ORNL: Living laboratory, biodiversity hub: The Oak Ridge National Environmental Research Park

Anyone familiar with the Department of Energy’s Oak Ridge National Laboratory knows it’s a hub for world-class science. The nearly 33,000-acre space surrounding the lab is less known, but also unique. The Oak Ridge Reservation, or ORR, is a key hotspot for biodiversity in the Southeast and is home to more than 1,500 species of plants and animals.

At the intersection of eastern Tennessee’s Anderson and Roane counties is an important subset of the reservation — the Oak Ridge National Environmental Research Park, or NERP – a 20,000-acre ORNL research facility that has been internationally recognized by UNESCO as an official biosphere reserve unit.

“The National Environmental Research Park is a living laboratory and a major resource for conducting ecological studies,” said Evin Carter, an ORNL wildlife ecologist and director of the Southern Appalachian Man and the Biosphere Program, or SAMAB. The NERP has been a core part of SAMAB, which focuses on sustainable economic development and conserving biodiversity in Southern Appalachia, since 1989.

With ORNL researchers and scientists from government agencies and academia using the NERP for diverse experiments each year, the park lives up to its status as a living laboratory.

It also lives up to its reputation as a biodiversity hotspot. As one of seven DOE-established environmental research parks reflecting North America’s major ecoregions, it represents the Eastern Deciduous Forest. The NERP comprises parts of this ecoregion that have been identified repeatedly as priorities for global biodiversity conservation, Carter said.

Today, this designation means more than ever as climate change alters ecosystems and biodiversity declines worldwide. According to a landmark international report, around one million plant and animal species are currently threatened with extinction.

On the ORR and the NERP, a number of research projects and conservation initiatives are focused on addressing these challenging environmental problems to preserve species for generations to come.

Providing a haven for wildlife

A key way the ORR and NERP foster biodiversity is by maintaining connectivity between habitats. Established by the federal government during the Manhattan Project, the ORR has escaped some of the intense development that has impacted nearby areas.

Between intertwining highways and stretches of suburbia, the space contains large tracts of forests, native grasslands, wetlands, caves, cliffs and cedar barrens all within one contiguous area. As human activity fragments ecosystems, this is increasingly rare — and extremely important.

“That habitat diversity creates a situation where you’ve got animal species here that are not found in surrounding areas,” said ORNL Natural Resources Manager Neil Giffen. “It’s like an oasis for them.”

Among those species are uncommon birds, such as the purple gallinule, and rare amphibians, including the hellbender and four-toed salamander. Also present are charismatic mammals such as river otter, fox, coyote and even bobcat. ORNL’s Natural Resources Management Team monitors and manages this wildlife as part of their mission as primary stewards for DOE reservation management under the DOE ORNL Site Office.

Carter, for example, is leading a large-scale project tracking how different forms of wildlife move within and across the reservation. The project’s findings could better inform how to plan development for the federal facilities within the ORR, including ORNL and the Y-12 National Security Complex, while minimizing impacts on wildlife.

ORNL’s Kitty McCracken, ecosystem management coordinator for the ORR, spends much of her time managing invasive plants. But she also leads a program monitoring bats.

The ORR is home to two endangered bat species — the gray bat and Indiana bat — and one threatened species, the Northern long-eared bat. McCracken uses acoustic monitoring technology to listen for each species’ distinct vocal signatures and may capture them for species verification using ultra-fine nets.

Since the program started in 2012, McCracken and colleagues have gained information about each species’ complex needs. In the summer, some species live only in certain types of trees, for instance, and some use different caves seasonally for various life stages, such as rearing pups or hibernating.

“Preserving a whole forest ecosystem is vital for taking care of the needs of these bats and other plants and animals,” McCracken said. Carter and McCracken work together to understand which of the ORR’s more than 40 caves are important to bats. Recent surveys of these caves have also revealed invertebrates and vertebrates not previously known to occur on the ORR, including two invertebrates that may be previously undiscovered species.

“There is undoubtedly more to be found,” Carter said.

Preserving plants for people

In addition to offering a sanctuary for animals, the ORR and NERP boast more than 1,100 plant species. The collection rivals that of the nearby Great Smoky Mountains National Park.

Some of these plants hold rich cultural importance. This fact prompted representatives of the NERP to participate in the Culturally Significant Plant Species Initiative, or CSPSI. This initiative is a collaboration between the Eastern Band of Cherokee Indians and SAMAB focused on the sustainability, conservation and management of plants with cultural significance to the Cherokee through education and increased access.

