Keys for California Vegetation

We provide keys to California’s vegetation that correspond with the revised national classification hierarchy of North American vegetation (Faber-Langendoen 2007, FGDC 2008). The keys for forests and woodlands, shrubs, and herbs lead through a series of couplets to groups of ecologically related alliances. Upon arriving at the list of alliances, choose the alliance that best describes the situation (some alliances exist in multiple places in the key). The alliance names denote the characteristic species for each vegetation type. The corresponding descriptions, grouped in alphabetical order following each key, clarify whether the characteristic species is dominant, co-dominant, or characteristically present in a stand in order to meet the alliance requirements. For definitions of commonly used terms such as “dominant,” “relative cover,” and “characteristic,” sees the Glossary of Commonly Used Terms. The key covers all provisional and full alliances plus semi-natural stands and special stands; it does not include the unranked types, which are found in Appendix 4. The following simple vegetation life form key will enable users to decide which main key to use. For those stands where disturbance or harsh environmental conditions make it difficult to determine which main key is appropriate, we provide some flexibility and place some likely confusable alliances in multiple keys. If stands are not easily keyed, check multiple descriptions and choose the best fit based on the species composition, the description of structure, and other supporting evidence mentioned in the text.

Key to Main Vegetation Categories

1. Trees evenly distributed and conspicuous throughout stand. In areas where vegetation cover is greater than about 20 percent, tree canopy may be as low as 10 percent over denser layers of shrub and herbaceous species. In areas where vegetation is less than 20 percent total cover, trees may cover somewhat less than 10 percent (as low as about 8 percent) but are evenly distributed across the stand. See key for Forests and Woodlands.
2. Woody shrubs or subshrubs conspicuous throughout stand. When total vegetation cover is over ca. 20 percent, the tree layer, if present, generally less than 10 percent cover in stand; herbaceous species may total higher cover than shrubs. Shrubs are always at least 10 percent cover. In areas where vegetation is less than 20 percent total cover, shrubs may cover less than 10 percent (as low as 2-5 percent in some desert stands), but are evenly distributed across the stand. See key for Shrublands.
3. Non-woody herbaceous vegetation, including graminoid and forb species, dominant throughout stand. When total vegetation cover is greater than about 20 percent, the layers for shrubs, subshrubs, and trees, if present, are of lower cover than herbs and less than 10 percent. If total vegetation cover is less than about 20 percent, shrubs, subshrubs, and/or trees may be present but are less than 2–5 percent cover and are not evenly distributed across stand. See key for Herbaceous Vegetation.