A Walk in the Woods: Rediscovering America on the Appalachian Trail

by Bill Bryson

For all its mass, a tree is a remarkably delicate thing. All of its internal life exists within three paper-thin layers of tissue—the phloem, xylem, and cambium—just beneath the bark, which together form a moist sleeve around the dead heartwood. However tall it grows, a tree is just a few pounds of living cells thinly spread between roots and leaves. These three diligent layers of cells perform all the intricate science and engineering needed to keep a tree alive, and the efficiency with which they do it is one of the wonders of life. Without noise or fuss, every tree in a forest lifts massive volumes of water—several hundred gallons in the case of a large tree on a hot day—from its roots to its leaves, where it is returned to the atmosphere. Imagine the din and commotion, the clutter of machinery, that would be needed for a fire department to raise a similar volume of water.

The mortality rate was 100 percent. In just over thirty-five years the American chestnut became a memory. The Appalachians alone lost four billion trees, a quarter of its cover, in a generation.

Every twenty minutes on the Appalachian Trail, Katz and I walked farther than the average American walks in a week. For 93 percent of all trips outside the home, for whatever distance or whatever purpose, Americans now get in a car. On average the total walking of an American these days—that’s walking of all types: from car to office, from office to car, around the supermarket and shopping malls—adds up to 1.4 miles a week, barely 350 yards a day.

periglacial climate—a zone at the edge of an ice sheet characterized by frequent freeze—thaw cycles that fractured the rock.

felsenmeer (literally, “sea of rocks”).

Between the 1940s and 1980s, the populations of migratory songbirds fell by 50 percent in the eastern United States (in large part because of loss of breeding sites and other vital wintering habitats in Latin America) and by some estimates are continuing to fall by 3 percent or so a year. Seventy percent of all eastern bird species have seen population declines since the 1960s.