Canopy vertical layers can be simply characterised by careful visual observations of different layers. Other physical measurements such as plant height, diameter at breast height, position of secondary branches can be useful key information for layer characterisation. Digital photographs taken from sideview are very important source of information to understand canopy stratification.
In complex dense rainforest canopies following layers can be identified:
Emergent Layer: Tallest trees that stand above from rest of the canopy underneath and well exposed to sunlight.
Canopy Layer: it is more or less continuous layer forming roof of the forest.
Understory Layer: It is form by short trees and shrubs growing in limited sunshine.
Field Layer: It is marked by dark (shaded) illumination conditions and dominance of herbs, grasses and ferns.
Ground Layer: It is forest floor and dominated by mosses, lichens and mushrooms.
Number of layers can vary depending on the type of forest and some other factors (such as management, herbivory).