Both the U.S. National Vegetation Classification (USNVC) and Canadian National Vegetation Classification (USNVC) share the same underlying “EcoVeg approach” to ecosystem classification. The purpose of the EcoVeg approach is to describe the diversity of terrestrial ecosystems across the globe and inform decisions about conservation and resource management. The approach provides an 8-level hierarchy for natural types, with three upper (formation) levels, three mid (physiognomic-biogeographic-floristic) levels and 2 lower (floristic) levels, and a separate 8-level hierarchy for cultural types. By using the same approach, vegetation ecologists in both the U.S. and Canada have been able to cooperate in the development of their respective national classifications. These national classifications have also been developed as part of a strong collaboration with subnational state and provincial/territorial partners. Here we summarize the current status of both classifications.
The USNVC covers all natural and cultural vegetation types found in the U.S., including the states and territories. Types are described based on their range-wide characteristics. In the lower 48 states, known natural types across all eight hierarchical levels have been described, largely through an extended literature synthesis, but with ongoing updates as plot data analyses are completed. In Alaska, Hawaii, and U.S. lands in the Caribbean, types have been developed to the group level, but are incomplete at the alliance and association levels.
The long-term goal for the CNVC is to develop a classification for all the natural and semi-natural vegetation in Canada. At this time, upper levels of the hierarchy characterize all vegetation in Canada, but the focus at the lower levels has been on forested vegetation. Classification of boreal forests is mostly complete, based on extensive plot data over most of Canada. Considerable progress has been achieved for temperate forests, particularly in western Canada. Thematic data gaps are significant for non-treed vegetation.
Together these classifications provide a North America wide perspective on natural ecosystems, suitable for informing ecosystem-based management, supporting monitoring and predicting change, and conducting conservation status assessments.