Physiognomy and Structure: This group is defined as an open to closed forest with a needle-leaved evergreen or evergreen-deciduous canopy.

Floristics: This coniferous or mixed conifer-deciduous forest group has an open to closed canopy ranging from 25 to 90% cover. Picea glauca is the most common conifer, but the hybrid Picea x lutzii occurs where the ranges of Picea sitchensis and Picea glauca overlap. Tsuga mertensiana may be codominant on late-seral sites where its range overlaps with Picea x lutzii (e.g., Kenai Peninsula, Alaska). Betula neoalaskana is the dominant deciduous species in this group south of the Alaska Range. Betula papyrifera var. kenaica occurs throughout the distribution of this group, and replaces Betula neoalaskana in southwest Alaska (west of the Alaska Range). Understories may be herb- or shrub-dominated. Common shrubs include Alnus viridis ssp. sinuata, Menziesia ferruginea, Oplopanax horridus, Vaccinium ovalifolium, Viburnum edule, and Rosa acicularis. Common herbaceous species include Calamagrostis canadensis, Chamerion angustifolium ssp. angustifolium, Equisetum arvense, Equisetum sylvaticum, Gymnocarpium dryopteris, Athyrium filix-femina, Heracleum maximum, Pyrola asarifolia, Streptopus amplexifolius, and Mertensia paniculata.

Dynamics:  The major disturbance processes are fire, insect infestations, wind, and logging. Lightning strikes and natural fires have historically been infrequent and the fire interval is relatively long. When fires do occur they are often large crown fires. Spruce beetle (Dendroctonus rufipennis) infestations are a major natural disturbance of spruce forests in the sub-boreal region. Spruce beetles typically attack larger, slow-growing spruce, but when forest and climatic conditions are favorable for population expansion, beetles become less selective and infest a wider range of tree sizes. Beetle outbreaks that thin stands and produce a growth release in surviving trees occur on average every 50 years in Picea glauca and Picea x lutzii forests on the Kenai Peninsula. Spruce beetle outbreaks that produce a more substantial thinning occur at longer intervals, with the last two severe infestations occurring in the 1870s-1880s and 1987-present. Over 1.3 million acres of spruce have been killed in an outbreak beginning in 1987. No association between spruce beetle mortality and fire has been found in the past (Berg 2004). Calamagrostis canadensis may proliferate rapidly from its pre-disturbance-level network of rhizomatous roots and develop into a thick sod that limits spruce regeneration within a few years following beetle-caused canopy thinning (Berg 2004). Rapid spread of Calamagrostis canadensis occurs primarily on sites with deep, loamy soils (Boucher 2003).