For 87 years, the Bartlett Experimental Forest has been a proving ground for almost every forestry treatment ever plausibly proposed for managing northern hardwoods. Vetting and spreading the best of these practices has been the life work of two scientists: Mariko Yamasaki and Bill Leak.
One morning last March, a logging crew unlocked a gate in the White Mountain National Forest in far northern New Hampshire, drove up a snowy road towing trailers heavy with feller-bunchers, harvesters, grapplers, delimbers, and chippers, and set to work on a 20-acre rectangle of mature forest. The stand held tall, log-rich beech, maples, ash, and birch grown over a century. The loggers drove off with almost every stick.
Three months later, I stood on the same road and looked at what was left. The woods had been free of snow for only a couple weeks; now fell a fine June rain. With me were forester Bill Leak and wildlife biologist Mariko Yamasaki, the US Forest Service researchers who had prescribed this clear-cut. They had 80 years of combined experience, most of it running and monitoring forestry and wildlife experiments in this 2,600-acre plot known as the Bartlett Experimental Forest. They knew the ground well. They had literally written the book – several books – on how to manage northern woodlands like these. Together they had produced the official US Forest Service guides to wildlife tree management in northern hardwoods and silviculture in the northern hardwoods and, with renowned wildlife biologists Richard DeGraaf and Anna M. Lester, the three-pound, 305-page doorstop of a book titled Technical Guide to Forest Wildlife Habitat Management in New England – works kept close at hand in foresters’ and landowners’ pickup trucks, offices, and living rooms all across upper New England. For many northeastern foresters who’ve come of age in the past 40 years, the names Leak and Yamasaki are synonymous with good, careful forestry.
To most eyes, of course, a clear-cut does not look careful. Having seen a number of harvest sites over the years, I could appreciate that this one was relatively free of the gullied skid paths and erosion that bad work creates, and it was ripe with fresh young greenery pushing up through the spare slash. Still, it wasn’t exactly pretty; just less hellish than a typical clear-cut appears to the casual observer. The only trees the crew had left were a dozen or so tall, twisted, limbless, extremely dead snags that stood darkly distant from one another. They looked like something out of a Harry Potter movie – an ancient wood, perhaps, after a visit from Voldemort.
Those ghostly standing trees puzzled me. I asked Yamasaki why the crews had left them.
She looked at the black holes and shook her head. “Bill?” she asked. He stood a few feet distant, looking at them. “You have an answer? Why they left these trees?”
Yamasaki’s question was a setup and a dig, part of the ongoing, understated, playful exchange the two direct at one another as they ponder problems in the woods or, in some cases, stupid questions from visitors. (“The chemistry between those two is just unreal,” one admiring forester had told me.) Leak, raising an eyebrow and smiling, looked back at us.
“Possibly they didn’t see ’em?”
Yamasaki laughed. Leak’s quip was his nod at how bad the clear-cut looked, how destructive the practice might seem to some observers. But the site’s nearly complete decimation (save for the snags left for wildlife habitat) was part of the point, and part of the reason they brought me here to start the day. From here we would go to stands that had been treated similarly 12, 22, 80, and 130 years earlier and that had grown back, healthy, productive, and diverse, full of good timber and wildlife. We would move backward in time, to sites that had been stripped as long ago as 1885, but forward in the life cycle of such a stand, from the apparent devastation before us to the rich variety of a mature forest very much like what had been cut down here in March. Our walk would also trace the transformation of Bartlett into one of the most influential places in American forestry; the extraordinary partnership of these two scientists; and their slow, quiet rehabilitation of the clear-cut into one of wildlife forestry’s most vital tools.
The Patch Cut
The Bartlett Experimental Forest came into being in 1932 – the same year Bill Leak was born. It was inspired by the scientific forestry movement, which had emerged over the previous few decades under giants like Gifford Pinchot, and it has since provided a lab in which to test practices both established and experimental. It holds a mosaic of prime, heavily forested, mountainous terrain that rises and falls and rises again from the outskirts of Bartlett, a river town, elevation 700 feet, to the 2,980-foot tip of Upper Haystack Mountain. White pines and hardwoods down low, spruce and fir and then krummholz up high, and, in between, bountiful expanses of New England’s cherished hardwoods: maple, beech, birch, ash, and aspen. Much of it had been cut hard, clear-cut with little planning or regard and no notion of best practices – “slicked off,” as Yamasaki put it – in the mid- to late-1800s. In the maturing woods that remained, the US Forest Service hoped to find ways to do things differently.
