he Oak Ridge Reservation has evolved into a nationally valuable natural resource over the past 50 years. Despite the well-publicized problems of contamination from the Department of Energy's Oak Ridge National Laboratory, Oak Ridge Y-12 Plant, and Oak Ridge K-25 Site on the reservation, the land has a regionally unique diversity of plant and animal species.
Occupying about 14,000 hectares (35,000 acres) of mostly contiguous native forest, the reservation land provides interior habitat for the area's sensitive species of wildlife. It contains relatively undisturbed ecosystems that are important habitats for many species uncommon or absent in surrounding areas. And, perhaps most importantly, it has experienced minimal impact from human land use for the past 50 years, providing an invaluable reference point for determining the effects of human development on natural resources.
When the land was acquired by the federal government in 1942 for the Manhattan Project, it consisted of approximately 1000 individual tracts of land that were primarily farmsteads. This land was a patchwork of forests, wooded pastures, and fields. Aerial photographs taken in the mid-1920s and late 1930s show that about half of the area was cleared. Some clearings for orchards and pastures were on upper slopes, rocky areas, and ridgetops; tillage crops were mostly restricted to lower slopes and bottomlands. Agricultural practices of the time resulted in severe erosion on most slopes. Not surprisingly, erosion gullies are still evident in some areas.
Except on very steep slopes, most of the forest was cut for timber, though not necessarily cleared. Many partially cut forest areas were used as rough pasture. After 1942, many previously cultivated fields developed into forests either through natural succession or planted seedlings. Between 1948 and 1954, many of the abandoned fields that were not already well stocked with naturally regenerating timber species were planted with loblolly, shortleaf, and white pine. Some of that pine is still evident today--or was until the spring of 1993. At that time, much of the remaining planted and native pine became infested with pine beetles. Heavily infested areas were cut to prevent their spread and salvage marketable timber. The forest gaps are now filling in by natural regeneration.
To a casual observer, the reservation land may appear wild and overgrown, suggesting that it is not being used to its full potential. The reservation may be compared to a picture that appears to you first as just a pattern of color. But as you relax, rid your mind of preconceived ideas of how the picture should look, and stare at it slightly out-of-focus, you begin to see the hidden picture in the pattern of colors. In this article, we will describe the hidden picture of the Oak Ridge Reservation that shows its value as a natural resource.
Forests, primarily oak-hickory, pine-hardwood, or pine, cover about 75% of the reservation. Contained within the larger framework of mixed hardwood and pine forests on the reservation are many ecological communities that are of special interest because of their unusual species assemblages, which often include rare species. Some of these special communities are more common in mountainous, coastal plain, or prairie regions of the continent, whereas others result from unusual or restricted soil-related and topographic features, such as uncommon soil types, seeps, springs, and river bluffs.
All reservation areas are relatively pristine when compared to the surrounding region, which has been strongly affected by agriculture, cattle grazing, and land clearing during the past 50 years.
More than 1000 different species of plants grow on the reservation, reflecting its diversity. By comparison, 1300 known plant species have been observed in the Great Smoky Mountains National Park, which has greater elevational changes than the Oak Ridge Reservation.
Rare plant population sizes may range from a few individuals to several hundred. Our Oak Ridge population of tall larkspur, one of the species under consideration for federal listing and listed by The Nature Conservancy as globally threatened, is one of the largest populations (if not the largest) known to occur anywhere in the world.
Topographic and geologic features often determine the presence of sensitive plant species. Because these features are discontinuous across the reservation landscape, some plant communities exist as highly patchy systems. These include cedar barrens and river bluffs. Some biotically important wetlands also follow this pattern.
The most widely distributed and perhaps important plant community on the reservation is the cedar barren. Although individually small in area, cedar barrens are fairly common on the reservation--and used to be common across East Tennessee. On the reservation these drought-tolerant plant communities occur only on shallow, flaggy soils, derived from limestone geologic material. Dominant species in the cedar barrens are grasses, such as little bluestem, and a variety of forbs, with some eastern red cedars and stunted oaks. Bare rock is fairly common. Cedar barrens are habitat for several species of rare plants. Prairie species more common in the midwestern United States are also characteristic of these sites.
River bluffs are found bordering the river reservoir where the Clinch River and Poplar Creek have cut through limestone ridges. River bluff communities contain an assemblage of plant species that flourish in these exposed, rocky environments where the buffering effects of the river provide humidity and some amelioration of extremes in temperature. This rugged environment is home for several rare plant species. Three of the four species under consideration for federal listing--false foxglove, bugbane, and white walnut--are found in this type of habitat.
About 500 acres of wetlands are also found throughout the reservation. Types include emergent communities in shallow embayments on Watts Bar and Melton Hill reservoirs, emergent and aquatic communities in ponds, forested wetlands on low ground along major streams, wet meadows and marshes associated with streams and seeps, and small headwater wetlands that have developed along nearly all seasonal and perennial minor streams.
Wetlands on the Oak Ridge Reservation help prevent flooding and flood damage, serve as filters to trap pollutants, and help control erosion . They also provide habitat to numerous species of fish, birds, and other wildlife. Over half of the listed rare plants for the Oak Ridge Reservation occur in wet areas.
Richness of plant species on the reservation that are provided protection by federal law exceeds that of the Great Smoky Mountains National Park on an area basis. (The Great Smoky Mountains National Park has the highest overall diversity of all national parks in the contiguous United States.) Thus, it is one index of the vital role played by our reservation both regionally and nationally in conserving biological diversity. The Oak Ridge Reservation has about four times as many listed species per unit area as the Great Smoky Mountains National Park--an impressive return in species preservation per investment in area.
