Forest fire near Boulder, Colorado raises issue of mountain pine beetle's impact on risk of fire in lodgepole pine forest.
The massive wind-whipped Fourmile Canyon Fire burning in the foothills west of Boulder, Colorado is not only the worst fire in the state's history in terms of structures damaged--169 homes and counting--popular sentiment dictates that the fire may also be an ominous sign of things to come, as the state's predominantly lodgepole pine forest continues to be decimated by the mountain pine beetle.
But according to preliminary research results from NASA and University of Wisconsin forest ecologists, large fires do not appear to occur more often or with greater severity in forest tracts with beetle damage. In fact, the researchers find that in some cases, swaths of beetle-killed forest may actually be less likely to burn than those without.
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Once restricted to high country hamlets like Breckenridge, Fraser and Steamboat Springs, when the mountain pine beetle epidemic crossed the Continental Divide in 2007 and into the foothills near Denver, Boulder and Fort Collins, it brought with it the popular belief that it would provide fuel for massive forest fires, the likes of which modern-day Colorado has simply never seen.
But the new research predicts less menacing fire behavior in pine beetle-damaged forests. And it may not only fly in the face of popular belief, it may completely upend it.
"Of course, we can't go out and actually set a fire in beetle damaged areas where we've got red, green or no needles," forest ecologist Phil Townsend said. "We just can't do that, so we collect data on the ground, we collect data from satellites, and then we build models of how much fuel is there and how burnable it is."
Link between pine beetles and forest fires questioned
First, while green needles on trees may appear to be more lush and harder to burn, they actually contain high levels of flammable volatile oils. When the needles die, those flammable oils begin to dry up and break down.
Second, when beetles kill a lodgepole pine tree, the needles begin to fall off and decompose on the forest floor relatively quickly. While those needles may provide good fuel for ground fires, they do little to ignite larger fires in the crowns of trees. Just as you can't start a fire in a fireplace with just large logs and no kindling, wildfires are less likely to ignite and sustain themselves in a forest of dead tree trunks and matted needles.
The Wilderness Society's Greg Aplet, who wrote about the impacts of the mountain pine beetle, seems to concur:
"Infrequent, large fires are the norm in lodgepole pine forests, and they are likely to be in the future — with or without beetles. There is general agreement that as the dead needles fall from the trees, the probability of crown fire will diminish, but the probability of surface fire may increase."
At this point, investigators and forest researchers agree it is too early to tell whether pine beetles had anything to do with igniting, spreading or sustaining the Fourmile Canyon Fire.
But regardless of whether pine-beetle forests will fan flames of the Fourmile Canyon Fire, it appears as though high winds will. Winds on Thursday afternoon are expected to pick up again, gusting to 50 mph.
Fire officials said it could take 10 days to contain the blaze.