By Sampson, Neil
American Forests , Vol. 95, No. 5-6
Wallace Kaufman's FOCUS feature on acid-rain/forest-health research ends with a plea for Americans to listen to, and use, scientific information. As one trained in science and working a career as a natural-resource conservationist, I'm strongly in agreement. But I'm also painfully aware of the limits of science and the scientific method in settling some of the major political questions of our day. The air-pollution issue offers a good illustration.
The relevant questions are three: 1) Should the nation move at this time to reduce air pollution? 2) Why? and 3) How? A careful reading of Kaufman's article (which, incidentally, fairly and accurately portrays the current state of acid-rain research insofar as I am able to determine) leads to the conclusion that several years of intensive research has produced no firm conclusion on the first question, mixed evidence on the second, and few if any clues on the third.
So the challenge is to take the scientific evidence that we have been able to amass and use it as one factor, but far from the only factor, in making a political decision. Starting in 1986, the Board of Directors and staff of the American Forestry Association started that process. Upon its conclusion, we came to a decision-one that elicited considerable criticism from many quarters for being scientifically insupportable. So we reviewed the decision, and reaffirmed our position. We now have another year's evidence, and debate. My personal judgment (the Board of Directors has not restudied the issue in 1989) is that our position is still valid and has, in fact, been strengthened by events and findings. Some of our critics will disagree, so it is worthwhile to restate our conclusions and set forth the case as we see it.
The answer to question No. 1 is: The United States should move swiftly and aggressively to reduce air pollution from both fixed and mobile sources. The risks and costs of further delay outweigh the risks and costs of making some mistakes and taking some wrong turns as we seek the most effective ways of getting air-pollution levels down. The reasons are several-fold:
1) Forest Impacts: Air pollutants have changed environmental conditions within forest ecosystems, and those changes are stressful to those ecosystems. It is not clear that they are stressful in all places and at all concentrations. But they are part of an ongoing syndrome, and add to it.
For the last decade, many of the nation's forest regions have been subjected to a higher-than-average drought incidence, which also stresses forests (see AMERICAN FORESTS, March/April 1989). Pollution-stressed forests are more susceptible to drought damage-and drought-stressed forests are more susceptible to pollution impacts. And in the process, the compound effects of these stresses may be overshadowed by the fact that it is an insect or disease outbreak that visibly kills the trees or alters the vegetative mix.
Does the fact that a bug administered the coup de grace obviate the fact that the forest was stressed and weakened by both drought and pollution? Obviously not. Has the forest survived drought cycles of this magnitude before? Almost certainly. Has the insect been a normal part of this forest ecosystem for centuries? Yes, except for introduced pests. What, then, is the new stress that provided the straw that broke the camel's back?" Air pollution gets a strong vote, even when it cannot be proven by laboratory or field studies that it was the singular or even primary cause. - We must also point out that forest impacts go far beyond treegrowth and mortality rates. Air pollution affects soil chemistry, water chemistry, air chemistry, visibility, sunlight transmission, heat reflectance, and average temperatures. The fact that none of these can be said to be affected to the degree that they exhibit toxic effects to higher plants is misleading. The relevant fact is that one portion of an ecosystem cannot be degraded without creating ripple effects that will eventually be felt throughout the system. …