Development of CNVC Associations

The Canadian National Vegetation Classification has adopted the definition of plant association proposed by the Ecological Society of America (ESA) Vegetation Classification Panel (2004): “A recurring plant community with a characteristic range in species composition, specific diagnostic species, and a defined range in habitat conditions and physiognomy or structure.” The CNVC Technical Committee has developed a document further outlining the association concept for the CNVC. In practice, CNVC associations are defined according to a combination of criteria, including:

  1. Species dominance;
  2. Diagnostic species that are indicators of a) ecological gradient (e.g., site moisture / nutrients; climate) or b) ecological processes (e.g., flooding, succession);
  3. Physiognomy (e.g., closed forest vs. ecological woodland; tall shrubs vs. prostrate shrubs).

Wherever units that approximate CNVC association standards are present within existing provincial / territorial classification systems, they are used as antecedents for development of national associations. When such units do not exist within jurisdictions, they are developed from first-principles data analysis in conjunction with provincial / territorial ecologists prior to proceeding to inter-jurisdictional correlation and the development of national (CNVC) associations.

Correlation of provincial / territorial associations utilizes plot data collected by these jurisdictions during development of their individual classifications. These antecedent units are compared analytically using multivariate and phytosociological methods, mediated by VPro software developed by the British Columbia Ministry of Forests and Range. Proposals for Canadian national associations are submitted to a panel of experts familiar with the ecological conditions of the region in question. This process is iterated until the regional panel accepts both the concept and data content of the associations in question, at which point these units are confirmed as CNVC associations.

Each CNVC association is described according to attributes such as vegetation condition, environmental context, dynamic regime, geographic distribution, soil and site characteristics, etc. in a standardized factsheet template. Factsheets are available in .pdf format from the Explore the Classification link in the navigation bar of this website.