What is a Prescribed Burn?
A prescribed burn is the safe use of fire under specific conditions to achieve land management objectives. Land managers write a “prescription” of criteria that must be met before ANY burning can be done. The parameters of this prescription include weather, fuel types and amount, nearby manmade structures, and topography.
Why Do Land Managers Conduct a Prescribed Burn?
Fire has been part of the natural environment throughout history, whether it was started by lightning or by man. Early European settlers observed Native Americans using fire to clear land for agriculture, favoring plants desired for grazing or food; to control dense vegetation that would provide cover for approaching enemies; to reduce wildfire hazards around villages; to keep travel pathways clear; and to herd animals for hunting purposes.
As more and more people settled the American wilderness, fire was suppressed because it was seen as a threat to homes, livestock, and crops. As the federal government began to take more of a role in western land management around the beginning of the 20th Century, fire control was one of its primary missions. In a matter of decades, many forests went from a regular fire regime to a suppressed fire regime. The ecological impacts were significant, and many are still not well documented.
With the absence of fire, shrubs and woody stems choked the understory of the forest, while midstory trees blocked sunlight and shade-tolerant trees became more prevalent. These crowded conditions and a build-up of leaf litter on the forest floor choked out herbaceous plants and created fuel loads for out-of-control wildfires.
The forest became much less diverse, which changed the number and types of plants available as a food source for native wildlife. Maples, with flat leaves that suppress fire, replaced more fire-hardy species like oaks, whose curled leaves had helped disperse the fire.
In prairies, woody plants took over, shading out native wildflowers and grasses. This left the landscape open to soil erosion, an abundance of invasive plant species, and a decrease in suitable habitat for native animals.
By conducting periodic prescribed burns, we lessen the likelihood of a destructive wildfire by reducing the amount of fuel on the ground that will burn. Prescribed fires can also help prepare the ground for planting or natural regeneration of seeds. It removes excessive plant material, reduces competition, and provides a chance for the seeds and soil to come into direct contact.
Another benefit of a prescribed burn is that it removes many of the fire-intolerant plant species that flourished during fire suppression, allowing more fire-tolerant native forest and grassland species to thrive. Prescribed fire can also help control insect and plant diseases by decreasing forest density and encouraging healthy new growth. Frequent, controlled fire also improves habitat for our native wildlife, which are adapted to open or partially open habitats.
What Happens to Animals During a Prescribed Burn?
Most animals will either flee a fire or, in the case of burrowing animals, move deeper underground. White-tail deer, mourning doves, and bobwhite quail simply run or fly ahead of the flame front. Insects either fly ahead of the flame front or fly up to the safety of the tree crown. Birds such as the great crested flycatcher take advantage of this smorgasbord of insects.
Won’t the Fire Damage Native Plants?
To survive a fire, a plant must be able to insulate itself from the heat of the flames. Bark thickness is one of the most important factors determining fire resistance of trees. Pines are examples of trees with thick bark that acts as insulation. Small woody plants and shrubs with thinner bark, tend to use the soil as an insulating layer to protect them. Some plants protect their buds as an adaptive strategy to survive a fire.
Other plants retain their seeds until a fire does occur or seed dispersal is triggered by fire. A number of pine species have cones that open only as the result of heat from a fire. These are called serotinous because their cones are held closed by a resin that is sensitive to and opens in high temperatures generated by fire. The rare prairie sunflower (Helianthus pauciflorus), found at Chesney Prairie Natural Area, is a fire-dependent species with roots that can reach over 7 feet long to help it survive prairie wildfires.