Arbor Culture 5/25/14: Controlled burns promote health of forest ecosystem

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Most of us who have lived in Florida for any period of time have witnessed columns of gray smoke emanating from wooded areas throughout Central Florida. Some of these smoke columns are substantial and may last for several days. Sometimes they are adjacent to the highways we are driving on; other times, we see them from a distance. 


So what is all this smoke anyway? More often than not, it is from a controlled or prescribed burn.

The term “prescribed burn” refers to the fact that the burn is conducted following a written prescription detailing the site, the desired weather parameters, the equipment and personnel needed to safely conduct the burn, and other information, such as downwind smoke considerations and any special items noted (such as bales of hay present, piles of logging slash, etc.). The prescription should include a map of the site, with the location of the firebreaks, access points, location of special items as described in the plan, and any other pertinent information which may be useful.

A “smoke plume map” must be included depicting the desired direction of the smoke and the distance to any smoke-sensitive areas such as roads, schools, hospitals, airports and other areas which may be impacted by downwind smoke. Prescriptions for burns by non-Florida Forest Service (FFS) personnel, which are to be conducted in urban interface areas, are usually reviewed in advance by a supervisor from the FFS. 

Prescribed burns are performed by various land managers, both public and private. While the FFS is often the agency conducting the burn, other entities may include water management districts, Florida parks, federal land owners (e.g., national forests and military installations), county governments and private landowners and ranchers. Prior to the ignition of the burn, a burn authorization must be obtained from the FFS dispatcher for the relevant county. If the FFS believes that conditions are not suitable for conducting a safe burn, they can deny the authorization. 

So why would anyone conduct a prescribed burn? There are many reasons, and various land managers have different objectives.

Probably the most common reason is simply for hazardous fuel reduction. The pine ecosystems in our area, as well as throughout Florida, accumulate understory vegetation, such as palmetto. This vegetation can serve as fuel for a fire.

The understory vegetation needs to burn approximately every three to five years, and if left unburned for many years, it becomes very tall and dense. If a wildfire breaks out in this dense understory — such as from a lightning strike or a carelessly tossed cigarette — a hard-to-control fire may result, endangering nearby homes, businesses and other improvements. In addition, thick smoke may blanket nearby roads, creating very dangerous driving conditions. 

Thus, a prescribed burn to reduce this hazardous fuel buildup can prevent a dangerous wildfire. Personnel and equipment are available to conduct a burn safely when weather conditions are suitable to keep smoke away from highways and other sensitive areas, and to allow the burn to burn slowly against the wind rather than rapidly and uncontrollably with the wind.

Pine ecosystems also require exposure of mineral soil to allow pine seedlings to sprout. Dense vegetation buildup prevents a suitable substrate for the successful establishment of pine seedlings. In addition, if left unburned, hardwoods encroach into these ecosystems, competing and interfering with pine growth and reproduction. Prescribed burns can reduce the hardwood encroachment and enhance the ground conditions for pine regeneration. 

Wildlife also benefits from prescribed burns. For example, gopher tortoises prefer more open areas to create their burrows and to forage on grasses. Dense buildup of palmetto and hardwoods reduces their preferred habitat. Prescribed burns can reduce this buildup of understory vegetation and enhance their foraging and burrowing habitat. 

Wiregrass is a native grass found in association with longleaf pine forests. Wiregrass requires fire to produce seed stalks for reproduction. A prescribed burn in May promotes these seed stalks. Other grasses and wildflowers benefit from spring burns, as well.

Cattle also benefit from prescribed burning. A burn in late winter/early spring removes the buildup of dead grass and promotes new growth, providing fresh forage for cattle. 

Many newcomers or snowbirds in Florida complain about the smoke from these prescribed burns. They do not understand the ecological benefits and are unaccustomed to these burns because most northern ecosystems, unlike ours, do not depend on burning to promote certain species or entire ecosystems.

Granted, unwanted smoke is undesirable and unhealthy. Fortunately, most prescribed burns are done safely, with little impact to residential communities. Occasionally, one reads of a prescribed burn that “escaped” and became a wildlfire, with dense smoke over roads or subdivisions. However, these are rare in comparison to the total number of prescribed burns performed without incident.

So please keep in mind that, although sometimes inconvenient and perhaps mildly irritating, a prescribed burn is much more desirable than a wildfire producing thick smoke, with flames racing toward homes or other buildings.

It’s not an issue of if an area will burn; it’s a matter of when. Therefore, conducting a prescribed burn safely, with established firebreaks and equipment and personnel available to control the burn, is preferable to uncontrolled wildfires such as we have all seen on the news lately in southern California.


Eric H. Hoyer is a certified arborist, a certified forester, a registered consulting arborist and a qualified tree risk assessor with Natural Resource Planning Services Inc. He can be contacted at erich@nrpsforesters.com.