In recent articles and editorials in the Helena Independent Record, there has been a call for logging parts of the forest surrounding the town to remove beetle-killed trees and thin forests to reduce future wildfires. Such solutions will not work because they ignore fire behavior and ecological research.
The first problem has to do with perspective. Neither wildfire or beetle outbreaks are "bad" for the forest ecosystem; instead they serve many important ecological purposes that are critical to the long-term health of the forest.
The fear that beetle-killed dead trees will increase fire hazard significantly is not well supported by scientific research. Fires are largely driven by climatic conditions such as low humidity, drought and wind, not the presence of fuel. Research in Yellowstone National Park found that beetles only increased the probability of burning by a mere 11 percent. Another study in Alaska found no correlation between insect outbreaks and wildfires occurrence.
It is fine fuels, not large trees and snags that sustain wildfires. In Yellowstone it was found that only 8 percent of the dead trees on the ground actually burned at all--and most were not consumed, just charred. Fires simply do not "stay" in one place long enough to heat a large log to the burning point unless there is an abundance of small fine fuels to heat them to the burning point. Thus dead logs either standing or falling over do not contribute significantly to fire hazard.
As a consequence, removal of large trees typical of most commercial logging operations does little to reduce fire hazard because it is the smaller trees, shrubs, and fine fuels that sustain large fires.
That's because fire hazard of trees is dramatically reduced once the needles and fine branches are broken off by winter storms.
In addition, there is some evidence to suggest that logging and thinning can increase fire hazard by opening up the forest to greater drying and increased wind speed -- both critical to the rapid spread of fires as well as greater growth of shrubs and small trees which provide the major fuel that carry and sustain wildfires.
Beyond the lack of fire hazard posed by beetle-killed trees, there are many positive changes that occur as a result of beetle outbreaks. One finds that forests quickly recover from beetle attacks. The remaining live trees (beetle rarely kill 100 percent of the trees), released from competition, grow quickly and soon fill the gaps created by beetle-killed trees.
While beetles pose no long-term harm to the forest, they do a lot of long-term good for forest ecosystems. They help to create an abundance of snags, which are important habitat for many wildlife species. For instance, 30 percent of the birds in the northern Rockies rely upon cavities in snags for their homes. Many bat species also rely upon dead trees for roosting.
Dead logs that fall into streams are a major source of structural habitat for aquatic species including trout. Indeed, fallen logs create 50 percent of the habitat in small and medium streams.
Rather than view beetle outbreaks as a disaster, we ought to be celebrating the fact that despite a hundred years of forest mismanagement by foresters and loggers, many of our forests still function properly.
The best way to protect homes and communities from fires isn't by logging the forest, but by mandating fire-safe home construction. For instance, just the addition of a metal roof will permit most homes to survive even a wind-driven stand replacement fire. Zoning to prevent home construction in fire prone landscapes will do more to safeguard a community than any amount of forest logging.
George Wuerthner is an ecologist, writer and photographer with 34 published books, including "Wildfire: A Century of Failed Forest Policy".
Posted in Opinion on Sunday, October 26, 2008 12:00 am
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