If the recent rains don’t complicate the picture, the Umatilla National Forest will use prescribed fire to treat about 1,000 acres this spring.
Forest personnel planned to treat several thousand acres until precipitation last month hastened the greening process and rendered some of the units less flammable.
“The moisture takes away the intensity we need,” said Chris Johnson, the forest’s deputy fire staff officer. “Those units will have to sit until fall.”
For the remaining acreage, the forest will use flame to burn slash, reduce the risk of large-scale wildfires and enhance wildlife habitat. Johnson said prescribed burning projects require crews, engines, dozers and helicopters to light, monitor and maintain the burn. Ground crews typically prepare the area beforehand by constructing fireline around the perimeter and igniting the fires with drip torches. On larger projects, he said, they sometimes ignite fires with the aid of helicopter firing devices, such as a plastic sphere dispenser. The devices dispense ping-pong ball-sized spheres injected with potassium permanganate.
“You can drop the balls through the canopy and they won’t ignite until they hit the ground,” Johnson said.
Another aerial method uses a helitorch, which Johnson described as a giant drip torch full of gelled gasoline that is mounted under the helicopter and disburses burning globs of fuel.
The actual amount of burning will depend on weather, fuels conditions and smoke dispersion forecasts. Each of the district’s four ranger districts — Pomeroy, Walla Walla, North Fork John Day and Heppner — has acreage available for prescribed fire. Predicting fire’s response to wind, humidity and other factors can sometimes be tricky and Johnson said prescribed burning is not without impacts.
“Managers work closely with the Oregon Department of Forestry and the Washington Department of Natural Resource in accordance with their smoke management plans to determine when, where, and how much can be burned on a daily basis,” he said. “Unfavorable weather conditions, especially those leading to an adverse smoke management forecast, are the primary reason a prescribed burn would be postponed.”
In many areas, he said, prescribed burning is the last of a series of treatments for vegetation management and fuel reduction projects. Burning often follows harvest or other thinning activities that remove some trees while retaining the largest, healthiest trees of the most fire-resistant species, such as ponderosa pine and western larch. He said smaller trees (ladder fuels) are removed, leaving stands less susceptible to crown fires. Prescribed burning completes the process by consuming the accumulated surface fuel.
Acres available for burning include Pomeroy Ranger District with 406 acres, Walla Walla with 825 acres, North Fork John Day with 855, and Heppner, with 11,101 acres.
Maps of the proposed prescribed burns are available on the Umatilla National Forest website www.fs.usda.gov/umatilla or at any forest office.
This story originally appeared in East Oregonian.