Incredible shrinking forests

January 27, 1992|By Liz Bowie | Liz Bowie,Evening Sun Staff

Maryland's ever-growing deer population is munching through suburban shrubs. Black bears, once hunted nearly to extinction, climb onto rural front porches. And wild turkeys soon will have set up residence in every county in Maryland.

As quickly as those game creatures are coming back, deep within Maryland's forests a host of songbirds and plants are disappearing. Biologists say both trends are at least partly linked to the shrinking of East Coast forests.

Large blocks of Maryland's woods now look like checkerboards, broken by development in the suburbs and logging in Western Maryland.

Wildlife that prefer open spaces -- such as deer, bears and turkeys -- have prospered. But lesser-known inhabitants fare poorly.

Take the worm-eating warbler. The average suburbanite may not know this little brown bird that pokes around in dead leaves, but it's as common in deep forests as cardinals are at backyard feeders. It spends most of the year in Central and South America, but every spring it comes north to breed in East Coast forests.

For two decades, the U.S. Fish and Wildlife Service's Patuxent Wildlife Research Center near Bowie has tracked the populations of warblers, wood thrush, red-eyed vireo and dozens of other songbirds as they migrated from the tropics. The scientists found that 75 percent of these species had declined, almost half of them significantly, in the past decade.

Wildlife biologists thought they might find that the songbirds were being harmed by the cutting of tropical rain forests.

But they found instead that some songbirds are more threatened by the cuts made in forests in the Eastern United States where they breed. While the condition of the rain forests is important, the birds seem able to adapt more easily to the disturbance there, said James F. Lynch, a research ecologist with the Smithsonian Environmental Research Center in Edgewater.

"We do have some effect on the fate of these birds by how we manage our forests in the Eastern United States," he said.

Native plant species are having trouble as well. Like General Motors competing with Toyota, the state's native plants are being crowded out by feisty foreign imports that seem perfectly suited for the disturbed forests now so common in the state.

As trees are cut down in the large forests of Western Maryland, sunlight pierces through to the forest floor, allowing different plants to invade the forest edges.

"When you open up the forest canopy, it promotes the growth of more aggressive, pollution-resistant species like garlic mustard," which grows over and kills native species, said Rodney L. Bartgis, biologist for the Natural Heritage program of the Maryland Department of Natural Resources.

If the trend continues, he said, Maryland will have few places that contain only the plants that grew here a couple of hundred years ago.

In Patapsco Valley State Park, a narrow forest on the edge of Baltimore and Howard counties, the native plant species have been wiped out, he said.

Sometimes, the immigrants aren't plants but birds. The brown-headed cowbird, for instance, elbows its way into the nests of native birds to lay its eggs. Their young are so plucky they push out the other chicks and make their adoptive parents raise them.

Maryland has lost 203 plant and wildlife species, and another 413 are endangered or threatened.

These trends worry environmentalists and some state natural resource officials who believe the answer lies in maintaining the large blocks of forest that are left.

"You have to decide that there are woods out there that are not going to be allowed to be fragmented," Mr. Bartgis said.

But that is not easy. Suburban sprawl is chewing up vast acres of trees. Between 1985 and 1990, Maryland lost 71,000 acres of trees, primarily to development. And in Western Maryland, where a half-million acres of private and public forest still dominate the landscape, timbering is a major industry.

State officials say they must manage the forests for the sometimes competing interests of timbering, wildlife and recreation.

But environmentalists argue that more land should be excluded from timbering for the enjoyment of people and to protect both plant and wildlife species that will only survive in the so-called old growth woods.

Only about 1,000 acres in Maryland have never been cut, said Daniel Boone, a forest ecologist for the Wilderness Society, as he stood in Belt Woods, an old-growth forest near Bowie. There, trees first sprouted about the time Lord Calvert took out his ax on Indian land.

Belt Woods is now only a postage stamp of a forest, slightly more than 500 acres surrounded by development, but it is vastly different from the average woods. Above Mr. Boone's head is a canopy of oaks and tulip poplars of all ages and sizes, from 5 feet to 150 feet. Among their branches is the highest density of forest-nesting birds in the United States, he said.

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