The species composition and structure of wetland forests is closely tied to the environmental conditions occurring at critical times in the species' life histories. Since the 1980s, we have been studying the demography of wetland forest species, including seed production, dispersal and germination, and seedling growth and survival under natural and hydrologically altered conditions in floodplain forests along the Savannah River and its tributaries. These bottomland hardwood forests and bald cypress-water tupelo swamps are abundant along the floodplains of major rivers throughout the southeastern US. Our approach is to use a combination of field and experimental studies to evaluate effects of natural and man-altered environmental conditions on population processes and long-term maintenance of these wetland forests. In a recent collaboration with the U.S. Army Corps of Engineers and The Nature Conservancy, we are studying the forest structure and species' recruitment along the Savannah River floodplain downstream of the Thurmond Reservoir.
Relevant publications: Battaglia, Fore and Sharitz 2000, Jones and Sharitz 1998, Megonigal et al. 1997, Jones et al. 1994
We are also examining the effects of natural disturbances such as floods and hurricane winds. The damage by Hurricane Hugo in 1989 to one of our study sites, the Congaree National Park, has provided a rare opportunity to examine immediate and long-term forest recovery in one of the few remaining old-growth bottomland hardwood forests in the Southeast. In our long-term studies, we are examining tree mortality patterns, regrowth, and the effects of environmental heterogeneity on woody seedling recruitment. This research has been partly supported by the U.S. National Park Service.
Relevant publications: Battaglia and Sharitz 2006; Allen, Sharitz and Goebel 2005, 2007; Battaglia, Sharitz and Minchin 1999
Numerous isolated depression wetlands (Carolina bays) occur throughout the southeastern Coastal Plain, however the great majority of these have been drained and destroyed in the last century. Nevertheless, those that remain are critical habitat for numerous animal and plant species. Our studies of the patterns of cyclic vegetation change in Carolina bays and the role of fire or other drought-related disturbances in maintaining species composition and diversity have shown that the seed banks in these wetlands are highly diverse and persistent. In collaboration with the U.S. Forest Service, we are examining approaches to restoring damaged Carolina bay wetlands, focusing on the role of the seed bank, on success of planting native wetland species, and on metrics for evaluating restoration success. This research has been funded by the U.S. Department of Energy and the U.S. Forest Service.
Relevant publications: De Steven and Sharitz 2007, Sharitz 2003, De Steven et al. 2006, Sharitz, Barton and De Steven 2006, Mulhouse et al. 2005
|Before removal of non-wetland vegetation||Year 1 after vegetation removal and hydrologic restoration||Year 5 after wetland tree planting|
In the southeastern U.S., the U.S. Department of Defense has extensive land holdings in the Fall Line region, along the interface between the Coastal Plain and Piedmont provinces. Throughout this region, there are extensive areas of sandhills, which support a unique flora and fauna, including a suite of threatened, endangered and sensitive (TES) plant and animal species. Forests on military installations along the Fall Line are managed to promote open pine woodlands as habitat for the federally endangered red-cockaded woodpecker (RCW). It is not known whether management directed primarily toward RCW populations (single species habitat management) is beneficial, or possibly harmful, for other sandhills TES species. A more holistic and efficient approach is needed to integrate the effects of land management, military training demands, and ecosystem sensitivities into management of sandhills communities and associated TES species that occur in these habitats.
We have been studying the effects of forest management practices and military training activities on ten TES plants of the Fall Line sandhills. We are combining studies of the population ecology of these species with habitat modeling, identification of potential additional habitats within a GIS framework, and experimental reintroductions to test effects of contrasting forest management and disturbance conditions on TES species survival and growth. This research is being conducted at Ft. Benning and Ft. Gordon, as well as on the Savannah River Site, and has been funded by SERDP (Strategic Environmental Research and Development Program).
Relevant publications: Young, Chang and Sharitz 2007, Dilustro et al. 2002, LaJeunesse et al. 2006