ASOTIN, Asotin County — Benjamin Zamora looked toward the brown haze of the 48,000-acre wildfire scorching part of southeastern Washington yesterday and saw an experiment on a grand scale.

The Washington State University professor has long studied how wildfires shape the region's forests. In the past few years, he burned and selectively logged a hillside just a few miles from the front line of what's been dubbed the School wildfire.

Now, Mother Nature is opening up a much bigger laboratory in a forest that had gone decades without fires that once shaped the ecology of the area.

"I'm really going to be curious as to what that area looks like," he said, gazing in the direction of the fire.

The wildfire, thought to have started after a tree fell on a power line, has burned through forests grown thick with fallen and fire-prone trees. The decades without the blazes that once periodically purged this forest likely stoked the fire's ferocity, Zamora said.

The largest wildfire in Washington state so far this year, it had burned 109 houses and cabins and was threatening 120 more yesterday afternoon, fire officials said.

The fire, and a number of smaller blazes, prompted Gov. Christine Gregoire yesterday to declare a state wildfire emergency, ordering state agencies to contribute to firefighting efforts. She also announced she has alerted the National Guard of a possible call-up if crews need help.

More thunderstorms with lightning were forecast for parts of the state early today, raising fears that fire crews could be stretched even further if new fires start. Fire officials were most concerned about the 1,500-acre Harker Canyon fire northeast of Davenport, Lincoln County, and west of Spokane. It has forced the evacuation of about 20 homes.

While the School fire has brought destruction — leaving at least six families homeless and costing $4.9 million to fight so far — it will also help return the area to a more fire-resistant, natural state in coming years, scientists say.

Zamora's experiment offers a glimpse into that future. Funded by a $100,000 federal grant and executed with the local Forest Service office, it's meant to gauge how the forest reacts to different tactics to reduce fire risk.

Standing on a dirt road high in the Umatilla National Forest, he pointed across a narrow valley to the hillside he's been working on.

That, he said, is something like these forests once looked. Big, fire-resistant ponderosas and western larches stood far apart from each other, surrounded by brown grass and the occasional bush. Patches of saplings dotted the slope.

There, a fire would probably sweep through the underbrush fast but stay relatively cool as forest fires go, Zamora said. The flames would have trouble climbing into the tops of the trees and jumping to other trees, a more destructive and dangerous event known as a crown fire, which probably has occurred in the School fire.

Instead, the fires would burn out underbrush and small, dead or fallen trees and kill off grand firs and Douglas firs whose thin bark leaves them vulnerable. The fires also could open up an area for grass and other plants savored by elk that roam the Blue Mountains.

But the section of the mountain range where the wildfire burns has earned the moniker the "Asbestos Forest," after going for so long without a big fire.

As a result, hillsides are crowded with trees and underbrush. Grand firs and Douglas firs have flourished, until now unchecked by flames.

The force of flames in such a stand of trees was illustrated a few miles away, where firefighters intentionally set the trees ablaze in order to deprive the uncontrolled fire of fuel if it ever reaches there.

The fire crackled through the limbs of fallen trees. Suddenly a tree would erupt with a whoosh, shooting flames 100feet up and heating the air 20 yards away.

After the wildfire finally dies, expect grasses to flourish amid the burned-out areas and for ponderosas and larches to resume the dominance they once held, Zamora said. Large trees or areas that escaped the most intense heat will help seed other areas.

But whether that stays the same depends partly on how the forest is managed, and whether agencies use controlled burns to mimic nature, he said.

The Umatilla National Forest, which encompasses much of the Blue Mountains, is already using controlled fires and logging that leave large trees behind to simulate natural forest fires, Zamora said.

But the forest also bears the signs of conventional clear-cuts where virtually every tree is leveled. In one opening near the front line of the fire, a sea of chest-high trees filled the area, all the same species and age.

"Now that's a monoculture," said Lori Hammer, an information officer for the fire response. "That's actually a fire hazard."

While there is broad agreement that many forests are clogged and prone to massive wildfires from years of aggressive firefighting, using logging to remedy the problem has proven controversial. Disputes have focused on how much logging should be allowed in the name of forest health, and what regulations should ensure it doesn't pave the way for environmental damage.

In his experiment, Zamora left some swathes untouched, set others on fire, and logged and burned others, leaving behind the occasional big tree. Now he's measuring how trees and grass grow back, how elk and deer use the area, and how much the soil erodes.

While his results aren't complete, Zamora said his general findings are encouraging. He has seen little sign of large-scale erosion. Evergreen seedlings are sprouting, and elk seem to be spending more time there.

But with the funding expiring for that project, he is turning his eyes toward land still smoldering and burning. More than a decade ago he catalogued plots of land in that area, creating a detailed account of what things were like before the fire.

"It would really be great if I could get sponsorship to go back," he said.

The Associated Press contributed to this report.

Warren Cornwall: 206-464-2311