A LYSIMETER SYSTEM FOR EVAPOTRANSPIRATION ESTIMATION FOR WETLAND VEGETATION

An experimental design which includes three lysimeters and one weather station was installed at the Fort Drum Marsh in the upper St. John's River Basin, Florida, to estimate evapotranspiration (ET) for wetland vegetation such as cattail (Typha domingensis) and sawgrass (Cladium j amaicense). Vegetative parameters as related to ET estimation were mea sured, including stomatal resistance, leaf area index, canopy height, plant density, fresh plant biomass, dry plant biomass, canopy temperat ure, air temperature, and plant spectral reflectance. After installati on, the data from four field trips showed that the lysimeter system pe rformed well. In particular, the normalized difference vegetation inde x (NDVI) derived from spectral reflectance measurements provided a use ful parameter for identifying cattail and sawgrass that could be used to estimate regional wetland ET in the future, using satellite imagery .