Physiognomy and Structure: Medium tall 5-15 m trees that are evergreen needle-leaved, evergreen sclerophyllous broad-leaved and deciduous broad-leaved.

Floristics: This macrogroup consists of various mixtures of oak, oak with pine or other conifers, conifers with broad-leaved evergreen trees, and rare limited distribution closed-cone cypress and pine trees. There are many combinations possible among wide-ranging oaks Quercus agrifolia, Quercus chrysolepis, Quercus douglasii, Quercus engelmannii, Quercus garryana, Quercus kelloggii, Quercus lobata, Quercus wislizeni that may also occur as monotypic stands. Conifers mix among them as well, including Pinus sabiniana, Pinus coulteri, Pinus attenuata, Pseudotsuga menziesii, and Pinus ponderosa. Highly localized endemic tree taxa include Hesperocyparis abramsiana (= Cupressus abramsiana), Hesperocyparis bakeri (= Cupressus bakeri), Hesperocyparis forbesii (= Cupressus forbesii), Hesperocyparis goveniana (= Cupressus goveniana ssp. goveniana), Hesperocyparis macnabiana (= Cupressus macnabiana), Hesperocyparis macrocarpa (= Cupressus macrocarpa), Hesperocyparis nevadensis (= Cupressus arizonica ssp. nevadensis), Hesperocyparis pigmaea (= Cupressus goveniana ssp. pygmaea), Hesperocyparis stephensonii (= Cupressus arizonica ssp. stephensonii), Hesperocyparis sargentii (= Cupressus sargentii), Pinus contorta var. bolanderi, Pinus radiata, and Pinus torreyana that occur in scattered groves along the coast. Hesperocyparis nevadensis and Hesperocyparis stephensonii also occur inland in scattered groves. Other endemic tree taxa, including Lyonothamnus floribundus, Quercus cedrosensis, and Quercus tomentella, occur in groves of the islands off California and Baja California and in disjunct mainland stands. Stands may be mixes of coniferous and broad-leaved evergreen trees. Characteristic trees include Pseudotsuga menziesii, Quercus chrysolepis, Notholithocarpus densiflorus (= Lithocarpus densiflorus), Arbutus menziesii, Umbellularia californica, Chrysolepis chrysophylla var. chrysophylla. Pinus coulteri, Calocedrus decurrens, Pinus ponderosa, and Chamaecyparis lawsoniana. Details on understory shrubs and herbs are available within the individual group descriptions.

Dynamics:  Fire is an important factor for much of this macrogroup. The more mesic forests burned less frequently, but many if not all types within the group experience recurring fire historically. Many of the endemic and rare pine species such as Pinus attenuata, Pinus contorta var. bolanderi, Pinus muricata, Pinus radiata, and all the Hesperocyparis species are serotinous and therefore rely on fire for regeneration (Barbour et al. 2007). These are relatively short-lived species and stand-replacing fire events optimally (historically) occur between 50- and 125-year intervals. More widespread species such as Juniperus californica, Pinus sabiniana, and Pinus quadrifolia are not serotinous and are fire-sensitive with relatively thin bark, while others such as Pinus coulteri has both serotinous and nonserotinous ecotypes. Stands generally survive under conditions of low fire intensity or in local fire-protected areas. Pinus sabiniana and Pinus coulteri are known to form stands in chaparral where fire has been absent for many decades, though older mature trees of these pines can withstand moderate-severity fire because they develop thick bark. Generally speaking, the oak, pine, and oak-pine mixed interior woodlands appear to thrive with frequent low-severity fires that maintained the open woodland or savanna-like conditions. Indeed frequent annual burning is required to maintain the woodland structure of large oaks with well-developed grassy understories of native perennial bunchgrass (Barbour et al. 2007).