Prescribed fire can be defined as a fire
applied in a skillful manner to wildland fuels, in a predetermined place,
under exacting weather conditions, to achieve specific management objectives.
For this reason prescribed fire is much different than arson fire. Arson fire
is a fire that has been set for destructive purposes and not for wildlife
habitat enhancement. Prescribed fire is one of the most cost effective and
dynamic methods known for managing wildlife habitat. The use of fire has
traditionally played a big role in habitat management. A burn will set back
natural succession and stimulate the growth of valuable grasses and legumes
through seed scarification (breaking down the seed coat). Prescribed fire
releases nutrients allowing lush herbaceous growth conducive to high insect
production while at the same time producing bare ground for better movement
The role of fire in habitat management has
become accepted and well used in the southern coastal plain states, while in
Kentucky the use of fire for habitat improvement is rarely used and not well
understood. Decades of fire prevention have led many to believe that all fire
is bad. However, under carefully controlled conditions fire can be a very
effective management tool. Most uses of prescribed fire in Kentucky are for
managing open lands (fields). Some beneficial uses of fire for wildlife
· reducing invasion
of trees and shrubs
· managing grassland communities
· removing excess leaf litter that inhibits
vegetative growth and wildlife use
· releasing seed for germination
· increasing species diversity
· reducing hazardous fuels
· controlling disease
factors influencing fire behavior include:
1) Weather Conditions:
Weather conditions control the effectiveness
and safety of
prescribed fire. Wind speed and direction is
the first condition you need to consider, followed by relative humidity,
temperature, fine fuel moisture, atmospheric stability, rainfall and soil
· Ideal transport wind speed, or wind
measured at 20 feet above ground level, should range from 6 to 18 mph for
smoke dispersion. This is the wind speed that is usually given by your local
weather center. Surface wind, or wind speed at eye level, should range from
1 to 3 mph.
· Relative humidity is the proportion
of moisture in the air, to the maximum amount of moisture the air is capable
of holding at the same temperature and pressure if it were saturated.
Relative humidity should
range from 30% to 50% for a prescribed burn.
· The temperature for a late winter to an
early spring burn should range from 20 to 60 degrees Fahrenheit.
· Soil moisture should be ideal if you have
received a 1/2" or greater rainfall within 1 to 3 days prior to the
burn depending on previous conditions. This is important to prevent rapid
spreading of fire and permanent damage to the soil and the microorganisms
that help maintain soil composition.
· Ideal fine fuel moisture (FFM)
ranges from 10 to 20%. This is directly controlled by relative humidity (RH),
rainfall & soil moisture. A rough estimate can be obtained by taking the
relative humidity and dividing it by 2: (RH ¸ 2 = FFM).
· Atmospheric stability
is the resistance of the atmosphere to vertical
movement. Unstable atmospheric conditions are preferred. Such conditions
promote rapid smoke dispersion but, if severe, can make fire control
difficult. Indicators of unstable conditions include wind gusts, clear
skies, and sometimes dust devils. Stable atmospheric conditions can cause
severe smoke problems. Indicators of stable conditions include haze, layered
clouds, and no wind or very steady low wind.
Topography, or the lay of the land, is also a
major influence of fire behavior. There are three main considerations
regarding topography: aspect, slope and terrain.
· Aspect is the direction a slope faces.
This determines the amount of heating it gets from the sun and the amount,
condition and type of fuels present. South and southwest slopes are normally
· Slope is the degree of incline of a
hillside, and determines the rate at which a fire burns. Fires burn more
rapidly uphill than downhill. The steeper the slope, the faster the fire
· Terrain is the shape of the land and has
major effects on fire behavior. Narrow canyons are conducive to the spread
of fire to the opposite side by radiation and spotting.
Three steps to
conducting a prescribed burn:
The first step in prescribed fire is to
evaluate the site to be burned. Conditions such as the amount and type of fuel
on the land, moisture conditions, expected environmental conditions and the
presence, size and expected effectiveness of firebreaks should all be
determined and recorded on a Prescribed Burning Unit Plan. The following
should be incorporated into a prescribed burning plan:
The map should show the boundaries of the planned burn, adjacent
landowners, topography, control lines (both existing and those to
be constructed), anticipated direction of the smoke,
smoke-sensitive areas, roads, and houses.
List equipment and personnel needed on site and on standby.
