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 lightening 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.
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.
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.
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.
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.
- See our April 15th news release and InciWeb maps for an overview of
Spring 2019 prescribed fire plans on the Wallowa-Whitman National
Forest.
- To learn more about wildlife and fire,
contact Mark Penninger, Wildlife Program Manager, Wallowa-Whitman National
Forest, mark.penninger@usda.gov, 541-523-1285.
Why do
we burn in the spring?
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?
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.
For
additional information:
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