For most ecosystem-related classification systems, vegetation is either the primary focus or is considered a major modifier for classifying other components. Systems that focus on classifying vegetation use either physiognomy, floristic characteristics, or a combination of the two. Physiognomic classification systems, such as Bailey's Ecoregions are generally based on the structure and growth form of dominant vegetation. These systems provide a fast and efficient method to characterize vegetation. Furthermore, this approach is readily adaptable for remote sensing, due to the "signature" characteristics of the dominant groups or communities.
Floristic systems are generally more detailed than physiognomic classification systems and are based on species composition. Since they rely on individual species information to achieve the classification, they usually require field data collection and are more data intensive. Habitat analysis classification, such as the Society of American Foresters Forest Cover Types is one example of a floristic-based system.
Vegetation classification systems that combine both physiognomic and floristic approaches may be the most widely applicable. The same system can be used for both broad overview projects and for local or regional projects that require finer detail, while maintaining a continuity of classification standards across all scales. A primary example of a combined physiognomic-floristic classification system is the National Vegetation Classification System (NVCS).
Data for use in developing classifications may be available from searches at two Web sites. First is the "Internet Directory for Botany," which is described at http://www.botany.net/IDB/index.html. Searches are initiated from http://www.botany.net/IDB/info.html. Second is the "Checklist of Online Vegetation and Plant Distribution Maps" found at http://www.lib.berkeley.edu/EART/vegmaps.html.
In addition to the classification systems examples above, other systems included in EMRIS that are either vegetation classifications or that use vegetation as a modifier include the US FWS ESM 103, Cowardin, and System for Remote Sensing.