Table 1: Major Types of Ecological Similarity

Ecological Similarity Code*

Ecological Similarity Name

Ecological Similarity Description






Physiognomic Structure (Map and reference have same NLCD class)

Where mapped and reference classes share same NLCD Class, such as:

-  N30-Barren (Includes all Barren Lands)

-  N40-Forest (Includes all Deciduous Forest, Evergreen Forest and Mixed Forest types)

-  N50-Shrubland (Includes all Shrub, Dwarf Shrub and Shrub/Scrub types)

-  N70-Herbaceous (Includes all Grassland, Herbaceous, Savanna and Shrub-Steppe types)

-  N90-Wetlands (Includes all Wetland, Riparian, Emergent Wetlands, Wet Meadows

and Greasewood Flats)



Dominant Species Composition

Where mapped and reference classes share dominant/diagnostic species as specified in concept of Ecological Systems. For example, if systems share dominant or codominant species, then species composition is similar. If systems share species that are only present, then species composition is not similar. Would also apply if the confusion occurs between systems where the dominant/codominant species is common, but has been identified to a different subspecies (i.e. Artemisia tridentata spp.).





(Form mosaics/ Ecotonal)

Where mapped and reference classes commonly form a mosaic, such as where patch or linear systems occur within matrix systems, or where broad ecotonal boundaries between the classes occur with regularity. This often relates to minimum mapping unit (scale) issues with mosaics of similar landcover types. Refrain from using this code when the possibility of juxtaposition is only a rare occurrence.






Special Substrates

Where mapped and reference classes share substrates with special properties that ecologically define each Ecological System. To be applied with the following substrates only:

-  Eolian (Sandsheets and Dunes)

- Bedrock (exposed weathering parent material); sparse vegetation (Barren) classes only

-  High Salinity (exposed marine shales, saline overflow /playas)


* These codes are to be applied on a mega mapping zone-by-mega mapping zone basis.