By Dan Rahn
University of Georgia

Decades of dire warnings from Smokey the Bear have given some
people the wrong idea about forest fires. They’re not all bad.

In the South, especially, regular burning in pine forests is good
when it’s properly done, said David Dickens, an extension service
forester with the University of Georgia Warnell School of Forest
Resources.

“It would have been better if all those ads had said, ‘Only you
can prevent forest wildfires,” Dickens said, emphasizing the
“wild.”

A basic premise of foresters is that in itself, fire is neither
good nor bad. “It simply changes the ecology of the forest,” he
said. “That can be good or bad, depending on what we value in the
forest.”

Millions of acres

Every winter in the South, he said, prescribed fires burn roughly
4 million acres of pine forests for specific management
purposes.

Done under the right conditions, prescribed fires reduce the risk
of more damaging wildfires by clearing out the undergrowth and
debris. That makes the forest safer for the trees, wildlife and
nearby homes and other property.

Dickens said clearing out potentially dense underbrush and debris
has other benefits, too. Among other things, it:

• Improves wildlife habitat, especially for deer, turkeys,
  quail and black bears, by enhancing the growth of more palatable
  browse and berry plants.
• Opens up access, allowing people to enjoy their woodlands
  more.
• Reduces the trees’ competition for soil moisture and
  nutrients.
• Serves a number of forestry and agricultural purposes, from
  reducing the risk of tree diseases to improving forage for
  grazing.

The right conditions

Foresters prescribe dormant-season fires for these purposes only
in the right combination of conditions, which normally begin
coming together in early November, Dickens said. By mid-March,
weather patterns typically become too unpredictable for
prescribed fires.

To burn out the undergrowth and debris without harming the trees,
foresters look for:

• A forest that’s neither too dry nor too wet. If it’s too dry,
  fires get hotter and more damaging. If it’s too wet, the smoke
  becomes more damaging to air quality.
• Temperatures between 30 and 55 degrees Fahrenheit.
• Relative humidity between 30 percent and 55 percent.
• Fairly constant winds between 5 and 12 miles per hour.
• A reliable wind direction that won’t take the smoke into
  sensitive areas, such as into a residential neighborhood or
  across a highway.
• A “mixing height,” or the point at which smoke hits turbulent
  air, of at least 1,700 feet.

Better smoke

The smoke from such fires is much less damaging to air quality
than that from wildfires, Dickens said.

“Most of the smoke is water vapor,” he said. “The whiter the
smoke, the higher the water content.” People with fireplaces can
see this easily if they’ve ever burned a piece of “green” or
unseasoned wood with a high moisture content.

Using fires to manage forests is hardly new, Dickens said. When
the earliest European settlers arrived in the Southeast, they
found native Americans already using fire to clear out the
undergrowth and improve hunting, among other things.

Now, most foresters advise burning pine forests every two or
three years. “Burning hardwood forests is a lot trickier,”
Dickens said.

Even pine forests on steep slopes aren’t good candidates for
burning, he said. Many conditions have to be right before a fire
can produce the desired benefits without causing unwanted
damage.