Summer's long drought points to drab autumn for leaf-watchers Dominant color likely to be brown

September 23, 1991|By Mary Knudson

Foresters and tree scientists are predicting mild to severe setbacks this fall in the normally colorful foliage show across Maryland and elsewhere along the East Coast because of the summer drought.

"What I'm afraid is going to happen is all the leaves are going to turn brown and drop off," said Bernie Zlomek, a forester in the Allegany County office of the Department of Natural Resources' Forest and Park Service.

"Normally you start to see a color change the first week in October," he said.

L "We should have a strong indication then of what to expect."

Autumn colors usually peak the second week in October in Western Maryland's Garrett County, he said. The Autumn Glory Festival will be in full swing in Oakland the weekend of Oct. 12, whether the landscape is truly glorious or not.

Stan Krugman, a plant physiologist and geneticist who is director of forest management research for the U.S. Forest Service, is more optimistic, but he believes that the drought "will probably temper the color somewhat."

A severe drought such as Maryland experienced hurts the general health of the leaves, he said.

"The leaf is a food factory," Dr. Krugman said.

It uses sunlight to convert carbon dioxide and water into nutrients. Sugars are synthesized as building blocks for proteins, fats, amino acids and other nutrients that are sent from the leaves through the entire tree and enable it to grow.

"When the drought comes along, it puts severe stress on the trees because you need water to carry out all these chemical processes," the scientist said.

"Without it, the chemical pathways are disrupted, and deterioration sets in."

Some leaves may just turn brown, the color of "the organic shell of the leaf, the structural material of the leaf," he said.

A drought is hardest on ornamental trees, whose root systems are shallow, Dr. Krugman said.

Fall arrives officially at 8:48 a.m. today with the equinox, when the Earth is tilted so that the sun crosses the equator, making days and nights equal in length.

But Maryland's trees have already sensed autumn's imminent arrival, beginning their chemical change, preparing to drop their leaves as a survival measure in advance of winter dormancy.

If leaves were to remain on a tree year-round, they would dry out during the winter and draw moisture from the roots, probably depriving the tree of needed moisture and killing it, Dr. Krugman said.

The loss of chlorophyll, the substance that keeps deciduous trees green during spring and summer, is what also causes the usual splendor of gold, rust, red and purple that attracts the leaf-watchers.

As the days have shortened, the chlorophyll in the leaves has begun to decay.

Scientists don't know exactly how it happens, but a tree's genes signal the growth of what are called abscission cells in the stems. They might as well be called scissor cells, because their function is to cut the leaves off the branches.

The cells grow in such a way that they are attached only to the leaf stem and not to the branch, so that when the cells have finished growing, the leaf simply drops off, Dr. Krugman said.

As chlorophyll slowly disappears from a leaf, yellow and brown pigment is uncovered. The remaining sugar in the leaf is converted into new pigments -- the reds, the blues and the purples.

Just how brilliant these colors will finally turn out to be this fall and how long the colors will last is hard to predict, foresters and scientists agreed.

But with temperatures dropping and the first hints of autumn in the air, Marylanders may want to start planning for weekend drives in October to see for themselves.

Green Ridge State Forest in Allegany County will offer a self-guided fall foliage tour.

Tourists are advised to stop at the forest office off Exit 64 of Interstate 68 to get a brochure and directions on where to start the tour.

The office is open six days a week from 8 a.m. to 4 p.m. and from 8 a.m. to 8 p.m. Fridays.

A staff member has reported that some reds and rusts are already visible there.

Mr. Zlomek said the only color he has seen so far in Allegany County is brown, but he added the encouraging note that stressed trees turn color and drop their leaves earliest, and are "by no means a forecast of what is to come."

In a good year, Western Maryland boasts brilliant red maples, bright yellow and bright orange sugar maples, hickories and oaks swathed in yellow, yellowish-brown and red leaves, all mixed in with the natural green of pines.

Maryland's foliage in a good year can compete with the mountain range forests of upstate New York and New England, but the forester isn't making any promises for this fall.

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