Above: State wildlife officials release a fisher, a member of the weasel family, into the woods of northwestern Pennsylvania as part of a School of Forest Resources program to reintroduce the animals to ranges they last roamed in the nineteenth century.

Since the first settlers set foot in Pennsylvania about 300 years ago, 156 plant and animal species--including the wild bison, the passenger pigeon, and the blue pike--have vanished from our borders. Today, some 351 Pennsylvania species are endangered or threatened, including the Indiana bat, the peregrine falcon, and the bog turtle. While Pennsylvania is renowned for its natural wonders and beautiful wild areas, some of the state's natural ecosystems are disappearing as well. Pennsylvania has lost 56 percent of its wetlands since colonial times, including about 28,000 acres between 1956 and 1979 alone. Many of the state's wildlife species depend on wetland habitat for survival, including 84 percent of amphibian species, 46 percent of bird species, 44 percent of reptiles, and 46 percent of vascular plants. Additionally, more than 4,500 miles of streams in the state have been polluted by mining runoff, agricultural practices, industrial development, and other sources.

Although Pennsylvania faces challenges to its wildlife and other natural resources, the scientific principle of biodiversity is driving research and education efforts that may help preserve and protect the Commonwealth's natural beauty. Biodiversity can be defined as how all living things exist in the vast spectrum of ecological habitats. Maintaining a diversity of plants and animals provides Pennsylvania residents with ecological benefits such as climate regulation and water quality. Biodiversity has an economic component because natural resources are used for food, shelter, medicine, and fuel. Biodiversity also gives us a spiritually and aesthetically pleasing place in the world which, with careful study and conservation, can be passed on to future generations. "We tend to think of wealth in very material terms," explains wildlife scientist Charles Schaadt. "As we lose biodiversity, Pennsylvania loses its greatest wealth, not just in terms of individual species, but in areas or materials that are as yet undiscovered or unexplored. It's a reason for national concern."

"There are many different levels to conserving Pennsylvania's biodiversity," says wildlife ecologist Robert Brooks. "Ultimately, the argument comes down to the fact that we don't know what will happen if we lose a piece of our ecosystem. If a species or habitat is doomed by something we did as human beings, how do we know what we have lost?"

We do know Pennsylvania has more than 3,500 species of plants and animals. If you include all living species--vertebrates, invertebrates, vascular and nonvascular plants, fungi, and one-celled organisms called protists--the count rises to more than 20,000 species. The number of species in an area is a prime component of biodiversity. Today Pennsylvania has 71 mammal species, 3,318 species of vascular plants, 379 bird species, about 75 species of native amphibians and reptiles, and more than 20,000 invertebrate species. Equally important is the number of individuals within a species, because greater numbers mean a particular species is less likely to fall victim to a catastrophe. For example, white-tailed deer, which occupy habitats across the state, are more secure than a salamander species found in just one swamp near Erie. Genetic diversity is extremely important in that each individual within a species can contribute a unique set of characteristics to the gene pool. A final component of biodiversity is community diversity. A community can be all-inclusive, like a mixed hardwood forest or a single swamp. Communities also can be stratified within a single habitat, such as the species associated with the soil, ground cover, shrubs, saplings, or canopy of the hardwood forest. According to the Nature Conservancy, there are 94 separate community types within our state, ranging from northern coniferous swamps to oak and hickory forests.

Right: Wildlife scientist Gerald Storm and project assoicate Matt Lovallo track deer using a mobile radio antenna. Storm, a member of the Pennsylvania Cooperative Fish and Wildlife Unit, is studying deepr population problems at the Valley Forge National Historic Park.

"We've just scratched the surface of studying biodiversity," explains wildlife scientist Gerald Storm, an adjunct associate professor in the School of Forest Resources and assistant leader of the Pennsylvania Cooperative Fish and Wildlife Research Unit at Penn State. "The task is to gather all the small-scale research and put it in a broader context. At the same time, no one has ever plotted an acre of ground in any one habitat and classified and identified every living thing that's there."

