Light Environments of Tropical Forests

Abstract

Measurements of photosynthetically active radiation (PAR) in tropical forests are reviewed and discussed. Many studies of the light environment in tropical forests have emphasized the importance of sunflecks to the total light energy reaching the forest floor. Much of the spatial variation in total daily PAR in understory environments has been attributed to localized sunfleck activity, but levels of diffuse radiation were also found to vary spatially. Values of percent transmission differs greatly among forests throughout the world, ranging from 0.4--3.8, depending on forest structure and weather conditions. Total daily photosynthetic photon flux density (PPFD) in understory habitats is often below 1.0 mol m-2 d-1, and measurements as low as 0.15 mol m-2 d-1 have been recorded.