The rainforest is one of the most amazing and mysterious biomes on earth. The Amazon rainforest, the biggest in the world, has been called the 'lungs of the Earth' because it provides so much of the oxygen that we breathe. But rainforests provide us with much more than just oxygen.
Tropical rainforests are so big and grow so tall that they are divided into four separate parts. Each part is almost like its own ecosystem, because most of the animals and plants that live there depend on each other to survive. Almost all tropical rainforests in the world follow a similar pattern.
The bottom of the rainforest is called the forest floor. This bottom-most layer only receives about 2% of the sunlight! That can be a big problem for plants, which all need sunlight in order to survive. Only plants well adapted to low light can grow here.
The forest floor plays an important role in the cycle of plant life in the rainforest. Here, decaying animals and plants disappear quickly because of the warm, humid conditions. The decomposed matter is then put back into the soil to generate new growth.
A bit higher from the forest floor is the understory layer. Whereas the forest floor is home to large mammals like rhinoceros and gorillas, the understory is home to hundreds of birds, small mammals and reptiles. Still only 5% of sunlight reaches this level, which means most plants here don't grow to be taller than 3m. However, many have adapted to the low light by evolving large leaves to absorb all the sunlight available.
The canopy is the main layer of the rainforest. It contains the majority of the largest trees here, which usually grow to be about 30 to 45 meters high! This is the part of the rainforest that holds the largest biodiversity, which means there is a large variety of animal and plant life. No one knows exactly how many species live here, but it is estimated that there are as many as 20 million arthropod species living in canopies around the world!
The emergent layer is the top layer of the rainforest. Only a small number of trees are found here, but they reach higher than the canopy trees and can grow to be as tall as 70 or 80m! Because they are more isolated up here, trees need to be able to withstand hot temperatures and strong winds.
The different sections of the rainforest work together to create an impressive biome. Sadly, the rainforests of the world are quickly disappearing as we cut trees down for wood and land. We may never find out all the secrets the rainforests of the world are hiding.
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