Newswise — Under one of the highest natural tree canopies in the world, University of South Carolina geographer Dr. John Kupfer can be found checking the vital signs of the floodplain that is the Congaree National Park. For six years, Kupfer, a specialist in biogeography and landscape ecology in USC’s College of Arts and Sciences, has conducted research in the park, taking students several months each year to check flood levels, rates of sedimentation and the health of plant species along the 27,000-acre tract of old-growth bottomland forest that is situated outside Columbia. More recently Kupfer has turned his attention to studying the effects of climate change at the park, which is the largest old-growth floodplain forest remaining in North America. The project is one of about a dozen around the country being funded by the National Park Service to look at the impact of climate change at the nation’s parks. Working with fellow USC geographers Dr. Greg Carbone and doctoral candidate Kimberly Meitzen, biologist Dr. Dan Tufford and a team of graduate students, Kupfer is creating computer simulation models that project how changes in temperature and precipitation and dam operations for water release will impact river flow, flooding, vegetation and wildlife over the next 50 to 100 years.
“Rivers respond to changes in precipitation and temperature,” Kupfer said. “Those changes alter the level and spread of water into the floodplain, cause environmental change to the habitat of key forest species. It is critical to understand this entire sequence of change.”
In the case of the Congaree, the release of water from the Parr Shoals Dam on the Broad River and Saluda Dam on the Saluda River also impacts the river flow, to a lesser extent. Kupfer said the Congaree National Park is a compelling place to understand floodplains and river-based systems.
“It is the best example of an old-growth floodplain forest that still exists in United States. Understanding the relationship of the river and its flooding to the park’s wildlife and vegetation is important to ensuring the long term health of the park. ” The park’s complex ecosystem is home to a wide variety of plants and animals. Species more sensitive to river flow and the spread of water across the land provide good indicators of how change in climate can impact the flora and fauna of the forest floodplain.
Based on previous research, the USC team identified 12 species representative of the flora and fauna in the floodplain that rely on and are sensitive to a variety of different river flow and flooding conditions. These include a variety of birds, fish, mussels, trees, mammals and amphibians.
Among the most visible is the bald cypress, the iconic tree most associated with the park, characterized by a wide-buttressed trunk and an abundance of woody “knees” that protrude upward from the swampy mud. “The bald cypress makes use of both low and high ranges of flow conditions,” said Meitzen, who is surveying the forest species and conducting the flood inundation mapping and modeling for the park. “Germination and growth require drought conditions, while its continued growth requires seasonal flood. These trees are slow growers, some may be as old as 500 to 1,000 years, and they propagate only when ideal conditions are met.” Meitzen said the bald cypress and the swamp tupelo, another tree common the park, thrive in sloughs (pronounced slews) and depend on high-water conditions for dispersing their fruits and seeds. Both trees are good species for tracking forest responses to climate-driven changes in river flow, she said. The redfin pickerel and orothonotary warbler also are sensitive to flooding. Meitzen says the redfin pickerel fish depends on medium- to high-river flow and flooding so that it can swim into the floodplain and spawn in late winter. The prothonotary warbler depends on low to moderate flood conditions during the late spring and early summer so that it can nest safely in tree cavities a few feet above the water. Remaining species in the study include the wood stork, wood duck, shortnose sturgeon, American shad, robust redhorse, redbreast sunfish, striped bass and blueback herring, Roanoke slabshell and yellow lampmussel. Using aerial LIDAR, a sophisticated instrument that sends laser pulses to capture images of the floodplain, Meitzen has created a precise, two-dimensional map of the floodplain that shows distinct land features and measures their elevation within a foot of accuracy. The map allows her to determine how a specific volume of water flowing down the Congaree River spreads into the floodplain and impacts vegetation and wildlife. To validate her predictions, she and Kupfer hike into the swamp to measure the water levels. The team also is relying on information from previous studies, including their own, on species and data about river flow from the U.S. Geological Survey in the Dept. of Interior. Kupfer said the hard part of the research, the modeling of the water elevation and flow levels of the floodplain is nearly finished.
“The final challenge is creating the future scenarios for changes in precipitation, temperature and dam-water release so that we can accurately simulate flooding or receding water levels at the park. This will allow us to project whether the habitat for that species is likely to expand or become smaller.” The team plans to create a series of educational materials, including a series of short videos and static maps, for the park staff to use to help educate visitors, school groups and others about the old-growth floodplain forest, how it floods, the impact that climate can have on that process and the many varied species that call Congaree home. Kupfer said researchers have long looked to Congaree National Park as a source of information and inspiration about bottomland forest ecosystems. He said his climate research will enable researchers to apply the findings to eight parks with bottomland forest ecosystem elements in the Southeast and the methodology to a variety of floodplain environments.
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