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Air pollution and forests: an update.

n the tranquil Vermont hills a few miles south of the Canadian border lies Dave Marvin's 800acre farm, where life has been getting tense. Marvin worries about the growing number of dying sugar maples he has seen in the last five years. He knows that U.S. Forest Service studies have been unable to link New England hardwood problems with acid rain or other air pollution.

"I'm not saying I can take you to a tree and tell you acid rain killed it," Marvin says, but he is sure he can't accept the Forest Service's no-link conclusions. "If the Forest Service and other scientists are wrong," he says, "I've lost everything. If I'm wrong, we've lost very little."

Marvin's feeling about his maples is very much like the feeling citizens all over America have about what seems to be an increasing number of dead trees and dying forests. And like Marvin, the public feels government has been too slow to act.

Both President Bush and William Reilly, the conservationist Bush has named head of the Environmental Protection Agency, have put air pollution list. Most scientists and government experts also feel it's important to start cleaning up now. Those who are most deeply immersed in the details of both forestry and budget struggles, however, are afraid headlines like "The Rain That Kills" and "Rain in Northeast Surprisingly Acid"' will lead to throwing money at the problem to appease public opinion while neglecting research and action in areas where results might be sure and important.

The effectiveness of our attack on air pollution may depend on whether the public and politicians have the patience to let the bandwagons roll by until they can absorb complex findings from chemical and biological research.

To learn what air pollution might be doing to forests, the Forest Service has joined forces with the Environmental Protection Agency. Their joint effort, the Forest Response Program (FRP), began in 1985 as part of the multi-agency National Acid Precipitation Assessment Program. FRP's research is done by four regional cooperatives, one national atmospheric research group, and the National Vegetation Survey.

With a budget of $17 to $18 million a year, the FRP is not the Manhattan Project of forestry, but program manager Gerard Hertel is getting the kind of scientific teamwork that won the war. While the effort may not produce any bombshells, after only three years its work has begun to reshape our understanding of how acid rain and air pollution in general affect trees and forests.

The results already surprise many, cheer some, and distress people who like simple answers.

THE NEWEST FINDINGS

EASTERN HARDWOODS: The Eastern Hardwoods Research Cooperative has produced the first study to document ozone concentrations in forested areas of north-central Pennsylvania and to determine the relationship between ozone dose and hardwood seedling growth in this region." Scientists found that ozone followed the sulfur-deposition pattern and exceeded EPA standards of 120 ppb (parts per billion) on some occasions at three different sites.

One of this group's most important findings was a direct correlation between the pattern of air pollution stretching from Minnesota to Ohio and sulfur levels on the forest floor. Scientists say this is the first concrete proof that soil sulfate levels are significantly raised by air pollution. Sulfur precipitation went as high as 31 pounds per acre per year in Ohio to less than 22 pounds per acre in northern Minnesota. The job now is to demonstrate what effects this extra sulfur may have on the health of forests.

Despite widespread reports to the contrary-including Dave Marvin's observations and definite sugar-maple decline in southern Quebec- preliminary surveys have shown no significant decline of sugar maples and other hardwoods in the Lake States or New England. A 1987 survey conducted by the Forest Service and the state of Vermont reported that -less than 0.5 percent of Vermont's hardwood forests showed any significant mortality. " It also concluded that "sugar maples were among the healthiest trees. "

Nevertheless, the Eastern Hardwoods Cooperative helped organize the joint U.S.-Canadian North American Sugar Maple Decline Project. Last year fieldworkers studied maples on 166 plots from Ontario to Massachusetts.

Acid rain cannot be ruled out as a cause of the Quebec situation, but the Forest Service thinks weather is a likely cause since the decline began with a warm spell followed by an extremely cold winter. Cold weather was the culprit in New York's 1986 decline and also in crown breakage that occurred the next year in Vermont.

Farther south, the Eastern Hardwoods Cooperative is creating a map of hardwood stands and soils across the Tennessee Valley Authority region. This basic data along with laboratory analysis will help determine whether species like white oak have been experiencing growth difficulties.

