Puzzling Holes in the Forest

By Anastasia Toufexis

Trees from Maine to Alabama are showing a decline in growth

In some sections of Georgia and South Carolina, yellow pine trees seem to be growing much more slowly than they once did. In southern New Jersey, patches of pitch pines have stopped growing altogether. So have parcels of spruce trees on Whiteface Mountain in New York. On Camels Hump, a major peak in Vermont's Green Mountain range, and Mount Mitchell in North Carolina, the highest peak in the East, red spruce are losing their foliage and dying, leaving barren patches on the once lush slopes. Says Botanist Hub Vogelmann of the University of Vermont: "There are some pretty big holes in the forest."

The decline, confined thus far mostly to the Eastern states, is puzzling scientists from Maine to Alabama. The mysterious selective blight may merely signal shifts in local ecological balances. Or, say the scientists, it may be the start of a trend toward devastation that could eventually engulf the entire Eastern green range. Their worry is not unfounded. An apparently similar malady has ravaged 34% of West Germany's wooded lands, causing an annual $509 million in damages to timber and related industries. So far, the U.S. decline has been measured mostly in aesthetic and recreational losses. But it is beginning to have an economic cost as well. Sugar Maple Harvester David Marvin, for example, has lost all the maple trees on ten acres of his 700-acre Vermont spread. A reduction in maple trees could spell disaster for the state's $10 million-a-year sugar industry. Other areas could be hit hard as well. Says Joe McClure of the Southern Region Office of the U.S. Forest Service: "Potential losses would be very significant if a long-term decline developed. Timber sales are just the beginning. The Southeast relies heavily on wood growing, transporting and manufacturing products from it."

To gather evidence of damage, the U.S. Forest Service each decade resurveys thousands of one-acre plots, checking the diameter and height of trees and looking for portents of new growth. The ongoing survey of Southern Piedmont woodlands shows that in the past ten years the growth rate of loblolly pine, a coniferous evergreen, has been 25% less than expected. Botanist Vogelmann's 20-year study of Camels Hump has shown a rapid decline in nine species of trees on the 4,083-ft. peak. The biomass (the combined weight of tree trunk, branches and foliage) has dropped sharply for several kinds of trees: 25% for sugar maples and beech and 34% for white birch. Red spruce has been the hardest hit, with a biomass decline of 71%.

Another clue comes from a study of 7,000 trees, sponsored by the Environmental Protection Agency. Scientists at Oak Ridge National Laboratory in Tennessee examined 14,000 core samples of the tree trunks. Their findings: beginning in 1960, in eight Eastern states, pitch and shortleaf pines and red spruce started to show narrowing growth rings, a sign of sluggish development. Similar changes have been noted in West Germany's stricken trees.

Still, most scientists agree that there is not nearly enough evidence to pin down the cause of the deterioration. Several possible suspects have been considered. Among them: insects, plant disease, poor soil condition and abnormal climatic changes. Experts note that the decline began about the time of the great Northeast drought of the early 1960s. "Drought is undoubtedly a major component of a large part of the decline," says Robert Rosenthal of the EPA. "But it doesn't explain it all. There is pretty good evidence that there are air pollution effects." Plant Pathologist Robert Bruck of North Carolina State University points out that tree growth slowed down in the early 1960s, just after extensive industrial expansion in the Ohio and Tennessee valleys. Says he: "Pollution from these industries got sent East, and the first things to intercept it were the forests at higher elevations."

Indeed, the most severe damage has occurred at high altitudes to such trees as the red spruce and Fraser and balsam firs. The summits of Camels Hump and Mount Mitchell are enshrouded for as much as a quarter of the year in clouds, which are loaded with acidic chemicals and toxic heavy metals. Says Arthur Johnson, a soil expert at the University of Pennsylvania: "Vegetation essentially combs polluted moisture droplets out of the clouds." Mountain tops at this altitude are also exposed to high concentrations of ozone and get more rain, which washes chemicals onto the trees. "Most people think of remote mountains as ideal vacation spots that are very clean, but they're not," declares Johnson. Many isolated areas in the mountains of New England have abnormally high levels of copper, zinc, nickel and cadmium. And the Green Mountains of New Hampshire, seemingly pristine, in fact rival big cities when it comes to lead pollution.

Researchers speculate that chemicals may work their damage in several ways. The excess ozone might open the pores of leaves, allowing acid rain to leach vital nutrients. Or acid rain may cause harmful changes in the chemical composition of the soil. Rain may also deposit toxic heavy metals that damage plants' root systems. Says Richard Phipps of the U.S. Geological Survey: "The darn thing is a heck of a lot more complex than we ever thought."

Solutions seem a long way off. Arboreal experts are only now beginning to assess the severity of the problem. The Forest Service, for example, has just started a study of the condition of yellow pine, the South's prime source of commercial timber. At Oak Ridge, botanists are examining samples of soil for traces of metals such as aluminum and zinc. In May, U.S. forest experts will travel to West Germany to compare notes with European scientists; in turn, German researchers will visit the U.S. in June. Says Fred White, staff forester with the North Carolina division of forest resources in Raleigh: "Initial answers for this phenomenon will probably be a combination of total nonsense, the truth and lots in between." --ByAnastasia Toufexis. Reported by Jay Branegan/Washington, with other bureaus

With reporting by Jay Branegan