Rain forest tree species grow differently depending on the amount of light they receive. Six species were studied to see how they respond to varying light levels. Saplings grew taller and had more leaves in brighter light. Some saplings actually lost biomass in bright conditions due to leaf shedding and stem breakage. Plants in the shade had thinner leaves but similar leaf area compared to those in the sun. The way plants allocate biomass to leaves changes with light levels, affecting their growth rates. Species vary in how changes in leaf thickness impact their growth. Overall, light plays a crucial role in determining how rain forest tree species grow.