Researchers try to get at cause of beech disease

New York forest devastated by pest imported in 1890

April 04, 2002|By Dina Cappiello | Dina Cappiello,ALBANY TIMES UNION

RENSSELAERVILLE, N.Y. - Surveying the young forests of the Helderberg Mountains in 1939, the naturalist Eugene Odum predicted that one day they would be ruled by giant stands of maple, hemlock and beech.

But when scientists from the State University of New York at Albany returned to the Edmund Niles Huyck Preserve and Biological Research Station to repeat Odum's work 60 years later, instead of smooth, gray-barked beech trees towering over the forest floor, they found a landscape full of signs of death and disease.

George Robinson found:

Ground littered with dead beech branches.

85 percent of the living trees' bark bruised and riddled with bumps.

The trunks, on average, smaller than they were six decades earlier.

"I started realizing that one of the major trees was in trouble," said Robinson, an associate professor of biological sciences at SUNY-Albany who, with Richard Hyman of the Edmund Huyck Preserve, recently submitted six years' worth of research to the journal American Midland Naturalist.

"Everywhere I went, the beech trees were representing different symptoms. I would find a tree that I would judge as moderately diseased, and the next year, it's broken apart," Robinson said.

Beech bark disease

He soon found the destruction had one cause: beech bark disease, which reached North American shores in 1890 at Halifax, Nova Scotia, on a load of ornamental beech trees from Europe.

It probably didn't reach the Huyck Preserve - and much of the rest of eastern New York - until 1960, well after Odum's initial research.

"I don't think anyone in the 1940s could have anticipated the effects of these disease pests," Robinson said.

Beech bark disease, which begins with an invasion of beech scale insects and later develops into a fungal infection, is now documented along the entire East Coast, with small pockets known to exist in popular hiking areas in Ohio and West Virginia.

While its discovery is by no means new in New York, scientists like Robinson are just beginning to decipher its effects.

"In New York, most of the beech are infected," said Robinson. "The question is what the future for us will look like."

Role of beeches

The beech tree - typically one of the oldest trees in the forest - provides nuts for forest animals to eat and leaf litter that replenishes nutrients in the soil.

Undiseased beech trees normally die by uprooting, offering a fresh pit for plants to invade. A diseased dead beech splinters apart, rather than uprooting.

Scientists suspect these contributions to the forest's ecology are being diminished as beech bark disease takes its toll.

"Because the forest changes slowly and forests live longer than we do, we are always in the process of learning," said Barbara Burns, a forest insect and disease specialist with the Vermont Agency of Natural Resources.

One thing is certain: Because of the bark disease, beech will not be as dominant a player in the forest of the Eastern United States as it once was.

"Beech does not disappear from the forest, even with beech bark disease. You end up with these thickets of young beech developing as the large trees are falling," said Phil Wargo, a forest pathologist with the U.S. Department of Agriculture's Forest Service in Hamden, Conn.

One of the hallmarks of beech bark disease, separating it from other tree pests - such as Dutch elm disease and the chestnut blight - is that it works slowly.

The scale insects - yellow, and about the size of the period at the end of this sentence - attack first, tapping into the sap just beneath the beech's thin bark for food. As they feed, they secrete a white, waxy substance.

Fungi invade next, aided by the insect that has disabled the tree's immune system.

Hope now rests in the American beech that are resistant to this one-two punch. In the Huyck Preserve, Robinson has found that 5 percent of beech trees are able to ward off the disease. Others can become infected and show no symptoms.

Scientists think that these genetically superior specimens are the best hope for survival, because federal and state governments have had little incentive to take aggressive action against the disease in a tree that historically has been of little value for timber.

"We are hoping that some of the more resistant trees survive," said Burns. "If they make the next generation of beech trees, the forest will be healthier."

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