Soil Redox Intensity Effects on Oxygen Exchange and Growth of Cattail and Sawgrass

The response of cattail (Typha domingensis L.) and sawgrass (Cladium jamaicense L.) to soil redox intensity (Eh) was evaluated to determine if the intensity of soil reduction could influence species distribution patterns of the two plants in Florida Everglades wetlands. Plants were grown in microcosms under controlled Eh levels of 500, 250, 0, and -200 mV. Redox intensity effects on root air space (POR), radial O2 loss (ROL) from plant roots to the rhizosphere, biomass production, and adventitious rooting were evaluated. Except for adventitious rooting, all the other parameters studied were governed by Eh. Whereas shoot and root dry weights decreased between Eh 500 and -200 mV, POR and ROL were increased. The results indicated that cattail has morphological and physiological attributes that may give it a competitive advantage over sawgrass along redox intensity gradients. Results suggest that hydroperiod or flooding regime, through its effect on soil redox conditions, may be an important variable regulating growth and distribution of cattail and sawgrass in the Everglades. There is a need to determine the relative significance of these findings in relation to other factors (e.g., P loading) contributing to the expansion of cattail in Everglades soils.