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Fires and Logging

Logging can increase fire risk or intensity in at least three ways.
  1. Logging generally leaves highly flammable logging slash.
  2. Logging opens up the forest canopy, which increases the temperature of the forest floor and allows more wind movement which also dries out the forest floor.
  3. Subsequent to logging, federal agencies are required to plant trees. These trees are generally the same age and generally planted too thickly so that enough of them will survive in the compacted soil resulting from the logging. (The health and vigor of these trees and remnant older trees is also compromised by the compacted soil.) These thick young plantations are much more flammable than the older forest that they are replacing.
Many recent fires have burned hottest where past logging has taken place.

Logging can increase fuel loading

There will always be a threat of catastrophic fire in any watershed. The U.S. Forest Service has a tradition of overstating fire risk so as to justify entry into watersheds. (See 1974 Bull Run lawsuit: Dr. Joseph Miller et al v. US Forest Service) Roading, logging and burning often lead to human-caused wildfire. In a recently published General Technical Report (PNW-GTR-355) titled Historical and Current Forest Landscapes in Eastern Oregon and Washington. Part II: Linking Vegetation Characteristics to Potential Fire Behavior and Related Smoke Production, by Mark H. Huff, Roger D. Ottmar, Ernesto Alvarado, Robert E. Vihnanek, John F. Lehmkuhl Paul F. Hessburg, and Richard L. Everett, the authors state that: Invoking fire risk is a common technique of those grasping for excuses to log. Any statement that logging an area will reduce fire risk is an unsubstantiated, simplistic view of fire ecology. Certainly, the "open parklike stand" that appears after "treatment" will have a modified fire risk. However this is an ecosystem that changes over time. These areas will have increased fire risk as the result of logging slash and they will soon have hundreds of seedlings that will all grow at the same rate, becoming thick with branches and brush within a decade or two. Unless a continual program of prescribed or natural fire is implemented the fire risk will grow.

Logged areas generally burn faster and with increased flame length

The same PNW-GTR-355 cited above states that: Increased rate of spread means that the perimeter of the fire will grow much faster. This faster perimeter growth will make fires in most areas harder to contain.

Logging warms up and dries out the logged areas

The Sierra Nevada Ecosystem Project (SNEP) is an ecosystem assessment project similar to the Interior Columbia Basin Ecosystem Management Project. A scientific assessment released by the Sierra Nevada Ecosystem Project on June 7, 1996, states that, "More than any other human activity, logging has increased the risk and severity of fires by removing the cooling shade of trees and leaving flammable debris." This peer-reviewed assessment by an independent group of 107 scientists was commissioned by Congress to provide essential information for an ecosystem-wide approach to land management.

There are a couple of other interesting findings about fire in the SNEP report as well. "Timber harvest, through its effects on forest structure, local microclimate, and fuel accumulation, has increased fire severity more than any other recent human activity.". . . "Although silvicultural treatments can mimic the effects of fire on structural patterns of woody vegetation, virtually no data exist on the ability to mimic ecological functions of natural fire." (p. 62 Sierra Nevada Ecosystem Project, FINAL REPORT TO CONGRESS)

Both of these documents are peer reviewed scientific findings. They are based on scientific observations of the behavior of real wild fires. They were both commissioned by the federal government and they both contradict timber industry propaganda.

Dead trees may burn slower and cooler than green trees

Recent research is also showing that the salvage rationale for harvesting dead trees; that they become potential fuel for catastrophic fires is simply not born out by the facts. Standing dead trees retard fires. An article by Tom Kizzia of Scripps-McClatchy Western Service reports that the conventional wisdom that bug-killed trees raise the odds of raging, out-of-control forest fires is proving wrong. It turns out that green trees are a greater fire hazard than standing dead trees. State and federal wildlife specialists say that this months forest fires on the Kenai Peninsula in Alaska have shown that standing gray beetle- killed trees are more likely to slow down a forest fire than send it racing out of control. A green forest in dry conditions is far more likely to generate an explosive inferno because of the flammable resins in the spruce needles and trees. John LeClair, state fire management specialist on the Kenai Peninsula said, "When the fire hit the bug kill, it became more approachable. The fire crews could start flanking it," when describing a 1991 fire that spead through green forest canopy, but slowed to a crawl when it hit the beetle kill. Matt Schneyer, a volunteer firefighter who worked to contain a 30-acre blaze in early May said, "The dead ones were just burning in place. The green ones were going up like bombs."

Quotes from scientists and others about the effects of conventional forest management on wildfire hazard

Public agencies have known about these problems for a long time. There are many references in historical Forest Service documents about fire danger being increased by logging. Here are a few of these references:

"Twentieth century forest management, for all its good intentions, has left a mess on the landscape".

"As a by-product of clearcutting, thinning, and other tree-removal activities, activity fuels create both short- and long-term fire hazards to ecosystems...Even though these hazards [with logging slash] diminish, their influence on fire behavior can linger for up to 30 years in the dry forest ecosystems of eastern Washington and Oregon". "Timber harvest, through its effects on forest structure, local microclimate, and fuels accumulation, has increased fire severity more than any other recent human activity. If not accompanied by adequate reduction of fuels, logging (including salvage of dead and dying trees) increases fire hazard by increasing surface dead fuels and changing the local microclimate. Fire intensity and expected fire spread rates thus increase locally and in areas adjacent to harvest". "Clearcutting can change fireclimate so that fires start more easily, spread faster, and burn hotter. The effect of these changes on the fire control problem is extremely important. For each man required to control a surface fire in a mature stand burning under average conditions, 20 men will be required if the area is clearcut". "We need to accept that in many areas throughout the region, past forest management may have set the stage for fires larger and more intense than have occurred in at least the last few hundred years". "Because salvage logging removes natural fire breaks, it homogenizes the landscape and increases susceptibility to catastrophic fires and insect outbreaks". "Intensive timber management contributes to additional fire hazards due to greater road access and associated increases in human-caused fires, operation of logging equipment, slash build-up following logging, and the associated decrease in moisture content of forest understories". "The original old-growth ponderosa pine were quite resistant to crown fires, because the frequent ground fires kept fuel levels from building too high. Excluding ground fires, coupled with forestry practices such as clearcutting that convert old-growth to younger stands, has increased the probability of a ground fire moving into crowns and gaining intensity as it spreads".

