On April 22, a spring wildfire roared through Penn State Forest in the New Jersey Pine Barrens, sending 100-foot flames shooting from the crowns of the pitch pines. The fire consumed half a square mile in 40 minutes and could be seen from space. By the time the New Jersey Forest Fire Service got it under control, it had burned 843 acres, an area the size of Central Park.
A week later, even as ash still swirled through air heavy with the creosote scent of burned resin and a cedar log smoldered at the edge of a swamp, the forest was being reborn. Pine cones that open only under extreme heat had released their seeds. Though the trees themselves were charred, almost all survived the fire. Where chest-high blueberry and huckleberry had burned down to pointy stubs, tufts of grass were sprouting.
Destructive fires in the West dominated the news this summer, but for eons fire has been not just an inevitable feature of the landscape, but essential to the forest’s health and continuity. In the vast wilderness of the Pine Barrens, the forest regenerates so fast that scientists studying the physics of fire use it as a laboratory.
Eleven weeks after the fire in Penn State Forest, at the height of summer’s greening, new blueberry bushes were already shin high. A grass that flowers only after fire had put forth purple-brown seeds. And scattered all through the fire site, bursts of bright-green pitch-pine needles grew straight out of scorched trunks.
“Fire and pines go together like peas and carrots,” said Bernie Isaacson, an assistant regional forester with the New Jersey Forest Service. “We joke that pitch pines don’t know when to die.”
The Pine Barrens are a million-acre natural reserve at the heart of the nation’s most densely populated state. Endless sand roads course though stands of pitch pine, a scraggly, decidedly unmajestic evergreen.
There are about 600 wildfires a year in the Pine Barrens, though only a few of this size, thanks to the efforts of the New Jersey Forest Fire Service. The fire service itself also burns about 20,000 acres a year in carefully managed chunks, creating breaks in the treescape and clearing understory to prevent bigger fires from engulfing towns and blueberry and cranberry farms that push against the forest edge.
The fire in Penn State Forest, about 90 miles southwest of New York City, started near the intersection of two sand roads marked with hand-painted wooden signs reading Lost Lane and Penn Place.
Like most fires in the pines, the Breeches Branch Fire, as it is officially known, is thought to have been caused by humans.
Investigators pinpointed its origin, marked with a ribbon of pink tape, by scrutinizing burn patterns on individual sticks and stones. “We get it right down to the size of a bottle cap,” said Shawn Judy, an assistant division forest fire warden with the fire service.
The fire’s source remains unsolved.
Part of the forest that burned in the fire had been burned just two years before by the New Jersey fire service and had already grown back.
This comes as little surprise to federal researchers up the road at Silas Little Experimental Forest, who have been developing tools to remotely measure the amount of “fuel,” or burnable material, in a forest, and measuring plant growth after a fire by how much carbon dioxide is being absorbed.
“By the following year, the system is taking up CO₂ at the same rate as before the burn,” said Ken Clark, a research forester with the federal forest service. “So it recovers basically within a year. I thought that was pretty amazing.”
Pitch pines have a whole repertoire of adaptations to fire. Some of their cones are sealed shut with wax and open like unclenching fists when the wax melts.
The tree’s armor-plate bark can be an inch thick, insulating buds that send out needles after fire strips off upper branches to free up nutrients and let in sunlight. Even after a fire hot enough to boil the liquids inside the bark and kill the main stem, a pitch pine can resprout at the base from buds in the roots.
When fire burns off the layer of dead leaves and needles on the ground, it exposes bare sandy soil that looks inhospitable but is exactly what pitch-pine seedlings need. “Because the soil is tight and compacted there’s no airspace, so the roots don’t dry out,” said Greg McLaughlin, state fire warden for the New Jersey Forest Fire Service. “The fire prepares the seedbed.”
The Pine Barrens are also home to an uncommon grass called the pine barren sandreed that needs fire to provide it open space. “Most of it is in Fort Dix” — the nearby Army base — “because they’re always firing bullets and flares,” said Andy Windisch, a fire ecologist for the state Forest Service.
But there is also a mini-savanna of reedgrass in Penn State Forest, and, triggered by this year’s fire, it flowered. There are several rare butterflies that in turn depend on the reedgrass, including the state-endangered arogos skipper. “These rare insects are expected to recolonize the burn site over time,” Mr. Windisch said.
It will not be long, said Mr. Judy, the assistant fire warden, before Penn State Forest is ready for another fire.
“Two years from now, three years from now,” he said, “you’ll have another day with nice dry air, another beautiful bluebird day, low humidity. A spark will get in there, and there it goes.”
