Cascading species shift looms in fire-starved Eastern woods

BIG PINEY RANGER DISTRICT, Ark. -- It was a rare patch of sunlight in a dark forest.

On a hot spring morning, foresters and scientists tromped through the charred understory of a burned patch of the Ozark National Forest. They had recently wrapped their work, dripping fire this way and that beneath an open canopy of oaks. Soon, they hoped, a succession of grasses would bloom in blackened soil, bathing in restored light.

The site is an atonement for the Forest Service's past sins.

A century ago, the Ozarks sparkled with sun. Periodic low-grade fires ripped through prairie grasses that waved between sparse oak and pine trees. Accustomed to fire -- dependent on it, even -- these trees' seeds survived to replace their ancestors, a pattern, and ecosystem, that lasted for thousands of years.

Walk through the Ozarks today, though, and there are few signs of that historic forest. Beneath aged oak and pine boughs is a dense mix of maple, ash and cedar. Starved of light, grasses no longer sprout. The butterflies have left, and so have the woodpeckers. Most of the forest floor is lifeless, smothered by layers of leafy duff.

Imperceptibly, at a decadal pace, the Ozark oaks and pines are departing, said Martin Blaney, a habitat coordinator for the Arkansas Game and Fish Commission and a member of one of the country's most aggressive forest-restoration teams.

"The next oak forest is not under the oak forest of the eastern United States now," Blaney said during a tour of the burn site, a patchwork of cedar, green grass and browned saplings. "And what's one of the ingredients we took out 90 years ago?"

It's become clear that many forests of the eastern United States -- from Wisconsin to Florida, Arkansas to New England -- are undergoing a rapid shift in character. A mosaic of oak, hickory and pine -- forests that rebounded even after the widespread clear-cutting of the 19th century -- are falling to species like maple and beech that fire once kept in check.

Many scientists now believe that humans maintained these forests, dominant in the Ohio River Valley and Appalachia, through fire. American Indians bent nature's bounty to their convenience, promoting easy access to fruiting trees and shrubs; European settlers followed suit. And now, by snuffing out fire, humans are causing a forest they created to disappear.


More than climate change, it is the starkest existential threat to these forests.

Half of the shortleaf pine east of the Mississippi River has disappeared in two decades. Oaks are in wide decline. And unlike the western half of the country, where fire suppression has made catastrophic conflagrations more likely, fire's disappearance in the East is creating moist, dark forests that are increasingly difficult to ignite.

That's the case being made by Marc Abrams, a forest ecologist at Pennsylvania State University who has spent his long career studying eastern oaks. A forceful presence, unafraid to anticipate where sparse data may take him, Abrams is a sort of James Hansen of the forest, unifying and pushing a trend that many had timidly kept confined to single forest types.

So far, his warnings have been proved true, scientists say.

"The forests are changing away from their historic norm in a way that's making them less flammable or less prone to burning -- which to some people might sound like a good thing," Abrams said in a recent interview. "But it's actually a bad thing. ... The oak, hickory [and] pine system is changing in ways that are irreversible."

These shifting, dense forests have become biological deserts, vulnerable to disease. The grasses and flowering plants that evolved in these open, fire-dependent systems now lead beleaguered lives. They grasp for the little sunlight that still exists, clinging alongside roads, beneath high-voltage power lines or in forgotten cemeteries. And few species are filling the gap left by their disappearance.

"There's just this tremendous drop in biodiversity," said Greg Nowacki, a Forest Service ecologist and one of Abrams' primary collaborators. "Equally, there's a tremendous drop in the number of animals that co-evolved with these systems. That is a major crisis that we're facing right now with fire suppression."

Most scientists agree that eastern oak and pine are declining, giving way to late successional trees, but some wonder whether Abrams has earned all his conclusions. Data about historic burning are sparse in the East; modern climate change may play a larger role than Abrams would like to acknowledge. Some view him as playing fast and loose with data, said Charles Lafon, a geographer and dendrochronologist at Texas A&M University.