Vic Jensen, the Bartlett’s first director, had actually started surveying the forest even before the proclamation creating it was signed. With “just a handful of guys,” as Leak described it, Jensen used transit, staff compass, and chain to divide the Bartlett into a grid of quarter-acre squares, or plots, marking each corner with paint on the closest tree. Then he and his team inventoried every plot, identifying and aging every tree over 1.5 inches in diameter at breast height (dbh). “All in two years,” said Leak. “On foot. And Vic Jensen didn’t even wear boots. Hardly, anyway. He always liked to wear moccasins.” Finally they bundled the plots into several dozen areas they called “compartments,” 20 to 50 acres each, that generally reflected natural boundaries like changes in slope, soil type, topography, or forest cover. These compartments, closely inventoried, would provide a data-rich platform for decades of examining, at both granular and landscape scale, how the forest responds to different natural events and experimental treatments.
In 1953, Jensen hired Leak, who had just graduated from the New York State College of Forestry. One of Leak’s early assignments was to cruise a stand in Compartment 22 that had been clear-cut about the time he was born, one of the first treatments carried out on the Bartlett. And like the clear-cut Leak and Yamasaki would show me 66 years later, it was both experiment and demonstration. Jensen, in keeping with the scientific view of clear-cuts at the time – almost any clear-cut, anywhere – had created this one as an example of how not to manage northern hardwoods. He even posted a big sign at its edge that stated, roughly, “This is NOT the way to manage a northern hardwood forest.”
When 22-year-old Bill Leak walked that stand, the 22-year-old clear-cut of 1932 had become a stand of hardwood saplings 12 to 20 feet tall. He and Yamasaki showed me one much like it the day I visited – a stand that, leveled in 1998, had grown into a pleasant grove of young hardwoods. The trees, broomstick to baseball bat in girth, and sporting fresh young bark and bright leaves, were spaced just widely enough to let us gather amid their trunks and talk. Leak and Yamasaki noted the expected species present: birch, beech, ash, and maple. Conspicuous among them were pin cherry trees whose bark, a luscious, variegated wine color, was darker than that of the other species and sported neat, chalklike, horizontal hash marks. They were beauties, but fading; some were bent, one almost to the ground.
These pin cherries, said Leak, were nearing the end of their short natural lifespans, and would soon die off, making way for knee-high maple seedlings for whom they had literally prepared the ground. In sites like this, pin cherries quickly occupy any fresh opening. By adding nutrients and creating a looser soil structure, they change the site in ways that favor maple. This is one of several reasons that, as repeated studies in the Bartlett have shown, small patch cuts like these tend to produce a forest mix with more maple than do approaches that preserve the canopy. The combination of more sun and richer, more aerated soil gives maples a boost that they usually don’t enjoy in the acidic, granitic soils that dominate much of New Hampshire and many spots elsewhere in upper New England.
Losing out to the maple in this case is American beech, a tree beloved by bears but worth far less than maple as timber. “Your favorite tree,” says Yamasaki, deadpan. Leak sighs. It’s not, he claims unconvincingly, that he doesn’t like beech. But since the stuff is notorious for pushing aside maple and is abundant in northern hardwoods no matter what you do, it’s good to have a tool that gives maple a boost.
Studious foresters know this now partly because the Bartlett for 87 years, and Leak and his colleagues for 65, have been trying and tracking the results of almost every forestry treatment ever seriously proposed or popular for managing northern hardwoods. Two of the most heavily tested treatments, for instance, have been shelterwood cuts, which aim to maintain a mature canopy but which often turn out to over-encourage beech; and single-tree selection, which creates only tiny openings that likewise favor beech.
Such experiments at Bartlett, which typically take decades, have produced an enormous amount of useful information. Perhaps the least expected finding was that clear-cuts, especially the small clear-cuts known as patch cuts, which run from a quarter acre to 5 or 10, repeatedly proved themselves an extraordinarily versatile, even indispensable, tool for managing northern hardwood forests.
This was beginning to show as early as the 1980s, though at that point it was known mainly to people who communicated with Leak, Yamasaki, and their colleagues. Their early findings were gradually seconded by scores and then hundreds of papers. But partly because most of the studies were small, few took much grip outside the Northeast.
In 1998, however, Leak published one of the first studies of how patch cuts worked over decades at a landscape scale. In the paper he examined what had grown in 61 years of small patch cuts in the Bartlett Forest. These small patch cuts, done in four rounds, in 1937, 1951, 1960, and 1992-1994, affected a total of 52 acres. When Leak inventoried these harvest sites, which at that point had been cut 4 to 57 years before, their growth confirmed what all the smaller studies had suggested: Compared to other harvest methods done elsewhere on similar ground in the Bartlett, patch cuts created a more diverse forest, with less beech and more maple, ash, and birch, which was more valuable both in timber production and to birds and other wildlife. His conclusion: the patch cut was a tool that, at least in this region, could not be responsibly left idle.