EASTERN SPRUCE-FIR STANDS: While New England's timber stands are at an historically high growth level, its balsam-fir stands remain the sickly child. On some mountains more than half the red spruce is now dead. These higher-elevation trees show a 1 percent decline over the past 10 years most of it in Maine, where the decline continues at two percent a year. The immediate cause is the spruce bud-worm.

In other high-elevation forests, the Spruce-Fir Research Cooperative found that areas of dead forests that look like European waldsterben (forest death) can seldom be traced directly to acid rain or mists.

However, Dr. Robert Bruck, a plant pathologist doing research sponsored by EPA's Mountain Cloud Chemical Program, says the damage to foliage is clear. He has measured pH concentrations of 2.8 during 16-hour mists. "After that event," he says, "the tips of needles were burned all the way through. I don't think you can find more direct evidence than that. "

At high elevations in North Carolina, the balsam woolly adelgid (aphid) seems to be the culprit in the highly visible death of Fraser firs. There, as well as farther north, sudden cold shock may also play a part. SOUTHERN FORESTS: Recent studies indicate that the Sunbelt may be on the verge of some of the same problems the Snowbelt has. Ann Bartuska, Director of the Southern Commercial Forests Cooperative, says, "As early as 50 years from now, perhaps 30 percent of soil types, sandy types especially, will be affected by increased nitrogen. " The problem here is not aluminum toxicity, as in Europe. Bartuska says most yellow pines in southern soils have adapted to naturally high aluminum levels. Much more important is relatively scarce phosphorous. Changes in soil acidity could tie up phosphorous, which in turn could limit the availability of other nutrients.

WESTERN FORESTS: Unlike the inconclusive studies back east, western studies have found at least one clear case of air pollution damaging a region's forests. Los Angeles' infamous smog drifting over the San Bernardino Mountains is killing trees. Ozone from auto exhausts and other sources is hardest on ponderosa and Jeffrey pines. In the Northwest, the Western Conifer Research Cooperative found that clouds as acidic as any in the Northeast drift from Washington's industrialized Puget Sound area over the forests around Mt. Rainier and the southern Cascades. Where sulfur-dioxide concentrations are high because of smelters, growth rates of southern Arizona ponderosa pines and Douglas-firs are declining.

The researchers, however, are not yet ready to discount the effects of growth competition among trees. At Riverside, California, in some preliminary results from seedling studies, sulfur and ozone actually seemed to stimulate Engelmann spruce and white fir to grow taller.

NATIONAL VEGETATION SURVEY: The work of the National Vegetation Survey arm of the Forest Response Program has yielded a crop of 75 reports, including ideas about the death of mountain forests. The decline of red spruce and balsam fir below 700-meter (2,300-foot) elevations, the Survey reports, cannot be directly linked to air pollution but can be explained in part by natural growth processes. Meanwhile, in New England, all major forest tree species except balsam fir and red spruce are currently growing at rates that equal or exceed the rates prior to 1960."

Analysis of some 2,000 tree cores from yellow pines in the Carolinas and Georgia has demonstrated that the valuable pine crop is growing 30 percent slower than trees in equivalent stands on the same kinds of sites 35 years ago. Most of this decline can be explained by changes in growing patterns, climate, and other natural causes. A small but significant part of the decline has yet to be attributed to any cause and could be related to air quality.

ATMOSPHERIC EXPOSURE COOPERATIVE: All of the projects mentioned so far are studying the effects of pollutants on trees and forests. The Atmospheric Exposure Cooperative studies the chemistry of air, clouds, and rain. Everyone knows that urban areas put tons of acid-forming chemicals into the air, but very few studies had been done of pollutants in rural air. Director Barry Martin, from EPA, oversees new monitoring stations in National Forests that will help create a computerized map of air pollution. That data can then be correlated with forest problems.

