Springtime Prescribed Fire Protects People and Wildlife

Fawn with blue lupine flowerAcross Eastern Oregon, lightning historically started fires in the mid-to-late summer, when grasses, pine needles, and other forest fuels were dry and highly combustible. Summer is also when relative humidity can be low in the Intermountain West, and winds typically accompany lightning storms. Dry fuels, low relative humidity, winds, and lightning are ingredients for a wildfire.

By mid-to-late summer, deer and elk have had their young. Most birds have nested, and their young are mobile and active. Most plants are well-past their flowering or budding stage. Trees, other plants, and wildlife in our area are part of an ecosystem adapted to wildfires that occur in the mid-to-late summer period. So it is reasonable to ask, “What are the benefits and consequences of applying prescribed fire in the spring?”

Possible concerns are that flowering or budding plants will be killed or damaged. Ground- and shrub-nesting birds will have their nests consumed by fire, possibly losing baby birds or eggs. Newborn deer and elk could be injured or killed. These are all valid considerations. This is why the Forest Service carefully develops burn plans that are designed to minimize these and other potential negative consequences.

Why do we burn? Our forests and grasslands developed with fire as a disturbance that rejuvenated plant life. We use the terms “fire-adapted plants” to describe plants that can tolerate fire and even flourish in the presence of fire. Many wildlife species depend on fire-adapted plants for nesting and foraging. Prescribed burning re-introduces fire that will consume some of the forest fuels, so that when a wildfire occurs later in the year, it is likely to be smaller and less intense. The long-term goal is to use fire in a controlled way, so that wildfires occurring later in the year can perform a more natural maintenance function in the forest -- reducing the need to invest millions of dollars and risk human lives to suppress wildfires.

Why do we burn in the spring? Late summer and early fall is often very hot and dry, with very low relatively humidity. Combine these conditions with high fuel loading that has accumulated from over 100 years of suppressing fires, and you have a recipe for large & severe wildfires that can damage forests and even soils. Soils damaged from intense wildfires can erode away or prevent a new generation of trees from becoming established. Spring burning creates gaps or breaks between forest fuels, consumes concentrations of fuels, and leaves a mosaic of burned and unburned areas.
Practically speaking, the Forest Service generally has two relatively brief "windows," in the spring and fall, to accomplish prescribed burning. These windows limit the Forest Service's ability to address the large areas of public land that are in need of fire. It would be difficult to move our forests toward a more fire-resilient condition if the fall season was the only time that prescribed fire could be used. Society’s appetite for smoke in their communities also influences when and how much the Forest Service can use prescribed fire.

How do we limit the harmful effects to wildlife when burning in the spring? Prescribed burn plans contain specific criteria that must be met before a prescribed fire can be ignited. The moisture content of the forest fuels and relative humidity must be within a certain range. Wind speed and temperature are factored in to determine how much smoke will be produced and which direction it is likely to travel. Additionally, steps are taken to avoid disturbance to nesting raptors (such as eagles, hawks, and owls). This may involve delaying the burning of an area, or adjusting the area to burn to reduce the chance of fire or smoke disrupting nesting raptors.

Because grasses and shrubs are very green in the spring, fire does not “carry” as well as in the fall. The fact that green grasses and shrubs do not burn very well means that many areas will remain unburned, having very little effect on flowering plants and the pollinators (such as butterflies, bumblebees, and hummingbirds) that depend on them.
The spring burning window also typically occurs several weeks before deer and elk young are born. However, just in case, fire crews do a walk-through of the area to make sure there are no young animals present. If they locate very young wildlife that are not capable of moving out of the area, adjustments will be made to avoid harming them.

The mosaic of burned and unburned areas that result from burning in the spring creates a highly valuable and attractive setting for many wildlife species, particularly once the area has recovered from the short-term effects of burning.

-Mark Penninger, Wallowa-Whitman National Forest Wildlife Program Manager