History

• As environments tended to fluctuate throughout the rest of the world over millions of years, forests near the equator subsisted and flourished because of the consistent rainfall. Huge regions of densely packed trees led to the creation of unique ecosystems that cannot be replicated anywhere else on the planet. Changes in sea level also created pockets of rainforests in southeast Asia with their own individual wildlife and ecosystems.
  
  

Rainforest Layers

• Rainforests are usually divided into four or five layers, though some forests vary. The overstory is the crowns of emergent trees that may grow over 50 meters tall. Below that is the canopy, which is a ceiling of densely packed trees spaced a few feet apart and growing at around 30 to 40 meters. The understory is a layer of widely spaced smaller trees around 20 to 30 meters tall. The shrub layer, so often conflated together with the understory, contains shrubs and juvenile trees running all the way to the forest floor, which is its own layer at the bottom of the rainforest.
  
  

Tree Diversity

• A 25-acre area in Borneo of southeast Asia may contain over 700 species of trees, equal to the diversity in all of North America. The Dipterocarpaceae family of trees contains over 500 species that typically grow between 40 to 70 meters tall. The name derives from its two-winged fruit. The Tualang species of the Fabaceae family is the third largest species of tree in the world. The highest recorded measurement of the Tualang is 88 meters. Trees in the lower canopy and below have elongated crowns to pick up light but are much more shade-tolerant, so they have adapted energy-saving strategies.
  
  

Animal Dependency

• Around 70 to 90 percent of the wildlife in the rainforest actually exists in the trees. Most adaptations are tailored to this lifestyle, including the prehensile tails of monkeys and diets heavy on fruit---Silver Gibbons, for instance, never descend to the ground in their lifetimes. Organisms like tree frogs might have adhesives on their feet that make them suitable for climbing, but most mammals, reptiles, amphibians, insects and invertebrates tend to be arborial to some degree. Even species of kangaroos, worms, crabs, porcupines and anteaters have adapted to trees. In turn, mammals, insects and birds become incredibly important pollinators and seed distributors that carry on the life cycle of the plants and trees.
  
  

Water and Energy

• Because an average of 50 to 260 inches of rain falls each year, these regions are perfect for the growth of trees and lush vegetation. However, rainforest soil is actually nutrient shallow and has little soluble minerals, but the dense number of insects, batcteria and fungi quickly decomposes dead plant and animal matter, which turns it into nutrients that can be used by trees. This short nutrient cycle means a quick turn around. Energy is also gathered by photosynthetic processes from trees in the canopy and eventually reaches all other organisms in the ecosystem.