Umbellularia californica Forest & Woodland Alliance
California bay forest and woodland

USDA Ecological Section Map

Summary Information

  • Primary Life FormTree
  • Elevation0-1200 m
  • State RarityS3
  • Global RarityG4
  • DistributionUSA: CA (NatureServe)
  • Endemic to CaliforniaYes
  • Endemic to California Floristic Province and DesertsYes
  • Date Added1995/11/01

Characteristic Species

Umbellularia californica is dominant or co-dominant in the tree or tall shrub canopy with Acer macrophyllum, Aesculus californica, Alnus rhombifolia, Alnus rubra, Arbutus menziesii, Corylus cornuta, Juglans californica, Notholithocarpus densiflorus, Pinus sabiniana, Platanus racemosa, Pseudotsuga menziesii, Quercus agrifolia, Quercus chrysolepis, Quercus wislizeni and Sequoia sempervirens.

Vegetation Layers

Trees < 25 (30) m; canopy is intermittent to continuous. Shrub layer open to intermittent. Herbaceous layer is sparse to abundant.

Membership Rules

  • Conifers < 30% relative cover in canopy, Umbellularia californica > 30% relative cover in the tree canopy (Keeler-Wolf et al. 2003a, Evens and Kentner 2006).
  • Umbellularia californica usually > 50% relative cover in the overstory as a tree or tall shrub; when with Alnus rhombifolia or Quercus wislizeni, > 30% relative cover (Klein et al. 2007).


Alluvial benches, streamsides, valley bottoms, coastal bluffs, inland ridges, steep north-facing slopes, rocky outcrops. Soils are shallow to deep, sandy to clay loams. The USFWS Wetland Inventory (1996 national list) recognizes Umbellularia californica as a FAC plant.

Other Habitat, Alliance and Community Groupings

MCV (1995) California bay series
NVCS (2009) Umbellularia californica forest alliance
Calveg Coastal mixed hardwood, California bay
Holland California bay forest
Munz Mixed evergreen forest
WHR Coastal oak woodland
CDFW CA Code 74.100.00

National Vegetation Classification Hierarchy

Formation Class Mesomorphic Tree Vegetation (Forest and Woodland)
Formation Subclass Temperate Forest
Formation Warm Temperate Forest
Division Madrean Forest and Woodland
Macro Group California Forest and Woodland
Group Californian broadleaf forest and woodland