Published on 04/07/14

UGA awarded $1.4 million to study critical earth zone in Sumter National Forest

By Sandi Martin

Looking back, it's easy to see where farmers in the 1800s went wrong. Attempting to grow profits from a lush environment, landowners cleared entire forests in the South to make room for agricultural farmland. But primitive agricultural techniques scarred the landscape, and when the profits dried up, they abandoned the barren land. Now University of Georgia researchers want to understand the ongoing repercussions of a bygone era.

Five UGA researchers in soil science, ecology, natural resource management and anthropology join U.S. Forest Service scientists to calculate how past land use has influenced the present environment-and how it will impact the future.

They were awarded $1.4 million from an overall $5 million National Science Foundation grant led by Duke University to set up one of 10 national observatories focused on the thin outer layer of the planet most important for human life. Geologists have dubbed it Earth's "critical zone," which includes everything from deep bedrock to the tops of trees.

Other participants in the five-year study include the Georgia Institute of Technology, the University of Kansas, Mississippi State University and Roanoke College.

UGA's researchers will help establish the new Calhoun Critical Zone Observatory located in the Calhoun Experimental Forest, a unit of Sumter National Forest in South Carolina.

Sumter National Forest is a 200,000-acre forest created in the 1930s on abandoned farmland and heavily logged forestland in the southern Piedmont. Suffering from soil erosion and overall land degradation, the U.S. Forest Service spent decades developing management practices to restore the land by setting up experimental watersheds, planting trees and launching a number of long-term studies to monitor progress on what was, at the time, a representation of the "poorest Piedmont conditions."

Each UGA researcher brings unique strengths to this interdisciplinary critical zone observatory, or CZO:

  • Aaron Thompson, an assistant professor in the College of Agricultural and Environmental Sciences department of crop and soil sciences, will focus on examining the chemistry of soils at the molecular level. He will study how human activities influence the way soil minerals and carbon interact to form either stabile soil organic matter or generate carbon dioxide gases.
  • Alexander Cherkinsky, a senior research scientist in the Center for Applied Isotope Study, will analyze the soil's carbon turnover rates as a result of anthropogenic and climate changes by studying its isotopic composition, including radiocarbon analyses.
  • Daniel Markewitz, a professor with the Warnell School of Forestry and Natural Resources, will study the forest's soils to determine spatial patterns from historical erosion and link soil attributes with forest stand conditions.
  • Don Nelson, an assistant professor in the Franklin College of Arts and Science department of anthropology, will study historic and current human interactions with the land and will develop, in partnership with land managers and forest users, ways to effectively communicate critical zone science.
  • Paul Schroeder, a professor in the Franklin College department of geology, will study long-term climate changes as recorded in the rocks and soils of the area to determine how fast shifts in the landscape took place.

    In addition to the UGA researchers, Mac Callaham, a research ecologist with the U.S. Forest Service's Southern Research Station on UGA's south campus and an adjunct professor in the Odum School of Ecology, will study soil organisms, such as ants and earthworms. He is interested in determining how the different organisms affect the soil and how water moves through the system.

    "This project is a very exciting opportunity for the forest service to join forces with our UGA colleagues and to leverage our investment in long-term studies for the development of cutting edge research like the CZO project," Callaham said.

    The researchers have a wealth of archived forest service data from the 1940s through the 1960s to compare modern results to, Markewitz said. In fact, some of the original monitoring equipment from the 1940s is still in place in the forest.

    “Recent advances in earth system science allow us to collect much more sophisticated data than was available to the forest service in the 1940s,” Thompson said. “But, the value of the historical data cannot be overstated. It is the combination of new advanced techniques and robust historical data that will allow us to design more accurate models of how land use influences ecosystem function and ecosystem-human relationships."

    Cherkinsky, who works in the state-of-the-art isotope laboratory, noted that "isotope data from soil organic matter provides a powerful constraint for determining carbon changes in response to human and climate impacts. Interestingly, the period of study at the Calhoun Critical Zone Observatory overlaps with aboveground nuclear testing in the 1960s that dramatically increased the radiocarbon concentration in the atmosphere. This isotopic spike or label allows us to trace carbon through the soil on the time scale of years and decades."

    The NSF and the European Commission fund critical zone observatories for interdisciplinary research of the planet's surface to better understand how human interactions and land use affects the vital ecological services this critical zone provides. These services include air, water, food, energy, mineral resources, natural habitats and other environmental conditions that support our basic needs.

    There are 10 critical zone observatories in the U.S. and more developing around the world.

    "It is a wonderful opportunity for UGA to have a CZO located in the Southeast and so close to campus," Thompson said. "Across the world, the CZOs are becoming regional centers for cutting-edge earth-system science. There are substantial long-term benefits for UGA students, researchers and the public."

    Schroeder hopes to change the perception that the environment isn't affected by what humans do or by natural changes. Many people "think the stream they played in as a kid will always be there and stay the same, but that's simply not true," Schroeder said. "With or without the influence of humans, the landscape does not sit still forever."

    Nelson said this project is a great opportunity to work with the public as well as land and forest managers to learn about how past and present land use leaves an indelible imprint on the environment.

    "The results of this type of research can help guide long-term management decisions that account for the ways in which people value and understand their forest," he said.

    For more information on the critical zone observatories, see

Sandi Martin is the public relations coordinator with the University of Georgia Warnell School of Forestry and Natural Resources.