Purpose:
In this experiment, we will measure light levels at the Selva Verde Lodge over a 24-hour period.

Background Information:
Light is a very important aspect of the rainforest environment. Within the rainforest, plants exist in a hierarchy--from the tallest tree down to the smallest moss, sharing resources within four basic layers in a tropical rainforest:

• Emergents: The few trees that grow above and beyond the canopy layer make up the emergent layer. They get the full force of drying winds, hot sun, and soaking rain. In order to better retain water, emergent trees have developed small leathery leaves.
• Canopy: The trees of the canopy are approximately 40 - 70 feet (11 - 20 meters) tall. The canopy layer, like the emergent layer, also gets the full force of wind, rain, and sun. This ample supply of sunlight explains why 90% of the rainforests photosynthesis occurs in the canopy. The lower levels, branches, trunks, and roots are where the food accumulates.
• Understory: Less than 1% of the light that the canopy receives, reaches the understory (also known as the subcanopy). Understory trees have thin trunks and their crowns are shaped like closed umbrellas, and they have also developed larger leaves to better absorb light in the dark forest understory.
• Forest Floor: The forest floor is dark, and very little plant life besides ferns and small broad-leafed plants grow here. Branches, rotten leaves and fruit, animal droppings, and other debris, that falls from above is quickly removed by fungi, termites, bacteria, and tiny tree roots.
In areas where trees are not as close together and sunlight reaches the forest floor, shrubs, grasses, and other forest plants grow. Mosses may also grow on the forest floor.

Millions of green leaves use each sunlit hour to produce stores of food through photosynthesis. This occurs at a fantastic rate. Few forests have canopies so dense that no direct sunlight comes through, and the rainforest is no exception. Each of the rainforest’s four layers has openings to allow light to penetrate deeper into the forest. Beams of sunlight falling through the openings in the canopy form 'sunflecks' on the forest floor. If a species cannot grow in the shade, its seedlings will not survive unless such an opening in the forest canopy occurs. Because storms often create openings big enough to allow full sunlight to reach the forest floor, species requiring significant high light levels to grow can survive.