SHOOTING BLANKS

FROM SMOKING GUNS

Linking acid rain directly to forest problems is like tracing a mugging to organized crime. When Gerard Hertel says that the balsam woolly adelgid has killed the Fraser firs and left acres of brown skeletons on North Carolina's highest mountain, few people believe it. They want a person, not a bug, brought to justice. The bug may have administered the coup de grace, but the public is convinced that air polluters set up the crime, and it wants justice. Many scientists are inclined to agree, but they have yet to produce evidence that meets scientific standards or that will move a bill through Congress. EPA's Barry Martin says that one problem in writing regulations for ozone pollution in the South is understanding the contribution made by turpines emitted by pine trees. Planting hundreds of thousands of acres of abandoned farmland with pine may have contributed to southern ozone levels.

"Ozone levels in the South can be 50 Georgia has demonstrated that the valuable pine crop is growing 30 percent slower than trees in equivalent stands on the same kinds of sites 35 years ago. Most of this decline can be explained by changes in growing pattems, climate, and other natural causes. A small but significant part of the decline has yet to be attributed to any cause and could be related to air quality.

ATMOSPHERIC EXPOSURE COOPERATIVE: All of the projects mentioned so far are studying the effects of pollutants on trees and forests. The Atmospheric Exposure Cooperative studies the chemistry of air, clouds, and rain. Everyone knows that urban areas put tons of acid-forming chemicals into the air, but very few studies had been done of pollutants in rural air. Director Barry Martin, from EPA, oversees new monitoring stations in National Forests that will help create a computerized map of air pollution. That data can then be correlated with forest problems.

SHOOTING BLANKS

FROM SMOKING GUNS

Linking acid rain directly to forest problems is like tracing a mugging to organized crime. When Gerard Hertel says that the balsam woolly adelgid has killed the Fraser firs and left acres of brown skeletons on North Carolina's highest mountain, few people believe it. They want a person, not a bug, brought to justice. The bug may have administered the coup de grace, but the public is convinced that air polluters set up the crime, and it wants justice.Many scientists are inclined to agree, but they have yet to produce evidence that meets scientific standards or that will move a bill through Congress. EPA's Barry Martin says that one problem in writing regulations for ozone pollution in the South is understanding the contribution made by turpines emitted by pine trees. Planting hundreds of thousands of acres of abandoned farmland with pine may have contributed to southern ozone levels.

"Ozone levels in the South can be 50 percent greater than in the North," Martin says. "Some of that can be due to pine trees, or greater sunlight, or higher temperatures. How do we know what the natural background level is?" Determining natural levels could be especially important in areas with high NO,, emissions from vehicles. NO,, acts on natural and manmade hydrocarbons to produce ozone. It might be that spending money to reduce vehicle exhaust could be more important in the South than in other regions. On a broader scale, do we know how much sulfur and particulates come from volcanoes? How acidic has rain been in the past? Ice cores show that rain in Antarctica has been acidic for hundreds of years. FRP researchers are testing the hypothesis that acid rain has elevated aluminum levels in the soils of the spruce-fir forests. Hertel notes that some southern soils do have aluminum levels that could be toxic to root systems. The presence of aluminum can prevent trees from using other nutrients like calcium. "We feel pretty confident," Hertel says, "that the only place aluminum could be playing a role is in the high- elevation areas." If Vermont sugarbush farmer Dave Marvin doesn't find much sympathy at the federal level, state foresters offer little but sympathy so far. Conrad Motyka, Vermont's Director of Forests, is frustrated by the difficulty of isolating cause and effect. Of the sugar-maple problem he says, "It's a bugaboo. If we view it from the combination of all stresses, it's a problem. If you want to single out pollutants, I can't. "

Motyka assigns sugar-maple problems to a number of intertwined stresses, including an explosion of leaf-eating pear thrips, and two very dry summers. He says, "Take 80-year-old trees that have been growing under the same water regime for 60 or 80 years, and all of a sudden reduce that water level only four to six inches -even that change could have a serious impact."

It's too early to single out any culprits, Joe Barnard agrees. "You can liken our field studies to cigarette cancer studies. If you look only at the population, you get correlations but not causes."

Dr. Ben Stout, an air-pollution expert with the National Council of the Paper Industry for Air and Stream Improvement, works for an industry with a lot to lose. Despite problems with acidification of lakes, Stout says acid deposition has not revealed its hand in the forests. You can jack it up to high levels and kill anything. At ambient levels we're still looking to find some significant impact on seedling growth from sulfur and nitrogen compounds."

