Quercus douglasii Forest & Woodland Alliance
Blue oak woodland and forest

USDA Ecological Section Map

Summary Information

  • Primary Life FormTree
  • Elevation30-1900 m
  • State RarityS4
  • Global RarityG4
  • DistributionUSA: CA (NatureServe) (FEIS)
  • Endemic to CaliforniaYes
  • Endemic to California Floristic Province and DesertsYes
  • Date Added1995/11/01

Characteristic Species

Quercus douglasii or Quercus ×eplingii is dominant or co-dominant in the tree canopy with Aesculus californica, Juniperus californica, Pinus sabiniana, Quercus agrifolia, Quercus lobata and Quercus wislizeni.

Vegetation Layers

Trees < 20 m; with conifers < 35 m; canopy is intermittent to continuous, or savanna-like; it may be one or two tiered. Shrub layer is sparse to intermittent. Herbaceous layer is sparse or grassy, and forbs are present seasonally.

Membership Rules

  • Quercus douglasii > 50% relative cover in the tree canopy; other hardwoods or conifers may be < 30% relative cover in the tree canopy (Allen et al. 1989, Evens et al. 2004).


Valley bottoms, foothills, rocky outcrops. Soils are shallow, low in fertility, moderately to excessively drained with extensive rock fragments.

Other Habitat, Alliance and Community Groupings

MCV (1995) Blue oak series
NVCS (2009) Quercus douglasii woodland alliance
Calveg Blue oak
Holland Blue oak woodland, Alvord oak woodland, Open digger pine woodland, Digger pine-oak woodland, Juniper-oak cismontane woodland
Munz Foothill woodland
WHR Blue oak woodland, Blue oak-foothill pine
CDFW CA Code 71.020.00

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