People use prescribed fire for different purposes in different regions of the state. Differences in local ecology, management priorities and historical use call for different approaches.
Burning reduces dead fuels in the understory of mature forests and after timber harvest. Burning also reduces “fuel ladders” — shrubs and small trees that could help wildfire reach tree canopies. Shrubs growing into grasslands can also increase the intensity of a fire. Prescribed fire can reduce the intensity of wildfires by removing fuel. Reducing the intensity of wildfires helps ecosystems recover. It also minimizes the economic losses from destroyed infrastructure and timber. While prescribed burns are not intended to stop a fire outright, burned areas can help firefighters safely prevent further spread. This is particularly true for prescribed burns in strategic areas — along ridges, next to roads and around communities.
Prescribed burning reduces competing vegetation and eliminates dead plant material. This material can obstruct agricultural operations and decrease forage quality for grazing wildlife and livestock. Competition also reduces the availability of water, nutrients and sunlight for desirable forage species. Prescribed burning improves rangeland health by increasing forage productivity and protein content, reducing encroaching woody vegetation, and making forage available earlier in the year than in unburned areas.
Lack of fire benefits many forest insects, such as bark beetles, Douglas-fir tussock moth and western spruce budworm. This is especially true when increased tree densities create stressful conditions. Dwarf mistletoe can also be a problem under these conditions. Prescribed burning can reduce tree densities and increase water and nutrients for remaining trees. Healthier trees are more resistant to insect and disease outbreaks. Burning felled or piled trees may also control insects or mistletoe in those trees before they spread to new hosts.
Fire suppression has reduced habitats, threatening many rare plants in Oregon. Prescribed burning can help restore these habitats. Grasslands, meadows and open forests are particularly important for rare plants in several parts of the state. This is an important reason for prescribed burning in places such as the Willamette Valley and coastal headlands. Plants in these places — like Bradshaw’s lomatium, Kincaid’s lupine and Cascade Head catchfly — depend on fire to maintain their habitats.
Fire is an important mechanism for promoting wildlife food sources. Following a fire, grass and shrub sprouts are generally more nutritious. Flower and fruit production also increase in some
species after fire. These changes can benefit pollinators and herbivores such as deer and elk. Dead trees turn into “snags,” which are important for many bird species. The space that opens up after fire can make it easier for predators — such as owls, hawks and bats — to travel and hunt. Reducing the likelihood of large, high-severity burn patches can also help maintain fish habitat by reducing erosion into waterways and maintaining riparian forests. Promoting wildlife habitat is an important motivation for Indigenous people, who burn meadows, marshlands and oak woodlands for this purpose.
Prescribed fire also supports resilient watersheds. It is critical to the health of many municipal water catchments. High-severity fires within municipal watersheds can seriously impact water quantity and quality.
Because of changes in the climate, extreme weather events are becoming more common. Under these hotter and drier conditions, forests tend to burn at higher severity. Increased drought stress after such fires can limit regeneration. In some cases, an area will burn again before trees can mature. Prescribed burning reduces competition and drought stress in trees, and decreases the likelihood of high-severity fires. This helps forests adapt to a changing climate.
Indigenous fire practitioners use fire to produce quality basketry materials such as beargrass, hazel and willow. They also use fire to maintain habitat for food and medicine plants such as camas, tobacco, biscuitroot and huckleberries. Cultural burning supports wildlife habitat and plays an important part in the traditions, culture and sovereignty of tribes. Tribal burning practices in Oregon today are diverse. They range from small, family-oriented burns focused on single cultural species to large-scale helicopter burns on reservation forests.