THE COLOR OF LIGHT IN FORESTS AND ITS IMPLICATIONS

Forests exhibit much variation in light environments, and this can aff ect communication among animals, communication between animals and pla nts, photosynthesis, and plant morphogenesis. Light environments are c aused by, and can be predicted from, the geometry of the light paths, the weather conditions, and the time of day. The structure of forests leads to four major light habitats when the sun is not blocked by clou ds: forest shade, woodland shade, small gaps, and large gaps. These ar e characterized by yellow-green, blue-gray, reddish, and ''white'' amb ient light spectra, respectively. When the sun is blocked by clouds, t he spectra of these four habitats converge on that of large gaps and o pen areas, so the single light environment during cloudy weather will be called open/cloudy. An additional light environment (early/late) is associated with low sun angles (near dawn or dusk); it is purplish. E ach light environment is well defined and was found in forests of Trin idad, Panama, Costa Pica, Australia, California, and Florida. Scattere d literature references suggest similar patterns elsewhere in North Am erica, Europe, and Java. Perceived colors of animals, flowers, and fru its depend upon the interaction between ambient light color and the re flectance color of the animal or plant parts. As a result, an animal o r plant may have a different appearance in each environment, i.e., a c olor pattern may be relatively cryptic in some light environments whil e relatively conspicuous in others. This has strong implications for t he joint evolution of visual signals and vision, as well as microhabit at choice. Plant growth and form may also be affected by variation in the color of forest light.