Quercus tomentella - Lyonothamnus floribundus Forest & Woodland Alliance
Island live oak - Catalina ironwood woodland and forest

USDA Ecological Section Map

Summary Information

  • Primary Life FormTree
  • Elevation0-450 m
  • State RarityS3
  • Global RarityG3
  • DistributionUSA: CA. Guadalupe Island, Mexico (NatureServe)
  • Endemic to CaliforniaNo
  • Endemic to California Floristic Province and DesertsYes
  • Date Added2016/10/27

Characteristic Species

Lyonothamnus floribundus or Quercus tomentella is dominant in the tree canopy with Quercus agrifolia and Rhamnus pirifolia. Shrubs may include Adenostoma fasciculatum, Arctostaphylos catalinae, Arctostaphylos insularis, Arctostaphylos viridissima, Baccharis pilularis, Comarostaphylis diversifolia, Diplacus parviflorus, Heteromeles arbutifolia, Prunus ilicifolia ssp. lyonii or Quercus pacifica.

Vegetation Layers

Trees < 20 m; canopy is continuous. Shrubs are infrequent to moderately continuous. Herbaceous layer is sparse to continuous.

Membership Rules

  • Lyonothamnus floribundus > 50% relative cover in the tree canopy (Rodriguez et al. 2017).
  • Quercus tomentella > 50% relative cover in the tree canopy, or co-dominant with Quercus agrifolia or other trees (Rodriguez et al. 2017).


Moist canyons and slopes, concavities, rarely exposed slopes. Soils are marine sedimentary (including calcareous), granitic, or volcanic substrates.

Other Habitat, Alliance and Community Groupings

MCV (1995) Catalina ironwood unique stands, Island oak series
NVCS (2009) Quercus tomentella forest alliance
Calveg Scrub oak, Canyon live oak
Holland Island chaparral, Island oak woodland, Island ironwood forest
Munz Chaparral, Southern oak woodland
WHR Coastal oak woodland, Mixed chaparral
CDFW CA Code 77.100.00

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