The key for Stout is the study of specific sites and soils. "In places where there is a very low nutrient capital,' he says, "if you go in once or twice and do whole-tree harvesting and take out all the needles and branches and everything else, you can show-and it has been shown in places in the northern Rockies-that you'll have bare soil where nothing will grow. But half a mile away, with a different soil with a different geologic base, you can crop for thousands of years before you begin to run into problems. I think the same kind of site-specific situation applies with air-pollution impacts on soils. "

If any villain has been caught with a smoking gun during these three years of intense study, it's not sulfur or nitrogen in acid deposition, but ozone. In dozens of lab and field experiments, ozone has all but signed a confession. Studies at both Duke and North Carolina State universities, for example, have confirmed that ozone exposure seriously reduces pine growth.

Even ozone, however, is not always dangerous. National Vegetation Survey Director joe Barnard says, "In 1988 ozone levels reached record highs, but trees in observation plots showed less visible damage than they did earlier under lower doses. One answer might be that the severe 1988 drought shut down the internal leaf activity that ozone affects."

Stout feels that data decisive enough to spur action on any air-pollution question will come only from field studies on whole stands. "We still do not have any evidence of stand response on a regional basis. Of course, there are point sources where we know we can kill forests. " He cites the San Bernardino Mountains east of Los Angeles. Evidence from seedling studies there leads him to believe "there may be an impact on forest growth, but the needed models or experiments haven't been done."

Forest-stand studies provide a needed picture because both acid deposition and ozone affect individual trees differently, while whole species or families can exhibit either immunity or extreme sensitivity. Although atmospheric pollution is a regional and national problem and the public demands broad answers, the response of trees and soils varies enormously over even small areas.

"We've got over 500 recognized families of loblolly pine in the Southeast," Stout says. "We know from the seedling work being done that only about 25 percent of those families appear to be sensitive to ambient levels of ozone." He speculates that we can get around the air-pollution problem by working with tolerant species.

Stout thinks we don't know enough to start issuing federal or state rules and regulations. "I just don't see the changes taking place fast enough to say we have to do something no matter what. "

At the Natural Resources Defense Council, which has taken the government to court dozens of times to try to get more action against air pollution, resource specialist Deborah Sheiman says trying to decide which forest stress is most important creates dangerous delay.

"I don't think we can pinpoint one particular culprit," she says, "but we know that man-made air pollution is one factor over which we have some control. We don't really have so much control over drought or climate. "

Many scientists willing to speak out feel it's time to risk erring on the side of prevention. Says Brent Tellion, Chief of Forest Protection for Vermont, "Every time we can reduce any type of pollution, we need to bite the bullet and do it. And people should be willing to pay to do it.

"I would like to see the U.S. Forest Service get off its duff and do a little bit better," Tellion continues. "I know Jerry Hertel and all the people who work in the Forest Response Program are trying hard to do it within the limits and dollars they're given. But I go up to Canada and see what the Quebec people are doing. They got $5 million last year to start a forest fertilization program. They have $25 million to set up forest health monitoring systems that include all the air-pollution gadgetry that you need to know what the hell's going on in there. I see this and wonder how the province of Quebec can do more than the whole United States can do?"

ACTION AND POLITICS Whether or not we know what to do, President Bush has seen enough evidence to ask Congress for 700 million to fight air pollution. Both scientists and politicians now wonder whether we will throw the money at the problem or apply it where success is most probable and necessary.

Even the most optimistic estimates of how much Congress will commit to air pollution don't include enough money to tackle a fraction of the problems. At the Forest Service's Washington research division, Dr. David Radloff says knowing where to spend it is not only scientifically difficult but also politically controversial.

President Reagan's first Director of Management and Budget, David Stockman, made this kind of problem the center of the administration's position. In a 1980 speech he asked, "How much are the fish worth in those 170 lakes that account for four percent of the lake area of New York? And does it make sense to spend billions of dollars controlling emissions from sources in Ohio and elsewhere if you're talking about a very marginal volume of dollar value, in either recreational or commercial terms?" That kind of question will probably occupy center stage during the Bush administration's attempt to fine-tune its environmental commitment in order to make its spending efficient.

