Physiognomy and Structure: Vegetation included in this alliance has an open tree canopy that is 15-25 m tall. A sparse to moderately dense tree subcanopy is generally present (5-15 m tall). The canopy is dominated by evergreen needle-leaved trees with the subcanopy dominated by broad-leaved or scale-leaved evergreen trees. A sparse to dense shrub layer may be present. It is typically dominated by broad-leaved evergreen shrubs usually less than 5 m tall. A sparse to moderately dense herbaceous layer that is dominated by perennial graminoids is often present. Perennial forbs may be diverse but have sparse cover. Annual forbs and grasses may be seasonally present.

Floristics: Woodlands included in this alliance are characterized by an open tree canopy, 10-25 m tall (although Pinus engelmannii which can grow to 35 m tall). The dominant and diagnostic species are the Madrean evergreen conifer trees Pinus arizonica, Pinus engelmannii, Pinus leiophylla, or less commonly, Pinus ponderosa, which often occurs at higher elevation or in the northern extent of alliance. The moderately dense subcanopy is dominated by Madrean evergreen trees, such as Quercus emoryi (at lower elevations), Quercus hypoleucoides, or Quercus rugosa, with a mixture of other small trees that may include Juniperus deppeana, Pinus discolor, Pinus edulis, Quercus arizonica, or Quercus grisea. Mesic semi-riparian sites may include scattered individuals of Hesperocyparis arizonica (= Cupressus arizonica), Fraxinus velutina, Juglans major, Platanus wrightii, or Prunus serotina. The shrub layer is typically moderately dense to dense depending on the density of the tree canopy, and is often dominated by the same Quercus species that make up the tree subcanopy, especially Quercus hypoleucoides and Quercus rugosa. Other shrubs, such as Agave parryi, Arbutus arizonica, Ceanothus fendleri, Garrya wrightii, Quercus gambelii, Quercus toumeyi, Quercus turbinella, Rhus trilobata, and Yucca madrensis (= Yucca schottii), may be present to dominant. The herbaceous layer is diverse and composed primarily of perennial graminoids, particularly Muhlenbergia longiligula and Piptochaetium fimbriatum, which can dominate the understory when the shrub layer is sparse. Other associated graminoids include Aristida schiedeana var. orcuttiana (= Aristida orcuttiana), Cyperus spp., Koeleria macrantha, Muhlenbergia emersleyi, Piptochaetium pringlei (= Stipa pringlei), and Schizachyrium cirratum. Forb diversity may be high, but few species have much cover. Some of the more common forbs include Artemisia ludoviciana, Brickellia lemmonii, Cheilanthes fendleri, Erigeron neomexicanus, Packera neomexicana (= Senecio neomexicanus), Penstemon barbatus, Pseudognaphalium arizonicum (= Gnaphalium arizonicum), Pseudognaphalium canescens ssp. canescens (= Gnaphalium wrightii), Solidago wrightii, and Thalictrum fendleri.

Dynamics:  Under historic natural conditions (also called natural range of variability, NRV), this type varied from open woodlands (10-20% cover) with pines dominating the overstory and perennial bunch grasses dominating the understory to moderately dense woodlands (20-40% tree cover) with less dense herbaceous layer and more tree and shrub cover. Lower elevation treeline of pines is primarily controlled by dry-season water stress (Barton 1993). Fire and drought are the primary disturbances of this type (USFS 2009). Information on fire-return intervals is varied depending on elevation zone, with fires frequently starting at lower elevations and burning upslope into the montane zone. Lower montane pine-oak stands had frequent, low-intensity surface fires (mean fire return every 6-14 years) as a result of lightning ignitions primarily between early spring and summer (Bahre 1985, Swetnam et al. 1992, Kaib et al. 1996, Swetnam and Baisan 1996, Swetnam et al. 2001, Schussman and Gori 2006). However, minimum fire-free periods of 20-30 years are necessary for pines to establish and become resistant (thick bark) to surface fires (Barton et al. 2001). More frequent fire favors oaks and other sprouting species over pines and other conifers, which can alter stand composition. Less frequent fire (FRI >50 years) results in more conifer recruitment and denser vegetation that can lead to higher intensity, mixed-severity and patches of stand-replacing fires that also favors oaks and other sprouting species (Danzer et al. 1996, Barton 1999, Barton et al. 2001, Schussman and Gori 2006). For the inclusions of ponderosa pine woodland in Madrean conifer-oak forest and woodland the historic mean fire-return interval is similar (Smith 2006). In Arizona and New Mexico, Swetnam and Baisan (1996) found the historic mean fire-return interval ranges from 2 to 17 years for fires scarring one or more trees, and 4 to 36 years for fires scarring between 10 and 25% of trees between the years of 1700 and 1900. However, in the more mesic subalpine fir communities, a fire-return interval of up to 400 years is not uncommon.

Stands have been impacted by fragmentation, silviculture, fire management, and livestock grazing over the last century. The lower montane woodlands are characterized by a strong perennial grass layer and are driven by many of the same ecological processes as encinal, primarily fire and grazing. The upper montane forests have less forage available and are less impacted by livestock but more impacted by logging and active fire suppression. Fragmentation of the landscape can impact the movement of fires that start in lower elevation savannas and woodlands and burn upslope into the montane zones. It is generally agreed that the fire regime has been altered by passive fire suppression via removal of fine fuels through livestock grazing, as well as active suppression over the last 100 years. This has reduced the number of fires and increased fire severity in conifer-oak forests and woodlands and adjacent vegetation types like encinal across much of the southwestern U.S. and adjacent Mexico (Kaib et al. 1996, Swetnam and Baisan 1996).

Structurally as the tree canopy becomes denser, the cover of shade-intolerant grass understory is eliminated and replaced with shade-tolerant shrubs or no understory when tree canopy closes. The Coronado National Forest Assessment (USFS 2009) shows a large forest structural class shift from historic natural or reference conditions to current conditions for two montane forest types. Madrean pine-oak woodland shows the largest declines in young pine without oak in understory (grassy) and old pine-oak woodlands with understory to old pine-oak woodlands without understory