Text Size:   A+ A- A   •   Text Only
Site Image
Background on Strategy F
Protect, maintain, and enhance the health of Oregon's forest ecosystems, watersheds, and airsheds within a context of natural disturbance and active management

What is a healthy forest?
Forest health is a social value based on both public perception and scientific information. We define a healthy, vital forest landscape as one that maintains its functions, diversity, and resiliency within the context of natural disturbances and is capable of providing people with the array of values, uses, and products desired now and in the future. Forests are "unhealthy" when potential disturbances, such as fire or pest outbreaks, are unusually frequent, severe, or widespread and when the desired outputs such as wood fiber, special forest products, and recreational opportunities cannot be provided or sustained. We view healthy forests as preferable to unhealthy ones because they are resilient and because they are capable of providing the goods, values, services and habitat upon which humans and plant and animal species depend.
Perceptions about forest health have evolved from a focus on preventing tree death from insects, disease, or wildfire to a concept of "forest ecosystem health" that ties together physical, terrestrial, aquatic, and human aspects of the landscape. The ecosystem concept also recognizes that forests are dynamic and that disturbance is an important element in maintaining desired forest conditions. In this document, policies for protecting, maintaining, and enhancing the health of forest aquatic and riparian systems are more thoroughly discussed under Strategy D.
What is known about major disturbances affecting forest health?
Oregon's forests are shaped by natural disturbance in the form of fire, storms, climate change, wildlife, volcanic activity, insect outbreaks, and diseases. Prior to European settlement, natural disturbances created a range of forest types, age classes, and structures across the landscape. Native Americans regularly set fire to assist in hunting game and to produce certain edible vegetation, and for other reasons. It has been estimated that fires burned approximately 790,000 acres annually; however, we have no estimate of the amount of presettlement acreage affected by insect outbreaks, diseases, and storm damage. It is known that disturbances such as windstorms or insect and disease outbreaks often set the stage for large-scale wildfires.
European settlement changed the pattern of disturbances on Oregon's forest landscapes. Most natural disturbances were seen as undesirable because they detracted from settlers' uses of and products from the forest. New sets of human-caused disturbances were added to the mix, and the natural disturbance pattern was greatly modified. Among the changes introduced by European settlement were suppression of wildfire; elimination of Native American burning; introduction of invasive non-native plant and animal species; land management activities such as livestock grazing, timber harvest, land clearing, and burning for agriculture and urban use; air pollution; and road building. The following passages discuss some of the major natural and human-caused disturbances affecting Oregon's forests.
Climatic and geological disturbance
Infrequent climatic and geological disturbance provides an important context for forest health. Short- and long-term climatic cycles influence the frequency and severity of disturbances such as fire and windstorms. Climatic changes are usually relatively slow, while geological events can be sudden and cataclysmic. The vegetation types now covering Oregon are relatively recent, having occupied Oregon since the end of the most recent glacial period (13,000 years before the present). During previous warmer climatic periods, species such as redwood spread much farther north from where they now exist. Cataclysmic events such as lava flows and the Lake Missoula floods have modified soils and vegetation in significant ways. For example, Willamette Valley ponderosa pine may be a product of the Lake Missoula floods.
The range of natural fire regimes in Oregon reflects current climatic, vegetative, and geological conditions. In moister regions, the return interval between wildfires (the fire frequency) may be 200 years or more, and the fires tend to be large, stand-replacing events. In drier regions, fire may come as frequently as every 10 to 15 years, often burning with low intensity, but not always; fires in some stand types (for example, lodgepole pine) are more often stand-replacing events. Much of Oregon's forest in the drier regions is characterized by fire return intervals of 35 to 100 years, and by a range of fire intensities.
During the 20th century, the suppression and prevention of wildfire became an important role of government for the purpose of protecting property and conserving existing forest values. Fire prevention and suppression changed the nature of forest structure and wildlife habitat across fairly significant portions of the forest. However, beginning in the 1960s, landowners, governments, and the scientific community began to recognize that attempting to prevent and suppress all forms of natural disturbance, particularly fire, was changing tree stocking levels, forest species composition, and fuel loading on many forests.
Today, almost a century of fire suppression in Oregon, coupled with reduced vegetation management on federal lands in recent years, has produced forests that are, across the landscape, more susceptible to catastrophic fire and insect and disease problems than those that existed before European settlement. Fire prevention and suppression without vegetation management to remove fuels will result in more uncharacteristic stand-replacing wildfires, particularly in eastern and southwestern Oregon. These wildfires will be more difficult and expensive to control (Figure 15).
