The canopy is the uppermost layer of a plant community and one of the vegetation layers. If the canopy is less than 12 feet high then the term overstory is typically used. It is the topmost of any vegetative layer overhead, usually with more or less continuous cover.
This layer receives the most sun, takes up the most space, and uses the most water of any vegetation layer. As it receives the most sun, most of the photosynthesis occurs here and therefore impacts the soil profile the most from its nutritional needs and leaf litter.
A canopy community member is dominant if contributes the most to cover the community, typically when the cover value is over 50%.
A canopy community member is codominant if the fewest species whose combined cover value composes the majority of the vegetation for their layer or, for the community as a whole, the overstory. It be codominant, species must usually have a coverage of at least 20 to 30 percent.