Models were developed to separate the radiation-transfer processes of plant canopies from those of the underlying soil surface. The effect of the canopy was then examined by applying the model to springtime measurements of the fluxes of short- and longwave radiation entering and leaving a pine plantation. The model showed that 10 percent of the shortwave radiation that was absorbed within the canopy and 20 percent of that leaving the upper canopy boundary originated as reflection from the forest floor. Longwave radiation emitted upward by the canopy during the daylight period exceeded that emitted downward by about 6 percent. The model confirmed the importance of the longwave component to net radiation of the canopy.