If the climate continues warming as predicted, spruce beetle outbreaks in the Rocky Mountains could become more frequent, a new multi-year study led by Colorado State University finds.
While insect disturbances naturally cycle through forests, the current spruce beetle epidemic affecting Colorado Engelmann spruce forests has been one of the largest on record. The Colorado State Forest Service estimates that since 1996, over 40 percent of the state’s high-elevation forests, encompassing an area larger than Delaware and Rhode Island combined, have already been affected by this latest cycle. According to the research team, this has resulted in a widespread die-off of trees valued for their contributions to clean water, recreation and wood products.
The study, recently published in Environmental Entomology, provides new clues about spruce beetle behavior. Study co-authors Seth Davis, assistant professor in CSU’s Forest and Rangeland Stewardship department, and Isaac Dell, a graduate student at Montana State University, combined new beetle population and environmental data with climate projection models to see what could be in store in the future.
“Unfortunately, what we found suggests there is no best-case scenario,” said Davis, a specialist in plant and insect interactions. “Even if the climate increases by just one degree Celsius, we can expect spruce beetles to reproduce at higher rates than we’ve seen, with more time to invade trees.