Snowy backgrounds enhance the absorption of visible light in forest canopies

The fraction of radiation absorbed in the canopy depends on the amount\nand angular distribution of the solar irradiance reaching the top of the canopy\nas well as the fraction of this irradiance that is transmitted through the canopy\ngaps and reflected back to the vegetation by the background. This contribution\nshows that the presence of snow on forest floors enhances the fraction\nof absorbed Photosynthetically Active Radiation (PAR). A global analysis\nof satellite-derived products reveals that this enhancement affects evergreen\nand deciduous forests of the boreal zone. This snow-related effect may\nusefully contribute to the photosynthesis process in evergreen forests especially\nduring spring time when radiation conditions are marginal but other\nphysiological constraints (such as temperature) permit the necessary biochemical\nfunctions to take place.