Simulation of evapotranspiration from Florida pine flatwoods

An evapotranspiration model (ETM), including three submodels of transpiration, rainfall interception and substrate (soil or water surface) evaporation, was developed for the simulation of evapotranspiration (ET) from cypress (Taxodium ascendens) wetlands and slash pine (Pinus elliottii) uplands in Florida flatwoods. Transpiration was scaled up from the leaf level to the ecosystem level by incorporating information on ecosystem structure (e.g. species composition, tree density, leaf area index), turbulence transport in and from the canopy, stomatal conductance and meteorological information. The rainfall interception submodel was physically derived from the interception processes. The substrate evaporation submodels for the open surfaces in the wetlands and forest floors in the pine uplands were developed based on field observations. The model was tested with an independent data set acquired by eddy correlation. Daily and seasonal patterns of ET, bulk aerodynamic conductance, bulk stomatal conductance and canopy dryness index of these two ecosystems were simulated and the sensitivity of ET to environmental conditions was evaluated.