By Donella Meadows

–August 25, 1988–

Every weekday morning this summer, six college students set out from the Ravine Lodge on Mt. Moosilauke in New Hampshire to spend the day measuring trees. They bushwack through the forest to 15 marked plots on the east side of the mountain. Each plot is 20 meters square; some are at low altitude, some medium, some high. There are 15 more plots on the west side; the two sides are studied in alternate years. The students carry rain gear, lunches, insect repellent, and small computers into which they enter data about every red spruce and balsam fir in the plots.

If you have ever wondered what it takes to PROVE that acid rain is destroying the forests, this is what it takes.

The students tag every tree and log its position, so it can be identified again two years from now. They classify it — is it dominant with its crown topping the forest, or intermediate, or low, suppressed in the shade of others? How much needle loss does it show? If it’s a sapling, how tall is it, what is its needle condition, how has it grown over the last two years?

When you’re measuring trees, you have to be careful where you step so you don’t disturb the fragile mountain soil. On some plots there are so many saplings it takes days of tedious work to measure them all. The ground is sloping and uneven — making grid measurements is not easy. You can get into arguments about whether a half-defoliated tree is in Decline Class 2 (10-50 percent needle loss) or Decline Class 3 (50-99 percent needle loss).

Back at the Lodge in the evening the students transfer their data from the field computers to diskettes for storage and statistical processing at Dartmouth College.

At other sites on Moosilauke researchers take core samples from tree trunks to measure growth rings. A meteorological station measures humidity, temperature, wind, ozone, and the acidity of rain, fog, and cloud (pollutants can be five to ten times more concentrated in clouds than in rain). Altogether nine professors from four universities are doing acid-rain studies on the mountain, with the help of 16 students and two lab assistants.

The smokestacks and tailpipes of this nation emit over 20 million tons of sulfur dioxide and nearly the same amount of nitrogen oxides each year. In the atmosphere these pollutants form sulfuric and nitric acid, which come back to earth in fog, cloud, snow, rain. You might think it obvious that a steady wash of acid would harm structures, statues, streams, soils, and forests. But the government and the polluting industries need PROOF before taking corrective steps that may cost billions of dollars.

Moosilauke is one of six study sites for spruce-fir forests (the others are in Virginia, Tennessee, North Carolina, Maine, and New York). Other studies are going on in southern commercial forests, western conifer forests, and eastern hardwood forests. The meteorological station is part of a multi-state Mountain Cloud Chemistry Progam. All field studies are coordinated with remote sensing data from satellites. This network of forest research is just one part of a national effort called NAPAP, the National Acid Precipitation Assessment Program.

NAPAP was mandated by Congress in 1980 and funded through 1990. Many of its research projects didn’t get underway until halfway through the ten-year period (the Moosilauke work began in 1986). This year NAPAP is costing the nation $83.5 million. That’s a lot or a little, depending on how you look at it. It’s one of the most complex environmental research programs the nation has ever undertaken. It’s one percent of the cost of correcting the faults of the B1B bomber.

Whether you consider NAPAP a big deal or a small one, it is not enough to PROVE that acid rain kills forests. It has proved that the rain is acid. (Moosilauke registered a pH 2.85 rain on August 20 — that’s nearly 1000 times more acid than normal.) There’s no doubt that trees are dying. In some places on Moosilauke 30 percent of the red spruce are standing dead; in places on Whiteface Mountain 60-70 percent are dead. Growth rings show that tree growth slowed 20 years ago — just when high smoke-stacks became a fashionable way to ease local air pollution.

But that doesn’t prove that acid rain is the cause of tree damage, or that the observed damage is unusual. Scientists aren’t even sure how long a dead spruce stays standing. It may be normal on Moosilauke for 30 percent of the spruce to be dead. The slowdown in growth may be due to climate change, or ozone pollution, or insect infestations, or some combination. Sorting out the possibilities will take more than $80 million a year and longer than ten years.

Experienced foresters say they have never before seen the kind of damage now evident in the spruce-fir forests. But that subjective testimony is not enough for scientists, nor for politicians, nor for a nation that likes cheap electricity and internal combustion engines.

So we have challenged ecologists to prove that air pollution IS damaging the forests, not pollution emitters to prove that it ISN’T. We all pay the research bill, which is large enough to be politically impressive, but not large enough, soon enough, to produce unsettling results while present politicians are still in power. While the studies go on, we make no special effort to reduce emissions. That would put the burden of uncertainty on the people who make their living in coal-burning industries. Instead, the burden of uncertainty is borne by all creatures whose lives depend on the integrity of the streams and soils and forests — and that includes us all.

Copyright Sustainability Institute 1988