SOIL-WATER TABLE, REDUCING CONDITIONS, AND HYDROLOGIC REGIME IN A FLORIDA FLATWOOD LANDSCAPE

Cypress/pine flatwoods are a dominant landscape of the lower coastal p lain of the southeastern U.S. It is clear that the cypress swamps are wetlands, but it is not clear that the intervening pine ecosystems wou ld meet hydrologic criteria of a wetland definition. Hydrology, as def ined by the periodicity of the fluctuating water table and its effect on the redox environment of the soil, will determine whether these are as are wetlands. The objectives of this study were (i) to evaluate the relationship between water table depth and redox environment for a ty pical pine flatwoods/cypress swamp landscape and (ii) to use this rela tionship to contrast the amount of the study area that would fit a spe cific wetland hydrology definition where that definition was based on either water table depth or the development of a reduced environment i n the soil surface. One hundred twenty water table wells were installe d in a grid system over a 42-ha study site, and water table depth was measured approximately every 2 weeks. At selected locations, redox ele ctrodes were installed at a 5-cm depth in pine planations growing on S podosols and landscape positions that were in transition between these Spodosols and the adjoining cypress swamps. A Geographical Informatio n System was used to calculate the area of the study site meeting diff erent criteria related to water table depth or soil reduction. Results suggest that 20 to 56% of the study area would meet a hydrologic defi nitions of wetland, depending on the hydrologic criteria used. In thes e landscapes, water tables between 15 and 20 cm below the soil surface promoted reduced conditions in the surface. This criteria could be us ed for evaluating redox conditions relative to hydrophytic vegetation and soil redoximorphic features.