A vicious cycle is brewing in Utah: Bark beetles are killing a lot of trees in the state. Dead trees are fuel for wildfires, which experts say contributes to global warming. And climate change is now being blamed for an increased population of bark beetles.

The Dixie National Forest bears one of the most obvious signs in Utah of the mark being left by a tiny tree predator commonly known as the bark beetle, a wood-boring insect that in large enough numbers can decimate an entire forest.

"We're talking hundreds of thousands of acres they have basically been wiped out — pretty much the entire spruce component in the Dixie National Forest," said Colleen Keyes, forest-health program manager for Utah Division of Forestry, Fire and State Lands. "It's really something to see. You would be very surprised. It's hard to describe until you see it — it's just dead trees as far as the eye can see."

From 1990 to 2005, just two types of wood-boring beetles affected more than 466,000 acres in Utah.

The huge bark-beetle family includes the Engleman spruce, Douglas fir and mountain pine beetles, native insects that have all been ravaging pine populations

throughout Utah and the West. In the Dixie National Forest, it's the spruce beetle, mere millimeters in length, doing the damage.

The U.S. Forest Service's Bark Beetle Technical Working Group calls the bark beetle an "agent of change" in conifer forests in the Rocky Mountain region, noting that the insects can play a critical role in the development and rebirth of Western forests.

In some areas, the beetle's numbers are considered to be in outbreak proportions, with potential negative impacts to recreation, wildlife and watersheds.

"It's very evident — it's very big," Dixie National Forest spokesman Kenton Call said about what the spruce beetle has done.

Most of the forest die-off has happened in recent years, he said. Dixie National Forest workers are now trying to salvage or thin out dead timber, which fits into the Forest Service's "scenery enhancement" project in a heavy-use area where there are cabins.

Call also said the problem with beetles is too big and complex to lay blame in just one or two areas, though he has heard more talk at the highest level of his own agency about the role of global warming.

"We're wrestling with the notion of how we mitigate the impacts of climate change, how we adapt in terms of our management," Call said.

In August, the National Wildlife Federation released a report that said global warming is increasing the wildfire risk in the West, leading to an accumulation of unsafe fuel loads that also serve as perfect breeding grounds for bark beetles. Once the bark beetles take hold, they add even more to a forest's volume of fuel for wildfires, which further contributes to global warming by releasing carbon dioxide into the atmosphere and decreasing a forest's ability to absorb carbon dioxide.

Keyes said old forests need proper management in order to reduce their susceptibility to a bark-beetle outbreak. Many bark-beetle varieties target weak or dying trees, usually older ones, that are less able to survive an attack. Years of fire-suppression efforts in forests have allowed those trees to become more dense.

People are building homes in some of those areas, and fire crews are being sent to areas of the forest that might otherwise be allowed to naturally burn, she said. She believes the forests need to be thinned and older trees removed.

"If we're not going to do it, the beetles will do it for us — and they won't pick and choose," she said.

Last February, the Utah Environmental Congress filed a federal lawsuit against the U.S. Forest Service, trying to stop the federal agency from logging 10 million board-feet of timber in the Dixie National Forest. The Forest Service had cited bark-beetle infestation as the reason for logging the timber.

But the environmental group's lawsuit claimed that a Forest Service-prescribed burn in 2002 went out of control and was ultimately the reason for the beetle outbreak. The lawsuit said Forest Service mismanagement caused a domino effect, requiring more time and less human intervention for healing.

Keyes said that the best hope this year for letting nature control bark-beetle outbreaks would be a cold Utah winter with several consecutive days of minus 40 or below at higher elevations. If that doesn't happen, Keyes said, the Ashley and Uinta-Wasatch-Cache National forests may see years of increased beetle activity.

E-mail: sspeckman@desnews.com