The purpose of this research is to examine patterns of growth and survivorship of tropical wet forest tree species, and to determine the factors which most influence these patterns. This project is a continuation of a long-term, multidisciplinary study of a diverse spectrum of canopy and emergent tree species in a Costa Rican Tropical wet forest (the La Selva Biological Station of the Organization for Tropical Studies). This phase of the research will focus on plant population processes, photosynthetic and growth responses of saplings and adults to environmental conditions, and forest-level evaluation of the light environment. Electronic light sensors and new techniques for computerized analysis of the forest canopy will be used to measure the distribution and variation in light availability to the trees during regeneration. Data will also be gathered on the physiological characteristics (photosynthetic capacity) of saplings and adults with known histories of growth and light environment. Such integrated information is critical for understanding and managing tropical forests, and can be obtained only by combining expertise from different fields.