of running fires
Fire behavior is dependent on the wind direction, and several
different kinds of fires exist.
|The head fire is one that is running with the
wind. Depending on the wind speed and other weather factors,
the flames of a head fire can be from a few feet to 20-30
feet high. The latter is definitely not advisable. A head
fire is potentially dangerous and should only be allowed when
it is running towards an area that has already been completely
fire proofed. Because head fires move rapidly, less of the
fuel is consumed. With tall grass prairies, a head fire is
virtually impossible to put out, whereas it is relatively
easy with a savanna burn where the fuel is oak leaves.
|The backfire is one that is running against the
wind. Because the wind is tending to push the fire back, toward
the area already burned, the backfire is a low-intensity fire,
hugging the ground, and moving slowly in the direction from
which the wind is coming. Since the flames are being pushed
behind the fire, in a direction where there is no fuel (it
has already burned up), flame lengths are low. Depending on
the nature of the fuel, the backfire may burn to greater or
lesser intensity. Because they move more slowly, backing fires
consume more of the fuel. A complete burn can be done as a
backing fire but because of its slowness, this is usually
Fire backburning through bur oak savanna
|The flanking fire is one that is sideways with
the wind. Depending on constancy of the wind direction, a
flanking fire may burn slowly or more rapidly, but usually
not as rapidly as a head fire.
fire burning through an Indian grass patch on a hill savanna.
|The strip head fire is probably the most suitable
for oak savannas. It burns a bit faster than a backfire, and
is adaptable to burn units of various shapes. A series of
strips are lighted, starting at the downwind side of the unit,
burning only one strip at a time. Because the strips are fairly
narrow, the fire is under good control. The strip-head fire
can also be expanded, if conditions permit and enough personnel
and equipment are available, so that several strips are lighted
in sequence proceeding toward the upwind side of the unit.
A strip head fire burns slightly faster than a backfire, is
relatively safe, and works well for burning rectangular or
odd shaped parcels. It is also cost-effective.
The perimeter fire is one that starts as
a backfire, proceeds as two flanking fires, and then finishes
once the unit is circled as a “head” fire. This can be the
fastest sort of fire, because once the unit is “tied off”,
the head fire quickly finishes the job. Most prairie burns
are managed as perimeter fires.
Remember: When choosing a burn technique, the level of experience
of the burn crew should be a major factor.
and running fires
If the burn unit is on the side of a hill, the flame characteristics
are mostly determined by the slope rather than the wind. A
slope lighted from the bottom will burn as a head fire, irrespective
of wind direction. This is because the rising flames burn
the fuel on the uphill side of the burning front, and this
phenomenon propagates up the hill. In addition, convection
and radiant heat move upward, resulting in more preheating
of the fuel and faster ignition.
fire burning uphill is equivalent to a head fire.
On the other hand, when the fire is lighted from the top,
the rising flames encounter fuel that has already been burned,
so that the flaming front burns down the hill like a backfire.
If the wind is also blowing upslope, it adds to the effect
of the slope. Thus, lower wind speeds are needed when burning
upslope than when burning on the level. If the wind is too
strong, an upslope burn may not be possible whereas the same
wind on a level burn might not be a problem.
the burn done
Weather and other conditions needed for the prescribed burn
are monitored, and when conditions are suitable, and needed
personnel are available, the burn is scheduled. The decision
to perform the burn is made by the person who is to be in
charge of the burn, the burn boss. Due to changing weather,
the decision to burn can only be done one or two days before
the burn. Sudden changes in weather or other factors may require
that a scheduled burn be cancelled at the last minute. The
acceptable weather conditions for the burn are laid out in
On the day of the burn
On the day of the burn, all personnel assemble at the site
well in advance of the time of lighting. Burn crew members
should have fire-resistant outer clothing, leather shoes,
and leather gloves. An orientation meeting is conducted at
which the details of the prescribed burn are reviewed by the
burn boss. The weather is reviewed, and weather variables
that might change (such as wind speed or direction) are identified.
If necessary, crew members will familiarize themselves with
the burn unit by walking the whole periphery. At this time,
the burn boss will point out items that might need particular
burn crew assembled before the burn. The burn boss describes
the burn in detail and assigns tasks. The locations of
fire breaks are reviewed on the burn map. Smoke management
issues are discussed.
Conducting the burn
For most burns, two fire lines are used, operating in opposite
directions. Each burn line has a line boss, who supervises
the fire on that particular line. Each line has at least one
crew member responsible for lighting, and other crew members
with water. The line boss directs the crew members, and maintains
communication with the burn boss. Usually the two burn teams
start at a single point and move in opposite directions around
the burn unit. Communication between crew members during the
burn is vital. For burn units of any substantial size, two-way
radios are essential. Before the burn begins, all radios should
be tuned to the same channel and checked.
Cell phones can also be used, although they are not as convenient
as two-way radios (see Safety, below).
Before the burn is started, a weather check is made to determine
wind speed and direction, temperature, and relative humidity.
