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Slash Pile, Burn Pile

When you drive through Rocky Mountain National Park these days, one of the stranger things you notice—once you’ve stopped being startled by the scenery or the elk—is the enormous piles of wood along the road. They’re shaped like teepees, they’re called slash piles, and they’re future bonfires: Last winter the rangers lit 5,700 of them in the park, sometimes hundreds in a single day.

Slash piles of beetle-killed wood along Trail Ridge Road in Rocky Mountain National Park. Photo by Robert Kunzig/NGS

The bonfires are the aftermath of the devastation wrought by the mountain pine beetle, which has killed trees, mostly lodgepole and ponderosa pine, in 70 percent of the park. The Park Service leaves most of the sad brown carcasses alone, with their drooping branches and rusty needles. It worries only about dead trees that might fall on people—the ones along roads, parking lots, campgrounds, and picnic areas. It slashes those trees, piles them up, and then burns them.

“You build the pile like a huge campfire,” says Mike Lewelling, the park’s fire management officer. “You start with the twigs and needles, then the branches, and the largest logs go on the outside. When the interior burns, all the heavy stuff falls in. That helps the pile burn thoroughly.” It also burns hot. Lewelling’s team lights the fires early in the morning, and for an hour or so the flames are 20 feet high. The goal is for the fire to burn out before nightfall so the smoke won’t become a hazard to motorists.

Lewelling expects to light a couple thousand bonfires this year, but right now the piles are just sitting there, drying out and waiting for winter. He’ll wait till after the first or more likely the second big snow. When the snow melts, it will drench the flammable leaf litter on the ground. This year above all, Lewelling needs to be sure there’s no chance of one of his bonfires spreading out of control: Coloradans have had their fill of wildfire in 2012.