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:: Home > The Watershed > Hot topic: Fire > Fuel Reduction
The Need for Fuel Reduction...

Fire behavior triangle: weather, topography, fuel

Fire behavior is determined by three factors: fuel, weather, and topography (the shape of the ridges and valleys in the landscape). Of these three, the only one that we can easily control is fuel. Most Oregonians agree that something should be done to reduce the danger of catastrophic wildfires. And the most logical way to do that is to reduce the amount of fuel available. There are several ways to reduce fuel:

Removing some of the trees in a stand keeps a fire from burning as intensely or moving as quickly as in an unthinned stand. By increasing the open space between treetops, thinning can greatly reduce the potential for a crown fire. Usually the smallest and weakest trees are removed, while healthy large trees with thick bark are left behind. A further advantage of thinning is that any younger trees left behind will grow large and become fire-resistant more quickly than they would otherwise.

Read more about thinning.

Thinned oinderosa pine stand. Photo by Steve Fitzgerald.

Firefighter starting prescribed burn with drip torch. Photo by Tom Iraci, USDA Forest Service.

Prescribed Burning:
Because the current unnatural accumulation of fuels was caused in large part by suppressing natural wildfires, it makes sense that the purposeful use of fire can reduce the amount of small trees, shrubs, and surface fuels, in the right circumstances. Often thinning must be done first, so that the prescribed fire does not burn too intensely.

Read more about prescribed burning.

Many pine forests in central Oregon have a shrub called bitterbrush in the understory. While bitterbrush is valuable as winter browse for deer, it becomes very dense without periodic low-intensity fire. Because bitterbrush is highly flammable, prescribed fire would burn too intensely and kill too many trees. On sites with fairly level ground, mowing is one of the easiest and safest ways to reduce the level of this fuel, especially near homes.

tractor mowing bitterbrush

pruned Ponderosa pine trees

Removing the lower branches of younger trees can prevent surface fires from migrating upward and killing their crowns. Low-intensity prescribed fires can scorch and kill these lower branches, but if there is too much fuel present for a prescribed burn, branches can be mechanically removed using chain saws or loppers.

Unfortunately, there is a lot of disagreement over which methods should be used. For instance, smoke from prescribed fire can be a health hazard to some individuals, and is considered an unattractive nuisance by many. Some people are suspicious that thinning to reduce fire hazard is just an excuse to increase the amount of timber being harvested from public lands. Despite these differences of opinion, there is widespread agreement:

Doing nothing is not the answer!

smoke from Biscuit Fire, © Karen Wattenmaker