Barkness is the immediate impression you get when you hug a huge tree. Ridges and valleys of bark ripple upward like water flowing, but the color is deep brown, the texture is scaly and rough, and the only motion is insects hovering over deep furrows. My neck is painfully cricked, but there’s no treetop in sight, just a distant canopy of needle and leaf shapes suffused with sunlight from above. The woods here are nearly as dense and green as a rain forest, but I’m not in the tropics, or even the fabled Douglas-fir cathedrals of the Pacific Northwest.

Eight of us have bushwhacked several hundred yards off a paved road in the Cataloochee Valley of Great Smoky Mountains National Park in North Carolina. We have lurched and staggered our way through glossy-leaved rhododendron warrens and entanglements of dog hobble to get to this particular eastern hemlock tree. It is one of the largest known of its kind anywhere. Its presence overwhelms all my senses. We are a group, quite literally, of tree huggers, and for a while we do just that in reverent silence. Then Bob Leverett pulls out his laser range finder.

“I use algebra, geometry and most of all trigonometry to get exact measurements,” he says. “I’m anal retentive on accuracy. It’s my way of communing.” Our hemlock measures precisely 173.8 feet tall, with a diameter of 48.2 inches.

Leverett is a mathematician and computer scientist from Massachusetts and one of a group of old-growth researchers in the eastern states. Considered an oxymoron only a decade ago, eastern old growth has achieved scientific legitimacy. It is the subject of professional conferences, publications and fieldwork that, as a side effect, nets new Big Tree champions for the national register published biannually by the American Forestry Association.

Until recently, everyone assumed that except for a handful of famous showcases, such as the Joyce Kilmer Memorial Forest in North Carolina, the original woodlands that covered most of the eastern United States had been cut into oblivion. Where once a squirrel could travel from the Atlantic Ocean to the Mississippi River without ever touching ground, it was thought that nothing but stumps and legends remained. Not so, it turns out. “By now, well over 2 million acres of eastern old growth have been tallied,” Leverett says, “and I wouldn’t be surprised if we find even more.”

The remnants of eastern old growth tend to be inaccessible, and that’s the secret to their survival. Small, scattered groves on the stoniest outcrops and steepest slopes and in the wettest swamps were rejected or overlooked by loggers. Every once in a while a surveyor’s error isolated an unclaimed tract. In a few notable instances, federal agencies managed to purchase and protect larger acreages as national parks or national forests just before the loggers arrived. But it wasn’t until researchers in the Pacific Northwest began to publish findings about ancient forests, defining them as distinct ecosystems with particular characteristics, that a handful of forestry professionals and environmentalists began to wonder what the new knowledge might reveal about the eastern forests.

“The far different climate and circumstances of the East produced old growth that’s more different from than similar to the West’s,” says Bob Zahner, professor emeritus of forestry at Clemson University and a leader in defining eastern old growth. “Tree species are much more varied, smaller and shorter lived. There are quantitative differences in such things as the amount of dead and downed wood and canopy layers. In particular, eastern old growth has a greater richness of herbaceous species and their insect pollinators.”

Zahner and other biologists have worked out a general definition of eastern old growth that encompasses about a dozen such measurable characteristics. Size is the least of them, because big trees in the East were mostly lost to merciless high grading that took the best specimens. As in the West, age is a paramount factor in determining if a stand is true old growth. Disturbance histories are crucial. Old growth purists recognize only those stands that have been minimally altered, and only by natural events, since Euro-Americans arrived on the scene. Some researchers argue that burning, farming and foraging by American Indians shaped the forests extensively enough that no virgin woods existed even before European arrival, and prefer the term primary woods. Defining the terminology of old growth is one of the problems that bedevils its advocates.

So diverse are eastern forest types that no standard classification system has yet been agreed upon. There are wide variations in climate and soils that affect different forests. Natural disturbances range from holocaustic hurricanes in coastal pine forests to the occasional emergence of small gaps in the canopies of deciduous forests farther inland. The resulting community types and subtypes number in the hundreds. They include forests as diverse as the rustling beech-maple-basswood woodlands that sweep from Minnesota to New England; assemblages of river birch, sycamore, cottonwood and elms that shadow the banks of major waterways; cypress-tupelo swamps along the southeastern coast and the Mississippi River; and fragrant pine-oak forests that grace dry, shallow soils almost everywhere.

The most widespread eastern forests before European arrival were the grassy woodlands of long-leaf pine, which included just a handful of trees per acre and low understories containing forty species per square meter. Those forests once covered more than 90 million acres of coastal plain and piedmont from Virginia to Texas. Most diverse were the forests from the central and southern Appalachians westward to the Ozark and Ouachita mountains. With well over 100 tree species and more than a thousand kinds of shrubs, herbs and forbs, these are the richest temperate forests in the world.

“Of the nearly 400 million acres of those original eastern forests, about half a percent remains,” estimates Mary Byrd Davis, a librarian-turned-conservationist. She’s currently updating her 1993 inventory of eastern old growth, the only document of its kind, which she compiled through tedious months of researching documents and contacting public and private natural resource agencies in every state east of the Great Plains. Much of the old growth that remains in the East, her research determined, is concentrated in three areas.

