Emergent trees are spaced
wide apart, and are 100 to 240 feet tall with umbrella-shaped canopies that grow above the forest. Because emergent trees
are exposed to drying winds, they tend to have small, pointed leaves. These giant trees have straight, smooth trunks with
few branches. Their root system is very shallow, and to support their size they grow buttresses that can spread out to a distance
of 30 feet.
The upper canopy of 60
to 130 foot trees allows light to be easily available at the top of this layer, but greatly reduced any light below it. Most
of the rainforest's animals live in the upper canopy. There is so much food available at this level that some animals never
go down to the forest floor. The leaves have "drip spouts" that allows rain to run off. This keeps them dry and prevents mold
and mildew from forming in the humid environment.
The understory, or lower
canopy, consists of 60 foot trees. This layer is made up of the trunks of canopy trees, shrubs, plants and small trees. There
is little air movement. As a result the humidity is constantly high. This level is in constant shade.
This is the layer that grows between the smaller
trees of the understory and the forest floor. This layer is mostly composed up of ferns, small shrubs and
wood. The shrub layer is lessThan ten feet in height
and younger, smaller trees awaiting a gap in the canopy to grow to full stature.
The forest floor is usually completely
shaded, except where a canopy tree has fallen and created an opening. Most areas of the forest floor receive so little light
that few bushes or herbs can grow there. As a result, a person can easily walk through most parts of a tropical rain forest.
Less than 1 % of the light that strikes the top of the forest penetrates to the forest floor. The top soil is very thin and
of poor quality. A lot of litter falls to the ground where it is quickly broken down by decomposers like termites, earthworms
and fungi. The heat and humidity further help to break down the litter. This organic matter is then just as quickly absorbed
by the trees' shallow roots.