"But I think the big picture is right," he added.

Indeed, even the Forest Service, which through its mascot Smokey Bear has been the primary perpetrator of this species shift, has broadly embraced the use of fire in Eastern forests. Smokey's motto, to little fanfare, has changed. "Only you can prevent forest fires," he once warned. But today, he says, chagrined: "Only you can prevent wildfires."

Despite this growing consensus, it is doubtful that the shift of the Eastern forests can be, or should be, wholly stopped. Settlement is too widespread, and the public understands little of fire. Few want smoke to fill their bucolic springtime valleys. But pockets of resistance remain, including an aggressive program in the Arkansas Ozarks.

Returning fire to the forest has proved far harder than fighting it ever was.

'We're a species of fire'

Standing on a road in the Ozark highlands between dense, dark forest and a patch of frequently burned, restored pine parkland, John Andre, a retired Forest Service ecologist, traces a line through 400 years of tumultuous history.

He runs his hand over a large cross-section of preserved shortleaf pine. These tree rings tell a simple story, he said. For nearly all its life, which began before the founding of Jamestown, the pine lived in fire. Every three to five years, for 300 years, flames licked its bark, leaving scars as the tree's cellulose looped back on itself.

"It went from 3.1 years to 80-plus years before there was ever another fire here," Andre said. "And that 80-plus years is what allowed a stand that looked like this historically" -- he gestured dismissively to the unrestored forest -- "to turn into that."

The pine's history was drawn out by Richard Guyette, a tree ring detective at the University of Missouri who has done more than anyone else to chart the incidence of fire in historic Eastern forests. Since his work began in the late 1970s, his lab has built up a database of about 20,000 fire scar dates east of the Rocky Mountains.

Guyette's work is meticulous, as much art as science, cross-dating the rings of preserved dead trees, and their scars, against living peers. It's a balancing act, Guyette said. Not every fire will burn a tree, and not every fire will encompass a study site. Put the two opposing uncertainties together, though, and it's a telescope to the recent past.

Much can be seen in these rings. The Cherokee Trail of Tears is visible, dragging from the Southeast to Oklahoma. The Civil War, too -- fire ceased in remote parts of Pennsylvania for a decade, as the wood workers went to war. But even more than single events, a way of life can be seen in scar records.

"If there's one thing I've learned in the last 30 years," Guyette said, "it's that people burned a whole lot in the old days."

There were many reasons to burn, Penn State's Abrams said. American Indians regularly burned the forest to clear undergrowth, prepare croplands and control insects. Fire improved forage for favored game. Fire kept fruit and nuts close to the ground, and granted control of growing cycles -- blueberry patches could fruit in succession, lasting a season. And the grassy, open parkland made travel far easier.

"You had this flux between black, green, black, green -- burned, unburned," said McRee Anderson, the Nature Conservancy's fire restoration manager in Arkansas. "This big mosaic of different seasonalities and effects."

It's a human dependence on fire that has never abated. It's just become more controlled.

"We're a species of fire, whether we like it or not," Guyette said. "Every one of us uses it. We use fire to drive around. To cook our spaghetti. [And] the more people there are, the more ignition potential lies upon the land."

There are other lines of evidence that support the widespread use of fire. Many early European explorers described open pine and oak woodlands, as did early tree surveys. And the first major soil charcoal study in the eastern United States, recently completed by Norm Christensen, an ecologist at Duke University, found fire to be regular in an Eastern forest for the last 4,000 years.

The importance of fire in the moist East, where lightning is rare and heavy humid air settles down during the night, has been a revelation for Christensen. When he arrived at Duke in the 1970s, fire was seen as unimportant outside of the coastal plains. Faculty warned him not to pursue the topic. It was a dead end.

"It's really only been the last decade or so ... [that] the issue of fire having truly shaped the many areas in the East has really become much more compelling," he said. "There's increasing amounts of data to support that idea."

