As part of the National Gap Analysis Program, Wayne Myers uses computers and remotely sensed landscape data to identify areas of Pennsylvania that are important for biodiversity.

Over the past 10 years, habitat loss has placed a number of once-common animals on the endangered species list, and wildlife experts fear that existing U.S. conservation programs are not adequately protecting biodiversity. The National Gap Analysis Program, sponsored and coordinated by the Biological Resources Division of the U.S. Geological Survey, aims to solve that problem by identifying gaps, or habitats and species that might be at risk of extinction without effective conservation efforts.

Penn State researchers are conducting the gap analysis for Pennsylvania. Since it would be too costly to evaluate every inch of land at ground level, Wayne Myers, associate professor of forest biometrics and codirector of Penn State's Office for Remote Sensing of Earth Resources, uses remotely sensed satellite images to create digitized maps of Pennsylvania showing land use, topographic features, and vegetation types. These maps are then placed into a geographic information system (GIS).

Simultaneously, associate professor of wildlife ecology Robert Brooks and his graduate students are gathering information on the habitat requirements of more than 400 species. "Over 200 of those are birds," Brooks says. "The rest are mammals, such as deer and raccoons, or reptiles and amphibians, such as snakes, salamanders, and turtles. Because we have to focus on habitat features on the ground that would be visible from outer space, we start with very general questions, such as whether a species is associated with forested or nonforested areas. Then we consider more specific information–for instance, is the species associated with ridges or valley floors, and how close must the species be to rivers or lakes?"

Myers correlates this habitat information with the satellite imagery to create maps that show areas of the Commonwealth that are important for biodiversity. "By overlaying these with maps of land ownership and management, we can use the GIS to find places where important habitats are threatened," he explains. "That GIS also will be used to identify sites that provide habitat for a wide variety of species, rather than focusing on the needs of just one species, so that local, state, and national conservation programs can be aimed at areas where such efforts are most likely to protect biodiversity."

When used in GIS, the data gathered for the project can help planners and others better understand land use patterns throughout the state.

While gap analysis focuses on the conservation status of major habitats, it also gives researchers a more objective understanding of Pennsylvania's landscape in general. By combining the information collected in the gap analysis project with maps of watershed boundaries, soil types, roads, municipal borders, and other geographic and geological features, Myers and collaborators in Penn State's Deasy Geographic Laboratory and Pattee Library have created a digital landscape database for the Commonwealth. An enormous amount of data had to be processed to accomplish the goal, but recent advances in technology have made this possible. "We worked with 10 satellite images covering all of Pennsylvania, and two of those completely fill a 650-megabyte CD-ROM," Myers notes. "It used to take weeks to process that amount of data, but because computers have quintupled their capacity in the last five years, it now takes hours or even minutes. Technology is reaching the point where this type of landscape analysis can be done using personal computers."

As Myers processes the satellite data, he also compresses each satellite image into 50 megabytes of data. "This is somewhat like converting oranges into a blended concentrate of juice and pulp," Myers says. "The concentrate is different from the fruit, just like the information in our compressed data is different from the information in the raw satellite files. But like the fruit concentrate, the compressed data can be stored much more economically, and it's simpler and more versatile for various uses. We now have landscape information for the entire state that will fit onto a CD-ROM. Digital Equipment Corporation has sponsored the production of 2,000 copies of the CD-ROM, so by this fall the data will be available to anyone who can use it in GIS applications."

Businesses, county planners, state agencies, schools, research institutions, nonprofit organizations, and federal agencies could use this geographic information for many purposes. "For instance, school districts might generate maps that show the area surrounding its schools so that students can analyze local land-use patterns in social studies classes," Myers notes. "Farmers could use it to see how their farm fits in with the surrounding landscape. If they wanted to know how much of the land around them is allocated to crop production, for example, or where nearby forest areas might provide habitat for pest parasites and predators, they can get that information from our database. I hope the birds-eye view this database provides can help people understand that what we do with our part of the landscape affects the whole ecosystem. If we all had wings like crows or hawks, we probably wouldn't handle our individual plots of land like we do."


–Eston Martz