Vegetation Committee

The Vegetation Committee collects information about plant communities in Alameda and Contra Costa counties. When most people think of vegetation, they think of general groupings such as chaparral, oak woodland, riparian forest, or grassland. While the grouping of plant communities into these broad terms is a good first step, these names do not give us enough information. For example, chaparral can be used to describe any type of vegetation dominated by evergreen shrubs with leathery leaves, whether it is dominated by oaks, manzanita, ceanothus, or chamise. Information about the plant species present in the vegetation and their abundance is more meaningful. This information is used for conservation planning, identifying rare vegetation types, and assessing habitat for sensitive plant and animal species. If everyone uses the same method for collecting information about the vegetation, we can analyze the data correctly. Otherwise, we are comparing apples and oranges.

CNPS uses the same approach for vegetation data collection as A Manual of California Vegetation (Sawyer and Keeler-Wolf 1995). It is based on a hierarchical classification similar to that used in floristics, where species are grouped into genera and then families and then orders and so on. In vegetation classification, the association type is the most specific and the most useful category.

An example of a hierarchical classification of a vegetation type: Physiognomic types: Riparian and Bottomland Habitat General habitat type: Riparian Forest and Woodland Alliance Type: Red Alder (Alnus rubra) Association Type: Red Alder/ Arroyo Willow (Alnus rubra/ Salix lasiolepis).

The East Bay Vegetation Committee collects field data following a standard CNPS protocol. The data will be used in updating future editions of A Manual of California Vegetation and towards determining priorities for protection and restoration in the East Bay.

Erin McDermott, former EBCNPS Vegetation Chair