Indeed, Christensen is a bit envious of the dedication Abrams has shown. He's been banging this drum for 25 years and must have felt like a lone voice, Christensen said.

"It must be a little sweet for him to ... [have] brought everyone else around."

Smokey Bear

If there's one villain for Abrams, it's the iconic bear with a broad-brimmed hat.

As Europeans expanded into the Appalachians and Midwest during the 1800s, a great hunger for firewood grew, fueled by rising population and the use of wood charcoal for iron furnaces. The "Great Cutover" had begun. Settlers denuded most of the Eastern seaboard and Ohio Valley by the mid-19th century; by 1920, 99 percent of the original Eastern forest was gone.

All this clear-cutting led to massive forest fires by the late 1800s, Abrams said.

"When you're doing that much cutting and leaving all the logging debris, that dries out and becomes very prone to burning," he said. "These million-acre fires were starting to break out pretty frequently."

Starting in the 1920s, the young Forest Service zealously cracked down on forest fires, including many Americans who still practiced American Indian-style "light" burning. (Fires persisted in some of the remote Ozarks until the 1950s, finally stopped by a dedicated ecologist winning residents over at church revivals.) While Smokey Bear himself did not exist until World War II, for a generation of scientists, his name has become a bit of an epithet, standing for the Forest Service's past management mistakes.

For modern forest ecologists, Smokey brings up a swell of mixed emotions.

"This is a difficult situation," said Nowacki, Abrams' collaborator, who remembers hugging Smokey Bear in his Midwest grade school. "Smokey's an icon. Smokey represents that fire can be very destructive. And we don't want to see human beings running around doing prescribed burns. Arson is a bad thing."

Few deny that uncontrolled fires threaten a chaos inimical to modern life. But what was missing during the Smokey Bear era, as Abrams calls it, was a balancing awareness that many forests cannot survive without fire's disturbance. For example, oak acorns prefer the bare ground of burned land. And oak's thick bark, rotting resistance and sprouting ability all favor it over maples when it comes to surviving flames.

Abrams laid out the fire dependence of oak in an influential paper two decades ago. It was a controversial thesis but is widely accepted now, Texas A&M's Lafon said.

"He's largely been vindicated in pushing that," Lafon added.

For Abrams, the plight of the pine and oak forest is a logical extension of his past work. It helps to consider the red maple, the shade-tolerant, fire-sensitive tree that is spreading throughout the Eastern forest. The red maple was once found only in moist conditions, along rivers and low lands. It was called the "swamp maple." But without fire to keep it in check, the maple's wide leaves began to block more sun, and its less flammable litter came to dominate the forest floor. A feedback loop toward darkness began.

Few scientists doubt the changes occurring in the Eastern forests; maple is ascendant, and oak is in decline. But some question whether enough data support Abrams' conjecture that fire was so widespread before European settlement. Did the fires stay close to American Indian settlements, or were they widespread? Were they all low-intensity burns, or did some rage like the massive crown fires of today's West?

"The bottom line is we don't have that much data that we'd like to have about presettlement fire regime," Lafon said. "A lot of things [are] not well-verified by data. ... [But] the big picture here is probably correct."

Fire is undoubtedly important, but the spread of maple is so broad across the East, from Maine to Florida, that it's hard to say, in a definite way, that fire is the primary driver, added Ryan McEwan, an ecologist at the University of Dayton. Factors like climate shifts, disease and deer increases cannot be ruled out from leading roles.

"It's hard for us to imagine across that whole landscape, that you could have a change in one process, fire, that would drive this massive shift in species composition," he said.

'Groceries on the ground'

In the Ozarks, foresters haven't waited for all the evidence. A catastrophe came first.

By 2000, the Ozarks' trees were packed together at record levels, about three times more per acre than two centuries earlier. Then, drought struck, followed by an invasion of red oak borers, which thrived with few woodpeckers to control their numbers. Within a couple of years, 300,000 acres of oak was left dead or dying.