If Pennsylvania loses its wildlife biodiversity, the state's economy could suffer. According to the 1991 National Survey of Fishing, Hunting, and Wildlife-Associated Recreation, 19 percent of Pennsylvanians over age 16 hunted or fished, which resulted in $1.3 billion in expenditures in the state. Some 44 percent of Pennsylvanians age 16 or older participated in such activities as photographing, feeding, or observing wildlife, which deposited $1.1 billion in the state's coffers. Outdoor sports enthusiasts such as bikers, cross-country skiers, climbers, and hikers all use natural areas for recreation and spend money for gas, food, and lodging, as well as equipment purchases. The state's parks received more than 36 million visitors in 1993, most of whom spent money within the park or in nearby communities. In fact, more than 35 percent of the state's land is available for public recreation.

But recreation isn't the only economic benefit of Pennsylvania's biodiversity. Pennsylvania's hardwood industry, worth about $4.5 billion per year, provides lumber, manufactured wood products, and cabinets to customers across the state and nationwide. Pennsylvania's natural resources also may hold the potential for the discovery of medicines and other products made from plants or other resources. Scientists have consistently found answers to medical mysteries in the natural world. For example, taxol, a powerful drug used to treat breast and ovarian cancer, was discovered in the bark of the Pacific yew tree, and vincristine, a compound used in the treatment of leukemia, is derived from the rosy periwinkle plant.

Biodiversity also is integral to a less quantifiable element of Pennsylvanians' everyday existence--their quality of life. The boating enthusiasts who take cabin cruisers out on Lake Erie and the rural residents fishing a small mountain stream both use the state's natural resources to do something they love. The same goes for the retired couple who build a small cabin in a mature forest or the farmer who restores a wetland to see what kind of birds arrive. "You can't really put a dollar value on the enjoyment people get watching birds or observing elk in the northern counties," Brooks points out. "Seeing an osprey plunge into a lake to grab a fish or following some tracks in the snow is not something that everyone must do, but spending time in natural habitats is healthy and fun. If these habitats were not there, life would be a lot less fun for many people."

Left: Wildlife scientist Margaret Brittingham's research interest in neotropical migrant songbirds focuses on the feeding habits of the birds while they migrate to and from Pennsylvania.

Over the past 10 years, Penn State's wildlife research has shifted away from a focus on particular species to studies of biodiversity. "In the past, wildlife research was synonymous with game management," wildlife scientist Margaret Brittingham explains. "The focus was an agricultural ideal in which we were producing deer and game birds for consumption. I think research now reflects the public's interest in wildlife of all kinds and in resource management. Researchers are beginning to explore how different components of the natural environment are interconnected."

Finding the connections between various species and their habitats is no easy assignment. Most researchers compare the process to putting together a jigsaw puzzle--in this case, a puzzle the size of Pennsylvania and one in which a good number of pieces are blank. In the School of Forest Resources, faculty and graduate students slowly fill in small pieces of information. Projects range in scope from examining the effects of a limestone quarry on a small stretch of a high-quality trout stream to a statewide analysis of wildlife population distribution.

"We're just beginning to define biodiversity in Pennsylvania," says Richard Yahner, professor of wildlife conservation. "To the average person, biodiversity may be seeing a chipmunk or gray squirrel in the yard. To a scientist, biodiversity includes how plants and animals function in different landscapes."

Until the late 1970s, wildlife conservation was defined as species conservation. Scientists concentrated on bringing back endangered or threatened species such as the bald eagle, the timber wolf, or the peregrine falcon. Researchers spent years compiling recovery plans and management strategies for single species. A few plans for the most visible species were even put into practice. While public interest was piqued by many of these photogenic animals, called "charismatic mega-fauna" by wildlife experts, little thought was given to the landscapes in which they lived. "Looking at communities over time helps focus conservation," explains Robert Carline, adjunct professor of fisheries science and leader of the Pennsylvania Cooperative Fish and Wildlife Research Unit. "It's a little less exciting--not many people want to hug a shrew--but it has helped scientists evolve to a point where we ask questions such as 'How do we go about saving a certain type of habitat that supports many species?' rather than focusing on conserving a single species."

Right: Robert Carline, leader of the Pennsylvania Cooperative Fish and Wildlife Unit, holds a male brook trout taken from a small stream near Tussey Mountain. Carline is studying the historic distribution of fish in the state.

