Revisions to the National Standards for the Physiognomic Levels of Vegetation Classification in the United States

Document number

not applicable

Maintenance authority

not applicable


To revise the physiognomic levels for the classification of vegetation in the United States as defined in the FGDC Vegetation Classification Standards (FGDC-STD-005, October 1997). The NVC framework was meant to provide an integrated hierarchy of physiognomic and floristic levels and types. The FGDC-STD-005 standard defined the physiognomic and floristic levels and provided a complete set of physiognomic types for the entire U.S., but a complete set of floristic types (alliances and associations) was not available at the time. Now that a draft set of alliance and association types are available (Grossman et al. 1998, Anderson et al. 1998, NatureServe 2001) we would like to establish procedures for better linking the floristic and physiognomic levels and types together in a coordinated fashion, while revising the draft set of physiognomic types. This project will revise the FGDC-STD-005. Our intent is to ensure that the physiognomic levels and types meet the need of the standard as originally stated, not to revise the basic purpose and scope of the standard.


The physiognomic standards of a national vegetation classification will be FGDC data content standards. The standards will include:

  • Classification methodology standards: to revise criteria for the definition of the physiognomic levels in order to improve their linkage with developing floristic units.
  • Application standards: to review how well the current physiognomic levels meet the needs of various applications, including links with remote sensing and links with scale.
  • Data collection standards: the current data collection standards are, in part, based on the current physiognomic levels. Data collection standards will need to be compatible with any revisions to these levels (i.e. important physiognomic criteria to be recording in the field)
The revisions will be made in order to clarify how best to use physiognomic criteria for defining units in the upper levels of the NVC standard.

Sponsored by

FGDC Vegetation Subcommittee

Project history

Document Version Date Custodian
2001-11-26 FGDC Standards Working Group