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Rebirth in Fire |
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Background
Information
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Wildland
fire is a natural process in the environment, much like floods, In order for fire
to occur, three elements must be present: heat, oxygen,
and fuel. These three elements form a “fire triangle.”
Fuel + Heat + Oxygen must be present for a fire. |
tornadoes,
etc., and natural processes cannot always be controlled. Some debate
occurs over whether wildland fire should be controlled, since it is
so beneficial to the natural forest environment. However, as humans
have encroached on the natural forest, fire has become a “hot topic.”
Some wildland fires are allowed to burn only to a certain point; others
are actively extinguished as soon as possible. And, in some areas, forest
managers use prescribed burns to maintain the healthy forest environment.
In order for people to appreciate the role of fire as a technique for
resource management, they must understand that fire can be beneficial
under the right conditions.
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Heat can be transferred in
three ways:
1. Radiation - a ray or wave; heat energy in the form of invisible light called infrared radiation; transferred through empty space. Radiation can dry surrounding fuels and sometimes ignite them. 2. Convection - heat is transferred through liquids and gases by means of up-and-down movements called convection currents. As temperature rises, convection increases as molecules move faster and become less dense. An example of this is a smoke column above the fire or smoke rising up a chimney. Hot gases and embers from it can dry and ignite other fuels. 3. Conduction - heat is transferred through the fuel, or from one fuel to another by direct contact of molecules. |
| Characteristics of
Fuel: 1. Moisture - how well a fuel will ignite and burn is dependent upon its moisture content or chemical composition. 2. Size and shape - light fuels such as shrubs, grasses, leaves and pine needles burn rapidly but are easily extinguished. Heavy fuels such as logs and limbs burn more slowly. 3. Fuel loading - the quantity of fuels in an area which is available for combustion 4. Horizontal continuity and vertical arrangement - the manner in which fuels are spread over a certain area. |
| Characteristics of Weather: 1. Temperature - fuel and ground temperatures are primarily due to direct radiation from the sun 2. Wind - encourages combustion and the spread of fire 3. Relative Humidity - low humidity takes moisture from fuels; fuels, in turn, take moisture from the air when humidity is high 4. Precipitation - fuel moisture is affected by the amount and also the duration of the precipitation. |
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Characteristics of Topography:
1. Aspect - the direction in which a slope faces relative to the sun 2. Slope - the amount of degree of incline of a hillside. The steeper the slope, the faster the fire burns up or down (depending on wind direction) 3. The shape of the country – box canyons, narrow canyons, and other rugged topographic features can influence the wind’s speed and direction. |
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In order to properly manage resources, natural resource managers sometimes start fires or permit naturally occurring fires to burn under very specific conditions. In addition to protecting life and property, a chief concern among resource managers is public reaction. It is essential that the public understand appropriate fire management policies, and that fire is a necessary part of ecological succession in many forested areas. In other forests, fire is used to maintain existing growth conditions. Succession occurs when one plant and animal community is gradually replaced by another. For example, when new and hardier varieties of plants are introduced, more animals are enticed to the habitat because food is plentiful. Fire enriches the soil, reduces insect pests and diseases and allows the germination of some plant species. Removal of fire from
an area may save some residential and business Some plants that require fire for reproduction may be endangered by the absence of fire. These plants exhibit serotiny; they store a large number of seeds over a period of years. When the heat of a fire cracks the resin bonds of the cone scales, the seeds are then dispersed. After a fire occurs, the successional areas which grow out of the burned habitat support species such as berries which produce food for animals. In tree savannas such as longleaf pine, fire removal may result in woody species invasion that chokes out herbaceous species. Controlled or prescribed burning has existed for the past 12,000 years in North America, when the first Native Americans used it to clear land and herd buffalo. Fire was used to drive animals from cover so that hunting could be accomplished more efficiently. Today, prescribed burning is used to resynthesize the natural pattern of fires in the wild. They burn in a patchwork pattern which helps create a diversity of habitats. |
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The objectives of prescribed burning are: |
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the past several decades, prescribed burning has become an accepted management
practice for many areas in North America. Problems occur when the public
is misinformed about forest fires and fear and alarm take hold. Fires
in the wildland /urban interface pose a special set of problems, as firefighters
are often trained to deal with either urban, structural fires or rural
forest fires, but not both. The key idea that needs to be stressed to
the general public is that often it is most efficient to “fight fire
with fire;” that is, to set fires deliberately so as to avoid larger
and more destructive fires in later years. |
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areas,
but it can be very detrimental to the forest habitat. For example, woody
debris, pine needles, dead leaves and ground cover will begin to accumulate
on the forest floor and the mineral nutrients in the wood are then returned
more slowly to the soil during decomposition. When fires do finally occur,
they may be especially hot, and thus more destructive, because of the
extra fuel.
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