A hardwood rangeland classification system for California is described. The system provides private landowners, land managers, and researchers a unifying framework from which known ecological and management information can be retrieved. Standardization of type names facilitates the exchange of information on hardwood rangelands within and among agencies, landowners, and universities. The dichotomous keys to the type descriptions ensure that the system is field oriented and user-friendly.

The classification system consists of 57 subseries arranged hierarchically within 7 Series. The oak series are defined by the dominant oak species present on the site. A Mixed Oak Series is also defined from sites that contain three or more species of oak at constancies of greater than 30%. This system does not include subseries descriptions for Engelmann or garry oak types.

The classification system was developed from approximately 4,300 plots collected as part of the Vegetation Type Map (VTM) survey conducted during the 1920s-1940s by the USDA Forest Service, Pacific Southwest Forest and Range Experiment Station, and approximately 500 plots collected as part of the Forest Inventory conducted by the USDA Forest Service, Pacific Northwest Research Station in the 1970s and 1980s. The base information on species composition, percent cover by species, tree stand structure, and environment was collected on 1/5-acre plots. Species cover was determined from a 33' by 66' belt transect on each plot.

The classification structure was developed using TWINSPAN, a polythetic, divisive classification program developed by Hill (1979a). Further analyses were performed using DECORANA, and frequencies, regression, and analysis of variance. The information contained in the final type descriptions was developed from VTM data only.

The keys and type descriptions have been field tested and verified at several locations in the State, such as Hopland Field Station, Sierra Field Station, Hastings Reserve, and the San Joaquin Experiment Station. The tests were conducted by individuals familiar with hardwood rangeland ecosystems and those who were not. Ongoing use of the keys and descriptions in other parts of the State will provide information for further refinement of keys and descriptions. Additional information on potential productivity and response to management will be incorporated into the descriptions by users as they identify the types that they are working in by the classification subseries names.