The nature of fire in a cool, moist state
By Madeline Bodin | April 27,2014
A controlled burn is conducted in the Dead Creek Wildlife Management Area spanning Addison, Panton and Bridport. The area is owned by the state and managed by the Vermont Fish & Wildlife Department.
“They call it ‘the asbestos forest’ because it doesn’t burn,” says Jim Esden, who oversees wildland fire prevention for the Department of Forests, Parks and Recreation.
The Midwest’s prairies burn regularly and naturally. The long-leaf pine savannahs of the Southwest can’t survive without fire. Catastrophic fires sweep across the Western states, causing death and destruction.
Here in Vermont, however, “because of the rain and the vegetation, it really doesn’t burn,” says Liz Thompson, director of conservation science for the Vermont Land Trust. “Fire is not part of the natural system.”
Vermont does have a brief fire season, generally from late March through early May, when weather and other conditions align to encourage the start and spread of wildland fires in pastures, hayfields, forests or brush.
“This is our fire season, right now,” says Tess Greaves, a fire-science expert with the Department of Forests, Parks and Recreation. “After the snow goes, but before it gets green.” Autumn is a secondary fire season when conditions can favor fire – after the leaves fall, the grass dies and before the snow comes.
Vermont averages 172 wildland fires a year, according to a National Weather Service report. Most are small — 95 percent are less than 10 acres and 59 percent are less than an acre, according to the report — and are quickly extinguished.
Many factors contribute to the timing of Vermont’s fire season. The most important factor, says Greaves, is relative humidity, which “plays a huge role in how dry the fuels are.”
The National Weather Service defines potential fuels for wildland fires by the amount of time it takes them to react to changes in the weather. Dried grass and dried leaves are “one-hour fuels,” explains Brooke Taber, a fire meteorologist with the National Weather Service in Burlington. That means it takes them just an hour to dry enough to burn in the sun. A tree more than 3 inches in diameter is considered a 1,000-hour fuel.
When predicting fire weather, Taber says, “fire weather forecasters are looking at relative humidity below 30 percent, sustained wind or frequent gusts of 25 miles per hour or higher, and rainfall of a quarter of an inch or less in the past five days.” Under those conditions, the Weather Service issues a fire watch or warning.
Fire season in Vermont is typically a small window in the spring because that’s when Vermont has the lowest relative humidities of the year, Greaves says. “Combine that with sun and wind, and these conditions combine to make it the most volatile time of year.”
Unfortunately, the time when Vermont’s landscape is most vulnerable to fire is the time of year that Vermonters most want to burn their winter yard debris. “People are the No. 1 cause of fires in Vermont,” Greaves says.
According to the National Weather Service, burning debris causes 41 percent of Vermont’s wildland fires. Lightning strikes cause a mere two percent.
But Vermont’s brief fire season is an opportunity as well. Since the landscape is so resistant to burning, fire season offers an opportunity for wildlife habitat managers to maintain forest openings conveniently with fire.
On April 17, Green Mountain National Forest officials announced plans to improve wildlife habitat in 300 to 400 acres of the 400,000-acre national forest with prescribed fire, also known as controlled burns. Controlled fire, says Green Mountain National Forest public affairs officer Ethan Ready, is simply more efficient than mowing or other methods to maintain clearings that are vital to many game species, like deer and turkey — and many other species of birds, including those in worrisome decline, such as woodcock.
In other areas of the country, controlled burns also help maintain fire-dependent ecosystems, without the danger that natural fires pose to lives and property. While a few ecosystems in Vermont appear to be fire-adapted, Thompson explains, there don’t seem to be any that truly depend on fire.
In 2010, the state conducted a controlled burn of 12 acres at the Sandbar Natural Management Area in Milton to encourage the growth of pitch pine, which is at the northern edge of its range in Vermont and is adapted to fire.
The red pine ecosystem is another fire-adapted ecosystem that is widespread in Vermont, Thompson says. Red pine sites, only a couple of acres here and there on the state’s rocky ridgelines, are some of the few places in the state where fires start from lightning strikes, she explains.
What kind of fire season will this be? To forecast fire weather, the National Weather Service looks at large-scale weather patterns, such as below-normal temperatures, higher precipitation and how long the snowpack lasts.
“This year was so cold that most of the mountains and valleys had snow in March and into April,” says Taber. “That makes for a shorter and wetter fire weather season.”
That’s an important reason to appreciate the long, cold winters. “Two years ago in 2012 we had an open winter – less snow – and we actually had wildland fire activity every month of the year,” says Greaves. A warming climate may mean more years like that one. “That is what I’m seeing for climate – fire seasons start earlier and last longer.”
Taber has been analyzing 34 years of fire data. Climate change may be giving us a longer fire season, but we are not necessarily seeing more fires each year. We almost certainly have our town fire wardens to thank for that, she says. After snow melt, state law says residents must get a permit from their fire warden before burning tree limbs or other natural debris.
“Every town has one,” says Esden. “Most fires don’t happen because the local fire warden says, ‘It is not safe today. I won’t give you a permit,’” he explains.
Esden hopes that living in the “asbestos forest” hasn’t made Vermonters complacent in the face of wildland fires. He emphasizes that Vermont has the tools to keep wildland fires to a minimum, even as our climate changes. It all starts with that call to the fire warden.
Madeline Bodin is a freelance environmental journalist who lives in Andover. She can be contacted at email@example.com.