Tropical forests provide homes to a multitude of life forms because they contain layers upon layers of habitats. While the boundaries are not always distinct, there are four major regions: the emergents, the canopy, the understory, and the forest floor.

Tropical forest systems are very different from other forests. Temperate forests store about half of the available minerals and nutrients deep in their soils as well as in the plants. In comparison, the fertile soil layer of most tropical forests is shallow. Heat, moisture and billions of organisms in the soil accelerate decomposition of the leaf litter. Then, the nearly constant rainfall quickly washes this humus into the porous ground where its nutrients are immediately reabsorbed and stored by the immense plant system.

Equatorial forests around the world are inexhaustible storehouses of genetic material. In these environments, where heat and humidity encourage rapid growth and change, new adaptations flourish. These once extensive forests contain 90% of the primate species, 60% of known plants, and 80% of identified insects. All together the remaining tropical forests contain at least half of the world's biodiversity (estimated at 3.5-30 million species of plants and animals) though they cover less than 7% of the land's surface.