Temporal patterns in evapotranspiration from lysimeters with three common wetland plant species in the eastern United States

Using replicated, whole plant lysimeters, we quantified and compared the da ily evapotranspiration (ET) rates and temporal ET patterns of three plant s pecies common in wetlands of the northeastern US: weeping willow (Salix bab ylonica L.), red maple (Acer rubrum L.), and cattail (Typha latifolia L.). For comparison and control, we simultaneously measured evaporation from bar e soil and open water. S. babylonica and T. latifolia had significantly hig her ET rates per unit leaf area than A. rubrum (P = 0.0002), and all plant species' ET rates were greater than evaporation rates from bare soil and op en water. Temporal patterns in ET over the study period were strongly corre lated with relative humidity for all treatments except T. latifolia. Within the shorter time frame of a day, the plants exhibited a peak in ET from 11 a.m. to 2 p.m. A comparison with studies in the literature indicates that the examined wetland species exhibited higher rates of ET and a more contin uous daily flux than do many terrestrial species. (C) 2001 Elsevier Science B.V All rights reserved.