February 2002

The Unsung Ancients

Very old trees aren’t necessarily as rare—or as big—as you think.

By David W. Stahle

Hemmed-in Hollow, Buffalo River, Arkansas: Specimens of post oak (Quercus stellata) up to 400 years old and red cedar (Juniperus virginiana) almost 900 years old survive on bluffs of the Ozark plateau and in the region known as Cross Timbers, which lies along the margins of the southern Great Plains. Photo by David W. Stahle

A priceless legacy was lost with the logging and clearing of America’s virgin forests: massive, majestic trees growing on productive soil were cut nearly to oblivion. Not all were destroyed—a scattering of big timber survives. Many ancient forests whose trees are of more modest stature also survive, largely because they’re at home on rocky, unproductive soil and are considered noncommercial by the lumber industry; some of the oldest trees ever found in North America endure in high, rocky solitude. They may not match our preconceptions of old-growth big timber, but tree-ring dating has proven their antiquity beyond all doubt.

Ancient woodlands are so common that in some areas—such as the Cross Timbers of eastern Oklahoma, the piñon-juniper woodlands of the Southwest, and the blue oak woodlands of central California—they dominate the landscape. Trees in these and other similarly austere woodlands often reach the oldest possible age for their tribe: oaks across the United States routinely live to more than 300 years, bald cypresses in the South to more than 1,000. Bristlecone pine trees more than 4,000 years old have been found in the Great Basin.

A 350-year-old Douglas fir faces El Capitan in Guadalupe Mountains National Park in southwestern Texas. Ancient Rocky Mountain Douglas firs (Pseudotsuga menziesii var glauca) range over the western cordillera from Oaxaca to British Columbia—the oldest found so far was dated at 1,275 years. Their intricate growth rings record the ebb and flow of drought and wetness throughout the West. Photo by David W. Stahle

Biological superlatives like old giant sequoias are easy to recognize by their size alone. But size gives no hint of the extreme antiquity of the more diminutive survivors of virgin forests. All old trees, no matter their size, share certain unmistakable traits of great age. Heavy limbs, a contorted and leaning trunk or a trunk with a spiral twist, hollow voids, a spiky top, and a craggy silhouette are all giveaways, not unlike the silver hair and wrinkled skin of “overmature” humans. You can often predict where to find ancient woodlands in the modern landscape—usually at steep, rocky, remote sites, where only the thrifty could survive. A careful reading of commercial logging history can also help pinpoint species and woodlands that have been left unmolested. American beeches, for example, were not heavily exploited during twentieth-century hardwood and pine logging on the Ozark plateau; some of the upland Ozark’s finest moist forests, containing giant hardwoods, managed to survive because they are dominated by stands of ancient beeches.

Not all the low-value virgin woodlands of America have survived, not by a long shot. Millions of ancient noncommercial trees had enough utilitarian value—or created enough of an obstacle to progress—to be sent to the guillotine. Vast areas of piñon-juniper woodlands were cut or bulldozed to make charcoal for the mining industry or to provide pasture for the cattle empire. Before the Great Depression, level tracts in Oklahoma’s Cross Timbers region, dominated by centuries-old post oaks, were cleared for King Cotton—only for the cotton to be blown away in the Dust Bowl drought.

Of the smaller old-growth woodlands that have survived, most have gone unrecognized and unappreciated. Stands of ancient low-grade yellow cypresses—including the magnificent millennium-old bald cypresses at Black River, North Carolina, and along the Cache River and Bayou DeView in Arkansas—grow at incredibly slow rates in a few remnant stands throughout the South. Northern white cedars, some more than a thousand years old, have been found on the Niagara Escarpment. Hemlock trees more than four centuries old still live on steep slopes from Alabama to Maine, although they are now facing destruction by the hemlock woolly adelgid, a pest introduced from Asia forty years ago. Pitch pines pushing five centuries survive on the Shawangunk Mountains, only a short drive from Manhattan; on the ski slopes of Wachusett Mountain (within view of the Boston skyline) stand 400-year-old northern red oaks.

	A blue oak (Quercus douglasii) in Pacheco State Park, central California. Blue oaks are resilient: they live on land that has been heavily grazed and invaded by nonnative grasses, and specimens of 200 to 500 years old are common. Covering almost 3 million acres, blue oak woodlands are one of the most widespread ancient forest types remaining in the Golden State. Photo by David W. Stahle

Down the famous Blue Ridge Parkway of Virginia and North Carolina, centuries-old weather-beaten chestnut oaks can be seen from the roadway. Bonsai-like Douglas firs and ponderosa pines animate the petrified lava flows of El Malpais National Monument in New Mexico. And so on, across the arid West, culminating with the Great Basin’s bristlecone pines, the oldest-known continuously living organisms on earth.

Although we’ve logged forests and cleared land prodigiously, we still retain a good part of our natural woodland endowment. Yet the significance of many modest-sized but venerable trees is too easily overlooked. Our misperception of their value and our continued disregard for their preservation may one day make them as rare as their big-tree cousins of the forest primeval.

Map of Ancient Trees of North America

This map shows the location of ancient forests across North America (except for the Arctic) that dendrochronologists have identified by examining tree rings. The forests range in size from twenty acres to well over twenty square miles. All contain trees that are at least 250 years old; many contain specimens more than 1,000 years old. David W. Stahle notes “Developing a profile of forest growth with a tree-ring chronology is an intricate and time-consuming process. Thousands of additional ancient forests are known that do not appear on this map, particularly in western and south-central areas of the United States.”

David W. Stahle, a professor of geosciences at the University of Arkansas, concentrates on the discovery, tree-ring dating, and conservation of ancient forest remnants, including those that host the oldest known tree in the southeastern United States and Mexico, the ahuehuete, or swamp bald cypress. He spent two adventurous years working with Marvin Stokes, longtime professor of dendrochronology at the University of Arizona, on the tree-ring dating of old roof timbers in missionary churches in northern Mexico. Stahle considers the large collection of tree-ring specimens that he culled from ancient forests in North America and Africa—now housed at the University of Arkansas—to be one of his principal achievements.

Copyright © 2002 American Museum of Natural History

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