Although the focus of most research has turned away from individual species, one Penn State program seeks to boost biodiversity by reintroducing the river otter and the fisher into habitats within the state. The ongoing study has met with resounding success. Otters and fishers, two sleek members of the weasel family, disappeared from Pennsylvania around the turn of the century. The otter's stream habitats were destroyed by pollution while the fisher, a forest dweller about the size of a cat, was depleted by trapping and the deforestation of most of Pennsylvania in the 19th century. "The extraordinary thing about the otter and fisher effort is its 'wonder value,'" says Brooks, who supervises the project. "If we can get people interested in a few species, they're more likely to become interested in protecting the habitat of more than just the river otter or another species."

According to Tom Serfass, the Penn State research associate who oversaw the reintroduction effort from 1990 to 1996, 103 otters have been released in six areas in northcentral and western Pennsylvania. About 165 fishers have been released in forested tracts in northcentral and northwestern parts of the state. Serfass, now an assistant professor of wildlife ecology at Frostburg State University in Maryland, has documented both reproduction and permanent otter populations at various release sites. The study broke new ground in wildlife transport issues, veterinary procedures, and genetic testing. The program also fostered similar efforts in New York and Maryland. In 1998, Serfass and Penn State wildlife scientist Walter Tzilkowski will begin a project to study the possibility of moving elk, which are found only in Elk and Cameron Counties, to other parts of the state. "I can tell you very practical reasons why we reintroduce these animals," Serfass says. "But the truth is, we do it because we are correcting past mistakes. And it feels good. Also, these beautiful and attractive animals have large home ranges, so protecting their habitat protects other species' habitats as well."

While the cuddly-looking fishers and otters make a photogenic case for reintroducing species into Pennsylvania, several Penn State researchers are deeply involved in large-scale projects to determine not only what type of wildlife is in the state, but also where these species live. Perhaps the largest project to center on such vast parameters is the National Gap Analysis program, coordinated by Wayne Myers, associate professor of forest biometrics. Using a geographic information system (GIS), graduate students overseen by Brooks and Storm collate information on specific habitat requirements for more than 400 vertebrate species. This information is entered into a GIS, a computer database that uses layers of maps and geographically referenced statistics to analyze information. The habitat data is then integrated with digitized maps of Pennsylvania showing land use, topographic features, and vegetation types [see A Birds-Eye View of Biodiversity, Penn State Agriculture Magazine On-line, Spring/Summer 1997]. "Based on the information we get from the GIS, we can establish parameters for sites favorable to certain species and apply those values to sites across the state," Storm explains. "We've already done a project like that for elk, as well as an analysis of habitat for a game bird, the American woodcock, and the bobcat."

By analyzing animal distribution on a statewide scale, researchers can get a visual image of gaps in species or habitat, readily identifying habitat areas that might be threatened or need further research. "The database eventually will be expanded to include GIS systems from state agencies," Storm says. "Land-use planners and wildlife managers will be able to see which land is controlled by different agencies and create a management plan that crosses political boundaries, making a more complete plan for conserving biodiversity."

Left: Penn State ichthyologist Jay Stauffer uses a process called electro-fishing to sample fish populations from Penn's Creek. Stauffer, shown here with graduate student Renee Ruffing and two other students, is studying how limestone quarrying operations might affect resident fish populations.

Penn State ichthyologist Jay Stauffer and Carline are using GIS technology to study the historic distribution of fishes in Pennsylvania. The researchers have entered data from 18,000 separate fish collections dating back to the mid-19th century to determine the influence of landscape and water quality on fish distribution. They also are examining how the introduction of exotic fish species has affected native fishes. Maps showing fish distributions at 25-year intervals suggest that several introduced species have affected native species. The most obvious examples are the expanded habitat of the brown trout, introduced from Europe in the 1800s, and the rainbow trout, introduced from western states in the 20th century. Both the brown trout and, to a lesser extent, the rainbow trout have outcompeted native brook trout in many areas of the state.

"Brook trout once were found in all our streams, but now are found primarily in small headwater streams in ridge or mountain areas," Carline says. "It's hard to say why the brook trout has been pushed out, but some of the factors include increased water temperatures and more nutrients in the valley streams. Also, brown trout and rainbow trout are bigger than brook trout, and a larger species usually wins in a fight for habitat."