"There is no doubt that big, thick-barked trees are most resistant to fire, and foresters have noted since the early decades of the century that plantations were particularly vulnerable to fire. Susceptibility was reduced with the advent of slash disposal. However, even with slash disposal, densely stocked plantations are more vulnerable to fires than healthy old-growth". David Perry, Ph.D., 1995. Ecosystem management in western interior forests "Those small logging operations create tremendous fuel loading where traditional logging operations occur. We're going in and taking out the large trees, and we're leaving the thickets behind, or we're leaving slash, heavily intermingled with built-up areas. The logging slash is supposed to be treated, but that's been a serious problem".

"More often than not, timber harvesting prescriptions have been 'high grades' -- take the biggest trees and leave the rest. And do a sloppy job in the process. Which means you end up with overstocked stands of small diameter trees....You end up with a fuel problem". "The slash treatment backlog has led to tremendous wildfire risk on lands recently harvested for either green timber or salvage". "Sparks from the logging railroads set alight piles of slash and dead wood left after cutting, and the resultant fires burned so hot that what grew up afterward were often thickets..." "It is after logging that the damage from fires is greatest, on account of the inflammable and unburned slash". "Where the cut has been heavy and the resulting debris correspondingly large, all the difficulties of fire fighting are proportionally increased. All kinds of waste material left in the woods supply food for the flames, but the leaving of large unlopped softwood tops on the ground adds enormously to the fury of a brush fire and greatly prolongs the length of time that slash remains a menace to its own and surrounding areas...Fires on cutover lands usually kill all standing timber left on the area burned, as well as all the young growth". "Within the last sixty years, however, fires have done little damage to the virgin timber, although prevalent on the cut-over areas...Fire on these areas is of the hottest character, and once started is extremely difficult and often impossible to check". "Fresh, dry slash of any species makes a high-intensity, unapproachable fire. A fire started in dry, fresh slash can become uncontrollable in seconds....It appears significant that many large fires in western United States have burned almost exclusively in slash. Some of these fires have stopped when they reached uncut timber; none has come to attention that started in green timber and stopped when it reached a slash area". "Logging slash was generally left where it fell creating abnormal fuel loads in these dry forests. Thus, the potential for future epidemics of insects and disease and more destructive fires was becoming established".

"Extensive railroad logging throughout the [inland West] region created dangerous levels of dry logging slash resulting in extreme fire hazard. For example, in 1931 on the Boise National Forest, stand-destroying wildfire burned 62,000 acres of ponderosa pine/Douglas-fir forest that had previously experienced only surface fires for, at the least, 300 years. Observers attributed the intensity of this fire to the large volume of slash created by railroad logging in the late 1920s".

"What is apparent to me now is that large salvage sale contracts are NOT a major part of addressing the large acreage and urban inter-mix needs. Planning and attempting to market several salvage sales, ranging from 100 to 7,000 acres, has shown that the value of salvageable material will not bear the cost of adequate treatment for fuels reduction and long-term forest health". Robert Harris, 1994. Supervisor of the Lake Tahoe Basin Management Unit, U.S. Forest Service

"In large wildland fires on urban-interface lands, city and county fire departments cannot protect every home. What I am saying is that all of us concerned with wildfires and the loss of life and property must begin addressing basic, common sense, fire prevention and fuels reduction guidelines for these areas".

"One are of increasing concern is the wildlnad/urban interface. Here, the forest health problems that lead to intense and inordinately hot wildfires are magnified by concerns for protection of buildings and human safety. In recent years, thousands upon thousands of homes have been built in natural settings where low-intensity fires once burned every 5 to 30 years". Jack Ward Thomas, Chief of the Forest Service, 60th North American Wildlife and Natural Resources Conference, Minneapolis, MN, March 27, 1995

"There may be an indication that harvested land had a better chance to burn black [most intense] when compared to unharvested land".

"Although salvage logging reduces fuel loading, the removal of overstory trees increases afternoon temperatures and windspeeds, and decreases relative humidity. This increases relative fire danger on the site". "As the loggers finished their work, they left behind a litteral wasteland. Great piles of slash -- small timber, branches, and other debris that had little economic value -- remained on the ground, sometimes in piles ten to fifteen feet high. They accumulated over a vast area, turned brown in the summer heat, and waited for the dry season, when a spark might set them alight". "Fires had long been common in the forests. Indeed, fires were an important reason why the pine was so abundant, for the tree was adapted to reproduce most effectively in newly burned-over lands. But the fires that followed in the wake of the loggers were not like earlier ones...". This list of quotes was compiled by:
Evan Frost,
Staff Ecologist
Northwest Ecosystem Alliance
efrost@methow.com
http://www.pacificrim.net/~nwea/
POB 1175, Twisp WA 98856
(509)997-9398

 

 

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