Associated Forest Cover
Tanoak grows within the life zones classified as the Canadian and Transition. It is the most abundant hardwood species in timber stands of the Coast Ranges of California (6) and southwestern Oregon. Tanoak is a common component in the following forest cover types (4): Redwood (Society of American Foresters Type 232), Pacific Ponderosa Pine (Type 245), Pacific Ponderosa Pine-Douglas-Fir (Type 244), Sierra Nevada Mixed Conifer (Type 243), and California Coast Live Oak (Type 255). It is a particularly important component of Pacific Douglas-Fir (Type 229) and Douglas-Fir-Tanoak-Pacific Madrone (Type 234).
The principal body of tanoak is a broad band along the inland side of the redwood belt. Here tanoak sometimes forms almost pure stands (6). More often it is an understory tree with Douglas-fir or is a component of hardwood stands or mixed hardwood-conifer forests. The most common hardwood associated with tanoak is Pacific madrone. Other frequent hardwood associates include giant chinkapin (Castanopsis chrysophylla), canyon live oak (Quercus chrysolepis), California black oak Q. kelloggii), and California-laurel (Umbellularia californica). Tanoak is found most often with Douglas-fir and redwood. Other common conifer associates are California white fir (Abies concolor var. lowiana), Sitka spruce (Picea sitchensis), sugar pine (Pinus lambertiana), ponderosa pine (P. ponderosa var. ponderosa), California torreya (nutmeg) (Torreya californica), and western hemlock (Tsuga heterophyl1a).
A large variety of shrubs, forbs, grasses, sedges, and ferns are also associated with tanoak. Generally these plants are not abundant on forested land, but, with tanoak sprouts, often become aggressive on burned or cutover areas. Among the most common shrubs are blueblossom (Ceanothus thyrsiflorus), California hazel (Corylus cornuta var. californica), salal (Gaultheria shallon), Pacific bayberry (Myrica californica), Pacific rhododendron (Rhododendron macrophyllum), flowering currant (Ribes sanguineum), thimbleberry (Rubus parviflorus), western poison-oak (Toxicodendron diversilobum), and California huckleberry (Vaccinium ovatum).
Two smaller plants producing woody growth above ground are prince's-pine (Chimaphila umbellata var. occidentalis) and Oregon grape (Berberis nervosa). Many forbs and grasses are plentiful in the tanoak range. Among the most important forbs are bull thistle (Cirsium vulgare), New Zealand fireweed (Erechtites arguta), Australian fireweed (E. minima), and western whipplea (Whipplea modesta). Common grass species include California brome (Bromus carinatus), soft chess (B. mollis), California fescue (Festuca californica), and California sweetgrass (Hierochloe occidentalis). Western swordfern (Polystichum munitum) and western bracken (Pteridium aquilinum var. pubescens) sometimes grow abundantly with tanoak. Sedges (Carex spp.) also are represented in some places.