Sonoma County borders San Francisco Bay to the south and the Pacific Ocean to the west. It includes the southernmost tip of a continuous temperate rainforest that stretches north along the coast all the way to Alaska. The Russian River flows south from its origin in Mendocino County, and then turns to the west, connecting with the ocean and creating a large, productive estuary. The county has a jumbled geology which produces many kinds of soils: rich volcanic soils, alluvial soils with drainage from sand to clay, and impoverished metamorphic serpentine soils. This, along with annual rainfalls ranging from near-desert levels of precipitation near San Francisco Bay to rainforest-like conditions in the northwest county, allows a great diversity of plant-life and habitats.


We have a wide variety of natural communities throughout the county.

A natural community is essentially what it sounds like:  groups of plants and animals living together, although the definition can also include physical properties and the processes that affect them.

The natural communities living around us here include mixed evergreen forests, oak woodlands and savanna, chaparral, northern coastal scrub, native and non-native grasslands, brackish and freshwater marshes, both riparian scrub and woodland, and coastal habitat such as dunes, bluffs and salt marshes. Sonoma County also has natural communities that are completely underwater, such as oceanic (marine), estuarine, stream and lake (lacustrine) habitats.


Why do we care about natural communities?

Understanding what the natural communities are, how they function, and how to keep them healthy is very important if we care about protecting wildlife. Here, we list and discuss the natural communities in our County as a way to help us understand where wildlife can live, be sustained, and thrive. It also helps to highlight areas that may need protection, restoration or corridors.


Where are these natural communities?

The California Department of Fish and Wildlife collects biogeographic data for California and has a map viewer called BIOS to display the data. Below is a map from BIOS which shows the most common habitats in Sonoma County – including the man-made land use categories of Cultivated Crops, Developed, and Pasture/Hay.

BIOS map

[Biogeographic Information and Observation System (BIOS), California Dept. of Fish & Wildlife,] Click to enlarge map.


Natural Communities of Sonoma County

The natural communities of California have been classified, sub-divided and described in great detail by CDFW, but on this site we will use just a few broad categories, the most common in Sonoma County from the map above.

Terrestrial Vegetation

  • Evergreen Forest
  • Mixed Forest
  • Broadleaf Forest
  • Shrub/Scrub
  • Grasslands (Herbaceous)
  • Wetlands


  • Cultivated Crops
  • Developed: High to Low Intensity
  • Developed: Open Space
  • Pasture/Hay


  • Lake/Reservoir
  • River/Stream


  • Kelp Forest
  • Pelagic