Tropical Rainforest Canopy Layers:
Most of life in the tropical rain forest exists vertically in trees, above the shaded forest floor - in the vegetative layers. Each rainforest canopy layer harbors its own unique plant and animal species interacting with the ecosystem around them. The primary tropical rainforest is divided into at least five layers: the overstory , the true canopy, the understory, the shrub layer, and the forest floor.
The Tropical Rainforest Overstory Level:
The rain forest overstory is characterized by overtopping trees that rise above the rest of the canopy, where tops of some species exceed 210 feet (65 m). These trees actually exist in a totally different climate when compared to other canopy levels - they thrive on a drier environment and higher winds. Birds of prey depend on this overstory.
The True Tropical Rainforest Canopy:
The rainforest canopy is a massively unbroken expanse of trees. Even so-called "closed" canopy trees rarely interlock or even touch. Instead they are separated from one another by a few feet. Why the branches of these trees do not touch is not known but thought to serve as protection from infestations from tree-eating caterpillars and tree diseases. Because of this, canopy dwellers have developed the ability to negotiate these gaps by climbing, leaping, gliding, or flying.
The Tropical Rainforest Understory:
The rain forest understory is shielded by the canopy from harsh, intense sunlight, drying winds and heavy rainfall. Thus the forest interior is a much less volatile environment than the upper parts of the canopy ceiling. The understory retains much of the forest's moisture. Because of low light, plants have to grow larger leaves to gather in existing sunlight. Much of a rainforest's flora and fauna live in the understory and there is a large concentration of insects here.
The Tropical Rainforest Shrub Level:
The rain forest shrub level is very closely associated with the understory level. This level is very important botanically. Curare comes from a tropical shruby vine, and is used as an anesthetic and to relax muscles during surgery. A person with lymphocytic leukemia has a 99% chance that the disease will go into remission because of the rosy periwinkle. More than 1,400 varieties of tropical plants, many shrubs, are thought to be potential cures for cancer.
The Lowly Rainforest Floor:
The rain forest floor of primary tropical rainforest is not a thick, tangled mass of plants. The floor is relatively clear of vegetation due to the deep darkness created by perhaps 100 feet (30 m) of canopy vegetation above. It is very dark on the rainforest floor. When in a primary tropical rainforest a flashlight may be more useful than a machete. This subdued light limits ground growth but the heat and humidity quickly composts leaf litter.