Assuming conditions are favorable, a small test fire is first
done to determine how the fuel burns. The test fire is done
at an upwind corner of the burn unit and is essentially a
small backing fire. The burn boss observes the behavior of
the test burn. If conditions do not appear satisfactory, the
test fire is put out and the burn crew moves to a different
location, or the burn is cancelled. Assuming the test burn
is satisfactory, a short strip of fuel is burned and observations
continue. Once the burn boss is satisfied with the behavior
of the fire, the two burn lines begin to proceed in opposite
directions around the burn unit.
test burn. The burn boss and burn crew observe the behavior
of the fire and make any modifications in the burn plan.
Each fire line has at least one drip torch. The fire is always
started at a good fire break on the downwind side of the burn
unit, and allowed to burn as a backfire along the inner edge
in order to create a substantial black line. Water is used
to ensure that the backfire does not jump the break and burn
outside the burn unit. Spotters should be positioned downwind
of and outside the area of the backfire. (See Spot Fires,
The burn boss is in communication with each line boss, who
report about the behavior and progress of their lines.
As the burn progresses, crew members with water cans spread
out along the burn line, looking for spot fires or other problems,
reporting frequently to the line bosses, and putting out any
fires that start to “creep” out of the burn unit.
Careful attention must be taken to ensure that the blackline
along the downwind side of the burn unit is wide and thoroughly
black. Crew members with water packs monitor to make sure
that the fire remains within the burn unit.
A spot fire is a fire that has started outside the intended
burn unit. Spot fires usually arise from wind-blown embers
that pass out of the burn unit and land upon nearby flammable
material. Since these embers are igniting a fuel outside and
upwind of the burn unit, the result will be the start of an
unwanted head fire. This a serious situation and one that
should be avoided at all costs. If a spot fire develops in
dry fine fuel and the wind is strong, such a fire can rapidly
turn into a roaring head fire which can be very difficult
To avoid a spot fire, personnel with water backcans called
“spotters” must be stationed upwind of the burn unit, and
if any “spots”arise they must move quickly to them and extinguish
them. Although the position of spotter is generally a boring
position on a burn crew, if a spot really does occur, the
spotters role is vital.
If a pumper unit is available, a wet line can be used to help create
a good black line on the downwind side of a burn unit, when
laying down a blackline. This is very useful in grass, especially
if the area outside the burn unit is also grassy. Although
a semblance of wetlining can be done with backpack water cans,
in most cases this technique will only be used if a high-pressure
pumper unit is available (on a truck or ATV).
of wetlining to control the edge of a fire break. The
unit to the right is not being burned.
A pumper unit is
needed for this task. The water moves ahead of the drip
torch and wets the
edge of the mowed fire break.
In this procedure, two (or more) people operate the pumper
unit and manipulate the hose, and the person with the drip
torch lights the fire behind the wetline. The wetline should
be laid down on the side of the break nearest to the burn
unit. The fire then backburns away from the wetline. Personnel
with backpack water cans can follow further back to make sure
that the burn does not cross the mowed fire break.
Wetlining can also be done in woods, but is less likely needed.
To quickly widen the blackline, strips of fire at right angles
to the backfire (called chevrons) can be made. These are useful
in savanna burns where oak leaves are the main fuel, because
oak leaves burn much slower than prairie grass and chevrons
speed up the burn process.
of "chevrons" to speed up the burn. These strips
at right angles to the fire line quickly
and create the desired "blackline."
Completing the burn
Once the downwind black line and corners have been secured,
the burn lines move in opposite directions around the flanks
of the burn unit. It is important that wide blacklines are
present on both the downwind side and the flanks of the unit,
before the upwind side is lighted. Lighting the upwind side
initiates the head fire and should greatly speed up the burn.
In some cases, interior lighting (sometimes called stripping)
may be necessary to widen out the blackline or to ensure that
all burnable material inside the unit have been burned. For
stripping, a second drip torch is sent into the interior to
light as directed by the line boss. Before any personnel are
permitted into the interior of the burn unit the burn boss
must make sure that the whole unit has been burned. Because
savannas burn less completely than prairies, stripping is
often necessary to achieve the desired degree of burn coverage.
lighting (stripping) is often needed in oak savanna burns,
especially in the early years of a restoration.
Once the unit has been completely burned, it is time for
mop-up. Before the burn unit can be left, it must be made
With prairie burns, mop up is fairly straightforward since
the efficiency of the burn is so high. The main thing is to
ensure that embers or other glowing materials are not swept
up by wind and carried into an adjacent unburned prairie.
Usually, such embers burn up quickly and do not cause a problem.
In oak savanna burns, on the other hand, dead timbers or other
burnable material that did not burn in the initial pass of
the flame front should be allowed to burn up on the ground.
Thus, as long as fire has been extinguished around the periphery
of the burn unit, it is desirable to allow the burn to continue.
Especially in recently restored savannas, slow burning may
continue for a day or two, to no harm to the savanna.
