A rainforest is a dense forest typically lush with broad-leaved evergreen trees. Rainforests are generally found in tropical areas with a high level of annual rainfall. The hot and humid weather precipitates the growth of many herbal medicines and trees. Rainforests are known to hold a diversity of fauna as well — over half of the world's species are approximated to dwell in rainforests.
Rainforests tend to grow in four layers of vegetation: the forest floor, understory, canopy and emergent layers. A large and unique diversity of animals and plants inhabit each layer. Moss, ferns and large animals occupy the forest floor, and mostly insects and large leaved plants dwell in the understory. The canopy's 100-foot-tall trees block sunlight and trap humidity in the lower layers, and many different animal species dwell there. Giant 200-foot-tall trees and birds mainly populate the emergent layer.
Rainforests are essential for the survival of the global ecosystem. Scientists estimate that 20 percent of the world's natural medicines are found in rainforests, while rainforest trees provide a majority of the oxygen found on earth. Rainforests once blanketed 14 percent of the earth, but because of commercial development, they only cover six percent now. (Photo: Wikimedia Commons)