Davis’s tallies show 376,000 acres of original peat and bog woodlands in the Boundary Waters Canoe Area Wilderness in Minnesota’s Superior National Forest; as much as a half-million acres (not all of which has been verified) of old-growth conifers, northern hardwoods and subalpine forests in the Adirondack Mountains of New York; and 175,000 acres of cove hardwoods and mixed forests in Great Smoky Mountains National Park. In addition, Byrd says, there are more than 77,000 acres of old growth that have recently been confirmed in the Nantahala and Pisgah national forests in western North Carolina.

Rob Messick, an independent researcher who has spent years studying Blue Ridge forests, is responsible for discovering much of that old growth. “The largest concentration, with a total of 38,937 acres, is in the Grandfather District of the Pisgah National Forest,” he says. “The remote steep slopes, gorges and winding waterways found on the Blue Ridge Front are the primary reason they remain there.” Why is old growth so important? The reasons go beyond mere novelty or the capacity to instill wonder in those who view them. When I asked Messick why he devoted years and wore out his knees searching for old growth, he gave a succinct answer: “Significant patches of uncut acreage give us the best chance of understanding natural forests.”

“Old growth becomes the original hypothesis,” agrees Peter White, director of the Botanical Garden at the University of North Carolina at Chapel Hill and a former research biologist for Great Smoky Mountains National Park, where he produced a panoply of papers on forest dynamics. “Old growth gives us our only chance of understanding what we’ve done to the rest of the landscape.”

And what we’ve done, ultimately, is lose productivity through soil erosion. “It’s impossible to prove by numbers without data from original soils,” White says, “but the fact that there are places in the park today that are treeless after being logged more than half a century ago provides an example in the extreme. We’d be best off protecting the small amount left for scientific study, because old growth could teach us how to have sustainable logging.”

Remaining old growth in the East also teaches us how little we know about forest ecology. In previous years, wildlife biologists seemed to fear and loathe mature eastern woods—they called them “biological deserts” solely because they didn’t seem to hold much browse for that foremost game animal, the white-tailed deer. Those biologists held these attitudes despite the fact that millions of deer skins were exported in the first two centuries after European arrival, as recorded in shipping logs.

Gradually, field research is revealing the importance of old growth in the lives of many species—even deer, which depend on mast from mature oaks and on the shelter that mature conifers offer from snow. Neotropical migrant songbirds, whose descriptive names read like jewels—golden-winged, ruby-crowned, yellow-rumped, rose-breasted, red-eyed, scarlet, cerulean—have received much research attention in recent years. Numerous studies show that the birds’ breeding success depends largely on unfragmented canopies that don’t attract the predators that reside near the edges of forests. Researchers have also learned that given a choice of dens, black bears much prefer holes high up in oak trees—accommodations that take centuries to produce. New species of mosses, lichens, spiders, millipedes, mites and earthworms are still being discovered in ancient ravines of bark, canopies snaggled by age, and the deep, rich soil of undisturbed groves.

Big trees are not determinants of eastern old growth, but they remain one of the most powerful expressions of ecosystem capacity, as well as provocateurs of emotional impact. The 2000 Register of Big Trees lists eighteen national champions from Great Smoky Mountains National Park, the largest concentration on any federal land in the continental United States, and an increase of nearly 70 percent over the number of park champions listed in 1996. This is not a statistical fluke. It reflects not only a fertile site and mild climate but also the determined efforts to better understand the ecological phenomenon of eastern old growth.

The recent recognition of the importance of Great Smoky Mountains National Park as a haven for old growth is due in large part to the efforts of Will Blozan, who joins us as we tramp through the park’s underbrush. In the early 1990s, Blozan, who is a technician for the park, discovered the big tree bonanza in the Smokies. Blozan’s tree-climbing ability is famous. He had climbed our behemoth of a hemlock several times, most recently for the cameras of the Tennessee News Network.

Other species of trees also caught his attention. With Leverett, he discovered the white pine that, until a hurricane blew off its top, reigned as the tallest tree east of the Mississippi. At 207 feet, it was a living testimony to the magnitude of the former forest, and the group that measured it sounded a cheer when they found the old stalwart. (Tears were shed later, when its truncation was discovered.) White pines were once the undisputed kings of the East, and frontier records refer to heights well over 200 feet. Nowadays, based on second-growth trees, field guides describe them as reaching only 100 feet.

So trees like our hemlock, which Leverett was respectfully measuring yet again, offer astonishing correctives to prior assumptions. They hint at unimagined complexities of community structures and the genetic potential of individual trees. Pressed against the runnels of bark, lost in a less mathematical world than Leverett’s but no less devout, I let the hemlock expand my capacity for thinking big.

Chris Bolgiano is the author of the prize-winning book The Appalachian Forest, A Search for Roots and Renewal (Stackpole Books, 1998).