Daily solar radiation measurements were taken below the canopy of a semideciduous forest and at an open site. The mean values obtained during the period of measurements (June, 2000 to January, 2001), were 1.1 and 19.3 MJ/m²/d, respectively. The transmission of solar radiation to the forest understory was influenced by the season of the year and varied from 3.3% in the summer to 8.2% in the winter. Regression equations were developed taking into account the differences among the seasons to estimate the solar radiation inside the forest as a function of the open site values.
Solar radiation; forest; agro-meteorology; transmission; microclimate
