Plenty, according to senior Gettysburg College environmental studies majors who studied the campus' more than 1,200 trees.

"Our research project goals were to inventory the existing land cover on campus, and to assess the ecological values of the trees - like absorption of air pollutants and reduced soil erosion - and their corresponding economic values," said Professor Randy Wilson.

The students' first step was to create a digitized map of the campus using the college's Geographic Information Systems (GIS) equipment and "CITYgreen," software developed by the nonprofit American Forests. The data collected and displayed showed the percentage of land covered by buildings, impervious surfaces, grass cover, forest patches and shrubs, bare areas, water and trees.

For each tree, students worked with the college's arborist to determine species, growing conditions, height, health and diameter. "This geo-referenced tree inventory allows you to click on an individual tree and obtain specific data collected for that tree," Wilson said. "It also allows you to continually update information, for instance, like when a new tree is planted. In addition, you can run queries on the entire data set to identify trees in need of special attention."

The inventory provided helpful and interesting information, such as: the Eastern White Pine appears most frequently among the species of trees on campus; and more than 700 of the 1,200 trees have the highest health rating, according to guidelines developed by the City of Sacramento's (Calif.) Parks Division.

The next step in the project was to conduct an ecological analysis of the tree and land cover. A variety of scientific methods measured the tree's ability to: absorb air pollutants; counter global warming and the greenhouse effect through atmospheric carbon sequestration (the rate at which carbon dioxide is taken up and stored by a tree); reduce surface water runoff; and provide wildlife habitat.

With the help of reference data gathered by the United States Forest Service for the city of in Baltimore, Md., students determined that nearly 382 pounds of ozone and 2,751 pounds of carbon dioxide were removed by the campus trees and land cover. The total dollar economic benefit of the trees' work against air pollutants was $2,635.62, according to the project.

In addition, the study determined that the total carbon storage capacity of the campus trees was 355.27 tons and carbon sequestration was 5.92 tons/year. And when students compared the current campus situation with a no-tree scenario, they found that approximately 2.1 million gallons of surface water runoff was prevented by the trees.

"By mapping and calculating the benefits of trees on Gettysburg's campus, we hope they will increasingly be incorporated into the college's landscape development plans," said Wilson. "In addition, our research - which I'm told would have cost tens of thousands of dollars if it had been done by a subcontractor - will be useful in campus planning efforts."

The project may also serve as a prototype for future work conducted for the local community and Adams County, according to Wilson. "County officials have also expressed interest in this," he said, "They interacted with the students and me during the course of the semester to lend their expertise."
"This information stresses the value and importance of trees," said Dick Schmoyer of the Adams County Planning and Development Office. "It could be useful when we discuss future park projects or planning regulations that contain landscaping requirements, which are often viewed as luxury. This study shows measurable value."

Issued 1/31/02