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ACID RAIN AND OZONE THREATEN SOUTHERN ECONOMY
AUBURN, Ala.__--Acid rain and ozone are aerial pollutants that are a
threat to Southern culture and economy. Recent research by foresters
in the Alabama Agricultural Experiment Station indicates the danger
from acid rain is only a potential one, but ozone is a more serious
and current threat to Southern pine forests.
Pine trees have long been a part of southern culture, providing aesthetic
beauty in recent years and essentials of life for early settlers. Currently,
pine trees represent a billion dollar business in Alabama and are the
single largest dollar volume crop grown in the State. In the mid-1980s
there was speculation that the growth rate of pines in the South was
being slowed down by acid rain and ozone.
Acid damages trees and, by getting into the food chain through lakes
and streams, causes widespread fish kills and wildlife damage in the
northeastern United States and northern Europe. Speculation has been
that acid rain is causing less spectacular, but significant reduction
in pine growth in the South. Researchers from Auburn University's School
of Forestry found that nitrogen and other nutrients in acid rain in
Alabama actually increased fertility and, subsequently, pine tree growth
at a test site in Auburn.
Auburn researcher Art Chappelka, an assistant professor of forestry
at Auburn, explained that acid rain on Southern forests is a "good
news, bad news" situation. "At the levels we are recording
acid rain here at Auburn, it has slightly increased pine tree growth
in the short term. However, acid rain may be harmful over the longer
duration. In our case, the soils here are deficient in nitrogen, sulfur,
and other chemical elements that make up acid rain. However, when soils
become saturated with these chemicals, they lose their capacity to absorb,
or buffer, these materials," Chappelka noted. If the levels of
acid rain increase and Southern soils lose their buffering capabilities,
trees and other crops could be in serious trouble, the Auburn researcher
speculated.
Ozone provided a more current threat to Southern pines in the Auburn
tests. The research team, which includes Chappelka, Graeme Lockaby,
an associate professor, and Ralph Meldahl, an assistant professor of
forestry, constructed 16 X 15-foot plastic chambers, manufactured both
acid rain and ozone, and pumped these pollutants into the chambers,
in which loblolly pines are planted. In these chambers, the effects
on pine seedlings of ozone at 2.5 and 1.7 times ambient air (the air
we breathe) and charcoal filtered air were compared.
"We found that genotypes, or families, of pine trees are affected
differently by ozone," Chappelka noted. Annual growth of pine trees
sensitive to ozone decreased up to 20 percent, while those not sensitive
to the pollutant had no growth reduction. Chappelka stressed that researchers
at other sites that are part of a five-state, multi-year test by the
Southern Forest Research Cooperative, administered through the U.S.D.A.
Forest Service under Program Manager Susan Medlarz, have shown growth
differences from ozone at ambient air levels.
Stratospheric ozone, commonly referred to as the Ozone Layer, filters
out harmful rays from the sun. Tropospheric ozone is formed nearer Earth's
surface from gases emitted from cars and factories. This is the ozone
that threatens Southern pines. It is transferred hundreds of miles in
clouds, and especially in the summer, tends to stagnate over the Southeast.
The air in areas inundated with these pollutants is second only to the
Los Angeles air basin in ozone concentration. The air in the Los Angeles
air basin often contains 2.5 times the ozone found in ambient air in
Alabama.
"Because of this tremendous potential for damage, we need to learn
more about the effects of ozone on tree growth. We need to know how
it effects other species of trees and how it effects different genotypes
of pine trees," Chappelka commented. The Southern forest resource
is estimated to be nearly $70 billion, and by the year 2030, the South
will account for 53 percent of the total United States timber harvest.
Even a small reduction in annual growth could cause hundreds of millions
of dollars of losses to the Southern economy, Chappelka concluded.
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By:
Roy Roberson
11/7/90
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