The Bird Nursery
Leak found that a patch cut could not only alter species mix to boost timber value and forest health, but also create habitat for some of the region’s most besieged wildlife: neotropical songbirds, whose populations are under pressure from cutting in their wintering areas as well as the northern forests in which they nest.
The Bartlett’s sustained work on songbirds began in the early 1980s, when Carl Tubbs, a Michigan native keen on wildlife, took the helm and recruited two key new people: He actively encouraged work by ornithologist Dick DeGraaf, of the University of Massachusetts at Amherst, who with his students and colleagues have now done decades of foundational research there. And he hired Mariko Yamasaki as a staff biologist.
Yamasaki, born in 1952, grew up in Michigan. After getting bachelor’s degrees in anthropology and zoology and a master’s in natural resources, all from the University of Michigan, where she studied with Tubbs, she discovered that no one in the state cared to hire a wildlife biologist who was a woman.
Eventually, she snagged a job studying bald eagles for the Bureau of Land Management out West, which led to a position in D.C. at the same agency. When Tubbs decided he needed a wildlife biologist to work with Leak at the Bartlett, he got hold of her and asked if she was interested.
“Tubbs said it was lonely there, and cold, and I’d have to work with this guy Leak,” she told me in June, sighing and giving Leak an accusatory glance, “but it was a good job.” She took it, and became not just Bartlett’s first female staff scientist and first Japanese-American scientist, but its first staff wildlife biologist.
“Up to then,” said Yamasaki, “timber and wildlife people mainly fought each other.” Yamasaki and Leak, however, quickly got along and developed an extraordinarily productive working partnership. Both loved to be in the woods. Both thrived on finding new things. Walking the woods they constantly test, trash, defend, and revise their own and each others’ ideas about the forest, birds, people, and what and when and how to cut trees. They razz, nod, smile, guffaw, roll their eyes, and laugh aloud at one another. They deploy the side-eye and the deadpan stare. This frictive, affectionate rapport, lively, wry, and quietly, spectacularly entertaining, has made them much sought after as guides and educators.
Yamasaki has been instrumental not just in this partnership but in making the Bartlett a fount of informative wildlife work. She, DeGraaf, and the many wildlife biologists they’ve worked with have produced dozens of studies on what songbirds and other wildlife species need and how forest management can help them. For female researchers, Yamasaki has provided both a model of how to work in a male-dominated environment and crucial support for their efforts. (One younger collaborator, ornithologist Carly Chandler, who now teaches high school science, told me how legitimizing it felt when Yamasaki drove to Amherst to sit in the audience as she defended her graduate thesis.)
Through her work and through her partnership with Leak, Yamasaki has helped make Bartlett an inviting and fruitful research site. In the 1980s and 1990s, for instance, studies at the Bartlett were among those showing that mature, intact northern hardwood forests were crucial as nesting habitat for neotropical songbirds, such as red-eyed vireos, summer tanagers, and black-throated blue warblers. Studies there have also revealed important habitat-bird dynamics that had been entirely missed. In the early 2000s, for instance, Chandler, then a young undergrad working summers as a technician in a project run by University of Massachusetts’ David King, made an unexpected and important discovery about the needs of the young songbirds who had just fledged from those nests in mature forest interiors.
While studying bird populations in the Bartlett during early-summer fledging season, Chandler was troubled to see few of them in the mature stands where they had hatched. Then, to her astonishment and delight, she found that the young birds, newly but clumsily mobile, were packing the young hardwood stands that rose from recent patch cuts nearby.
These finger-sized saplings, tightly spaced and nearly impenetrable for humans or anything else of size, were of the sort that many foresters and loggers called, with disdain, “peckerwood.” But as Chandler and others in King’s crew soon learned, young, vulnerable fledglings and their parents found in such post-cut growth both better cover and more food (“lots of bugs and butterflies,” according to Chandler) than they could in the mature nesting woods nearby.
“Ornithologists had spent a lot of time focusing on nesting habitat, for good reason,” says Chandler. “But we hadn’t looked at the rest of the life cycle, and what happens when the birds fledge. This shows a second habitat that in many ways is as important as the nesting habitat.” Other work in New England would confirm that, at least in areas with plentiful mature surrounding forest, clear-cuts under 50 acres reliably boosted the number of bird species. Chandler had stumbled upon a bird nursery.