Insects and disease
Outbreaks of native forest insects such as the Douglas-fir tussock moth or western spruce budworm get relatively more public interest than forest diseases, though diseases kill or damage more trees and thus have a more significant effect on timber management. The aggressive fire-suppression policy has created conditions that favor increased insect and disease outbreaks. Overstocked stands grow less vigorously and become increasingly susceptible to pest infestations. Changes in species composition from fire suppression also make stands more susceptible to root diseases and stem decays. Increased tree death from insect and disease infestations and other agents over the last two decades has increased the potential for catastrophic, stand-replacing fires.
Timber management
Most private forests and some public lands have been intensively managed for timber for decades. On these lands, harvesting is now the most frequent disturbance event. In addition to harvesting trees and modifying vegetative succession, timber harvest and road-building can, in some instances, affect the timing, frequency, and intensity of disturbance events such as shallow, rapid landslides (see Strategy D).
Forest roads, power lines, and rights-of-way also change disturbance patterns by allowing access to the forests, which can result in more human-caused wildfire ignitions and increase the spread of exotic plants. However, roads provide necessary access to forests for fire suppression or restoration-oriented management activities.
Stands with a mix of species that approximates the composition of native forests are usually more resilient to insects and diseases than single-species stands. Stands with species that are not genetically well adapted to the site or to the local climate are also more susceptible to insect and disease outbreaks.
In western Oregon, coastal clearcuts often have been replanted with Douglas-fir on sites previously stocked with western hemlock and Sitka spruce. This has resulted in a severe problem with Swiss needle cast disease. Native root diseases also spread in areas planted to poorly adapted species. Planting root disease-resistant or -tolerant species and using local seed sources can reduce insect and disease damage and also contribute to native plant and animal habitat. Surveys show that landowners are beginning to plant a mix of tree species better adapted to local sites.
In eastern Oregon, intense fire suppression and the harvesting of larger, higher-value ponderosa pine and western larch over the last century have changed forest conditions significantly from those that existed in the 1800s. Some stands are now dominated by densely stocked, and generally smaller, shade-tolerant true firs and Douglas-firs, which are less fire-resistant and more susceptible to root diseases and stem decays than ponderosa pine and western larch. This shift in species composition and stand structure has increased tree death and caused heavy accumulations of highly fire-prone vegetation. The resulting insect epidemics and wildfire, along with timber harvesting, have led to dramatic declines in standing timber volumes on affected private lands, and possibly to increases in understocked areas in what were previously productive forest stands. Other forested areas remain highly overstocked.
Wildlife and livestock management
Native animals such as deer, elk, and beaver can be natural disturbance agents in some areas of the forest. Usually such disturbances are minor or localized, but that is not always the case. Today in the northeastern United States, foraging by unusually high deer populations is altering the plant species composition of the region's forests in undesired ways.
Livestock grazing can be managed to emulate disturbances from foraging by native animals and to provide an additional economic incentive to retain low-productivity private forestlands in forest use. However, intensive, poorly managed livestock grazing dating back to the late 1800s has eroded streambank cover, increased the encroachment of juniper forest into rangelands, and contributed to the spread of invasive non-native plants.
Land conversion
While management for timber or grazing may modify natural disturbance regimes, land conversion for urban and agricultural uses is the ultimate disturbance, because the site no longer returns to forest. The amount of forestland conversion was significant during settlement, but Oregon's land-use system now limits such changes (see Strategy C).
Invasive non-native species
In the last century, the introduction of non-native pathogens, plants, and insects has impaired forest health in Oregon. White pine blister rust, for example, has virtually eliminated western white pine from areas in the Coast Range and Cascades. Insect and disease introductions during the last century that have had significant impacts on the forest ecosystem also include Port-Orford-cedar root disease and balsam woolly adelgid. Eradicating an established population of European gypsy moth during the 1980s required an effort costing millions of dollars.
The recent detection of sudden oak death disease in southwestern Oregon exposes a new threat to several important tree and shrub species. The introduction and spread of invasive plants like Scotch broom, gorse, English ivy, and Himalayan blackberry to forestland poses an indirect threat. These non-native plants typically reduce native-plant diversity on a site and prevent or delay the regeneration of trees.
