A COMPARISON OF WETLAND TREE GROWTH-RESPONSE TO HYDROLOGIC REGIME IN LOUISIANA AND SOUTH-CAROLINA

Numerous investigations have examined the growth of wetland tree speci es under a variety of hydrologic conditions, Most studies have compare d flooded versus non-flooded conditions in greenhouses or in one to a few field sites near each other or within the same region. Comparisons of wetland tree growth among widely separated areas of the country ar e rare, This study compared the diameter growth of Nyssa sylvatica var . biflora, Nyssa aquatica, and Taxodium distichum trees from Louisiana (Gulf Coastal Plain) and South Carolina (Atlantic Coastal Plain). In both regions, individual trees were distributed along a gradient of hy drologic regimes from infrequent to permanent flooding, Nyssa sylvatic a var. biflora was restricted to periodically flooded sites in both re gions. Within these sites, this species showed little response to diff erences in mean water depth. In contrast, significant differences amon g hydrologic regimes were detected for N. aquatica in both regions. In Louisiana, patterns of growth response did not correlate with the gra dient of hydrologic regimes, but in South Carolina maximum growth was inversely related to mean water levels during the growing season. Maxi mum growth of T. distichum trees was observed at sites with shallow, p ermanent flooding in both regions.