Wildfire linked to bugs, warming

Wildfire linked to bugs, warming

26 July 2008

published by www.thenewstribune.com


USA — A forest fire burning southeast of Mount Adams is the latest manifestation of a troubling relationship between climate change, insects and wildfires, scientists and land managers say.

A lightning strike started the Cold Springs fire July 12 in dead and dying trees. As of Friday, the fire had covered 12 square miles in steep terrain, destroying valuable timber and choking off access to hiking trails and campgrounds.

The blaze began in a remote area of Gifford Pinchot National Forest that was already ailing, its drought-stressed trees under siege by insects.

“I don’t think there are too many people who are surprised it caught on fire,” said Terry Shaw, a plant pathologist and chief scientist at the U.S. Forest Service Western Wildland Environmental Threat Assessment Center in Prineville, Ore.

The first 12 days of firefighting cost more than $8.6 million. More than 1,100 people were deployed to fight the fire at its peak. Fire bosses don’t expect to contain the blaze until late next week.

On Thursday, U.S. Forest Service researcher Susan Hummel visited the smokey, charred area where the fire was discovered. “The fire killed off what wasn’t already dead,” said Hummel, who had previously identified the “whole suite of diseases and insects” that had attacked the subalpine firs and lodgepole pines there.

From its original point, the blaze moved east, skipping from the national forest to private timberlands, Yakama tribal lands and forests managed by the state Department of Natural Resources.

The area is part of a transition zone on the east side of the Cascade Mountains, where firs familiar to Western Washington residents give way to pines more common in drier climates.

Even before the Cold Springs fire , scientists exploring the connection between wildfires and climate change had identified the site as vulnerable to burning this summer, said Ron Neilson, a U.S. Forest Service bioclimatologist in Corvallis, Ore. Neilson leads a group of researchers who use computer-based climate and vegetation models to predict wildfire risk.

OKANOGAN ANOTHER HOT SPOT

Besides the Cold Springs fire site, another forested hot spot on Neilson’s wildfire forecast map is the Okanogan region, near the Canadian border. That’s where the so-called Tripod fire raged over more than 177 square miles in 2006. It cost more than $68 million to fight that fire.

Among other things, the Tripod fire put a spotlight on the relationship between insects and wildfires.

Neilson is among those who validate the connection. “You trip the drought domino and you also trip the bug domino,” he said. “Bugs will basically make things worse. It acts like a positive feedback loop.”

So far, Nielson’s group of wildfire prognosticators have not factored pests into their computer models.

“We’re just getting into this fire and insect interaction,” said Don McKenzie, a Forest Service research ecologist who works at the Pacific Wildland Fire Science Laboratory in Seattle. Among other things, his group has studied how bark beetles contributed to the Tripod fire.

“It’s tough,” he said. “Projecting what’s going to happen at a particular place, we haven’t got there yet.”

ANNUAL SURVEY WATCHED

Meanwhile, Karen Ripley, an entomologist, or insect scientist, keeps a close eye on annual aerial surveys used to map pest-infested trees in forests across Washington. She is forest health program manager for the state Department of Natural Resources.

When she found out about the Cold Springs fire, what first came to mind was an ongoing western spruce budworm outbreak that’s plagued the region since 1992. Budworms are caterpillars that eat needles.

Forest Service literature describes them as the “most widely distributed and destructive defoliator of coniferous forests in Western North America.”

When budworms infect trees, that also makes the trees susceptible to invasion by beetles, which burrow into bark and gradually kill trees. Scientists have proved that warm temperatures make beetles more voracious and reproduce faster.

Warm temperatures also stimulate plant growth. But trees need moisture, too. And trees suffering from lack of water are more vulnerable to insects.

“Drought definitely has a part in this,” Ripley said of the Cold Springs fire.

To reduce fire risk on state-managed forests, the DNR has thinned stands to foster the growth of more drought-resistant species, such as Ponderosa pine and larch, Ripley said.

It’s too early to say whether the treatment in the Cold Springs area limited fire losses. After the fire is out, she plans to visit the site. “I’m pretty disappointed in that fire,” Ripley said.

As for budworms, Ripley said Douglas firs, grand firs and subalpine firs are particularly vulnerable. Successive annual outbreaks weaken trees, then destroy them.

Also near Mount Adams, another pest called the balsam woolly adelgid has complicated the scenario. It’s an invasive, aphidlike bug that emits a toxin and kills firs.

Ripley pointed out that many forests east of the Cascade Mountain crest are vulnerable to insects. The western spruce budworm, in particular, has done damage that’s obvious to people traveling through many of the state’s mountain passes. “It’s a very widespread outbreak,” she said.

Ripley said problem areas include Chinook Pass; along U.S. 12 east of White Pass and Rimrock Lake in Yakima County; Blewett Pass on U.S. 97 between Cle Elum and Leavenworth; and Highway 20 west of Mazama in Okanogan County.

This is particularly troubling because of recent Canadian research that shows fires in budworm-infested forests throw burning material, also known as spotting, twice as far as other fires, Ripley said. Spotting spreads fires to unburned areas.

STUDYING CLIMATE CHANGE

While the budworm epidemic is worrisome, it doesn’t mean the entire east flank of the Cascades is about to go up in flames, said Shaw, of the Western Wildland Environmental Threat Assessment Center. “But certainly portions are going to go up, as they already have.”

For the past few years, forest managers have blamed past fire suppression efforts for allowing forests to grow too thick and increasing the risk of major firestorms, such as the Tripod fire.

But new analyses of the effects of global warming appear to suggest that climate will influence the incidence of fires more than past forestry practices, said McKenzie, who works at the Seattle fire science lab.

“We’re seeing that climate change is becoming more and more important,” he said.

As for the Cold Springs fire, not everyone agrees that climate contributed to it. Hummel, the forester who has studied areas burned by the Cold Springs fire, said she’s not a climate expert, but doesn’t blame global warming.

“This fire behavior is consistent with the ecology of these forests,” she said.


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