American Roots: Sure, Coastal Redwoods Are Grand. but What Do You Know about Eastern Hemlock, Bald Cypress, or Ponderosa Pines? A Tour of Old-Growth Forests around the United States
McManus, Reed, Sierra
The term "old-growth forest" may conjure images of the West's majestic redwoods and Douglas firs. But stop there and you deny yourself the graceful pyramid form of an eastern hemlock, the massive buttresses of a bald cypress rising from an ink-black bayou, or the park-like expanse of a ponderosa pine forest.
Old growth is found in nearly every state in the nation, ranging in size from several acres to well over 20 square miles. While biologists have no concrete definition of the term, it generally refers to forests that have suffered little or no logging or livestock grazing, and appear largely as they did prior to European colonization. Naturalness and age rather than tree size alone distinguish an ancient stand.
Yet not all trees in old-growth forests are old. These woods are mosaics, a mix of saplings, mature trees, and trees 150 years or older. (In western conifer country, for example, old-growth forests are generally considered those with at least eight trees per acre exceeding 200 years in age or 32 inches in diameter.) While 360-foot-tall California redwoods are hard to miss, the largest trees in old-growth eastern or midwestern woods might, at around 150 feet tall, be only 20 to 30 percent larger than midsize specimens nearby. What catches the eye of the forest ecologist are the common traits of many ancient groves: deep, multilayered canopies; an abundance of shade-tolerant understory plants; plentiful snags and downed trunks; and trees with heavy limbs, spiky tops, craggy silhouettes, and contorted, leaning, or spiral trunks rutted with cavities.
Besides genetics, factors that keep most eastern old growth from soaring to the skies are thin, rocky soils and frequent hurricanes, windstorms, and ice storms. The tallest tree in the eastern United States, a 207-foot white pine growing among other giants in the Cataloochee Valley of Great Smoky Mountains National Park in North Carolina, wasn't discovered until 1995--and promptly lost its topmost 35 feet when Hurricane Opal tore across the South that fall, nearly losing its title in the process. (The most ancient eastern forest is also found in North Carolina: a stand of 1,700-year-old bald cypresses at the Nature Conservancy's Black River Preserve. More common eastern species like red spruce live only about 400 years.)
The most significant reason that old growth is rare, of course, is that so much of it has been cut for timber. Just 500,000 acres of old-growth forest remain in all of New England and New York. In fact, more than 99 percent of eastern old-growth forests, and more than 90 percent on the West Coast, have been heavily logged. At least half of what's left in the East is still open to logging, according to the Kentucky-based Eastern Old Growth Clearinghouse.
Much more than curiosities, ancient forests are nurseries of biodiversity. Abounding with live and dead trees, decaying logs, and thick layers of moss and leaves, they provide flourishing wildlife habitat. Birds thrive in their high canopies and trunk crevices, while fish benefit from the nutrients their woody debris provides to sheltered streams. An exhaustive University of Wisconsin study of northern forests found that old-growth areas had the "highest bird densities and species richness." Even-aged, managed sites (like tree farms) were the least diverse. Biologists traced the decline in 11 species of old-growth-dependent birds in Southern California's San Jacinto Mountains as logging continued over a 30-year period. Nature writer Robert Michael Pyle (who holds a doctorate in forestry and environmental studies) says a visitor can sense the difference immediately: "The industrial woods may be deep, they may be dark, but they are not diverse. You couldn't imagine Sasquatch lurking in such a stand; your children would not look for leprechauns behind the shamrock sorrel. It takes time, lots of it, to make such a place. …