In addition to water, fire is a dominant environmental force that structures and maintains ecosystems throughout south Florida. In fact, some ecosystems depend upon fire for their survival. Periodic burning allows the proliferation of fire-evolved plant species and reduces or eliminates competing species. Also, people have long realized that fire can benefit wildlife in many ways such as increasing food abundance or opening habitat. Additional benefits include reducing accumulated fuels that contribute to devastating wildfires, increasing scenic vistas, and controlling disease.
Historically, the fire cycle was governed by lightning that came with summer thunderstorms. But as humans have moved in these fires have been suppressed. Now land managers try to mimic these fires using prescribed burns. Burning at Corkscrew Swamp typically occurs between November and May and is conducted under the supervision of a certified prescribed burn manager. The sanctuary maintains a fire cache of protective gear, hand tools, a wildland fire engine, and a water tanker.
One of the land management tools used at Corkscrew Swamp Sanctuary is prescribed burns. These burns are a very cost-effective way of managing the land, and the reasons behind the frequency and time of year depend on the desired impacts on the ecosystems burned. Marsh and savannah areas burn every 1 to 3 years. This can be beneficial for numerous grasses and wildflowers because fire can actually enhance seed germination. Pine flatwoods, high pine, and shrub wetlands often burn in intervals of 3 to 7 years. The season of the burn also impacts the vegetation greatly. Pine trees are at a higher risk of mortality in the fall because of higher energy demands in the winter combined with new growth emerging in the spring. If you wish to protect hardwoods, early spring burns should be avoided because the plants have used up their energy putting out new leaves and are less likely to recover. Areas such as hammocks will burn more infrequently.
One benefit of these fires is the reduction of hazardous fuels thus increasing protection for people, facilities, and even forests. These burned areas become firebreaks during wildfire outbreaks. Additionally, there are numerous ecological benefits. Burning enhances habitat used by wildlife including endangered species including the Florida panther, gopher tortoise, eastern indigo snake, and red-cockaded woodpecker. Many people worry about wildlife mortality due to fire, but this is actually rare. Animals are more directly impacted by the alteration of their habitat. Certain species of plants only appear the first 1-2 years after a burn. Many trees benefit from fire. The naked seeds of pine and other species such as wiregrass are favored by access to bare mineral soils. Thus burning increases minerals and nutrients in the soil and opens up bare patches for seeds to take root. Ultimately, a land manager desires a mosaic of different ecological transitional stages for plant communities that can be maintained over time with burning. Without fire, hardwood species eventually come to dominate an area. For example, over time without burns, the wet prairie off of the boardwalk at Corkscrew would likely transition into a mesic pine flatwood. There are additional benefits to burning such as controlling disease and insects, clearing overgrown riparian areas, etc. Think of the abundance of new, highly nutritious green shoots growing a month after a prescribed burn. These higher-nutrient grasses and forbs are better for herbivores such as deer. Deer are frequently sited in recently burned areas foraging.
Corkscrew Swamp Sanctuary is sectioned off into burn units. These burn units help us to use fire as a management tool. Firebreaks are usually already in place and need only be refreshed instead of newly made thus minimizing soil disturbance impacts which often favor invasive plant species. These units also help with recording the frequency of fires. Fire units often follow borders between different vegetative communities. The wet prairie is a different burn unit than the pine flatwoods around the the Blair Audubon Center. The wet prairie is on a more frequent burn rotation than the flatwoods.
There are disadvantages and risks associated with prescribed fires. For the personnel, it is a hot and tiring all-day process with risks to personal health from smoke inhalation, injuries due to falling or tripping over unseen debris (downed trees for one), overheating, dehydration, etc. Fires can and do occasionally get outside of the burn unit perimeter. Staff must work quickly and efficiently to suppress these. Other risks include fires burning too hot and moving too slowly which can lead to the burning of tree roots or even the ignition of peat (depending on soil moisture conditions). Because of the complexities associated with prescribed fires, crew leaders on prescribed burns must be trained and certified.
Planning a prescribed fire takes training and knowledge of the ecosystems, topography, weather, and fire behavior. Before a burn is conducted, it is decided under what kind of weather the burn should be conducted. The area to be burned and how it will be burned are also noted. Additionally, we look at how the wind is going to impact the surrounding areas, and we avoid wind conditions that would put smoke over roads, airports, etc. It is calculated using a smoke screening test. These are parts of a burn prescription and are required for every burn. Firebreaks or plow lines are put in or replowed as needed ahead of time. These act as access roads for burn crews as well as to help contain the burn within the desired area. On the morning of the burn, if the weather is favorable then the Florida Division of Forestry and local fire stations are called for permits using the burn prescriptions.
Prescribed burns are an extremely useful land management tool that helps control exotics, perpetuate fire-dependent species, improve aesthetics, and enhance wildlife habitat.