The Oak Ridge Reservation lies in what is called the Ridge and Valley physiographic province. This area, characterized by the elongated ridges and broad-to-narrow valleys, is between the Cumberland Plateau and the Smoky Mountains. Within this province is a low level of land preservation. In contrast, the Blue Ridge physiographic province (where the Smoky Mountains occur) has a relatively large proportion of protected natural vegetation.
The Oak Ridge Reservation was selected to be a Biosphere Reserve in 1988 and is a unit of the Southern Appalachian Biosphere Reserve . It plays an important role as the only representative of the Ridge and Valley physiographic province in the international United Nations Educational, Scientific, and Cultural Organization (UNESCO) Man and Biosphere Program.
As would be expected given the diversity of plants and habitat types, the reservation supports a wide variety of wildlife species. Checklists include 60 reptilian and amphibian species; 63 fish species; more than 120 species of terrestrial birds; 32 species of waterfowl, wading birds, and shorebirds; and about 40 mammal species. Habitats supporting the greatest number of species are those dominated by hardwood forests and wetlands.
The reservation is a Tennessee Wildlife Management Area. Restoration activities by the Tennessee Wildlife Resources Agency (TWRA) with the Oak Ridge National Environmental Research Park have resulted in a wild turkey population that is now estimated to have 500 to 600 individuals. TWRA now traps them here to stock other sites. Young turkeys (poults) may be seen in the spring, and groups of 20 to 30 adults are commonly spotted in the fall in favorite feeding places.
The osprey is now successfully nesting and breeding on waterways adjacent to the reservation. Because of restoration programs like this across the state, the osprey has recently been downlisted from "threatened" to "in need of management" in Tennessee. Nesting platforms were put up in 1988. Young ospreys, which are counted and banded by TWRA, were found at three of the platforms in 1994.
Smaller streams and tributaries on the reservation, unlike those in the surrounding area, are minimally affected by sedimentation from construction and agriculture. The Tennessee dace, a fish species listed by the state of Tennessee as "in need of management," is found in numerous streams and tributaries on the reservation. Populations here appear to be stable, in contrast to declining or absent populations in streams outside the reservation. The dace is a pollution-intolerant species that currently inhabits only 45 sites in East Tennessee, and its statewide distribution is concentrated in streams in the Cherokee National Forest in Polk County and on the Oak Ridge Reservation.
We are currently exploring what the role of the Oak Ridge Reservation may be in the migration and nesting of neotropical land birds. Because of the presence of a large forested area that provides important interior habitat, we think that the reservation may play a role in providing refuge for migratory birds (as well as our bird residents).
When the land that is now the reservation was selected to be federal land, the criteria were based on isolation for security reasons. These are not the same criteria used to designate most other public lands such as national forests or national parks. The land did not have breathtaking features such as high mountains, waterfalls, or great stone arches. It was typical East Tennessee land experiencing typical East Tennessee land use.
But because it became federal land 50 years ago, it is no longer typical of East Tennessee. As urban and agricultural development have expanded in the region surrounding the reservation, the types of ecosystems native to our area have become less widespread. Thus, their existence on the reservation has become much more important--on a local, regional, and even national level.
In Oak Ridge we have a natural resource that is of national value. As development in the Ridge and Valley continues, the Oak Ridge Reservation will play an increasingly important role in the understanding and protection of regional ecosystems.
The authors would like to acknowledge assistance in obtaining reference material, data, and manuscript review from the many individuals who work with and care about the natural resources on the Oak Ridge Reservation. Special thanks go to Debra Awl, Rebecca Cook, Hal DeSelm, Jim Evans, Cindy Gabrielsen, Robin Graham, Jim Loar, Jason Mitchell, Larry Pounds, Lon Rathmell, Barbara Rosensteel, Mike Ryon, Andrew Schiller, Beth Schilling, John Smith, Robert Washington-Allen, Warren Webb, and Liz Vail.
Patricia Dreyer Parr, an Oak Ridge native, is currently area manager for the Oak Ridge Reservation and a research staff member in ORNL's Environmental Sciences Division (ESD). She was manager of the Oak Ridge National Environmental Research Park from 1984 to 1994. She joined the ESD staff in 1974 after receiving her B.S. degree in biology from Tennessee Wesleyan College. In 1981, she earned an M.S. degree in ecology from the University of Tennessee at Knoxville. Parr has served on the Oak Ridge Reservation Resource Management Organization (reservation land use planning) since 1984. She is the ORNL representative on the Public Affairs Committee of the Southern Appalachian Man and the Biosphere program. She led the development of the Ecological and Physical Sciences Study Center (ORNL program for precollege education) in 1984. She is a member of the Tennessee Wesleyan College Natural Sciences Advisory Board and vice president of the Association of Southeastern Biologists.
Linda K. Mann, a native of Montclair, New Jersey, who has lived in East Tennessee for most of her life, earned a B.S. degree in botany in 1967 and an M.S. degree in ecology in 1976 from the University of Tennessee at Knoxville. Her career at ORNL started in 1968 in the Biology Division, where she served as a laboratory technician. In 1970, she transferred to ORNL's Environmental Sciences Division (ESD), where she worked as a laboratory and field technician and as a research associate in a variety of ecological disciplines, including radiation ecology, effects of air pollutants on vegetation, forest nutrient cycling, soil carbon cycling, and terrestrial ecology in impact assessments. She is the ORNL representative on the Southern Appalachian Man and the Biosphere Natural Resources Management committee. She also serves as secretary-treasurer of the Roane County Soil Conservation Service board of supervisors and as a member of the Ecological Society of America and of the Soil Science Society of America.
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