"They managed for this condition," said Doug Zollner, director of conservation science at the Nature Conservancy's Arkansas branch, which helped spur a statewide adoption of large-scale fire restoration. "This is what they wanted. And it died within two years."

After the borer catastrophe, the scientists came out of the woodwork, said Andre, the retired Forest Service ecologist. (Andre is such an adherent of prescribed burning that he regularly chars his own forest and farmland.) The service had deployed fire to restore shortleaf pine since the 1980s, but the parcels were small, 60 acres a pop. Stemming the oak and pine decline would mean working on, eventually, about 300,000 acres.

The team faced a fair amount of resistance, both from the Forest Service -- loggers are often concerned that burns will damage wood -- and Arkansas residents. One of the most difficult lobbies to win over was the turkey hunters, convinced that the fires would consume the nests of their preferred prey. It's a work in progress, but many hunters now prefer recently burned sites to the closed-canopy forest.

"The animals that are indigenous here, most of them are fire-dependent," said Blaney, from the Arkansas Game and Fish Commission. "They are disturbance-oriented, including the most popular, white-tailed deer and turkey. ... As we got a garden under these plants, it was just a smorgasbord of tubers and seeds and fruits."

"This is what we say," Blaney said during a recent tour. "Groceries on the ground."

Nearby, other team members muttered in reflexive accord: "Groceries on the ground."

These ground-bound "groceries" are in stark contrast to the forest that had developed in the Ozarks, said Theo Witsell, a state botanist, as he walked into a typical closed-canopy forest. The floor was in shadow, obscured by a thick midstory of young trees. The few species that grew on ground refused to flower, depriving insects of nectar.

"There's no fruit or seed resource for wildlife," he said. "You're getting the same few species over the entire landscape. Lots of poison ivy; [it's] shade tolerant. Here it is here. You get muscadine grapes, but they're not fruiting. They're just suppressed."

Decomposing leaves sit 6 inches deep in some places -- a blanket on the soil. Beneath the duff sits a rich bank of seeds left from the forest's open days, dormant for 50 years, but ready, perhaps, to be resurrected by fire. No one knows how long the seeds will last. Many have expired. It's an ecological tragedy, said Nowacki, Abrams' collaborator.

"This is where we're losing the game, ultimately," he said.

Thanks in large part to the effort of Anderson, the Nature Conservancy fire manager who spends his days crisscrossing the state from one burn to the next, one motel to the next, Arkansas foresters now regularly ignite thousands of acres at a time. During peak season, it's not uncommon for 20,000 acres to burn in one day.

The fires are seeded, at times, by helicopter-borne self-igniting spheres that resemble nothing so much as ping-pong balls. Controlling the flames requires all the skills of firefighting: plotting breaks along roads and rivers, gauging a steady wind and the land's slope. Few prescribed fires jump their bounds; Arkansas' nighttime humidity makes quick work of those. Smoke is the bigger problem. Once, a smoke column swung into the air, traveled 18 miles west and landed on urban Fayetteville. No one was pleased.

Many of the state's foresters have seized on fire as a sort of panacea. They've gotten the itch to burn. Yet the resources for restoration aren't there. A decade ago, the Ozark National Forest would burn about 25,000 acres a year. And while plans would have that number rise to 100,000 acres, it has instead fallen as limited national funds for burning are spread across a broader pool. They'll be lucky to do more than 15,000 acres this year, said Mark Morales, a district fire management officer for the Forest Service.

It's like what Morales tells his men, many of whom now ask to burn their forest acreage.

"Put a map on the wall, throw a dart: Yeah, we need to burn there," he said. "I agree. There's no doubt, ecologically -- everywhere we can say, yes, we need to burn that. But we can't do it on every acre."

Big questions

If there's a model for a restored Eastern forest in Arkansas, it's Buck Ridge.

