An ugly and puzzling problem in our forests has the attention of two Utah insect scientists.
Barbara Bentz and Liz Hebertson study how beetles no bigger than a black bean are killing vast stands of conifers.
You might call them CSI's of the forest.
And, with winter coming on, one the most important tools in their probe will be the weather gauges on Utah's mountainsides.
It turns out that the shorter, milder winters in Utah's mountains have been a boon to the beetles behind the killing. The weather changes, perhaps a local reflection of global climate change, allow the beetles to multiply more rapidly.
For the Spruce bark beetle, for instance, a life cycle that used to take two years now often takes just one year.
For the Mountain pine beetle, a different species, winter nights don't get frigid enough, long enough to kill off many beetle communities the way they sometimes did in the past.
Between the longer summers and warmer winters, there are many more beetles, more insect mandibles chewing on the forests, strangling the trees by cutting off the food and water that nourish them.
More than 200,000 acres of Utah pine, fir, spruce and Douglas fir trees are in various stages of death because of beetles. Ultimately, foresters would like to know what needs to be done to stop the slaughter. But they have not discovered any simple answers.
"It's so complex," said Hebertson. "There is so much we don't know."
An entomologist for the U.S. Forest Service's Forest Health Protection office in Ogden, she spends her days cruising western forests, tracking the marauding insects and huddling with other foresters on how to stop the devastation. She looks scientifically at both the forests and the trees.
But the "carnage" she studies is not easily overlooked by anyone who spends time in Utah's forests or anyone who looks up at its forested mountain landscapes. The dead zones appear as dappled patches of bright red and gray trees - even in the green of spring.
Up close, she can easily spot trees in peril. Some, like the green-needled Ponderosa pine she approached one recent morning, are already dying.
Hebertson looks for dribbles of clear or cloudy sap that pour from holes in the bark. She looks for piles of woody dust at the base. Both are signs that beetles have already burrowed in. But the dust piles mean the beetles have already killed a tree.
She chips away a plank of bark. When she peels it away, there are vertical "egg galleries," pencil-width tunnels where invading beetles have positioned eggs. Horizontal channels mark where beetle larvae have fed until they can set out on their own.
All four types - spruce bark beetles, mountain pine beetles, pinion ips and Douglas fir beetles - together have made an all-you-can-eat buffet of Utah's conifers.
"There are very few stands right now that aren't infested, said Larry Johnson, timber coordinator for the Wasatch-Cache National Forest.
While spruce beetles spread through southern Utah forests over a decade, the numbers of Mountain Pine beetles have exploded on the north slope of the Uintas in the past four years, he said.
Many factors are to blame:
The dry weather stresses trees and makes it hard for them to defend themselves.
Tree thinning that can help slow the beetles' spread has met environmentalist and aesthetic objections.
Public pressure, often from people who have built woodland homes, has forced forest managers to let trees grow into the big, tasty banquet that has fueled the beetles' expansion throughout the state.
And now wildfires that might have naturally thinned the forests have to be doused to protect those homes even though fire can help limit the beetles' spread.
"We just hazve a lot of susceptible landscapes," said A. Steve Munson, a forest health protection manager with the Forest Service in Ogden.
"We have kind of set the table for those insects, a banquet."
Bentz, who works at the Forest Service's Rocky Mountain Research Station in Logan, has been studying beetles for three decades. Her research focuses on the complex relationship between the beetles and temperature.
She notes that the gradual, upward shift in low temperatures already appears to have affected beetle populations. Beetles can withstand temperatures as low as 35 degrees Fahrenheit. They have anti-freeze chemicals in their blood.
This natural quality, plus the higher temperatures, has pushed the beetle epidemic higher into the mountains and made it spread rapidly to more forestland.
Following these trends - beetle species by beetle species - will help forest managers make educated projections about what is happening to the natural balance throughout the West.
As they watch thousands of hour-by-hour temperature and snow readings over the winter, research scientists like Bentz are seeing clues that suggest changes not only on the trees, but on the water supply and the other wildlife.
"The outbreaks," she said, "may be so big [that] we know we are seeing a huge change."
Hebertson points out that managing the forests in this environment is difficult. Many of the possible fixes - pheromone patches, chemical sprays and forest thinning, for instance - don't make sense. They might be too expensive or create other problems without offering a reliable, long-term fix.
"People need to see the carnage," Hebertson said, "to understand [the beetle outbreak] can impact the resources they enjoy."
On a stop last summer at Provo River Falls, two women asked to make sense of what they were seeing.
"I just kept noticing all the dead trees," said Suzanne Edwards, a Park City resident.
"If you can save the trees, I'm all for it," added Kenlyn Dollar, a Floridian with a home in Park City.
In the end, Hebertson was able to reassure them. "The stands will come back over time," she said.
The forester sees public education as a critical part of the beetle solution. When they are reminded, people understand that beetles and their tree-consuming ways are essential to the forest cycle. They have been for thousands of years, and the trick seems to be understanding how their role may be changing in the future.
fahys@sltrib.comThe Salt Lake Tribune
