The nature of fire

& & by Ruth Thorning & & & &





The Bitterroots and the Sapphires are burning--200,000 acres or more in eight days--and fire season has just begun. For the families in the East Fork Canyon south of Darby, whose homes went up in flames on Sunday, it is a disaster. For the hundreds of valley residents who have built along the urban/forest boundary, it is a constant, gut-churning worry that they might face the same fate. And for those who have been evacuated from Rye Creek, the East Fork and the little town of Pinesdale, it brings the fear of what they will--or won't--return to. But from Nature's long-term view, this is just what the valley needed. And she's taking care of her own--with minimal interference from humankind.


Sula Ranger Dave Campbell is dealing with an interesting dichotomy of feelings these days. As a professional forester, overseeing the Bitterroot segment of the Selway/Bitterroot Wilderness, he deals with fire every year. After all, it's an integral part of the natural life cycle. As a Bitterroot Valley homeowner on Altavista Loop on the slopes of Blodgett Canyon, he's also an evacuee, wondering if anything else will be left when he's allowed back.


"I guess I benefit from the two perspectives," Campbell says. "I get to see fire a lot, but never on such an intimate level before. I know what it's like to walk from room to room, trying to decide what I should take with me."


Campbell knew the valley would burn this summer--it was set up to happen last fall, he says. Last summer and fall were extremely dry. Mature trees went into the winter primed to burn, and the cold freeze-dried them even more. The early spring, hot and basically rainless, left the large living trees stressed and dehydrated. The dead fuels on the ground were tinder dry. The fire possibility quotient--called the Energy Release Component--measured higher in early spring than it had even in the late summers of 1988 and 1994, both heavy fire years.


"Fire needs three thing: fuel, oxygen and an ignition source," Campbell says. "Everything's here. Mother Nature bats last. Right now, she's batting cleanup."


The dry lightning storms that sweep through the region each summer provide a ready source of ignition, and will for weeks to come. Scientists estimate the earth receives 8 million air-to-ground lightning strikes in any given 24-hour period. About 20 percent of those--1.6 million--are high-amperage "hot" lightning discharges with the potential to start fires. When the fuel conditions are right on the ground, fires start.


And fuel conditions are right in the Bitterroot this year in a long-term cycle that has come before and will come again.


The fires on Blodgett Canyon are a bittersweet vindication to Jack Losensky. A retired U.S. Forest Service ecologist/historian, Losensky was commissioned in 1988 to prepare a report on the ecological condition on the canyons from Sawtooth to Blodgett. The conclusions in his 12-year-old report are being written in flaming script on the mountainsides today.


"We did the study because of concerns that we were losing the old-growth condition of the faces," Losensky remembers. "But we were losing the old growth because we were doing nothing. And, because of the controversy and the concerns about visuals, nothing was done."


The 1988 Losensky report detailed high tree mortality from mistletoe, mountain pine beetle and spruce bud worm; a marked increase in "ladder fuels" from seedlings and saplings under the older trees; and a shrub population that had grown out of reach of big game animals.


The unstable stands were moving toward climax in 1988, and Losensky predicted an acceleration of the conditions over the next 20 years, if they survived that long. "Increased fuel loading will also make it increasingly difficult to control fire starts," Losensky wrote, predicting a major stand replacement fire within 30 years. It lasted 12.





Nothing came from his report. Spring and fall burning was not an option because of the nature of the vegetation and the threat of uncontrolled fire. The other option would have been some type of logging operation, but that was opposed by almost everyone who had the canyon faces as a view. So the problems continued. Trees continued to die and fuel-loading grew.


Today, Losensky estimates the burnable mass on the lower slopes of the east-facing canyons at 10 to 30 tons per acre. That increases with elevation. The higher slopes are carrying 50 to 60 tons per acre. In the area of the Coyote fire complex to the southeast of Hamilton, in an ecosystem made up largely of lodgepole pines, the load increases from 75 to 100 tons per acre.


"The upper slopes will be 'stand replacement' fires," Losensky says, deploying a common euphemism in forest-fire circles. "Everything will be gone. In the lower portions there will probably be some stands left. In the open areas, the fire can run on the ground and move through, but in the ladder fuels, it climbs into the trees and gobbles them up."


This is not unexpected. Losensky speaks of the cycle of fire and the burns in the recent past--on his historic scale that's back into the 1700s. Fire burns in a mosaic. Even the most intense fires have quieter periods. In the aftermath, about 30 percent will be burned out, about 20 percent will be untouched and the remainder will be somewhere in between, Losensky says. Fire was a regular part of the cycle and ran through the valley from the Bitterroots to the Sapphires repeatedly, low-intensity burns for the most part in a largely ponderosa pine ecosystem.