Prescription: The amount of fuel, fuel moisture, weather
conditions and desired intensity of the burn.
Generally the best time to conduct a prescribed burn is during the
period from February 1 to April 15. Check with KY Division of
Forestry regarding fire regulations.
Day: Normally, plan burning operations so the entire job
can be completed within the same day. Start between 10 a.m. and
noon if conditions are favorable and if Kentucky forest fire laws
Plan: Make sure all firebreaks are within the suggested
guidelines. Choose the correct firing technique for your desired
results. Make sure all weather patterns are within the suggested
guidelines. Test burn with a small fire to check smoke behavior
and fire intensity. Be alert to changing conditions.
Patrol the area until the fire is completely out with no danger of
re-ignition or smoke problems.
Control lines or firebreaks are physical
changes on the landscape which allow for control of the burn. Firebreaks
should be a minimum of 8-15 feet wide and should border the entire burn area.
There are essentially 4 different types of firebreaks commonly used.
· Natural firebreaks are changes in the
landscape, such as streams, rivers, ponds and roads that prevent the fire
from continuing its path due to a loss of fuel.
· Constructed firebreaks can be established
by mechanically disturbing the soil or spraying the vegetation with water or
fire retardant to remove fuel or make it unavailable to burn.
· Another method includes the use of planted
or existing barrier crops or strips that are fire resistant. Crops such as
winter wheat, winter barley, annual rye-grass, orchardgrass and clovers are
usually "green" during the recommended burning dates.
· A final method requires careful control of
fire under very slow burning conditions to create a "black zone"
where the fuel has been removed and the fire is then suppressed. Generally
this type of firebreak is more difficult to install. However, it can be
installed as an enhancement to other firebreaks by utilizing strategic
placement of fire in the burning plan (see firing techniques below). The
most common application of this type of firebreak is by the use of
backfire-burned fire lanes.
3) Firing Techniques:
Techniques used to start and control the
fire vary form site to site. Generally, a back-fire or a fire started along a
firebreak, such as a road, plow line, stream or other barrier, and allowed to
burn into the wind, is most commonly recommended. Other types of recommended
firing techniques include; strip-heading fire, flanking fire, ring fire and
point source fire. Explanations of these
can be found in A Guide for Prescribed Fire in Southern Forests.
Contact the National Interagency Fire Center, Attn: Supply, 3833 S.
Development Ave., Boise, Idaho 83705. Order NFES # 2108.
Management and Other Considerations
Smoke management must be incorporated in the
planning period. Obtain weather and smoke management forecasts for reference.
Comply with air pollution control regulations. Do not burn during pollution
alerts or low transport wind conditions. Burn when conditions are good for
rapid dispersion or during slightly unstable atmospheric conditions. Use
caution when near or upwind of smoke-sensitive areas such as towns, schools,
highways or public park areas. Do not burn if smoke-sensitive areas lie within
1/2 mile downwind. Estimate the amount and concentration of smoke you expect
to generate. Always use a test fire to confirm smoke and fire behavior.
There are a number of other features that will
affect a prescribed burn. For these reasons it is recommended that contacts be
made with KY Department of Fish and Wildlife Resources Wildlife Division, KY
Division of Forestry, and others who have successfully used prescribed burns
to manage habitat. Always notify the local fire department(s), adjacent
landowners and the Division of Forestry of your burn plans. The KY Division of
Forestry (KRS 149.400) regulates burning in and around Kentucky’s woodlands.
By contacting the Forestry Division (800/866-0555) you will be able to acquire
any burn bans or restrictions in your area. Current laws state that from
February 15-April 30 and from October 1-December 15, you cannot burn within
150 feet of any woods or brushy area except between the hours of 6:00 p.m. and
6:00 a.m. local time. Consideration must be given to the down-wind effects of
the resulting smoke and the need for adequate manpower for suppression and
control. Experimentation is part of learning the technique. Start off by
burning a small plot and increase plot size as your knowledge increases.
Always start the planning process with a
desired objective in mind, develop a complete written plan, only burn when
environmental conditions are correct and make a record of the final results by
noting the good and bad points. Retain the plans, prescriptions, conditions,
records and results for future reference. NEVER
ATTEMPT TO BURN ALONE, WITHOUT A BURN PLAN, OR WITHOUT PROPER GUIDANCE AND
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