Physiognomy and Structure: Evergreen, scale-leaved trees of moderate to high density and high (60-100%) cover. This canopy can be over 50 m in height in some stands. Cold-deciduous or sclerophyllous broad-leaved trees commonly form a subcanopy. On serpentine soils, these forests grade into woodlands with irregular canopy closure. The understory usually contains a layer of tall (2-5 m tall), ericaceous shrubs of moderate (25-60%) cover and a short-shrub layer (0.5-2 m tall) with 10-40% cover. The herbaceous understory is typically a dense layer of shade-tolerant ferns and forbs.

Floristics: Despite the small range of Chamaecyparis lawsoniana, vegetation within this alliance is diverse. In the northern portion of its range, Chamaecyparis lawsoniana grows with Tsuga heterophylla, and in coastal stands with Picea sitchensis. Pseudotsuga menziesii is common, or codominant, in most stands. Other conifers that may be found include Abies lowiana (= Abies concolor var. lowiana), Abies magnifica, Callitropsis nootkatensis (= Chamaecyparis nootkatensis), Picea breweriana, and Taxus brevifolia. The northern stands lie north of the Rogue River, Oregon, and are the most extensive, continuous, and productive forests within this alliance. Understories are somewhat typical of the coastal forests of central Oregon, often with a broad-leaved tree subcanopy of Acer macrophyllum, Chrysolepis chrysophylla (= Castanopsis chrysophylla), Notholithocarpus densiflorus (= Lithocarpus densiflorus), or Alnus rubra, and a tall-shrub stratum of Acer circinatum, Rhododendron macrophyllum, Vaccinium parvifolium, or Gaultheria shallon. Shorter shrubs may include Chimaphila umbellata, Leucothoe davisiae, Mahonia nervosa, Paxistima myrsinites, Rosa gymnocarpa, Rubus ursinus, and Vaccinium membranaceum. Herbaceous layers commonly have shade-tolerant species such as Clintonia uniflora, Goodyera oblongifolia, Linnaea borealis, Oxalis oregana, and Polystichum munitum.

South of the Rogue River, stands become more scattered and extend into the interior to become important components of the mixed evergreen and montane forests of the Klamath-Siskiyou mountains. In the mixed evergreen forests, Arbutus menziesii, Calocedrus decurrens, Notholithocarpus densiflorus, Pseudotsuga menziesii, and Umbellularia californica are common in the tree canopy. Important herbs may include Xerophyllum tenax, in addition to the species listed above.

Dynamics:  Chamaecyparis lawsoniana is a somewhat shade-tolerant conifer. It regenerates under its own shade and will eventually dominate stands where it co-occurs with Pinus spp., if disturbance is absent. Conversely, it appears to be less shade-tolerant and much more fire-tolerant than Tsuga heterophylla or Picea sitchensis, and can vigorously colonize recently burned substrates. Mature individuals of Chamaecyparis lawsoniana have thick, fire-resistant bark which allows them to persist through repeated fires. Phytophthora root rot, a water-borne disease spread by logging and other anthropogenic disturbances, is severely impacting stands of this alliance throughout its range. Many stands have been lost to this pathogen, and populations are presently in decline throughout the range of the species.