“This Living Experiment”
Thus have bloomed the results of the ongoing experiment that was and is Bartlett Forest. The forestry and much of the wildlife community have largely absorbed these lessons, though it took time. Yet these findings, particularly the regeneration and rebirth of clear-cuts, have challenged and still challenge the thinking of many devoted to forestry and wildlife but less familiar with the science surrounding them. As I found when talking with friends about this research, the very idea of clear-cuts as a tool of good ecosystem management tends to startle laypeople. This is partly the legacy of the loud, angry battles and culture wars that occurred in the 1990s and 2000s over forestry in this country. In the Pacific Northwest and Mountain West, the conflict over spotted owls and heavy cutting created a “national train wreck,” as the Washington Post called it, that dominated national forestry news for a decade. In and around New England, meanwhile, the converging forces of mechanized harvesting, extensive spruce budworm salvage operations, and sometimes desperate harvesting of industrial owners whose mills were going under created similar tensions. University of Massachusetts ornithologist David King says these debates, so often centered on both the natural impacts and aesthetics of the worst clear-cuts, colored everything. It was during this time that he studied forestry and wildlife science in undergrad and grad school out West. He returned “with the assumption that clear-cuts had no place in responsible forestry.” He credits the work done by Leak and Yamasaki and others at the Bartlett and elsewhere with changing his mind. The evidence, he says, speaks for itself. In the fledgling study, for instance, “there were times that a clear-cut was about the only place you could find those birds.”
Anthony D’Amato, director of the forestry program at the University of Vermont, who has worked with Leak and Yamasaki for years, agrees with King on the importance of that work. Yet he adds that while clarifying the value of small, judicious clear-cuts is a huge accomplishment, the team’s bigger contribution is to recognize – and eloquently, constantly insist on and demonstrate – the primacy of the site in determining treatment. This, insists D’Amato, is “Bill and Mariko’s real lesson: You must cater your silviculture to the particular ecology of your sites.” In this context, the small clear-cut is vital because it can so often allow you to do that. There are many times the clear-cut will not serve, of course. D’Amato has been on sites where Leak advocated against patch cuts because the soil already favored maple enough that a clear-cut would serve no purpose. At other times he’s seen Leak argue for bigger clear cuts – not to generate more harvest, but to create more bird habitat.
“He recognizes there’s not a one-size-fits-all tool. The treatment should be dictated both by the objectives and the ecology of the site.” Or, as Norman Maclean once put it, “If you don’t know the ground, you are probably wrong about nearly anything else.”
Lately, says Yamasaki, much of their work is talking – leading tours and workshops, walking seminars of the sort they offered a University of New Hampshire class in March and me in June, to show people the forest and what and how they can learn from this living experiment growing at their feet.
UMass ornithologist David King says it’s hard to overstate how much these outings have influenced forestry in the Northeast, and beyond. In decades of making themselves available, Leak and Yamasaki have talked to hundreds, perhaps thousands of people. “And if you’re in forestry or wildlife and have been out with them,” says King, “you cannot help but have your thinking changed.”
Yamasaki and Leak clearly like these outings – pressing up hills and through the woods to see what’s doing, Leak with a ski pole as walking stick, his concession to being 87, and Yamasaki almost always with binoculars around her neck and a shovel in her hand, so she can dig in and see literally what soil gives rise to the trees she’s under. These walks let them see a wider variety of site conditions than they would otherwise. And every trip out adds more data, more observation, more chance to notice and add color to Bill and Mariko’s long study of this land. They also just like getting out. Where else can you always find something new? You can never really stand in the same forest twice.
The day before I toured the Bartlett last June, the USDA Forest Service National Silviculture Workshop, at its annual meeting in Minnesota, gave Bill Leak its lifetime achievement award. Accepting it on his behalf was his colleague and friend Anthony D’Amato, of the University of Vermont. Doubtless some at the meeting figured that the constraints of old age kept Leak home. But he’d never really even considered going. He wanted to be out in the woods.
Based in Montpelier, Vermont, David Dobbs is a frequent contributor to National Geographic, The New York Times, and other national publications. He is the co-author, with Richard Ober, of The Northern Forest.
The Resilient Forest Series, Part 3
- Part 3: The Wired Woods
- Part 3: The Birds of Hubbard Brook
- Part 3: Getting the Woods Right
Our special thanks go to the Emily Landecker Foundation, the Dorr Foundation, the Davis Conservation Foundation, the Larsen Fund, Melinda Richmond, and the Samuel P. Hunt Foundation for their support of this work.
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