Additional information necessary to understand this classification includes these Class level definitions-

Forest (I): Vegetation dominated by trees with their crowns overlapping, generally forming 60 - 100% cover; includes reproductive stages or immature secondary growth stands that are temporarily less than 5 meters or 16.5 feet tall.

Woodland (II): Open stands of trees with crowns not usually touching, generally forming 25-60% cover. Canopy tree cover (rarely) may be less than 25% in cases when the cover of each of the other lifeforms present (i.e. shrub, dwarf-shrub, herb, nonvascular) is less than 25% and tree cover exceeds the cover of the other lifeforms.

Shrubland (scrub) (III): Vegetation dominated by shrubs greater than 0.5 meters or 1.5 feet and typically less than 4 to 5 meters or 13 to 16 feet in height, forming greater than 25% cover, with trees forming less than 25% cover; shrub cover may be less than 25% in cases where the cover of each of the other life forms present is less than 25% and the shrub cover exceeds the cover of other life forms; does not include developing secondary associations dominated by tree species.

Dwarf-Shrubland (IV): Vegetation dominated by low-growing shrubs and/or trees, usually under 0.5 meters or 1.5 feet tall; dwarf-shrubs generally form greater than 25% cover, although (rarely) may be less, and tree and taller shrubs generally form less than 25% cover.

Herbaceous vegetation (V): Herbs (graminoids, forbs, and ferns) dominant, generally forming at least 25% cover. Trees, shrubs, and dwarf-shrubs generally with less than 25% cover. Herbaceous cover (rarely) may be less than 25% in cases when the cover of each of the other lifeforms present (i.e. tree, shrub, dwarf-shrub, nonvascular) is less than 25% and herbaceous cover exceeds the cover of the other lifeforms.

Nonvascular vegetation (VI): Nonvascular cover (bryophytes and lichens) dominant, generally forming at least 25% cover. Trees, shrubs, dwarf-shrubs, and herbs generally with less than 25% cover. Nonvascular cover (rarely) may be less than 25% in cases when the cover of each of the other lifeforms present (tree, shrub, dwarf-shrub, and herb) is less than 25% and nonvascular cover exceeds the cover of the other lifeforms. Crustose lichen-dominated areas should be placed in the Sparse Vegetation class.

Sparse vegetation (VII): Vegetation is scattered or nearly absent; total vegetation cover, excluding crustose lichens (which can sometimes have greater than 10% cover) is generally 1%-10%.