But the changes in the past 150 years altered the normal cycle. Irrigation on the valley floor stopped the fire's sweep from side to side. Eighty years of fire suppression and extremely limited logging in the last 50 years on the western faces led to the development of dense understory and a decadent ecosystem heavy with Douglas fir. The area was ready for fire 12 years ago. Fire came home this summer.


Losensky lives on Mill Creek. He and his wife are also evacuees. He is not too concerned about his property. He took the expertise of a life-long career and thinned and cleared his land, leaving pockets of trees to enhance the scenery and provide game security. His home is relatively safe.


But many others are not. Losensky knows of many homes close to the forest boundary, log homes with quaint shake roofs, glistening in the baking summer sun under fresh coats of log oil.


"Insurance companies are primarily Eastern-based and they don't consider the cyclical risks we face here," Losensky says. "There's no penalty for people building in bad locations and not taking precautions."


Losensky believes that people must be touched emotionally and personally for changes to occur. Education about the high risks on the western faces and the need to do something to reduce those risks needs to take place now, he says.


"By not doing something at that time [1988], we lost the whole face and put people at risk," Losensky says. "Maybe by the time people have stared at this for another six weeks they'll be so sick of it, they'll let something be done in the future."


Campbell agrees the fires were inevitable. "Fire, particularly here, is the engine that drives the whole system. In the absence of other management action, fire is needed."


The high plateau, low-moisture ecosystem of the Bitterroot Mountains compounds the problems. Trees die and fall, but they don't decay.


"An old forester told me there are only two ways trees leave the Bitterroot, on a log truck or on a column of smoke," says Campbell. "We don't have enough moisture to allow most of the downed stuff to rot."





Fuel, oxygen, ignition. Fire is a rough beast, conceived in a million-megawatt blinding light, spanked into angry screaming life by a hot, heavy-handed wind spewed from a canyon mouth. Hungry, looking for food, energy, fuel--anything with which to grow.


And now we are finding it on the overgrown slopes of the Bitterroots and Sapphires. Feeding, growing, seeking more. Wobbly baby steps becoming surer, faster. A complex series of chemical and physical events are happening. Conditions are optimum now, and the baby beast grows.


Small fuels on the ground--dying grasses, duff, pine needles--dry each day in the baking sun. The baby beast nibbles and its appetite grows. Needle-toothed flames seize the tiny offerings and reach for larger branches, downed logs and trees.


The appetizers are quickly consumed, but it wants more. The volatile oils and resins locked within conifers are the perfect formula for fire growth. Subalpine fir is the taste treat of choice. When green, it is one of the most flammable of all conifers, heavy with resins. Its branch structure is ideal to support the growing beast and lift it into the taller trees.


The wind is there to support as well. The greatest variable, it helps and hinders in its wayward way. Gradient winds are created when large air masses move across the face of the warming earth. Rising temperatures move the air masses, creating upslope winds. By 10 am on most summer days, the upslope winds pick up, pulling air up the valley's mountain canyons. The narrower the canyon, the higher the velocity.


The growing beast is a voracious consumer of oxygen. It needs more and more to devour the fuels in its path. As it grows and widens, the beast creates its own draft, pulling more and more air in to aid its digestion. It has created its own wind.


A battle begins between the fire and the gradient winds. When the gradient winds are stronger, the fire moves with the prevailing wind. But let it grow large enough and it escapes the wind's power, moving at will to follow topography and fuel sources.


At one point last week, the fires on the face of Blodgett were moving two ways at once, Losensky says. Pushed by gradient winds in the narrow canyon and slammed back by the fire draft, the air was so turbulent that slurry bombers had to abort their runs, or risk being pushed into a cliff face.


Humidity and temperature combine to either calm the beast or incite it to grow larger. Higher temperatures, lower humidity and pre-heated fuels help the young fire grow. Lower temperatures with higher moisture help slow it.


Night falls and earth cools, and the beast lies down a little, creeping slowly along the ground. An occasional burp sends a tongue of flame skyward but, for the most part, feeding is more difficult and most of the forest's overstory is spared from the humidity-deadened appetite. During the day, it ranges freely, moving at speeds of a mile or more an hour. At night in the valley's high mountain elevations its speed can drop to a foot or two an hour.


It likes steep country, the steeper the better. It moves fastest upslope and the sound of its passing is often compared to the rush of a steam engine, a breathy roar. The steeper the slope, the closer the beast is to its food source. In narrow canyons, the radiant heat blasted off one canyon wall can spawn a new fire beast on the opposite side. Long narrow valleys become horizontal chimneys, whipping the beast to faster speeds with huge drafts of air.


