August 06, 2020
Wildfires areviewed in an almost universally negative light; however, not all are detrimental. Fire is a natural part of the ecology of both grasslands and forests. In fact, some forest types require periodic fires for sustained health of the ecosystem. A controlled burn can suppress brushy hardwoods that grow up under fire-tolerant pines, maintaining the pine forest. Fire can stimulate the germination of desirable forest trees and improve the grass and forb understory, thus providing browse for deer and bugging areas for turkeys. Fire also can reduce the litter on the forest floor, returning nutrients to the soil.
When fire is excluded from a forest habitat for a long period of time, however, flammable litter builds up under the trees, creating the potential for destructive wildfires. This is especially problematic in areas where homes and businesses have encroached into wildlands and the landscape has been fragmented by urban sprawl. The longer fire is excluded from these areas, the higher the risk of a destructive wildfire occurring. Indeed, the intensity of a wildfire often is directly related to the length of time fire has been suppressed in the area.
Throughout the southeastern U.S., all the piney woods ecosystems are in some way dependent on fire. Land managers burn these ecosystems regularly to control brushy hardwoods and reduce the danger of wildfires. Although fewer northeastern habitats are fire dependent, savvy land mangers use prescribed fire to maintain healthy forests and reduce the threat of wildfires in urban areas adjacent to wild lands.
According to Michael Crawford, Land Steward for The Nature Conservancy (TNC) in New Hampshire, the pine barrens habitat, part of which is found in the Granite State, is a fire-dependent habitat.
"The pine barrens stretch from New Jersey up into Maine," Crawford says. "Fire has been present on the landscape for a long time; there are fire-adapted species, such as pitch pine, scrub oak and blueberry. There’s quite a bit of evidence that the red pine stands in the higher elevations have a pretty rich fire history."
Other fire-dependent ecosystems include grasslands and some blueberry barrens, Crawford says. "The migrant blueberry farmers that used to come through New England would pick their blueberries and then light the hillside," he says. "It used to be common to see a lot of smoke in the air. But now, with all the towns, and fire departments on every block, fires don’t go anywhere. It’s really changing the forest system. We’re losing a lot of species diversity, and in some areas the forest is completely changing because fire suppression has been in place so long that the fire-adapted species are withering away." This kind of fire suppression program protects businesses and homes, but it also can mean the loss of unusual and rare species that can only be maintained by periodic fires.
In the pine barrens systems where fire has been excluded, and where the density of pitch pine and scrub oak has increased, a substantial risk of wildfire exists.
"We don’t see it too often this far north, but there’s a history of some pretty large wildfires that stretched all through Maine and New Hampshire," Crawford says. "There also have been some pretty large wildfire incidences in Massachusetts."
In areas without prescribed fire programs, he says, a substantial risk exists for a major wildfire incident.
"If there’s not active management on many areas, eventually they will burn," he says. In areas such as these, controlled fires not only help maintain healthy forest ecosystems, they also help prevent future wildfires.
One Maine habitat type that naturally burns fairly frequently is the sandplain system found on deep sand and gravel deposits that were left by the glaciers. "Those systems tend to be really droughty, and they have fire-tolerant and fire-maintained plants," says Nancy Sferra, Director of Land Management for the TNC in Maine. "We think the fire return interval on those sites is probably every 12 to 60 years."
At Waterboro Barrens, west of Portland, TNC uses controlled burns to maintain the pitch pine and scrub oak community that’s adapted to periodic fires. "There are some other small areas that are burned regularly, but it’s not broad scale," Sferra says.
TICKING TIME BOMB
In Pennsylvania, TNC Fire Manager Patrick McElhenny says a number of forested areas have significant fuel loads. This resulted in small wildfires during dry periods several years ago.
"The last couple of years, however, have been cool and wet, and we’ve had almost record low numbers of acres burned in Pennsylvania," he says. "But that can change very quickly. If we have a year or two of severe drought, we will be in the same situation Tennessee was in a few years ago with severe fires. There are some large fuel loads in some areas and there could be some real issues in areas where we’re already trying to do some prescribed burns to resolve the problem."
McElhenny says habitat fragmentation, encroaching urbanization and improved fire suppression all have helped allow these fuel loads to develop. An increasingly volatile fuel load is a natural progression from this situation.
"The fact is, since the 1950s and 1960s, we’ve had a big increase in fire suppression," McElhenny says. "If there’s a fire, someone is usually on it pretty quickly. We don’t have the very low humidity and crazy winds they have in the West, but we do have areas with a lot of fuel built up where fires could happen."
Not every forest ecosystem in the Northeast is a candidate for a prescribed burn. Forest types that are dependent on fire, however, benefit from it, and periodic managed fires in these forest types result in healthier forests and far fewer destructive wildfires.