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Prescribed Burns Used As Land Management Tool

Tribune photo by ROBERT BURKE

A controlled burn, such as this one on Balm Scrub acreage, can prevent accumulation of decayed plants that fuel a raging inferno.

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By SUSAN M. GREEN

The Tampa Tribune

Published: July 11, 2008

Updated:

RIVERVIEW - First, it was too dry.

Then it was too wet.

Bill Carlisle would like to set the wilds on fire, but Mother Nature isn't cooperating.

Maybe she remembers when setting the woods and meadows aflame was her job.

Since May, Carlisle has been trying to fill a prescription for a burn that will stimulate native wiregrass to grow on a scrub habitat in southeastern Hillsborough County.

Periodic wildfires, long part of the natural rhythm of Florida's environment, help maintain native habitats by gobbling up leaf litter and stimulating healthy new growth. But it's too risky to let nature take its course on thousands of acres of environmentally sensitive preservation land that's hemmed in by human population growth.

Employees of Hillsborough's Parks, Recreation and Conservation Department try to meet the needs of many plant and animal species and stave off runaway wildfires by conducting 40 to 50 prescribed burns a year on about 3,200 acres of preservation land.

"The main thing keeping us from doing more burns is the amount of urban-wildlife interface," said Carlisle, the parks department's prescribed burn coordinator.

That's conservation lingo for residential subdivisions, roads and shopping centers springing up on the borders of land set aside for wildlife or water resource protection.

Carlisle and others who plan periodic land management burns not only have to contain a blaze to the acreage marked for treatment, they have to consider how it might affect neighboring homes and farm fields.

"Where the smoke is going; that's the No. 1 thing we have to worry about," Carlisle said. "You can't shut down I-75. And some sites have homes on four sides."

To manage smoke, burn coordinators scour weather reports for forecasts about humidity, temperature, rain and most of all, wind direction. All those factors are double checked by the state Division of Forestry, which issues permits to burn. Carlisle rattled off dozens of state and local agencies that also receive notification once a burn permit is issued.

In Florida's predevelopment days, most wildfires started from lightning strikes during the rainy season. Land managers tend to favor burning during the cooler months, Carlisle said, to reduce the fire's intensity.

Conservation division workers have cut "miles and miles" of fire lanes through county-owned preservation tracts to keep flames under control. The goals are to protect neighbors and also keep the vegetation that thrives on a good scorching from being burnt to cinders by an over-intense fire.

For example, native pine trees need periodic fire to germinate. If a fire burns the conifer's crown, however, the tree will die.

Even with precautions, however, problems can arise. An unexpected wind shift or drop in humidity can affect smoke and flames, as it did in January, when smoke and fog blinded motorists on Interstate 4 in Polk County and led to deadly accidents.

Not burning the land from time to time is a bigger mistake, Carlisle said. After a series of devastating wildfires, the federal government launched a campaign in the 1940s to stamp out forest fires as soon as they sparked.

As a result, when the woods do catch fire, the accumulation of decayed plants fuels a raging inferno that's harder to knock down, Carlisle said.

"All fires were deemed bad, so they started trying to put out every fire as quickly as they could," he said. "Instead of having numerous low-intensity fires, you had infrequent high-intensity fires you couldn't stop."

"We're still trying to catch up with decades of fire suppression."

Carlisle points to a 400-acre wildfire that snarled traffic and evacuated homes in the Riverview area about two years ago. The fire started on an overgrown section of the county's Golden Aster Scrub Nature Preserve. Drifting smoke led officials to close sections of Interstate 75.

When the flames reached parts of the parcel that had been subjected to a prescribed burn a few months earlier, he said, they fizzled from lack of fuel.

Carlisle said the county conservation staff takes pride in the fact that none of its prescribed burns have damaged buildings or shut down roads.

But he and others take the possibility of that seriously. They always have to worry about an errant sea breeze.

"It is a huge responsibility," Carlisle said. "A routine day can turn into a nightmare in a heartbeat."

FLORIDA'S FIRE-DEPENDENT SPECIES

Here is a partial list of plants and animals that need periodic fire to thrive:

• Florida scrub jay

• Red-cockaded woodpecker

• Gopher tortoise

• Gopher frog

• Bobwhite quail

• Sherman's fox squirrel

• Emerald moth

• Longleaf pine

• Wiregrass

• Pine lily

• Ocala sand pine

• Florida rosemary

Compiled from listings of the University of Florida Cooperative Extension Service and Archbold Biological Station in Lake Placid.

Reporter Susan M. Green can be reached at (813) 865-1566 or sgreen@tampatrib.com.

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