An upward-sloping 29-acre woodland tucked in state wildlife land north of the Ozark National Forest, Buck Ridge is a gateway to the past. About 250 species of plant can be found in its understory, an astounding diversity. Through the year, each wave of grasses flowers taller than the last, chasing light. By midsummer, they are waist high; by the end of the year, the big bluestem grasses reach 6 feet high.

"Everything is adapted to work well in this system," said Witsell, the botanist.

Possessing the rare ability to identify nearly any plant on sight, Witsell scrambled around the ridge like Darwin first alighting on the Galapagos. He listed off rare species that could only be found in a sun-drenched forest: Chapman's purple top; Nuttall's pleat leaf; snakeroot; all kinds of legumes; four different violets since leaving the car.

Above the grasses, the "swee-swee-swee" call of a redheaded woodpecker rang out.

"Those redheads are woodland birds," said Steve Osborne, a retired Forest Service officer from Ozark National Forest. "You hear them all over the place right now. They're here because of this treatment. I can tell you in the years past, I could go for months without seeing one of them in the national forest."

For all its success, Buck Ridge's restoration was not easy. The state has burned the ridge seven times in the past 15 years. Even then, the restoration did not truly take hold until a second tool was added: targeted herbicides. The dense pack of young trees did not easily give way, and so, in 2008, the forest managers injected herbicides into all the woody stems measuring from 1 to 10 inches in diameter.

From an ecological standpoint, the herbicides are not a problem, Witsell said.

"It's a surgical approach," he said. "You're not spraying this from an airplane. You're injecting it into the tree trunks. And it's obviously not hurting the flora on the ground."

But the hard truth scientists have found is that fire is often not enough to restore the forest. Most often, prescribed burns have to be combined with logging and herbicides, an active type of management that makes some environmentalists queasy. But perhaps it's no surprise that such drastic steps are needed. Keeping fire out of the forest was itself a massive management choice, if one belatedly known.

"It's been many years since fire was an active agent on our landscape," said Nowacki, the Forest Service ecologist. "We're dealing with decades here. And so it shouldn't be surprising it might take decades to rehabilitate the forests."

Indeed, much of the Forest Service's interest in the historical fire conditions of the Eastern forest has been driven by the notion that logging can be ecologically justified. It's the subtext for much of its financial support, Duke's Christensen said. Even Abrams is studying how well harvesting and herbicide injections can take the place of fire.

For Christensen, efforts like Buck Ridge bring together larger questions of restoration. If humanity created and maintained these open, Eastern forests in the first place -- if these are the first forests of the Anthropocene -- then shouldn't foresters actively choose the woodland they want, rather than using an arbitrary, uncertain historical baseline?

"It puts the burden on defining a restoration target on the managers themselves," Christensen said. "They say, 'I get to decide what's going to be here in the future.' Justifiably, public agencies are really uncomfortable with that. Do they even have the social license to do that?"

Despite sounding the alarm for 25 years, Penn State's Abrams has doubts that much can be done to get the Eastern forest back to where he'd like, especially with fire. There's too much settlement and too much land in private hands. Liability is a huge concern for those rare escaped fires. Climate change could make it difficult for the trees to survive.

A threshold has been passed. The oak and pine forest will never be what it was.

"I would like to see increased used of burning in the East for these fire-adapted forest types," Abrams said. "But I realize we're never going to have the extent of burning that we [had] before European settlement."

What will survive are pockets, traces of humanity's original sway over nature.

Standing near the top of Buck Ridge, where the post oaks spread their limbs wide, their girth a sign of the savannah forest this was and is again, Anderson, the hustling fire coordinator, stopped to survey his team's work. This is an ecosystem that hasn't been seen since the American Indians hunted in Buck Ridge, since the early settlers, he said.

And yet, in the soil, the seeds waited, returning in full bloom.

"It all says, 'Yes, yes, yes. We want more of this,'" he said.

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