Deschutes & Ochoco National Forests
Crooked River National Grassland

Forest visitors to the Central Oregon Cascades expect to see healthy, green forests, accentuated with large yellow bark ponderosa pine. Instead, what they now see is a mixture of many dead and dying trees within a canopy of green.

As motorists drive over the Santiam Pass they ask: What is wrong? What caused this? What can be done about it? The questions are numerous; the solutions complex.

Most obvious to the visitor, is the heavy defoliation caused by the western spruce budworm, an insect that feeds on tree needles. The budworm, however, is just a symptom of the problem. The forests are unhealthy, because the trees have become un-naturally overcrowded.

CROWDING AND STRESS

On the east side of the Santiam Pass, old growth ponderosa pine forests historically had only 20 to 30 trees per acre. The absence of fire has allowed a dramatic increase in the number of trees, mostly white and grand fir. Some forest stands now have more tha 1,000 tree per acre.

The overcrowding has resulted in competition between trees. Thus, trees are weak and prone to disease and attack.

INSECTS AND DISEASE

Across the landscape, a number of insects and diseases are affecting the forest. The western spruce budworm is the most apparent. It is a needle eating insect that lives and feeds primarily on fir trees, they typically do not feed on ponderosa pine. As the white and grand firs increased there was more foliage for the insects to eat. This, combined with the drought, has allowed insect populations to increase to epidemic levels.

To understand how the forests developed to this state, it is important to understand how human influence on natural ecological processes has changed the character of the forest.

The forest today is very different from the forest that existed 100 or even 50 years ago. Until the mid to late 1800's the forests were thinned by low-intensity wildfires. These fires burned over the same areas every 10 to 20 years at lower elevations and every 75 to 100 years at the higher elevations, killing most of the true fir leaving the fire-resistant pines, and in some areas Douglas fir, to flourish.

Early people routinely started fires to drive game, clear undergrowth, and encourage new growth for wildlife. In 1864 a state law outlawed the deliberate starting of fires. The practice of fire exclusion began, and has continued to the present.

DISEASE

Although not nearly as obvious, tree diseases kill more trees than insects do. In fact, most of the dead trees in this area were actually killed by root rot acting in concert with the budworm.

Root rot is a fungus that decays the roots of trees. Under conditions of stress trees are especially vulnerable to attack by root disease. Firs are especially susceptible. Under current forest conditions the pines are also stressed and they, too, are attacked.

HIGH FIRE DANGER

Trees killed by insects and disease add more fuel for fires in a forest already choked with debris. The potential for fires has soared. These high intensity fires can claim human lives, destroy private property and public treasures.

WHAT ELSE CAN BE DONE?

We have two choices. We can do nothing, or we can take some type of forest management action. If nothing is done, insects and disease will eventually reduce the number of trees. However, this may take many trees. However, this may take many years. More than 100 years of excluding wildfires has changed the forest. Corrective actions are limited by existing laws such as the Endangered Species Act and the Clean Air Act. They are also influenced by the public expectations of what the forest should look like.

Three basic forest management tools or corrective actions are possible. One is to spray the forests with BT (a microbial insecticide). BT has been widely used as a short term control for budworm outbreaks in the past. It kills budworms and temporarily allows budworm affected trees to "green up". It does not correct the underlying cause of the problem, which is too many trees and too little space. Thinning of the forest stands needs to follow spraying. If this is not done, severe budworm defoliation will occur again because the budworm's main food source has not been removed. Prescribed burning is another excellent tool for removing excess trees and debris from the forest floor. As with the natural fires of the past, the firs would be thinned out, larger trees and fire tolerant pine would remain. In most areas the long period of fire exclusion has allowed fuels to accumulate to the extent that prescribed burns may not be feasible. Removal of some trees to reduce fuel loading BEFORE any prescribed burn would be essential.

The third type of treatment action is to remove some of the excess trees. Thinning, a commonly used technique, would reduce overcrowding and stress, increase vigor, favor trees resistant to insects and disease, and reduce fuels. Openings may be created in some areas for the planting of insect and disease resistant pines. Thinnings and openings will significantly change the appearance of the forest. Treated stands may look sparse and less luxurious. Many people want to see the continuous, dense green forests of the not too distant past. Unfortunately, those forests are not and never were biologically maintainable. Removing excess trees and debris is costly and will take decades. Some areas, such as Wilderness and Research Natural Areas may never be treated because of laws under which they were established which limit management activites.

An important issue is the protection of habitat for the Northern Spotted Owl. Historically, most of this area was not spotted owl habitat. However, it has become habitat due to the exclusion of fire and the increase in fir trees. The spotted owl and its habitat are protected by the Endangered Species Act. These issues must be considered when evaluating treatment options. In addition, temporary court injunctions limit virtually all vegetative treatments in this habitat type.

The public has a strong desire for answers, but solutions to forest health problems are complex and long term. Any solution will require public support which will come only after greater understanding. For more comprehensive information contact your local Forest Service office.

USDA Forest Service - Deschutes & Ochoco National Forests
Last Modified: Monday, 23 May 2005 at 16:58:21 EDT