USA — A fire exclusion plan adopted at the turn of the 20th Century wasdesigned to dramatically decrease the occurrence of wildfires on all forestedland.
Although successful, Carl Skinner of the U.S. Forest Service, said firesuppression has created severe fire problems in the western United States.
Skinner, science team leader with the Pacific Southwest Science Research Stationin Redding, was at Dunsmuir’s River Exchange Center Thursday to discuss howsuccessful fire exclusion has resulted in dense forests and increased surfacefuels.
As a result of fire suppression and human activities, fires do occur lessfrequently, Skinner said. However, because of the increased fuels, whenthey do occur they are likely to be very severe.
He said in recent history, there have been several record years for wildfires inthe west, largely due to the increased fuels.
Skinner said climate plays a role in the severity of wildfires, including thosein the Klamath Mountains region.
This area has a Mediterranean-type climate, he said. It ischaracterized by wet, cool winters and dry, warm summers.
He said in the Klamath Mountains region, the Mediterranean climate results inperiods of high velocity winds and low humidity, which are prime critical fireweather conditions. The result has been a number of wildfires in recent decadesincluding the 2001 Oregon fire west of Weaverville that burned more than 1,600acres and 13 homes.
Global warming is also becoming a factor, Skinner said. It is a factthat the earth is becoming warmer.
During a slide presentation, Skinner discussed ways of creating fireresilient forest stands with different fuel treatments. These treatments includeprescribed burning, mechanical thinning (harvesting) and a combination of thetwo.
The objective is to reduce surface fuels, reduce ladder fuels and reduceforest canopy density, he said.
Skinner said prescribed burning is effective in reducing surface fuel such asfallen dead trees and limbs. However, he said it is less effective at reducingcanopy density.
Skinner said thinning can be effective in creating a healthy forest standwhile reducing the threat of major wildfires. However, from a marketablestandpoint, larger trees, which Skinner said are the most fire resistant, areremoved for harvest because they provide more income.
Skinner said a combination of harvesting and prescribed burning can be effective,especially in forests like those in the Sierra Nevada range that have mixedconifers. He said thinning, along with prescribed burning of surface fuels, canresult in healthier stands and a reduction in the threat of wildfire.
Skinner said the type of treatment depends on the type of forest. He said manyforest types such as wet Sitka spruce, coastal Douglas fir, mountain hemlock andsubalpine fir are not normal candidates for fire.
However, forests that have long dry seasons each year with easily combustibleforest floors such as ponderosa pine, mixed conifer and drier Douglas fir are atrisk for fire, Skinner said.
While thinning and prescribed burning can be effective in helping prevent majorwildfires in the future, Skinner pointed out they can also have negativeenvironmental impacts. These include soil impact and erosion from harvestingoperations and air quality and health effect concerns from burning.
While there may be some negative environmental impacts, they need to beevaluated against the option of no action, Skinner said. It may bedifficult to define the probability of a particular stand burning at some timein the future, but the probability that substantial areas of dry forest willcontinue to be burned by severe wildfire is known – and it is high.
Thursday’s presentation by Skinner was the first in a series of programs theUpper Sacramento River Exchange plans to hold regarding watershed health andsustainability.