Big Cypress National Preserve
When we bought our camp, it had a couple of Java Plum trees out on the
edge of the clearing. After twenty years or so, these trees got very
large, but also we discovered that young offspring were spreading. The
Java Plum is a non-native tree that is considered an exotic, but it was
only a few years ago that we realized it was also invasive, (spreads). We
used a herbicide on the big trees, and killed them, but attempts to find
an kill all the offspring was near impossible in the thick palmettos. Just
when we thought we had them all, more would appear. It was clear to us the
only way to get all the offspring was to burn. Even if the fire didn't get
them, we would be able to get to them with herbicide, once the palmettos
were burned back. So, since it is almost impossible for a land owner
to get a burn permit, I requested the NPS to conduct a prescribed burn.
I'm sure there were good intentions, but it was almost two years before
this weekend arrived.
|Planning a prescribed burn actually starts a few days
before the actual burn. The weather plays a most important role in the
burn, a weather report showing potentially good weather for burning
is needed for the day of the burn. So the weather is checked to determine
if a burn should even be planned.
If the weather forecast is for good burn conditions, the burn in planned. This includes scheduling fire crews and equipment and in the case of the Six Pack Burn, the positioning of equipment into the back country.
|http://flame.fl-dof.com/||On the day of the burn, the National Park Service, in
order to obtain a permit for itself or a private land owner, must contact
the State Division of Forestry to obtain a burn permit. The permit is
issued depending on weather conditions, how the smoke plume will
effect aviation or vehicles on highways.
Minimum requirements for the prescription include: site and fuel description; map of the area to be burned; personnel and equipment to be used; desired weather factors; desired fire behavior; ignition technique; time and date the prescription was prepared; authorization date and time period; an evaluation and approval of the anticipated impact of the proposed burn on smoke-sensitive areas.
|The fire crew's most important challenge is to conduct a
prescribed burn that does not endanger the safety of the crew or private
property. Natural firebreaks are considered in setting the limits of the
prescribed burn. These can be wet lands, open prairie or ORV (buggy)
trails, (some purists might argue ORV trails are not natural, but they do
stop fires from traveling). The burn plan must also consider escape routes
for the crew.
The crew also faces the challenge of creating a fire that is hot enough to remove the under brush, but not hot enough to destroy trees. To accomplish this, careful consideration of the wind and humidity is required,
Wind is required to move the fire along and disperse the heat of the fire. A fire sitting in a calm spot can send heat directly up into a tree canopy and kill the tree. Of course too much wind can send a fire out of control. These factors, especially weather prediction and others determine a burn plan.
|Immediately before the beginning of the burn, fire
equipment is checked, including personal equipment carried by each of the
fire crew. The crews clothes were fire resistant, long sleeve shirts
(bright yellow), bib overalls, gloves, boots and hard hats. Each of them
wore backpacks containing their equipment.
In the case of the Six Pack burn Two fire buggies were stationed in the clearing around the camp buildings. Each of them was running both the fire fighting water pumps and the buggy engines, (encase of a need for quick relocation), during the burn. The NPS interns were responsible for monitoring the weather. They had handheld equipment to take humidity and wind direction and speed readings. They took the readings before the beginning of the fire and approximately every half hour during the fire. This update information was relayed to all of the fire crew via radio during the fire.
|Depending on the burn plan, a fire is almost always set at
the downwind limits first and the fire burns into the wind. This
establishes a burned area done at low intensity to keep it tightly
controlled. Once the control area is established,
additional fires can be
set at increasingly upwind distances, depending on how the intensity of
the fire is going. If the fire is not burning intensely, a head wind fire
can be set (up wind side), which would result in the most intensity fire.
Rules of Thumb for a prescriptive burn:
Executing the Burn:
|It is the nature of pine and palmetto islands to burn
intensely, but for a short duration. This fact is what allows pine cones
to pop open during a burn, allowing new pine tree seeds to be released. A
fire too hot or too long a duration, incinerates the pine cones rather
then popping them open.
Pine trees have a bark that acts as an insulator from fire. This allows the trees to survive both prescriptive and natural fires. A fire that is too hot destroys young pine trees. A fire at extreme intensity will also kill adult trees.
The hardwood trees, like myrtle tree, are almost always killed in a fire. This is why pine trees and palmetto plants predominate the pine islands in the Big Cypress Swamp. When it is a long time between burns, the myrtle and other trees start to dominate and crowd the islands and prairie.
The palmettos and cabbage palms, they seem to recover from any type fire. In a low intensity fire, the green part barely looks hurt, in an intense fire, they look like charcoal trunks, but they always survive and re-grow.
|It is the nature of fire to produce smoke as it starts,
and then as the flames get intense, the fire consumes most of the smoke
and the smoke plume reduces. As the fire dies out the smokiness returns.
The fire crew is completely obscured in the picture.
In the picture to the right, you can see wind borne ash, (click on picture for larger view) some of which is still burning. I took this picture after retreating from the smoke and wind borne ash. Since I was not wearing fire protective clothing, the hot ash would burn as it landed on me, so I beat a hasty retreat.
|This picture demonstrates the heat generated by the fire. The spots in picture are wind borne ash. The picture is distorted by heat waves. (click on picture for larger view).|
| This is where a prescribed fire becomes an art, rather
then pure science. The crew uses judgment on how the fire is preceding and
incorporates changes in the plan as the prescriptive burn takes place.
Their judgment is critical to the result.
Wind is another item that is critical to the result. On a day with variable wind speeds or direction, judgment really becomes important on the part of the crew. The crew works with nature, but nature is really in control, a wind shift or increase or decrease of the wind makes a big difference in the result.
|After discussing the results of the burn up to that point. A new section of the prescribed burn is set. This process was repeated over and over again, until the prescribed burn was completed. A second crew was working simultaneously on another part of the pine island to speed up the process. The two crews and additional support remain in radio contact during the whole process.|
|As the picture to the left shows, even sparse palmetto brush can generate a intensely hot fire.|
|The picture to the left show a NPS Fire Engine. These are custom build to traverse the Swamps and varied terrain of the Big Cypress National Preserve. They have a un-usual look as compared to standard fire engines, but they are a very capable piece of equipment for fighting fires..|
|Top view of Swamp Buggy Fire Truck. They have three permanent seats for the crew. Additional crew, when needed can sit on the storage box. Next to the hose reel is a suction hose for refilling the water tank when needed. The fire pump is gasoline powered and is installed behind the front tire on the side.|
|Passenger side view of the Swamp Buggy Fire Truck. Fire starting drip torches and extra fuel is stored between the wheels on the side. These Fire Buggies are heavy and though they have large tires, with a full load of 200 gallons of water, they have to pick and choose their route through the swamp.|
|Backside view of the Swamp Buggy Fire Truck, with the fire just in front of it.|
|The picture shows how close the controlled fire was to the camp buildings. You can also see at the very left of the picture that a complete burn was not accomplished. The wind died down just as this area was burning and therefore it was not completely burned. This is where nature is really in control. The fire crew works with nature to accomplish the prescribed burn, but the whims of ole mother nature are really in control.|
|There was a big difference in the effects of the smoke when the fire was approaching camp from the down wind side, verses the up wind side.|
|My thanks to the Fire crews, Each and every one of them was friendly, professional and willing to let me pester them for information about what they were doing and the methods of prescriptive burns. Thanks for the successful burn!|
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Story by Steve, written on February 29th, 2004