Ben Stout offers an example of how easy it might be to waste money on a seemingly good cause. The Department of Energy, he says, 'is spending fantastic sums of money on CO, research' and global warming. Through photosynthesis, of course, trees take C02 out of the air. So DOE should also be funding research on ozone, Stout says. "You can talk about planting trees till hell freezes over, but if we are continuing to produce ozone, which reduces the rate of photosynthesis, then we end up with a zero sum game or a negative situation. "

David Radloff says that with government agencies as well as citizen groups, unions, and industry all trying to say where to spend or not to spend federal money, specific research can prove critical. "That's certainly the case when you get input from half a dozen agencies with very diverse viewpoints such as EPA, the Forest Service, the Department of Energy, NOAA, and the Tennessee Valley Authority. Convincing arguments and hard data are needed to convince people with different philosophies that you need to take costly measures to protect forest resources."

Sheiman, at the Natural Resources Defense Council, says the answer has to be national in scope. She says state and local officials support NRDC's national effort because they believe adopting local standards stricter than those in other regions puts them at a disadvantage in keeping and recruiting industry. She says local and state officials "really would prefer to have directives that put them on equal footing with the rest of the country in terms of emissions control and regulation. "

Whether or not Congress and President Bush achieve a general reduction in air pollution, the Forest Service and state agencies are moving ahead with the kind of science that will tell us

where our money will do the most important

work. joe Barnard of the National

Vegetation Survey says, "The

Forest Response Program has turned

peoples' attention to the need for a

real monitoring program so we can

say what's really happening."

Scientists want such a program

badly. Vermont's Teillon says, "People

say the forests are in better health than

they were 10 years ago. Well, dammit,

10 years ago we weren't smart enough

to know enough to measure forest

health so that we could compare it. So

we now have some baseline data in

place on fir-spruce and northern hardwoods,

and we're working on other

species."

Teillon says this kind of science will

lead to an approach that is less subject

to wild swings toward a single fashionable

issue.

If the controversy over acid rain has

achieved any one thing of clear value,

it is a giant and rapid increase in our

knowledge of tree physiology and forest

ecology. How effectively we deal

with air pollution and other forest

problems may depend on how well

that knowledge is communicated to

the public.

Denis Thomas Dubay, a botanist at

North Carolina State University specializing

in air pollution, says that now

that public concern supports action,

scientists should "be more forthcoming

in explaining the results and consequences

of their research. But," he

adds, "the public and the government

need to be there to listen to and understand

what the scientists say. "

In an article titled, "Why Scientists

Hesitate To Speak on Air Pollution,"

Dubay expressed a wish that is nowhere

so important as in the controversy

over what to do about acid rain.

"May our future leaders and fellow

citizens recognize the need for an accurate

portrayal of the role of scientific

evidence in solving problems, for scientists

eager to talk to their neighbors

about their research, and for scientific

literacy for everyone from the President to your favorite first-grader. It's a

hazardous world for those unwilling

or unable to try to understand the difficult

problems. " Opposing Interpretations of Existing Scientific Knowledge as Rationales for Acid Rain Policy Rationale for Deferring Additional Action

Aquatic ecosystem effects are only documented

damages in eastern North America.

Fish population losses are limited to

a small percentage of the takes that

have been studied in the U.S., primarily

in the Adirondacks.

Nonaquatic ecosystem effects theoretically

are plausible but only circumstantial

evidence exists. Terrestrial ecosystem

findings are complex and equivocal

with only limited empirical data for ad.

verse effects on forest productivity, crops,

or soils. Sensitive soils may require decades

for cation depletion.

The effects of acidic deposition are sufficiently

ambigious to preclude calculating

a target loading rate that definitely alters

aquatic or terrestrial systems.

Nitrate often dominates the acidity re.

leased during spring snowbelts in the

northeast but insufficient data are available

to develop target loadings for nitrate

induced water quality effects.

Existing data offer little evidence that

the acidity of precipitation in eastern

North America has been increasing for

decades.

