Forest Regeneration Research Looks at the State of Pennsylvania's Forests

  • If you look closely at this image, you can see that in the foreground, deer have browsed the forest down to ferns. On the foreground/left a fence that kept out deer allowed plants to flourish. Photo: Al Cambronne

August 30, 2013

Deer have been blamed for decades for mowing down sections of forests with their insatiable appetites for plants and their love of rubbing antlers against tree bark. Over the last decade, however, the Pennsylvania Game Commission has cut back deer herds, by in some places as much as 40 percent.

Duane Diefenbach, an adjunct professor of wildlife ecology at Penn State, is working on a study looking at whether forests are bouncing back. He says the forests have to some degree responded in kind to the lower number of deer.

“In some of the state forests there’s twice as many, you know, small seedlings on the forest floor than there were ten years ago,” Diefenbach says.

Forest experts aren’t seeing quite the plant regeneration they’d hoped for though.

“When you take a closer look you’ll see that many of the species that are coming back are least palatable to deer,“ says Diefenbach. In addition to lush, prehistoric looking mountain laurel and ferns, he says “things like black birch, because deer really don’t prefer those over others, so you’ll get lots of black birch regeneration, some red maple because it’s relatively fast growing. Beech because it’s very resistant to deer browsing, but if you look for tulip poplar or white oaks or red oaks you’ll see that they’re still struggling.”

So what’s going on? Diefenbach and others at various agencies are working on a long-term study to answer that question. They’re examining state forests in Bald Eagle and Rothrock in central Pennsylvania and Susquehannock State Forest in northcentral Potter County. The research team says a number of other factors such as soil acidification, in addition to deer, may be holding back forest regrowth.

Soil acidification can be caused by a variety of factors—including nitrogen emissions from power plants. There are also insects and disease that can stifle forests. In addition, the region doesn’t have the big fires like those recently seen in the West, which are destructive, yet the mechanism some trees use to regenerate.

According to Diefenbach, "because of fire suppression, species such as oaks that respond very well after fire are at a disadvantage.”

Although deer aren’t considered the only culprit in the state of the forests, the research will focus on the creatures and hunters to get a better picture of this piece of the puzzle. They’ll be reaching out to the outdoors community how often they’re hunting and how many deer they kill in the specific 20-square-mile areas they study. To get hunters to talk, they’re even offering a hundred bucks—dollars that is—to those who capture tagged animals.

Hunters who don’t catch one of the specially tagged deer but who still want to add their two cents to the research can find a link to register at the DCNR website.