However, Carline adds, there is little evidence to show a relationship between the gain of exotic species and the loss of native fishes. Most of the species that have disappeared from the state were native to heavily industrialized areas near the Schuylkill and Delaware Rivers and were driven out by pollution. "At the watershed scale, which includes 110 separate watersheds in Pennsylvania averaging 400 square miles apiece, we haven't seen widespread effects associated with exotic species," Carline says. "The effects occur on a local scale. We've actually found a few species we thought were gone."

Stauffer's research on the localized introduction of a tiny fish, the banded darter, into the Susquehanna River drainage shows how a new species can push a native fish out of its preferred environment. Banded darters are what Stauffer calls "generalists"--fish that can thrive in a variety of habitats. "They can exist everywhere--in pools, in vegetation, in swift water and in other areas," he says. A generalized species pushes out more specialized species by taking over habitats and dominating the food supply. Stauffer says the banded darter has displaced other darter species, such as the tessellated darter and the shield darter.

Not all large-scale Penn State projects examine how species are distributed. Brooks and graduate student Tim O'Connell have just completed an analysis of how bird communities in mountainous areas can be used as indicators of habitat quality. The study, which started in 1994, examined sites stretching from New York to North Carolina. The study is part of a larger Environmental Protection Agency project to develop tools to assess the environmental quality of landscapes. O'Connell visited 126 sites across the mid-Atlantic highlands assessment area (a mountainous region following the Allegheny Ridge to North Carolina), taking bird population counts and rating the landscape condition on a scale ranging from "pristine" to "highly disturbed." He then classified each bird species into one of 31 separate categories, called "guilds," which contain groups of species which need similar habitat, food, or other factors. For example, birds that nest in tree cavities and birds that feed on nectar would constitute separate guilds. By correlating guilds to the environmental condition of the landscape, O'Connell can create an "environmental report card" for these highland areas. "Guilds such as insect-eating birds require habitats with abundant plant life to thrive, which means the landscape they live in is less likely to be one that's disturbed, like a farm or subdivision," O'Connell says. "If a habitat-specific bird is sighted in an area where it hadn't been seen in recent years, then that bird serves as an indicator species to show the habitat is changing."

"When you're trying to understand the entire landscape, you can't afford the time and equipment to study everything," Brooks explains. "But we can understand how bird communities, which have large habitat areas because of their flight capability, respond to landscape disturbances, and we can use them as surrogates for the whole system."

Understanding how birds use their environment also has been a question of lasting significance for Margaret Brittingham. Her research centers on neotropical migrant songbirds, which migrate from Mexico and Central and South America to breed in Pennsylvania's huge expanse of deciduous forests. Many of her studies have taken place from May to August, when the birds are breeding and nesting. Most of her studies examine why migrant songbird populations have declined over the past 40 years, exploring such factors as predation, parasitic cowbirds, and forest fragmentation. Now Brittingham and graduate student Paul Rodewald are trying to learn how these neotropical migrants use habitats during migration to and from Pennsylvania. These birds migrate at night, stopping when their supply of stored fat from previous feedings is depleted. To gain energy for continued migration, the birds must gorge on fat-rich food, sometimes doubling their body weight, like tourists parked at a pancake restaurant for several days, eating 15 times a day.

Left: Penn State researchers are studying the Louisiana waterthrush to see how the environmental problems are affecting other migratory songbird species.

Rodewald is studying five habitat types: mature forest, forests under 30 years old, early successional growth after a clearcut, forested edge habitat near agricultural fields, and suburban woodlots. Last fall, he visited 25 sites to find out which songbird species use what habitats. Next year, he will double the number of sites. By noting the abundance of such tempting bird morsels as pokeberries, dogwood berries, and spice bush, then counting the bird species using these sites, Rodewald can develop a snapshot of how migrant songbirds use landscapes during their trip. "Most of our research has focused on preventing more forest fragmentation to preserve nesting sites," Brittingham says. "This study shows that the birds use many different habitats during migration."

"In the spring many birds use suburban woodlots, perhaps because insects emerge there earlier," Rodewald says. "They also use forest and forest-agriculture edges, which means farmers and homeowners could try to manage for these migratory stopovers."

