Since the 1990s, a variety of partnerships including federal, state, local agencies, and non-governmental organizations have been developing maps and other information about the distribution, abundance, and diversity of aquatic, wetland, and terrestrial habitat types at the time of European contact in various regions of California. Most of the efforts summarized here follow a methodology of historical ecology research developed by the San Francisco Estuary Institute (SFEI). An understanding of past landscape patterns, processes, and functions helps scientists and land managers quantify landscape change, identify restoration targets and opportunities, and develop strategies for more integrated and functional landscape management.

This compilation layer represents a simplified version of the historical ecology mapping completed to date for Alameda Creek, Ballona Creek, East Contra Costa County, Laguna de Santa Rosa, Lower Walnut Creek, Napa Valley, North San Diego County Lagoons, Petaluma River, Sacramento-San Joaquin Delta, San Francisco Baylands, San Gabriel River, South Santa Clara Valley, Suisun Landscapes, Tijuana River Valley, Western Santa Clara Valley, and Ventura County. More detailed mapping and associated information is available within the dataset's metadata.

For more information visit www.sfei.org/programs/rl/historical-ecology.