TUCSON, AZ (KOLD News 13) - Have you ever wondered why fires are intentionally prescribed to certain areas throughout Southern Arizona year after year?
Prescribed fires are intentionally set by trained fire managers under predetermined environmental conditions to meet a wide variety of park management objectives including reducing the risks of unnaturally heavy fuel buildup, the potential for destructive wildfires, and the potential loss of life and property; and to perpetuate species that require the presence of fire for survival. Much like a doctor would provide a planned course of action for a sick patient, the fire managers prescribe a specific treatment to maintain a healthy ecosystem.
Benefits of prescribed fires:
- Reduces fuel build-up, dead wood, overcrowded, unhealthy trees, and thick layers of pine needles that can all contribute to catastrophic wildfires.
- Breaks up continuous fuels. Prescribed fire creates a mosaic of burned and un-burned vegetation across the landscape which breaks up continuous fuels which can help limit or slow the progression of large, unplanned wildfires in the future.
- Prepares the land for new growth. When excess vegetation or needle layers are burned off, nitrogen and other nutrients are released into the soil and become available for new plants to grow.
- Helps certain plants/trees germinate many native plant and forest communities have adapted to fire for their germination and growth. Seed contact with bare soil (such as that exposed by a fire) is necessary for some species to naturally regenerate.
- Naturally thins overcrowded forests. Historically, natural fire thinned New Mexico’s forests. Thinned forests can recover faster and are more resistant to insect and disease attacks. Currently, most of New Mexico’s mature forests are overcrowded, resulting in a lack of vigor and health.
- Creates diversity needed by wildlife. Fire creates a varied land and vegetation pattern that provides diverse habitat for plants and animals. Grazing wildlife benefit from new growth as shrubs produce succulent edible leaves when re-sprouting after a fire.
- More efficient than mechanical treatments. Prescribed fires typically cost less than mechanical fuels reduction and are more efficient for treating larger areas.
- Produces less smoke than wildfires. Land managers are able to plan for prescribed fires. They get to choose the areas they want to burn, the size of those areas and the weather and wind conditions that must exist before they begin burning. This allows them to control the fire more easily and limit its size. Those choices don’t exist with wildfires. In addition, wildfires that start in areas that haven’t been managed with prescribed fire often have more fuel, because vegetation in the forest understory has built up, and dead vegetation has not been removed.
A burn prescription helps ensure that the objectives of the burn are met, as well as addressing safety issues. Land managers determine if the resource would benefit from a slow, consuming fire versus a hotter fire. The burn prescription determines the environmental conditions necessary for meeting resource objectives in a safe, effective manner. The prescription includes how the fire will be ignited and contained and what resources, such as fire engines and personnel, must be on site before burning may begin. The window of opportunity for prescribed burning is very small. Safety factors, weather conditions, air quality, personnel availability and environmental regulations are continually monitored before, during and after the burn.
Prescribed burns are conducted by trained fire management professionals who have studied fire behavior and fire control techniques. These prescribed burn professionals help ensure the safety of the burn crew, nearby residents, and property.
Fire creates a mosaic of burned and un-burned vegetation. As the fire moves along the forest floor it clears out dead and downed logs. Occasionally trees can torch and/or crown. This provides the establishment of meadows and provides openings and gaps on the landscape that provide for biodiversity. After a fire, the forest is reborn in the nutrient rich ash that fertilizes the soil. Many plants and animals are fire-adapted and some depend on fire for reproduction.
Not only do our forests depend on fire, wildlife does as well. This is a slow moving fire, and most wildlife can easily fly, flee or burrow to escape the flames and ultimately benefit from a diverse mosaic of habitats created by beneficial fires. These habitats provide a variety of food, forage and cover that native wildlife species depend on and need to survive and thrive. Many animals like to forage along the edges of burned areas and find cover in un-burned areas. Standing dead trees provide habitat for cavity-nesting birds.
Controlling where the smoke will go is an important part of every prescribed burn. Before each burn, land managers look carefully at what they plan to burn and the proximity of houses, roads, and other smoke sensitive sites to the planned burn area. The burn prescription is then written to mitigate negative impacts of smoke, especially to individuals who may be smoke-sensitive. Smoke, however, is a natural byproduct of fire and some amounts are unavoidable. Periodic prescribed burns prevent heavy fuel accumulation that would send a larger amount of smoke into the air should an uncontrolled wildfire occur.
The amount of smoke is not a reliable indicator for being able to manage a fire. Increasing heat and winds and changing fuel types will affect the amount and color of the smoke created. Since increasing heat and wind usually occur in the mid-afternoon, people should expect more smoke to build into a column in the afternoons. Very dark smoke and visible flames often indicate that the fire is burning in heavier fuels – such as dead logs on the forest floor.
Smoldering and smoke emissions may last an additional three to 10 days after ignition is complete. Smoke may settle when air temperatures cool at night and in the early morning hours. Smoke usually lifts during the day.
Fire managers work closely with the Arizona Department of Air Quality (ADEQ) to minimize the impacts from smoke. They try to select days to burn when weather conditions will help move smoke up and away from our neighboring communities. A project can be broken into several smaller blocks so that smaller amounts of smoke are produced at any one time.
Breathing smoke is not healthy for anyone, but some people are at greater risk, including people with heart or lung diseases, such as congestive heart disease, chronic obstructive pulmonary disease, emphysema or asthma. Children and the elderly also are more susceptible to smoke.
You may have a scratchy throat, cough, irritated sinuses, headaches, runny nose and stinging eyes. Children and people with lung diseases such as asthma may find it difficult to breathe as deeply or vigorously as normally, and they may cough or feel short of breath. People with diseases such as asthma or chronic bronchitis may find their symptoms worsening.
For more information, please visit https://wildlandfire.az.gov/useful-links#Smoke.