“As Cherokee, we’re not third-, fourth-, fifth-generation farmers,” said Tommy Cabe, the forester for Eastern Band’s natural resources program and CSPSI organizer. “We’ve been a part of this landscape for millennia, and we have the longest-running relationship with the diversity of this ecosystem.”

That relationship involves using native trees, shrubs, grasses and mosses in food, medicine, art and in artisan goods, Cabe said. White oaks, ramps and river cane, for example, play important roles in Cherokee basket making, cooking and as material resources, respectively. But as factors such as habitat loss and overharvesting by outside groups put these plants at risk, organizations involved in the NERP saw a need to collaborate to protect them.

Jamie Herold, a plant ecologist at ORNL, has been involved with CSPSI since it launched in 2017. The program started as an effort to create a seed bank for plants of interest to the Cherokee.

“From that it grew at least tenfold,” Herold said. “We started having more meetings and ideas about how we can incorporate the science and the conservation efforts and education.”

After a strong start that included the publication of a charter and the formation of subcommittees, the COVID-19 pandemic slowed CSPSI’s progress. As uncertainty surrounding the pandemic lingers, the initiative’s constituents are making decisions about CSPSI’s next steps.

Outside of CSPSI, native plants are still top priority for the NERP, where Herold leads research and management of the park’s vegetation. Landscaping projects at ORNL harness native plants and in 2019, an area in the western part of ORNL’s campus featuring 52 native tree species became a certified arboretum. The ORR Plant and Animal Reference Collection additionally contains more than 3,000 plant specimens collected over 70 years – plus insect, mammal and bird specimens.

Studying invisible ecosystem forces

Over the years, many scientists in ORNL’s Environmental Sciences Division have used the NERP for large-scale environmental research on topics including clean air and water, impacts of energy sources and even tree growth under increased carbon dioxide conditions.

Much of this research was conducted in Walker Branch Watershed, a seminal research catchment that advanced understanding of the cycling of elements on land and in water beginning in the 1960s.

In stream ecosystems, nutrient cycles become elongated spirals as water carries elements downstream. The first study that developed and tested the methods for measuring the spiraling of nutrients in stream ecosystems took place in this watershed.

“These techniques are now used by scientists across the world,” said ORNL aquatic ecologist Natalie Griffiths. “In the past decade, we have applied these methods to examine not only how nitrogen and phosphorus individually spiral in stream ecosystems, but also how these nutrients interact to affect their spiraling dynamics.”

ORNL’s Elizabeth Herndon, an environmental geochemist, focuses on terrestrial cycles within the Walker Branch Watershed. “One of the research questions I’m working on is trying to understand how organic matter is stored in soil,” Herndon said. Organic matter contains carbon, so understanding the chemical and microbial processes by which organic matter is preserved or breaks down in soil and releases carbon into the atmosphere is vital information for climate change research, she added.

Herndon and a team of postdocs and students are investigating what happens to leaf litter decomposition under the warming conditions associated with climate change. For almost a year, they’ve warmed leaf litter in mesh bags using small heaters and tracked the leaves’ decomposition. They’ve also tested adding manganese, a micronutrient thought to contribute to the breakdown process.

Herndon said she benefits from her study plot’s short distance from ORNL and from the nearby Oak Ridge National Ecological Observatory Network field site, which provides her with supplemental data.

ORNL’s Scott Brooks uses the NERP to study a different global issue: mercury pollution. Brooks studies how microbial activity and hydrology influence the chemistry and cycling of mercury in the environment. A neurotoxin, mercury has negative health effects in people and can cause reproductive issues in animals.

For more than 10 years, Brooks has run experiments on decades-old mercury contamination in East Fork Poplar Creek and Bear Creek, which both wind through the ORR. The proximity of the creeks to the lab allows him to collect “samples of opportunity.”

“If we know something is going to change, we can get out and get samples quickly in advance of that event, such as rainfall that might stir up sediment and change the amount of mercury in the water,” Brooks said.

Whether studying microbes, bats or biodiversity, the researchers who use the ORR and the NERP agree: Like the species who call them home, these spaces are worth protecting.

Research within the Oak Ridge Reservation and ORNL National Environmental Research Park is supported by the Oak Ridge Office of Environmental Management and the Biological and Environmental Research Program within the DOE Office of Science.