The commLevel attribute specifies a level in the taxonomic hierarchy to which a class belongs. Field commLevel is an open list with the possible values defined by the classification system employed. If the party responsible for the record in the commStatus table is using the U.S. National Vegetation Classification, the acceptable levels are defined in the Vegetation Classification Standard of the Federal Geographic Data Committee as adopted June 1997. The standard is available at http://biology.usgs.gov/fgdc.veg/standards/vegstd.htm and the allowable entries for each of the physiognomic levels are listed in the appendix (see http://www.fgdc.gov/standards/documents/standards/vegetation/tables19-41.pdf). If the Braun-Blanquet classification system is employed, the acceptable values are defined in the International Code of Phytosociological Nomenclature (Weber, H.E., Moravec, J. Theurillat, J.-P. 2000. Journal of Vegetation Science. 11: 739-769).
closed List of Values:
Value
Description
Sorting
Physiognomic class
the first physiognomic level in the NVC hierarchy; based on the structure of the vegetation and determined by the relative percentage of cover and the height of the dominant, life forms (Grossman et al. 1998).
1
Physiognomic subclass
2
Physiognomic group
the level in the classification hierarchy below subclass based on leaf characters and identified and named in conjunction with broadly defined macroclimatic types to provide a structural-geographic orientation (Grossman et al. 1998).
3
subgroup
4
formation
a level in the NVC based on physiognomic grouping of vegetation units with broadly defined environmental and additional physiognomic factors in common. (FGDC 1997). Grossman et al. (1998) clarified this definition as a level in the classification hierarchy below subgroup which represents vegetation types that share a definite physiognomy or structure within broadly defined environmental factors, relative landscape positions, or hydrologic regimes. Both of these definitions derive from Whittaker 1962: a "community type defined by dominance of a given growth form in the uppermost stratum of the community, or by a combination of dominant growth forms."
5
alliance
A grouping of associations with a characteristic physiognomy and habitat and which share one or more diagnostic species typically found in the uppermost or dominant stratum of the vegetation. (This definition includes both floristic and physiognomic criteria, in keeping with the integrated physiognomic-floristic hierarchy of the NVC. It is similar to the FGDC 1997 definition: a physiognomically uniform group of Associations sharing one or more diagnostic (dominant, differential, indicator, or character) species, which, as a rule, are found in the uppermost stratum of the vegetation.)
6
association
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.
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