IN THE SPOTLIGHT
As forests die, questionable anxieties thrive
The forest around Grand Lake, Colo., is neither pretty nor, for the most part, green. Whole mountainsides are draped with dead trees bearing orange needles and bare branches. The pine beetles have attacked, and people have responded with chainsaws, insecticides and anxiety about fire.
Conventional wisdom suggests that decades of U.S. Forest Service policy of extinguishing all fires on public lands—also called “fire suppression”—have left forests more prone to beetle attacks, and that these dead trees are more likely than live trees to erupt in wildfires.
But the latest and best scientific research does not buttress conventional wisdom. The research suggests that the pine-beetle outbreaks coincide with warmer, drier years. It finds no compelling evidence that once the dead needles have fallen from the trees (i.e. when the “red phase” disappears a few years after attack) dead stands of pine are more likely than live stands to burn. Scientists also find no evidence that this outbreak is unprecedented over time spans of several centuries, or that human fire-suppression has made western U.S. forests unusually prone to fire.
Further, a team of scientists suggests that some policies and treatment options—thinning forests far from human homes, for instance—is ineffective.
Thomas Veblen, a professor of distinction in geography at the University of Colorado, acknowledges the barrier of intuitive wisdom. “The knee jerk response from the public, politicians and many forest managers was that dead trees would result in a great increase in fire hazard,” he says.
But in several controlled experiments, other researchers have found that dead trees—even those bristling with dry, brittle needles—are not more likely to ignite.
Tania Schoennagel, a research scientist in the geography department and a member of Veblen’s lab, notes an experiment in which a stand of trees was “girdled,” or chainsawed around the perimeter to cut off the trees’ circulation (and ultimately simulate pine-beetle kill).
That dead stand of trees and a still-living stand were ignited, and both groups burned the same, Schoennagel noted. High-severity, infrequent fires are normal for boreal and high-elevation forests, she adds. “What we saw in Yellowstone in 1988 was completely business as usual for lodgepole pines, although terrifying for humans.”
Such conclusions contradict conventional wisdom, which has driven major public policies and expenditures.
“The large stands of beetle-kill trees seen today in Colorado pose a threat of severe wildfire, placing numerous communities at risk,” Mark Rey, former undersecretary of agriculture, said in 2006.
At the time, Rey was endorsing an expansion of the Healthy Forests Initiative and the Healthy Forests Restoration Act, which were predicated on the belief that fire-suppression efforts of the last century have created unhealthy, unnaturally dense forests that were thus prone to wildfire.
As he announced the Healthy Forests Initiative in 2002, former President George W. Bush said the nation had shirked its obligation to preserve “good forests” for future generations: “We need to thin. We need to make our forests healthy by using some common sense,” the president said.
“We need to understand, if you let kindling build up and there’s a lightning strike, you’re going to get yourself a big fire.” In the context of forest policy, the president used the phrase “common sense” six times that day.
Veblen, Schoennagel and leading experts from Colorado State University and the University of Idaho have responded to such intuitive knowledge with a rigorous assessment of research on forest-insect outbreaks and wildfire.
This excerpt is reprinted with the permission of Clint Talbott. To read the rest of the article visit the Colorado Arts & Sciences Magazine website.
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