As part of the Land Use Effects on Amphibian Populations (LEAP) study, the researchers will conduct similar experiments in their respective regions over the next five years. In the first year (2004), experimental arrays are being created at four wetlands in each region. Each experimental array is centered on an existing isolated or ephemeral wetland, with the terrestrial habitat adjacent to the wetland divided into four equal-sized quadrants 6 to 10 acres in size. Each quadrant is randomly assigned a different treatment representing a continuum of disturbance: 1) complete clearing with coarse woody debris (CWD) removed, 2) clearing with coarse woody debris retained, 3) partial cutting (e.g., thinning), or 4) uncut forested control. Quadrants will be allowed to undergo succession in subsequent years, yielding the opportunity to follow changes in vegetation structure and amphibian responses over time.
"Several aspects of this study make it unique," said Whit Gibbons, an investigator on the project and a professor of ecology at SREL. "First the experimental nature and replication of treatments and experiments at both local and regional scales provide an unprecedented opportunity to identify major factors affecting the persistence of amphibian populations, such as differences in life history among salamanders, frogs and toads. Second, because recent research is revealing the extent and importance of upland habitat use by amphibians, this study will focus on the responses of terrestrial life stages of pond-breeding amphibians to upland habitat alteration."
The researchers will use a combination of mark-recapture studies, field enclosures, radiotelemetry and other techniques to estimate the demographic parameters (e.g., survival, reproductive success) underlying population dynamics and to observe amphibians during their migrations in and out of the wetlands. The advantage of using these direct methods (as opposed to such indices as relative abundance and species richness) is that the results can be used to model the responses of different species to forest management at larger spatial and temporal scales, something the researchers will undertake in the final phases of the project.
SREL is located on the U.S. Department of Energy's Savannah River Site in Aiken, South Carolina and research there is partially funded by a grant from the DOE Office of Science's Biological and Environmental Research (BER) program and its Environmental Remediation Sciences Division to identify, understand and anticipate the long-term health and environmental consequences of energy production, development, and use. The SRS is a former nuclear production facility and a federally designated National Environmental Research Park located near Aiken, S.C.