Environment: Puzzling Holes in the Forest

• Share

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.