suppression because of the potential for increasing the simplicity of a forest and thus its susceptibility to future infestation.”
The yearlong review of more than 300 studies published in scientific journals was done to gather the existing literature at a time when logging and insects are becoming an increasingly political issue across the country, Xerces Society director Scott Black said Tuesday.
The 2003 Healthy Forest Restoration Act, enacted to streamline environmental analyses of national forest logging to reduce wildfire danger, also makes provisions for controlling insects, particularly in the southeast. It was bitterly opposed by environmentalists as an excuse to promote logging.
The review concluded that logging and extinguishing wildfires over the past century has created forests with less complex mixes of species, which are less able to withstand insect outbreaks.
It added that insects are an important part of forest ecosystems, breaking down dead wood into soil, serving as food for birds and other wildlife, and contributing to the regeneration of some types of trees, such as lodgepole pine, by creating conditions for the fires needed to open their cones.
Chris West, vice president of the American Forest Resource Council, a timber industry group, criticized the review, saying that thinning was a well-documented strategy for increasing the vigor of trees and their ability to naturally fight off insects.
“Society’s demand for wood products is our reason for being in business,” West said. “We can either harvest trees that are in a weakened condition or infested with insects, or we can cut green trees somewhere else.”
The Xerces Society is a nonprofit organization based in Portland, Ore.
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