UNIVERSITY PARK, Pa. -- Acid rain is more responsible than white-tailed deer for Pennsylvania forests not regenerating, claims a Penn State College of Agricultural Sciences forest hydrologist, who recommends applying lime to remedy the problem.

"I agree that we need to control deer numbers," says Bill Sharpe, who has been studying the effects of acid rain on Pennsylvania forests for 25 years. "But the problem with our forests is caused by more than just deer. The acid-sensitive tree species such as red oak and sugar maple are not going to regenerate well -- whether deer are eating them or not. I am worried that we will suffer all of this heartburn over deer and still have a huge problem on our hands."

The problem, according to Sharpe, is that Pennsylvania is downwind from the greatest industrial complex in the world -- the Ohio Valley -- and the state's forest soils have been absorbing acid precipitation originating from there for many decades. The acid comes from sulfur dioxide in the emissions from coal-fired generating plants in Ohio, Indiana, Illinois, West Virginia and western Pennsylvania.

"Pennsylvania has been the victim of the most acidic precipitation in North America," he says. "The acid deposition leaches aluminum out of the soils, is toxic to plants and also lowers the availability of calcium and magnesium, which are essential elements for plant growth. It has also eliminated fish from headwater streams all over the state.

"We have a forest regeneration problem and a forest health problem -- our forests are sick, but we aren't sure how sick," Sharpe adds. "We do know there is very little regeneration of red oak and sugar maples are dead and dying across hundreds of thousands of acres. And it's obvious deer are not killing large trees. We also know that liming improves sugar maple health and growth."

Sharpe says state and federal agencies that manage vast tracts of forests in the state -- as well as many university forest scientists -- disagree. They have concluded that deer overpopulation is solely responsible for damage to Pennsylvania forests. But Sharpe claims it's not that simple and believes recent moves by the state to drastically reduce deer numbers will not help much.

"They can kill all the deer, but it will take a lot more than that to fix the forests," he said. "The problem is that nothing is growing well. In places where soils are not buffered by naturally occurring calcium, there is no regeneration of acid-sensitive tree species. I'm offering a different hypothesis -- the deer are not the main problem."

In 1998, Sharpe assembled a blue ribbon international team of acid rain researchers to look at Pennsylvania's forest health problems. Their conclusion was that conditions in Pennsylvania's forests were as bad as they had seen anywhere in the world.

In a subsequent Penn State book published in 1998 by Sharpe and associates, titled "The Effects of Acid Deposition on Pennsylvania's Forests," the following species are listed as acid sensitive: red oak, sugar maple, pin oak, black oak, quaking aspen and hickory. Species listed as relatively tolerant of acidic soils are white pine, chestnut oak, black birch and striped maple.

"Foresters complain about the proliferation of striped maple in Pennsylvania's forests without making the connection that it tolerates soil acidity well," says Sharpe.

"Much has been published in the scientific literature and the popular media about Pennsylvania's problems with regeneration of new forests following harvest or other disturbance," the book states.

"Virtually all of the information that has been produced on this subject singularly and without question blames Pennsylvania's forest regeneration problems on an overabundance of white-tailed deer.

"Little, if any, effort has been expended on a wider understanding of this problem -- an understanding that takes into account the presence of other serious potential stresses to regeneration, among which is acidic deposition-related soil acidification.

"To understand what is happening to Pennsylvania's forest regeneration, one must embrace the concepts of multiple environmental stresses acting simultaneously," the book continues. "Only in this manner can both observations and research results about regeneration failure be properly interpreted. The fact that deer eat seedlings is indisputable. . . However, what has been completely overlooked is the condition of the seedling being eaten and its capacity to deal with the stress."

To battle soil acidification, Sharpe advocates a simple technique -- applying a ton and a half of dolomitic lime per acre when trees are harvested. He believes liming would cost less than $100 an acre -- far less than the $370 an acre he says the Bureau of Forestry and timber companies now are spending to fence harvested areas and the $100 an acre they are spending to spray herbicide to limit growth of ferns, which compete with tree seedlings.

"Our data indicate that red oak grow better when treated with lime high in magnesium," says Sharpe. Lime amounts used in Sharpe's research projects have varied by up to 10 tons per acre, but his most recent work with a 1.5-ton per acre rate has convinced him that it is enough. "The calcium and magnesium have been leached from the soil," he says. "It has to be put back if we want the trees to grow.

"We all want the same thing -- a healthy, productive forest," Sharpe says. "I'm just suggesting another way to get it."

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EDITORS: Bill Sharpe can be contacted at 814-863-8564 or wes@psu.edu.

Contact: Jeff Mulhollem jjm29@psu.edu 814-863-2719 814-865-1068 fax #179