Increased commerce, a mild climate, and a continuous influx of people make western Oregon particularly vulnerable to the introduction and establishment of exotic insects, pathogens, and plants. Increasing levels of international and interstate trade in logs and wood products, in particular, make it likely that new pests will be introduced in the future. The introduction of exotic insects and diseases is increasingly becoming a serious threat to the health and vitality of forest ecosystems.
The first lines of defense against non-native species are programs to detect, monitor, and eradicate them and prevent further introductions. When exotic plant diseases become established, breeding programs for disease resistance may become critical to the survival of native tree species.
Air pollution
Urban and suburban development to accommodate Oregon's growing population will continue to be a threat to the state's air quality. Visibility and air quality in forest areas is degraded not only by prescribed fires and wildfires but also by air pollution from factories, vehicles, woodstoves, agricultural burning, and other non-forest-related sources. Prescribed fire can be used to achieve desired future conditions in many of the state's forest types. However, for it to be successful, very large acreages need to be burned annually, particularly in eastern and southwestern Oregon. It may be increasingly difficult in the future to make this strategy available to forest landowners and also meet air-quality requirements for urban, rural, and forest areas.
Air-pollution damage to vegetation is an important indicator of forest ecosystem health, but one that has so far had little impact here. Oregon has only recently documented air-pollution impacts to sensitive lichen species downwind of major urban areas. Because of a relatively small urban industrial sector in the region and dominant marine air currents passing over Oregon from the west, our forests have had little exposure to airborne pollutants, compared to other areas of the country and the world. However, air-pollution effects on forest vegetation will probably increase with Oregon's population and may also result from increasing industrial emissions originating in other parts of the world.
How do current government policies affect the strategy of protecting, maintaining, and enhancing forest ecosystem health?
The Oregon Department of Forestry was established in 1911 because of the need to suppress wildfires, which threatened public safety, timber values, and private property. Wildfire suppression on forestlands is still an important mandate for the agency today, as it is for the federal land management agencies and every state forestry agency in the West. In the past, the objectives of forest landowners and government policies alike focused on limiting damage to timber values from natural disturbance agents such as fire and native pests. Today, management objectives on most federal lands no longer emphasize timber values. Today we also understand that forest ecosystems must be managed in the context of the natural disturbance events to which they are well adapted.
Oregonians continue to expect the department to carry out its aggressive protection of private property from fire. This is mandated by law and paid for by both the State General Fund and forest landowners. At the same time, the department is being increasingly challenged to take part in emerging state and national policy initiatives that call for reintroduction of fire to restore forest ecosystem health.
There is strong agreement among foresters, forest scientists, and most Oregonians that hazardous fuel conditions need to be more actively managed so that fire-dependent forest ecosystems can better meet our environmental, economic, and social needs. Additionally, there are broad areas of social agreement about how to enhance ecosystem health in the forests of eastern Oregon. Oregon's An 11-Point Strategy For Restoring Eastern Oregon Forests, Watersheds And Communities, 2001 provides a clear outline of how government agencies, other landowners, and rural communities can work together to achieve this goal. This approach has been applied at a landscape scale in the three-million-acre Blue Mountains Demonstration Area project. The project focuses generally on watershed management and specifically on reduction of fuels by reducing tree densities across the landscape.
Prescribed fire can be used to achieve desired future forest conditions. However, very large acreages need to be burned annually. The costs associated with controlled burning are high, and considerable controversy surrounds prescribed fire because of the risk that fires will escape and burn onto other ownerships, and because of air-quality problems associated with smoke. The technique remains especially controversial in the aftermath of property damage caused by an escaped prescribed fire near Los Alamos, New Mexico, in 2000.
Silviculture is another pathway to achieving forest health goals. Combinations of tree thinning and prescribed fire can be designed to reduce fuels and wildfire risk on a site-specific basis. These combined treatments may often be the best choice if both short- and long-term risks to forest resources are evaluated and managed. However, lack of public trust, increased procedural workloads, and legal challenges have resulted in ongoing analysis and decision-making backlogs. For example, for most Forest Service project analyses with any commercial timber component, normal procedural requirements alone take an average of four years to complete.
Conflicting government policies and processes are major reasons why needed fuel-management work is not getting done. While the federal Endangered Species Act is a valuable tool for protecting imperiled forest species, it has an inherent bias favoring reduction of short-term adverse effects. Long-term habitat degradation from landscape-scale changes in forest conditions-such as wholesale changes in historic wildfire regimes in fire-dependent forests-are often discounted in the analysis of forest management projects. While the National Fire Plan calls for aggressive fuel reduction on federal lands, public controversy, lack of funds and staff, and substantial environmental analysis requirements have led to far less treatment than anticipated (Figure 16).
