Notholithocarpus densiflorus Forest Alliance
Tanoak forest

USDA Ecological Section Map

Summary Information

  • Primary Life FormTree
  • Elevation100-1500 m
  • State RarityS3.2
  • Global RarityG4
  • DistributionUSA: CA, OR (USDA Plants)
  • Endemic to CaliforniaNo
  • Endemic to California Floristic Province and DesertsYes
  • Date Added1995/11/01

Characteristic Species

Notholithocarpus densiflorus is dominant or co-dominant in the tree canopy with Acer macrophyllum, Alnus rubra, Arbutus menziesii, Calocedrus decurrens, Chamaecyparis lawsoniana, Chrysolepis chrysophylla, Cornus nuttallii, Pinus coulteri, Pinus lambertiana, Pseudotsuga menziesii, Quercus agrifolia, Quercus chrysolepis, Quercus kelloggii, Sequoia sempervirens, Torreya californica, Tsuga heterophylla and Umbellularia californica.

Vegetation Layers

Trees < 45 m; canopy is continuous. Shrub layer is open. Herbaceous layer is sparse.

Membership Rules

  • Notholithocarpus densiflorus > 50% relative cover and > 10% absolute cover in the tree layer; present in the regeneration layer (Jimerson et al. 1996).
  • Notholithocarpus densiflorus > 50% relative cover in the tree layer; usually regenerating in the understory (Evens and Kentner 2006).
  • Notholithocarpus densiflorus > 60% relative cover in the tree layer (Keeler-Wolf et al. 2003a).


Raised stream benches, terraces, slopes, and ridges of all aspects. Soils are deep and well drained.

Other Habitat, Alliance and Community Groupings

MCV (1995) Tanoak series
NVCS (2009) Not treated
Calveg Tanoak
Holland Tan-oak forest
Munz Mixed evergreen forest
WHR Montane hardwood
CDFW CA Code 73.100.00

National Vegetation Classification Hierarchy

Formation Class Mesomorphic Tree Vegetation (Forest and Woodland)
Formation Subclass Temperate Forest
Formation Cool Temperate Forest
Division Western North America Cool Temperate Forest
Macro Group Californian-Vancouverian Montane and Foothill Forest
Group Vancouverian evergreen broadleaf and mixed forest