BIG ELK MEADOWS — Federal burn crews in Colorado forests, racing against early snowmelt, have intensified culling and are on pace to break records this year by igniting more than 40,000 piles of chopped trees.
The U.S. Forest Service has declared this essential — to protect proliferating houses built in the woods and to try to restore forest health.
But studies show cutting, dragging, heaping and burning trees as a strategy may also hurt the forests it is intended to help.
The yellow-clad crew members lug diesel-gas drip torches up and down mountainsides. Each pre-positioned pile poofs into smoke and orange flames. The crews count on winter snow to keep flames from spreading.
“So this is one hazard, the overhead powerline. Don’t light anything underneath it,” Forest Service burn boss Tim Egan instructed last week, 10 miles southeast of Estes Park, mobilizing a team bolstered by AmeriCorps volunteers.
The problem is that intense heat from pile-burning can melt soil, leading to reduced absorption of water and erosion, said University of Colorado ecology and evolutionary biology professor Bill Bowman, director of the school’s Institute of Arctic and Alpine Research mountain station.
And pile-burning spurs weed invasions into forests.
“We found that, after trees were cut and placed into slash piles, there was a tenfold increase in bare soil and a fourfold increase in nonnative invasive plant species,” Bowman said.
For years, of Colorado’s increasingly populated Front Range have deteriorated because of . wildfires, costing $1 billion a year, is deemed necessary as county authorities allow new building in burn zones.
Federal foresters say they aim to mimic stunted . They conduct broad controlled burns where possible. The U.S. Fish and Wildlife Service plans to burn 530 acres next week to revive prairie at the Rocky Mountain Arsenal National Wildlife Refuge.
Pile-burning in forests.
However, Colorado health officials also have raised concerns about smoke. State air tests have found controlled burns produce particulate pollution at levels up to seven times above the health standard.
The Colorado Department of Public Health and Environment is with land managers. CDPHE issued 306 burn permits in 2013 and 324 permits in 2014, state Air Pollution Control Division spokesman Chris Dann said.
State records show 39,968 piles were burned under state permits in 2013, increasing to 42,879 piles in 2014.
Health officials plan to monitor pile-burning, Dann said. “We have an ongoing interest in learning more about the smoke impacts of these burns, as evidenced by the fact that we’re seeking pilot projects that include air monitoring for both pile and broadcast.”
Federal records show 5,243 acres statewide were thinned by pile-burning last year, and officials estimated 10 piles were formed on each acre. Forest burn crews are on target to surpass a higher pile-burning target this year, Forest Service spokesman Lawrence Lujan said.
Forest Service researchers have found that soil under smaller piles, five yards or less in diameter, regenerates in a few years but that blackened burn circles can remain for decades and pile-burning can aggravate weed invasions and spill nitrates into streams. Yet agency environmental reviews concluded that protecting homes and trying to reset forest health outweighs ecological harm.
“In this situation, pile-burning makes the most sense,” agency spokesman Philip DeSenze said.
On the mountainside, Egan monitored wind to make sure smoke dispersed as required under a state permit, while burn crew members torched 70 piles. They consolidated charred chunks.
“There’s an ecological effect. It’ll take time for this ground to heal,” Egan said, pointing to a blackened circle.
Foresters have considered a “lop and scatter” approach that would avoid dragging chopped trees into piles. But scattered dead wood could fuel wildfires, Egan said. Mulch, reseeding and spraying to control weeds are possibilities.
The pile-burning divides .
In Big Elk Meadows, most residents dread wildfires that could threaten their homes. But some oppose pile-burning, saying piles should be left as cover for rabbits, turkeys and other wildlife.
“Look at all the wood that goes to waste,” said Ray Merry, 77, driving nearby as flames raged. “And talk about carbon dioxide.”
Bruce Finley: 303-954-1700, bfinley@denverpost.com or twitter.com/finleybruce
