Pennsylvania's changing forests to affect economics, wildlife

University Park, Pa. -- The forests in what is now Pennsylvania were much different before 1865, according to an expert in Penn State's School of Forest Resources, who notes they still are changing, and in ways foresters don't much like.

Imagine our old forests dominated by huge, spreading American chestnut trees, which have disappeared from the landscape, victims of a blight. The durable hardwood and nuts they provided have been sorely missed by humans and wildlife alike.

"And we know that the percentage of conifers in our forests was considerably higher 150 years ago," says Jim Finley, professor of forest resources. "And now the eastern hemlocks are threatened by infestations of an invasive species, the hemlock wooly adelgid and hemlock scale.

"But no one living has ever seen that kind of forest here, so as foresters, all we can do is to manage what we have," Finley adds.

Thanks to the invention and wide use of the steam log loader, crosscut saw and light rail, the "era of forest exploitation" began in the latter part of the 19th century, and led to clear-cutting of vast tracts of Pennsylvania forests, Finley says. Most of the state's forests were cut between 1865 and 1920, according to Finley.

The forests that grew back have been dominated by oaks, valuable species both for the hardwood and acorns they provide. But oaks are not regenerating in Pennsylvania forests -- a phenomenon that will mean changes in the forest product output and perhaps untold upheaval for wildlife. "Whether it is because of too many deer browsing, acid rain or competition from other species resulting from fire suppression, it is bad news," Finley says. "The decline of oaks will be a major change."

The trend is well established, Finley points out. "According to data from the U.S. Forest service, red oak remains the number one forest tree in terms of timber volume, but it is now eighth in total number of trees," he says. "Red maple is number one in the number of trees and black birch is now the second most common tree in the state."

What that means is that the forests are being taken over by red maple, and if the current trend continues and today's forests are cut through, there will be fewer oak trees in the future. "The practical implication is a drop in the value of timber in Pennsylvania," Finley says. "But from an ecological perspective -- just talking about the resiliency of the forests -- the change in species is major.

"We know that if we don't have red oak and white oak trees, we won't have acorns for wildlife," he adds. "By comparison, red maple seeds mature in the summer when there are lots of other foods for wildlife to eat. They are not nearly so valuable to animals."

But Finley does see some positive developments on the horizon that may help offset negative forest trends. Scientists are close to genetically engineering and breeding a blight-resistant chestnut tree. "So it is possible that in coming decades, we can reintroduce chestnuts back into Pennsylvania forests," he says.