Forests in Decline

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There's something in the air, and it's most certainly not the fresh breath of spring.

In 1982, the Federal Republic of Germany reported that 8% of its forests had lapsed into serious decline. A number of species showed yellowing, loss of leaves, deformed shoots, deteriorating roots, thinning crowns, and loss of growth . . . and many trees had died. Cries of alarm went forth. But by the next year the damage estimate had grown to encompass a full 34% of Germany's forests—including 76% of all firs, more than 40% of spruce and pine, and half of all the trees in the famous Bavarian and Black forests. The total area affected by such tree damage in Germany is now estimated to be almost 6,200,000 acres, and sick trees in other western European nations-such as Austria, Switzerland, and France—bring the total threatened acreage to almost 10,000,000.

In the U.S.—after several years of sporadic reports of forest damage at high-elevation locations such as Camel's Hump, Vermont, where 70% of the red spruce have died since 1964—researchers around the country are beginning to confirm that forest damage isn't confined to the Northeast.

At altitudes above 6,300 feet on Mount Mitchell, North Carolina, and the surrounding Blue Ridge and Smoky Mountain peaks, the growth rate of red spruce and Fraser fir has dropped 40% since the early 1960's, and many trees have died. The defoliated white corpses of many of these evergreens stand as testimony to some new weakness . . . one that can't be attributed solely to known natural causes. For example, though red spruce may have become more susceptible to the ravages of the balsam woolly aphid, a long-standing enemy, the effects of that pest don't explain the dieback of Fraser fir, which is immune to that insect's attack.

At lower elevations, the United States Forest Service has tentatively concluded, stands of southern yellow pine have for some reason experienced a 25% growth decline in the last 30 years. And researchers in the Ohio Valley have identified damage and growth declines of evergreens and hardwoods over an area stretching from Wisconsin through Indiana and Ohio. What's more, besides the well-known damage to evergreens in New England, maples in parts of Vermont have recently been found to be reproducing poorly and to have declined 25% in overall mass.

THE TOXICANT HIT LIST

What's happening to the world's forests? Are these die-offs attributable to natural stresses? Few scientists believe so. More and more experts are concluding that the trees are succumbing, at least in part, to man-made pollution—in the forms of acid rain, ozone, nitrogen oxides, sulfur dioxide, and toxic heavy metals. It may be that just one of these toxicants is overwhelming trees in isolated instances, but in general the problem seems to be the combined effects of all or many of these pollutants.

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