While birds are among the most watchable species for many Pennsylvanians, some researchers are looking closely at insects. Extension entomologist Gregory Hoover says there are several lifetimes worth of research in understanding the connection between insects, animals, and the environment. After all, while there are 71 mammals native to Pennsylvania, there are at least 312 species of caddis flies alone. Hoover just completed a four-year project to document the distribution of mayflies across Pennsylvania. He and several graduate students collected mayflies from aquatic habitats ranging from crystal-clear mountain streams to polluted creeks near industrial sites. After collecting approximately 17,000 specimens at more than 400 different sites, he has documented some 230 species in the state. He recalls collecting 15 different species one night from a single light outside a convenience store near the Susquehanna River.

His project also may identify specific mayfly species that can be used as indicators of water quality. "Pennsylvania is a very rich state for mayflies because we occupy a meeting ground for southern and northern distributed species," he says. "While no mayflies are present in a heavily polluted stream, certain species may begin to appear as a stream improves over time." Hoover has documented that the mayfly Stenacron interpunctatum will be one of the first to reinhabit a marginal water quality site. Another species, Epeorus pleuralis, inhabits only streams of pristine quality. He also has documented species that are native only to certain areas of Pennsylvania, such as the Poconos and Lake Erie. An avid fly fisherman, Hoover says the information collected also can be used by anglers. "If flyrod anglers know what kind of mayfly is in a particular stream, they'll know what type of imitation fly to select from their fly box," he says.

As scientists explore the connections between wildlife and landscape, many projects are focusing on previously unexamined species. This trend is due partly to the introduction of Pennsyl-vania's Wild Resources Conservation Fund license plate. The fund, which has sold more than 235,000 wildlife plates, has provided more than $3.5 million to finance research related to Pennsylvania plants and nongame animals. The license plate fund has allowed scientists to follow their curiosity into areas that may not have been examined otherwise.

Right: Richard Yahner, professor of wildlife conservation, takes a swipe at a native butterfly at a study site near State College. Yahner is studying how native butterfly species use different types of habitat.

For example, Rich Yahner, a wildlife expert who has studied animals ranging from chipmunks to goshawks, has been swinging a butterfly net through various types of Pennsylvania landscapes to study how these beautiful insects use different types of environments. With a grant from the license plate fund, he is examining 20 farmland sites divided into forest edge, road, hedgerow, and woodlot habitats. At each site he notes the abundance of butterfly species, as well as the richness of wildflower species. "A colleague once told me you can't spend your life studying one species," Yahner says. "It's been really fun to approach this butterfly project with techniques I've used for mammals and birds. When I started, I thought there were three types of butterflies--orange, yellow, and black. Now I can identify 30 different species in a single habitat."

Yahner has found that the most developed landscapes, such as farm fields or suburban yards, are home mostly to exotic species such as orange sulfur or cabbage white butterflies. In more protected landscapes, such as forest edges, he has found an abundance of native species, including great spangled fritillaries, red-spotted purples, and pearl crescents. In addition, the population of native wildflowers, aided by the pollination activities of the butterflies, is much more diverse in the less disturbed landscapes. Based on his findings, Yahner has outlined some management recommendations for forest managers, rural road supervisors, and farmers. "Leaving field edges wild and road edges in forests unmown until after the growing season maintains habitat not only for butterflies but also other species that may use it," he explains. "If we don't maintain butterfly habitats, it can have a domino effect on the area's biodiversity. If butterflies decline, it can mean a decline in wildflowers, and that can affect other species that use butterflies or caterpillars for food."

Although many Penn State wildlife research projects are centered on various types of habitat, others are very site-specific. Charles Schaadt, who works at Penn State DuBois, has conducted several studies in some of the state's few remaining tracts of old-growth forest, where beech, hemlock, and white pine trees more than 400 years old reach 150 feet in height. The two largest remaining tracts of old-growth habitat are Cook Forest State Park, with 494 acres, and the 4,000-acre Tionesta Scenic and Research Natural Area in the Allegheny National Forest. Schaadt and former Penn State researcher Christopher Haney recently outlined how neotropical migrant songbirds such as the brown creeper, Blackburnian warbler, and black-throated green warbler depend on old-growth forest for nesting. Schaadt is now exploring how salamanders use old-growth habitat.

