Utah's fir trees at risk from
balsam woolly adelgid

June 20, 2024
Above: A drone photograph in Farmington Canyon shows the several level of infestation of balsam woolly adelgid infesting subalpine fir.

A nonnative tree-killing insect is invading northern Utah, attacking subalpine fir and potentially triggering yet another die-off of the region’s long-stressed conifer forests.

Introduced from Europe into the Pacific Northwest about a century ago, the balsam woolly adelgid (BWA), or Adelges piceae, was first detected in Utah in 2017 and has been spreading around the Wasatch Mountains, visibly affecting many of the popular recreation canyons outside Salt Lake City.

New research from the University of Utah, conducted in partnership with the U.S. Forest Service, has documented the current extent of the adelgid infestation and created a model for predicting its severity around the Uinta-Wasatch-Cache National Forest.

The study documented a clear relationship between the infestation’s severity and temperature, according to lead author Mickey Campbell, a research assistant professor in the Department of Geography (soon to be merged with the Environmental Studies program and renamed the School of Environment, Society, and Sustainability.)

PHOTO CREDIT: MICKEY CAMPBELL The crowns of infested fir trees exhibit crown deformities.

“We took that climate-to-severity relationship along with a series of climate projections and we were able to map current and future exposure to BWA damage at a high spatial resolution,” Campbell said. “The idea [is], in 2040, 2060, 2080 and 2100, based on these different climate projections, determining how exposed these areas are to the potentially damaging effects of BWA. And indeed, we find that for an insect that prefers warmer areas, a warming climate is going to provide it with more opportunity to cause damage.”

The role of climate change

The study appears this month in the journal Forest Ecology and Management. Co-authors include U Biology Professor William Anderegg, director of the Wilkes Center for Climate Science and Policy. [The center hosts its annual Climate Summit on May 14-15, where Anderegg will give opening remarks.]

According to Anderegg, the new study suggests climate change is playing a role in Utah’s adelgid infestation.

“The main pieces of evidence are how strongly temperature is related to the spread and severity of BWA,” said Anderegg, a specialist in forest ecology. “That tells us at the very least as temperatures go up, we should be concerned about more spread and higher severity infestation.” Covering the Wasatch, Uinta, Bear River and a few lesser mountain ranges in northern Utah, this national forest is among the nation’s busiest for recreation. It features five major ski areas that border several others and sees more visits than all of Utah’s national parks combined.

Read the full article by Brian Maffly at @TheU.

Hear the Interview of Dr. Mickey Campbell ( Lead Author and research assistant professor in the Department of Geography) with Ross Chambless on the spread of balsam woolly adelgid in Utah on The Wilkes Center for Climate Science & Policy page.