Quercus lobata Forest & Woodland Alliance
Valley oak woodland and forest

USDA Ecological Section Map

Summary Information

  • Primary Life FormTree
  • Elevation0-775 m
  • State RarityS3
  • Global RarityG3
  • DistributionUSA: CA (NatureServe) (FEIS)
  • Endemic to CaliforniaYes
  • Endemic to California Floristic Province and DesertsYes
  • Date Added1995/11/01

Characteristic Species

Quercus lobata is dominant or co-dominant in the tree canopy with Acer negundo, Alnus rhombifolia, Fraxinus latifolia, Juglans hindsii, Juglans hindsii × regia, Platanus racemosa, Populus fremontii, Quercus agrifolia, Quercus douglasii, Quercus kelloggii, Quercus wislizeni, Salix gooddingii and Salix lasiolepis. Shrubs and lianas may include Aristolochia californica or Vitis californica.

Vegetation Layers

Trees < 30 m tall; canopy is open to continuous. Shrub layer is open to intermittent. Herbaceous layer may be grassy.

Membership Rules

  • Quercus lobata > 35% relative cover in the tree canopy with Acer negundo, Alnus rhombifolia, Fraxinus latifolia, Populus fremontii, or Platanus racemosa present (Hickson and Keeler-Wolf 2007).
  • Quercus lobata > 50% relative cover in the tree canopy or > 30% relative cover when other tree species, such as Q. agrifolia or Salix lasiolepis, are present (Allen et al. 1989, Keeler-Wolf and Evens 2006).


Valley bottoms, lower slopes, summit valleys. Soils are alluvial or residual. The USFWS Wetland Inventory (2016 national list) recognizes Quercus lobata as a FACU plant.

Other Habitat, Alliance and Community Groupings

MCV (1995) Valley oak series
NVCS (2009) Quercus lobata woodland alliance
Calveg Valley oak
Holland Great Valley valley oak riparian forest, Valley oak woodland
Munz Northern oak woodland
WHR Valley oak woodland
CDFW CA Code 71.040.00

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