Chemical transformation p@ are

not well understood so specific source-receptor

relationships cannot be defined.

Current uncertainties preclude specifying

an optimal spatial strategy for imposing

emissions reductions.

lAck ability to measure reliably dry de.

position which may be especially important

for local source contribution to total

deposition.

Existing atmospheric models cannot

predict event variability in deposition but

episodes of high acidity may cause much

of the acidification. Rationale for Taking Action Now There are thousands of potentially sensitive watersheds throughout eastern North America whose fish populations may be threatened by acidification. Adverse effects on forest productivity and other terrestrial ecosystems may result from acidic deposition through mechanisms such as leaching of soil nutrients or mobilization of toxic metals. Responses are likely to be subtle arid, therefore, difficult to detect prior to onset of major damages. Sulfur appears to dominate on a long-term average basis. Aquatic responses have been shown on a limited empirical basis at deposition rates of 30 kg/ha/yr with some responses observed in the 20 to 30 kg/ha/yr of wet sulfate range. The areas of highest sulfate deposition lie over and immediately downwind from the region of maximum SO2 emissions in eastern North America. For a given emission magnitude, acid deposition attributable to a source will de. crease as distance between source and receptor increases. Existing models and empirical data for zones of influence suggest that in the eastern U.S. sources more than 1,000 km (600 miles) distant from receptors probably contribute much less acidic deposition than do closer sources. Existing models and data analyses can give a qualitative sense of the relationship between sources and receptors. S02 emissions reductions over a broad area for a long time period may provide essentially proportionate reductions in acid deposition, if all other climatological inputs are held constant. Prospects High for Clean-Air Action Despite the high level of public concern last year about acid rain, smog, ozone depletion, and global warming, Congress was again unable to pass Clear Air Act amendments. Scientific uncertainty about how specific airborne pollutants affect forest ecosystems has made legislative responses extremely difficult from a technical perspective. And the potentially disruptive economic implications of such responses have resulted in intense regional conflict, and political stalemate. However, there is a growing consensus that clean-air action must be taken soon.

In the Senate last year, Clean Air Act revisions focused on the treatment of acid rain" (sulfur dioxide and nitrogen oxides), while the House of Representatives dealt primarily with urban smog" (ground-level ozone and carbon monoxide) and toxic pollutants such as aluminum, lead, and zinc.

The one bright spot from last year was passage of the Forest Ecosystem and Atmospheric Pollution Research Act (P.L. 100-521). It directs the Forest Service to conduct a 10-year study on the effects of atmospheric pollutants on forest health and productivity. This effort will complement the work currently being done by the Forest Service and Environmental Protection Agency under the National Acid Precipitation Assessment Program, and will provide more comprehensive data on the impact of acid rain, ozone, and heavy metals on tree growth.

Several changes bring improved prospects for the passage of clean-air legislation in 1989. President Bush, in his first major budget address to the nation, broke with the "research only" position of the Reagan Administration and promised action on acid-rain legislation. Bush's new Environmental Protection Agency administrator, conservationist William K. Reilly, has stated that he would deliver proposals to the Senate in late February that will "lead to a substantial reduction in acid rain by the end of the century, " and address the urban smog problem. Although several clean-air bills have already been introduced this year, Congress is now waiting to see the Administration's proposals.

Shifts in congressional leadership and perception suggest that clean-air legislation may become a reality this year. With George Mitchell as its new Majority Leader, the Senate is much more likely to act on a clean-air bill, though Senator Robert Byrd will still be a major force in determining the bill's provisions. In the House, Speaker Jim Wright of Texas has stated that he is committed to moving a clean-air bill through the 101st Congress-A commitment he has not made in the past. And Congressman John Dingell has said that he may introduce a comprehensive clean-air bill this year, whereas his past bills have dealt only with toxic pollutants.- GERALD j GRAY
COPYRIGHT 1989 American Forests
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Copyright 1989, Gale Group. All rights reserved. Gale Group is a Thomson Corporation Company.

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Title Annotation:includes related information
Author:Gray, Gerald J.
Publication:American Forests
Date:May 1, 1989
Words:4856
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