As it grows, the beast claims more territory and begins to reproduce. A huge column of smoke rises and becomes a convection plume. It draws in air and carries burning embers higher and higher into the sky on superheated gases. Finally, the irresistible force of gradient winds breaks the plume's power and spews the embryonic beasts spiraling earthward again, anywhere from 100 yards to four miles ahead of their raging parent.


"Stand replacement" is a polite way to say everything is gone. An eerie moonscape of powdered gray dirt and tree skeletons remains behind, silent testimony to the beast's passage.





Thousands of firefighters are doing battle in the Bitterroot, trying to save lives and structures. They are still winning that battle for the most part; in the fastest-growing valley in the Northwest, 52 homes, and no lives, have been lost since the start of 50 fires that have grown into the largest fire complex burning in the continental United States.


Mike Edrington is ordinarily the regional fire/aviation director for the U.S. Forest Service in Oregon. Now he's the area commander of the four fire complexes in the Bitterroot Valley, overseeing the incident commanders who control the resources committed to each of the four fires.


Edrington has explained the fire priorities in numerous meetings with state and local officials and the public over the past week. With the bitter lesson of Storm King Mountain in everyone's minds, the first priority is the safety of the firefighters and the public. In descending order after that are the structures, private lands and, finally, public lands.


"We're a long way from looking at the fourth issue," Edrington says. "We're making our expectations pretty practical, and we'll be doing that for quite a while--until we get enough resources in here and a break in the weather. It will take a lot of people and certain weather conditions before we begin to fight it."


Crews assigned to the Valley Complex south of Darby have spent the week protecting homes. Yankee Unit is typical--a crawler dozer with an operator, a "cat boss" who directs the dozer, a pumper truck and water tender, and a flatbed truck to move the dozer and transport vehicles for the 21 young firefighters from Maine who cut fire line on terrain too steep for the dozer.


For the past week, they've cut lines around homes and reopened old logging roads to allow access to the fire. Sometimes the lines hold and back-burning heightens the chance for a home's survival. Just as often, within minutes of completing work in an area, workers watch the fire overrun their lines. Then they move a way off and start again.


They put in a 17-hour day Sunday, and the Vogt Ranch and all its buildings were still standing in the Sula Basin when the sun came up Monday morning. The crew ate a scratch meal, caught a few hours sleep and headed out again at 6:30 the next morning.


Dave Campbell describes the fires as "wearing" on the public. People can see the fires surrounding them. They smell the smoke and hear the sirens and see the fire crews deploying.


"They see us and want us to put the fires out--now--but that isn't possible," Campbell says. "We can muster all kinds of equipment and manpower, but we end up with a big dose of humility in terms of what we can and can't do."


Fires of the magnitude now burning in the Bitterroot will burn until fall rains or snow extinguish them. It was an unseasonably early snowfall that stopped the great Sleeping Child fire of 1961, not the 4,000 firefighters who were battling it. A significant change in the weather is needed to allow the fire crews to do more than try to direct the flanks of the fires away from populated areas.


"With these kinds of years, you just stand back and wait," Losensky says. "People just don't understand how dangerous it is out there. The more days we can slow and delay it, the better chance we'll get weather to stop it. There's no way to win the battle against these kinds of fires. It will be September before anything changes the situation."


Throughout history, the valley burned on a regular cycle with overlapping burns of varying intensities, Losensky says. And what doesn't burn this year has the potential to burn just as intensely next year or the year after that.


"In the short term, we can expect these conditions on a 10-year interval," Losensky says. "It's the normal cycle. Each year we don't do something about the forest condition, we set it up for a little harder, more intense burn. We have thousands more acres out there that are primed and ready to go. We don't have to worry about ignition--we get plenty of it."





In a few weeks, the fires will die, the fire camps will be dismantled, and the firefighters will disperse. The burn scars will remain.


But with the fall rains and the winter snows will come the promise of renewal. Lodgepole pine and many flower species are cerotinous--it takes a fire to release their seeds. Green will sprout as soon as the ground cools and moisture arrives; not everywhere and not all at once, but it will come.


Next spring, the fire's path will fill with new growth, such as mushrooms feeding off the nutrients freed by the fire. The following year, Losensky promises a wildflower bloom of proportions unequaled in the valley for three centuries. The year after that, the replacement trees will become visible, poking up among the standing skeletons of their ancestors.


"The faces of Blodgett and Mill Creek and Canyon Creek have changed. They won't be the same again in our lifetimes," Losensky says. "But they aren't designed to remain the same. That's not nature's way."





This article first appeared in the Missoula Independent.