Baldcypress Restoration in a Saltwater Damaged Area of South Carolina

Baldcypress (Taxodium disf ichum (L.) Rich. ) seed was collected in 1992 from nine different estuarine areas in the southeastern United States (Winyah Bay, SC, Ogeechee and Altmaha Rivers in GA, Loftin Creek, FL, Ochlockonee River FL, Mobile Bay, AL, West Pearl River, LA, Bayou LaBranche, LA, and Lake Chicot, LA) and planted in Clemson University’s Hobcaw nursery in the spring of 1993. Germination ranged from a low of 16 percent for seed from FL to 58 percent for seed from NC. Seedlings were grown in the nursery for two growing seasons, lifted, and planted in an area killed by saltwater introduced by Hurricane Hugo’s (1989) storm surge. Half of the seedlings were protected with tree shelters. Seedlings averaged 122 cm tall upon planting. Survival after 6 years was 99 percent. Height growth of seedlings in tree shelters was significantly higher than those not in tree shelters for each year except during year 3. Among the seed sources, seedlings from the Loftin Creek, FL source have shown greatest growth, with and without protection, for all growing seasons except the first year. After 6 years, average height of tree-shelter protected seedlings was 393 cm while the average height of non-protected seedlings was 281 cm. Tree-shelters increased early growth of seedlings, but once they emerged from the tree-shelter, growth differences between shelter and no-shelter treatments decreased and seems to be more related to the degree of deer herbivory experienced by unprotected seedlings. INTRODUCTION Low-lying coastal forested wetlands are particularly vulnerable to saltwater intrusion. Subsidence and sea level rise along the Northern Gulf of Mexico coast are causing increased flooding and saltwater intrusion into freshwater areas (Guntenspergen and others 1998). As a result, baldcypress (Taxodium dist ichum (L.) Rich. ) and water tupelo (Nyssa aquatica L.) forests are being killed (Allen 1992, Krauss and others 2000, Pezeshki and others 1990). In addition, saltwater flooding caused by storm surges can significantly alter forest communities (Conner 1993, Gresham 1993, Williams 1993), and it may take years before the forest recovers (Conner 1995). Hurricanes are recognized as a normal part of the climatic regime, and natural ecosystems have developed morphologically and ecologically to aperiodic disturbances (Conner and others 1989, Pimm and others 1994). Hurricane wind damage is related to storm intensity, duration, forest structure, and soil conditions (Gresham and others 1991, Loope and others 1994). Forests generally recover quickly from wind damage. However, areas impacted by saltwater intrusion may require artificial regeneration in order to ensure adequate stocking. For example, when Hurricane Hugo came ashore north of Charleston, South Carolina on September 21, 1989, its storm surge was estimated to be as high as 3 m at Georgetown (Williams 1993). High winds and saltwater intrusion damaged an estimated 1.8 million ha (about $1 billion worth of timber) of South Carolina’s forests (Hook and others 1991, Marsinko and others 1993). Previous studies have shown some promising results indicating that baldcypress may tolerate some degree of salinity (O-8 ppt). Studies in Louisiana have shown that substantial intraspecific variation in salt tolerance exists within baldcypress populations (Allen 1994, Allen and others 1994, Krauss and others 1998, Pezeshki and others 1995). These studies were conducted under greenhouse conditions. The only field study that could be found was that of Krauss and others (2000), who planted baldcypress seedlings grown from seed collected in Louisiana, Mississippi, and Alabama. Survival and growth of baldcypress seedlings varied significantly among different salinity, hydrologic, and vegetative combinations in areas impacted by saltwater intrusion, and certain genotypes of baldcypress maintained greater height growth when planted in degraded wetlandsThe major objective of this project was to determine if there are baldcypress populations in the southeastern United States that can survive and grow in saltwater damaged areas. A secondary objective was to determine whether or not using treeshelters would increase survival and height growth of planted baldcypress seedlings. MATERIALS AND METHODS Hobcaw Forest is located 7 km southeast of Georgetown, SC (figure 1). A portion of the forest on the western edge of the property was damaged by saltwater intrusion when Hurricane Hugo’s storm surge flooded the forest in September 1989. The impacted forest was originally dominated by baldcypress. The soil is a Hobcaw soil (fine-loamy, siliceous, thermic, Typic umraquults), very poorly drained, and moderately permeable with less than 2 percent slopes. Although high concentrations of salinity were found in the site up to 30 months after the hurricane (Williams 1993)‘ there was no detectable salinity at the time of planting. ‘Professor, Baruch Institute of Coastal Ecology and Forest Science, Box 596, Georgetown, SC 29442; Graduate Student, Clemson University, Department of Forest Resources, Clemson, SC 29634, respectively Citation for proceedings: Outcalt, Kenneth W. , ed. 2002. Procaedings of the eleventh biennial southern silvicultural research conference Gen. Tech. Rep. SRS-48. Asheville, NC: U.S. Department of Agriculture, Forest Service, Southern Research Station, 622 p.