The influence of floating vascular plants on the diurnal fluctuations of temperature near the water surface in early spring

On clear days the temperature in a mat of floating Lemnaceae was 40 to 11° above that of the surface of the open water. The temperature of the environment 2 cm above or below the plant surface closely followed the surface temperature's quick response to changes in net radiation. The plant surface reflects more energy and transmits less than the open water, therefore there is less fluctuation in temperature in the water o cm and more below the floating plant surface. This results in a diurnal thermal stratification. At the surface of the open water changes in temperature tended to be smaller and slower, related to the air temperature; and, with wind disturbance, the water profile maintained relatively homogeneous temperatures.