Burning material well within the unit can be left as long
as the smoke is not too bad, but burning wood or brush along
or near the control lines must be extinguished. The most common
problems in savanna burns are flaming or smoldering downed
logs, overhanging branches (especially dead branches) that
are on fire, and chimneys. A chimney is an upright tree, usually
dead, with fire inside of the trunk.
rather bad "chimney" that has to be dealt with
in mop-up. If the savanna unit had been fireproofed before
the burn, this probably would not have happened. If this
tree is near the edge of the burn unit it will have to
be cut down to extinguish it.
It is essential that in a savanna burn no burning materials
are left near the edge of a burn unit.
A major advantage to having a truck or ATV-mounted pumper
unit is that it provides high-pressure water that can be used
to put out smoldering logs or other large-sized fuel. A log
should first be broken up, either with a foot, a shovel, ax,
or a fire rake, to expose the source of fire. When the interior
of the log is exposed to air, it may start to flame.A strong
stream of water from the pumper should be directed at the
flames unit until they are put out.
Overhanging tree branches are more difficult to deal with.
If the burn unit has been prepared ahead of time, this problem
should not arise. If a branch high in a tree continues to
smolder, it may be necessary to cut this branch so that it
can be extinguished on the ground.
If a chimney cannot be extinguished, it may have to be cut
down with a chain saw and the fire then extinguished. Sometimes
a single chimney can take an hour or so to deal with.
The burn boss will decide when the burn is safe to leave.
Often, only one or two people need be left to monitor smokers.
trees and savanna burns
Although oak trees are relatively fire resistant, smoldering
wood that lies next to trees can cause minor fire damage.
Due to the manner in which the fire moves, the backside (upwind)
side of a tree will be hotter than the downwind side, due
to the manner in which the fire burns. Thus, after a burn
is completed, the whole burn unit should be examined and any
hot or burning debris should be kicked away from the tree
Standing dead trees are especially prone to ignite at the
base. There is a hazard that such trees might topple over
if the base is burned too much. This presents a personnel
hazard as well as a problem with mop-up. Especially after
the burn has been completed, personnel should be cautioned
to be on the alert for trees that might topple.
Comparison of different kinds of burns
A brief summary of the differences between three kinds of
burns, prairie, savanna, and woodland, is given in the table
|Type of burn
|Time to complete;
chimneys; brush piles
The prescribed burn is one of the most useful tools in ecological
restoration, and if carried out properly should be incident-free.
However, it must be carried out by trained personnel, and
based on a precisely written burn plan. Fire should not be
used casually or without proper thought and direction.
A burn should never be started until the burn boss has verified
that conditions are safe. Personnel on the burn must be totally
informed of the burn and their particular part in it. Each
line boss must at all times keep track of all personnel on
that line. It is especially important to keep all personnel
away from the front of the flaming front of a head fire. Most
important is to never attempt to out-run a head fire.
Although good 2-way radios are expensive, they are very important
for the conduct of a burn, and for ensuring the safety of
personnel. If there are insufficient radios for all personnel,
then each person without a radio should be paired with someone
who has a radio. Topography, trees, and smoke can reduce the
visibility of personnel.
Cell phones can also be used, although communicating by them
is slower and less efficient. Although cell phones are less
subject to interference than two-way radios, and have wider
coverage, reception in remote areas is often spotty. If cell
phones are to be used, ensure that they will work well in
the burn area before relying on them and program the phone
numbers of all the cell phones being used. Ideally, the burn
boss and line bosses should have a cell phone as well as a
The burn boss is responsible for keeping in touch with each
line boss, and ensuring that all personnel on that line are
accounted for. Frequent radio contact informing all participants
of the progress of the burn is very important.
A first aid kit and plenty of drinking water should always
be available. Proper clothing is important. Leather boots
and gloves, eye protection, and fire-resistant clothing (Nomex)
are essential. Clothing of synthetic fibers like nylon should
not be worn, as they melt at relatively low temperatures.
Long sleeve shirts and long pants should be worn, as well
as hard hats. For visibility, bright colored-clothing should
Most members of the public will consider any fire to be a
wildfire and dangerous. It is vital that the public be informed
of the nature of the burn, and protected from the burn. Casual
observers should not be permitted. Dangerous situations can
create liability concerns and should be avoided.
for a successful savanna burn
- Have all fire
breaks made before the day of the burn.
- Start early
enough in the day
- Always have
plenty of drip torch fuel, usually twice the amount you
think you might need.
- Always have
plenty of water, and place water bottles or tanks at various
locations along the burn unit but outside the fire break.
- Always keep
vehicles well outside outside the burn unit.
- Keep all personnel
accounted for. Especially before lighting a head fire, make
sure that all personnel are outside the burn unit.
- If the burn
is going well, expand it to other units if time permits.
You may not have favorable weather again for a while.
- Try to do larger
burns. Finding the right conditions and obtaining a competent
burn crew is difficult, so the golden opportunity should
not be lost by doing small burns. Try to do the largest
burn consistent with facilities and personnel.