Forest Floor.
A very little amount of light is able to reach the forest floor.As it is hard for light to reach the forest floor, it then makes less light reach the plants so then the plants can only grow slowly.This layer is also the layer with some of the most leafs.
Understory.
The understory is quite open and also has many bugs and insects.There are only some rivers in the understory that let some of the light pass through the trees and on to that layer.
Canopy
The canopy blocks most of the light that goes through and into the understory.This layer is one of the tallest layers but is the second tallest layer.
Emergent layer.
The emergent layer is the tallest layer and also has the most least trees which helps let some light pass though it and on to the other layers.