Natural vegetation refers to the plants and other flora that make up the plant life in the region. The natural vegetation will determine the characteristics of the area.
There are eight levels within the natural vegetation classification system. Each of these levels are identified based on certain criteria and their ecological contribution.
For instance, upper levels include formation, formation subclass and formation class. These are typically known as forest and woodland areas, which can be found across the U.S.
Division, macrogroup and group comprise the middle levels of the natural vegetable classification system. These demonstrate continental climate differences and refer to forests like Northern Vancouverian Montane and the East Cascades Oak-Ponderosa Pine Forest.
Lower levels include alliance and association. These tend to include diagnostic species that form multiple layers and growth forms. This includes Ponderosa Pine - Oregon White Oak Woodland Alliance.