He is comparing five old-growth plots in Cook Forest with five plots in nearby S.B. Elliott State Forest, which, like most of the state's forests, is about 80 to 90 years old. So far, Schaadt has found seven salamander species in old-growth habitat, compared to just two species in younger forests. Preliminary data show that of these species, the red-backed salamander is about 20 times more abundant in old-growth tracts than any other salamander. "Because there is so little old-growth forest left in Pennsylvania, it really hasn't been studied as an ecosystem," Schaadt explains. "Working in an old-growth forest has a magical and spiritual component that is difficult to describe. Finding how salamanders use it is a small part of the puzzle, but if we can uncover some valuable components of this ecosystem then we can set aside younger stands of trees and manage them to become old-growth forest."

Penn State researchers also study pollutants and other factors that affect specific habitats. Ichthyologist Stauffer and graduate students Renee Ruffing and Tim Stecko are analyzing fish and aquatic invertebrates in Penns Creek, Elk Creek, and Pine Creek. A limestone quarry near Spring 29 on Pine Creek is scheduled to open by 1999, which may affect the biodiversity of these streams. Stauffer and his students are counting fish and invertebrate populations both upstream and downstream from the quarry. The researchers are paying particular attention to the stream bottom, or substrate. "Within the substrate, there is an area of particular importance called the hyporeas region, which can extend down about 27 inches," Stauffer explains. "The hyporeas region is sort of a fluid substrate where water currents flow through spaces between the pebbles, sand, and sediments. Insect larvae live in this area, and trout make spawning nests there."

Limestone sediments, which are used in the manufacture of concrete, may be particularly threatening to the biodiversity of a stream bottom, Stauffer says. The fine limestone sediments produced by a quarrying operation could penetrate the stream bottom and act as a cement within the substrate, ruining the spawning grounds and suffocating the eggs and insect life. In the months to come, the researchers will dig up and examine spawning nests in different areas of the stream, estimating the survival of trout eggs and young, as well as the abundance of larval and adult insects.

Together, all of Penn State's research in biodiversity has been but a ripple in a much larger pool of questions about how our wildlife and the environment function together. Much remains to be done. Conserving biodiversity is a struggle when the state's natural habitat is fragmented or under the control of different agencies or owners. "In a state where 79 percent of the state's forested land is controlled by 500,000 private forest landowners, public education must become the foundation of any biodiversity conservation effort," Yahner says. "Penn State resources and education programs have become an integral part of an overall effort to raise the profile of biodiversity. And like the study of biodiversity, the effort has only just begun."

Aldo Leopold, the father of modern conservation, said it best in his 1949 book, A Sand County Almanac: "The last word in ignorance is the man who says of an animal or plant 'what good is it?' If the biota, in the course of eons, has built something we like but do not understand, then who but a fool would discard seemingly useless parts? To keep every cog and wheel is the first precaution of intelligent tinkering."

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Faculty and staff referenced in this article are Margaret Brittingham, associate professor of wildlife resources; Robert Brooks, associate professor of wildlife ecology; Robert Carline, adjunct professor of fisheries science in the Pennsylvania Cooperative Fish and Wildlife Research Unit; Gregory Hoover, extension entomologist in entomology; Charles Schaadt, assistant professor of wildlife technology, Penn State DuBois; Jay Stauffer, professor of ichthyology; Gerald Storm, adjunct assistant professor of wildlife science in the Pennsylvania Cooperative Fish and Wildlife Research Unit; and Richard Yahner, professor of wildlife conservation.


Research discussed in this article is funded by the Wild Resources Conservation Fund, the Penn State Cooperative Wetlands Center, the Pennsylvania Agricultural Experiment Station, the Pennsylvania Fish and Boat Commission, the Pennsylvania Game Commission, the Pennsylvania Department of Conservation and Natural Resources, the U.S. Environmental Protection Agency, the U.S. Geological Survey, the Penns Valley Conservation Association, the Pennsylvania Federation of Sportsmens' Clubs, and the Allegheny National Forest.