Under current federal fire-suppression policy, homes in the wildland-urban interface receive fire-suppression priority, even though most homes are insured and homeowners can take action on their own lands to mitigate the fire hazards and risk to their homes. Private forestlands managed for timber and other values are usually not insured, and managed forests are at high risk from wildfire spreading from federal lands. Thus wildfire originating on or spreading through federal lands presents underappreciated yet significant risks to private forest management investments. Future wildfire policies should better balance the risks to private forestlands with risks to homes and other structures in the interface. For example, when a decision must be made whether to allocate wildfire-suppression resources to protect $1 million in uninsured private timber or to protect an insured structure with a replacement value of $100,000, the limited firefighting resources should be allocated first to the protection of timber values.
While the Oregon Department of Forestry has clear statutory authority in fire suppression on forestlands, the law prescribes a less clear role for the agency in fuels management. It is clear that fuels management is key to reducing fire risk and hazards in the urban-forest interface. However, Oregon laws that make landowners and forest operators liable for escaped fire and that impose smoke management restrictions discourage prescribed burning on private lands. In recent years, federal money has been available to help private landowners reduce fuel loads in specific areas. The areas targeted by this incentive program are forests that are at high risk from wildfire and that have homes nearby.
Maintaining and enhancing visibility in wilderness areas and in national parks (Class I Visibility Areas) is a state and national goal under the federal Clean Air Act. Visitors to Oregon's Class I Visibility Areas experience some of the best visibility in the country, and the Oregon Smoke Management Program has been instrumental in making that happen. Regional haze-reduction goals have also been established under the Clean Air Act. Continued implementation of the Smoke Management Program will be essential in ensuring those goals are met.
Anticipated increases in prescribed-fire treatments on federal lands through the National Fire Plan and the Western Governors' 10-Year Comprehensive Strategy will present further challenges in meeting the public's desire for smoke-free air. This work will require better coordination and monitoring, more sophisticated forecasting, and increased public education. Greater public acceptance of alternatives to burning, including mechanical treatments, may offer the best opportunity to reduce smoke emissions.
Oregonians have many different views on how the state's forests should be managed, and so their views on the potential forest health risks and effects from natural and human-caused disturbances are also very diverse. However, we all must understand there are no islands of forest big enough in Oregon to isolate the effects of our choices related to fire, fuels management, invasive plants and animals, and air quality.
In the past, the objectives of both Oregon forest landowners and government policies focused on limiting the damage from natural disturbance agents such as fire and native pests. Today we understand that forest ecosystems in Oregon are well adapted to natural disturbance events and can absorb and recover from them much more quickly and completely than they can from the effects of exotic pests or pollution. Future Oregon forest policies must take the initiative in monitoring and responding to these new, under-appreciated but significant threats to forest ecosystem health and vitality.
What are the key interactions of this strategy with other strategies?
Protecting, maintaining, and enhancing forest health and vitality affects, and is affected by, other strategies and policies for managing Oregon's forests. Here are some examples of these interactions:
  • Introductions of non-native plants and animals often reduce the diversity of native plants and animals.
  • Carbon emissions from forest fires are not preventable, but the increased use of prescribed fire on federal lands may result in decreased carbon emissions by preventing much larger emissions from catastrophic fires.
  • Large-scale controlled burning on federal lands to thin dense forests and reduce fuels may degrade air quality in areas of eastern and southwestern Oregon.
  • Limiting opportunities for prescribed burning because of air-quality concerns may affect the timely reforestation of forestlands after timber harvesting and may result in the increased use of herbicides on some sites.
  • Implementing Oregon's An 11-Point Strategy For Restoring Eastern Oregon Forests, Watersheds And Communities, 2001 and other fuel-reduction programs should result in economic benefits to local communities.
  • Promoting Oregon's self-sufficiency in wood products could reduce the need to import raw wood and thus lower the risk of introducing invasive non-native species.
  • Establishment of invasive non-native species could lead to quarantines and the loss of important markets for Oregon's forest products and other plant industries (e.g., nurseries).
What are potential indicators to measure progress toward accomplishing this strategy?
Area and percent of forest affected by processes or agents beyond the range of historical variation (for example, areas of forest in which fire condition classes are different from those of presettlement times).