Large Deer Population Takes Toll on Saplings : Forestry: Researchers are studying ways to protect young trees in the Northeast.

The black cherry saplings growing in a clearing in Mohawk State Forest never had a chance. Their pencil-thin trunks were chewed off a few inches above the ground.

“Those are sprouts that came up this year,” said George R. Stephens, chief of the department of forestry and horticulture at the Connecticut Agricultural Experiment Station. “Already they’ve been browsed back.”

The situation in Mohawk forest is not unlike that in many other places in the Northeast. Deer are chewing young trees to the ground as fast as they sprout.

So numerous are the white-tailed deer, and so damaging can their feeding be, that a few U.S. scientists are investigating whether it is worthwhile in some areas to enclose young trees in protective shelters.

Using a technique pioneered in England, the scientists are experimenting with various kinds of plastic or mesh tubes intended to protect saplings until their tender branches are out of the reach of deer.

Stephens and Jeffrey S. Ward, the research station’s assistant scientist in forest ecology and the organizer of the experiment, are studying the fate of more than 2,000 saplings in experimental plantings in Mohawk forest and two other Connecticut sites.

The system can be expensive and time-consuming: The tubes cost about $2.50 each and must be set up by hand. But in some places, the technique is one of the few choices left for a property owner trying to grow trees.

Deer populations in the Northeast are high--Connecticut’s current deer population is estimated at 34,000--because less and less land is open to hunting and habitat for deer is, in some ways, improving.

“Uncontrolled deer populations have the capacity to negatively impact our native plant communities,” said Mark Ellingwood, a biologist for the state Department of Environmental Protection, whose specialty is deer. “It helps if people realize there is a cost associated with not controlling deer populations.”

Deer concentrations often are especially high in areas where hunting is prohibited, such as Mohawk forest, or suburban areas where hunting is either not sensible or frowned upon.

“As the population becomes more urbanized, it becomes less tolerant to the presence of deer and less accepting of regulated hunting, so it’s a Catch-22 of sorts,” Ellingwood said.

Two scientists at the University of Massachusetts tried the tubes last year in a small experiment near Quabbin Reservoir in New Salem, Mass., using two-foot-tall red oak trees.

One group of trees was planted in the open, another was enclosed by a fence, and a third group was put in tubes. The first group of oaks was eaten, the fenced group grew one foot over the season, and the tubed group grew two feet.

“The advantage is, they act as a greenhouse in a way,” said Matthew J. Kelty, assistant professor of forestry at the university. “They increase the humidity levels and the temperature, especially early and later in the growing seasons. So it’s much as raised hothouse beds would be.”

Even where deer are scarce, the tubes help urban shade trees become more quickly established, said David M. Smith, professor of silviculture, or forest cultivation, at the Yale School of Forestry and Environmental Studies.

The experimental plot chosen in Mohawk forest was cut over last year because the stand of red pine that dominated it was diseased and dying. Because of the large number of deer in the forest, Stephens said that without help, new trees would not be able to get established for many years.

On a nearby piece of forest that also was cleared, the only tree sprouts doing well are striped maples, a tree that deer seem to avoid. That tree, however, never grows very large, has little value for wildlife and almost no value as timber, Stephens said.

Stephens and Ward are testing seven kinds of shelters on five tree species: Norway spruce, white pine, hemlock, red oak and black walnut.

The tubes typically are left on for several years. In time, the plastic breaks down and falls to the ground.

One concern of the scientists is the long-term health of trees raised in tubes. Smith said the trees apparently grow taller more quickly, but perhaps at the expense of trunk thickness and tree strength. Once the shelters are removed, “the tree could flop over,” he said.