“The problems are long term and, by necessity, so are the solutions,” says the Penn State forest scientist. “Forest problems seem decades away. But those problems are insidious in the sense that they can be with you for a long time and you don’t even know it. By the time you are aware of them, it may already be too late. Examples we see in today’s forest are the effects of decades of deer damage and acid rain.”

McDill should know. He developed forest-management computer models now being used by the Pennsylvania Department of Conservation and Natural Resources’ (DCNR) Bureau of Forestry to guide tree harvests on 2.1 million acres of state forestland.

Forest management in the Commonwealth is serious business—and big business. The state is recognized as the nation’s largest hardwood producer. The wood products industry contributes more than $5.5 billion annually to Pennsylvania’s economy and employs more than 100,000 people. And the outdoor tourism and recreation business the forests support—such as hunting, fishing, hiking, camping, bird- and wildlife-watching, cross-country skiing, and snowmobiling—generate billions more in economic activity.

“The goal of our work is to help the people who manage the forests do the best job that they can,” says McDill. “Our computer models show how things work in the forest over time. These models arebased on data, and where we don’t have actual data, we make assumptions based on the best information available. The models are explicit, and the assumptions can be changed to see how they aff ect the outcomes.”

Using McDill’s software, foresters can determine how many of what type and size of trees need to be harvested where, and for how many years or decades, to shape a desired future forest. Factoring into the equation that state forests encompass more than 2 million acres, one begins to see the complexity. “Right now, all the forest is more or less the same age,” he says. “We need to get a better age distribution. Stands of trees might be even-aged, but the idea is to get a mix of stands across the forest. We are planning generations ahead.”