Nomenclature Conventions for CNVC Units

Unit Names

In general, CNVC nomenclature for classification units follows USNVC rules as presented by Jennings et al (2009) and Faber-Langendoen et al (2014). When CNVC units are equivalent to USNVC units, the two classifications share names and identifier codes (for code conventions, see below). When a CNVC unit differs in concept from a similar USNVC unit, or when the CNVC recognizes a unit that is not contained in the USNVC, the CNVC assigns a unique name and identifier code.
Nomenclatural Conventions for CNVC units:
  1. For units at the upper 4 levels of the hierarchy (Formation Class, Formation Subclass, Formation, Division), the CNVC shares all names and codes with the USNVC and follows USNVC nomenclatural rules (see Faber-Langendoen et al 2014, p 551). 
  2. For units at the lower 4 levels  of the hierarchy (Macrogroup, Group, Alliance, Association), equivalent CNVC/USNVC units share names and codes, and follow USNVC nomenclatural rules (see Faber-Langendoen et al 2014, pp. 551-52; Jennings et al 2009, pp. 190-91).
  3. For unique CNVC units at the Macrogroup and Group levels (including subtypes), the CNVC does not use scientific names but provides English and French names which include dominant/diagnostic species and ecological/biogeographic/physiognomic descriptors.
  4. For unique CNVC units at the Alliance and Association levels (including subtypes), the CNVC assigns names using a combination of dominant and diagnostic plant species and omits ecological/biogeographic/physiognomic descriptors from the names. Scientific, English and French unit names are provided using accepted species names from the CNVC plant species list.
  5. Nomenclature for plant species follows the CNVC conventions described in Botanical Nomenclature.
  6. Among the dominant and diagnostic species that the CNVC uses to name a unit, a hyphen (-) separates those occurring in the same stratum.  A slash (/) separates different strata. Species in the dominant stratum appear first, followed successively by those in other strata. Within a stratum, the order of species names reflects decreasing levels of dominance or diagnostic value. Species that have important diagnostic value but occur with low constancy in the unit appear in parentheses ( ). 
  • The CNVC determines dominance by % cover of species or groups of species within a stratum.
  • The CNVC ascribes diagnostic value to species according to their fidelity to ecological conditions that are primary determinants of the vegetation described by the unit. For example, diagnostic species could indicate certain edaphic conditions, successional status, (bio)geographic location, climate, etc. 
  • Use the Glossary to find  definitions for ecological and physiognomic terms.

Unit Codes

In addition to its long form name, each CNVC unit is assigned a unique alphanumeric identifier. This code consists of an alphabetic letter or combination of letters followed by a number. The alphabetic prefix indicates the level of the hierarchy that contains the unit, and the numeric part of the code distinguishes it from other units at the same level. Where a CNVC unit is equivalent to a USNVC unit, the two classifications share the same code. In the lower four levels of the hierarchy some units are unique to the CNVC; in these cases the alphabetic prefix starts with the letter ā€˜Cā€™.
The table below displays the alphabetic prefixes for identifier codes at each level of the CNVC hierarchy, both for units shared and not shared with the USNVC. The ā€˜_ā€™ indicates a numeric value.
Code Prefix Hierarchy Level  (USNVC or CNVC)
C_ _ Formation Class (unit and code shared by CNVC and USNVC)
S_ _ Formation Subclass (unit and code shared by CNVC and USNVC)
F_ _ _ Formation (unit and code shared by CNVC and USNVC)
D_ _ _  Division (unit and code shared by CNVC and USNVC)
M_ _ _ Macrogroup (unit and code shared by CNVC and USNVC)
CM_ _ _  CNVC Macrogroup (unit and code not in USNVC)
G_ _ _ Group (unit and code shared by CNVC and USNVC)
CG_ _ _  CNVC Group (unit and code not in USNVC)
A_ _ _ _ Alliance (unit and code shared by CNVC and USNVC)
CA_ _ _ _  CNVC Alliance (unit and code not in USNVC)
CNVC_ _ _ _ _ CNVC Association (unit and code not in USNVC)
Any code with an alphabetic suffix
(e.g. CG_ _ _a)
Lower case letter at the end of a code indicates a CNVC subtype (unit and code not in USNVC)