Physiognomy and Structure: These are conifer-dominated woodlands, forests, and savannas, with grassy or shrubby understories. Shrubs can be broad-leaved deciduous or microphyllous evergreen (sagebrush), while the graminoids are primarily bunch grasses, along with rhizomatous grasses. Understories are generally low to moderate in cover, especially in the most droughty and rocky sites. In some cases due to a climate-edaphic interaction, the structure is that of widely scattered trees over "shrub-steppe" of sage, bitterbrush, or sparsely distributed grasses.

Floristics: This group includes two physiognomic phases: true woodlands of Pinus ponderosa with shrubby or grassy understories, and "wooded steppes" with widely spaced, scattered Pinus ponderosa trees over generally shrubby but sparse understories. The former are generally fire-maintained, while the later are often too dry and with widely spaced vegetation to carry fire. Pinus ponderosa var. ponderosa is the predominant conifer; Pinus flexilis or Pseudotsuga menziesii may be present in the tree canopy but are usually absent. The understory can be shrubby, with Amelanchier alnifolia, Arctostaphylos patula, Arctostaphylos uva-ursi, Ceanothus velutinus, Cercocarpus ledifolius, Physocarpus malvaceus, Purshia tridentata, Rosa spp., Symphoricarpos albus or Symphoricarpos oreophilus, and Vaccinium cespitosum as common species. In transition areas with big sagebrush steppe systems, Artemisia arbuscula, Artemisia tridentata ssp. tridentata, Artemisia tridentata ssp. wyomingensis, Artemisia tripartita, Artemisia tridentata ssp. wyomingensis, Artemisia tripartita, and Purshia tridentata may be common in fire-protected sites such as rocky areas. Deciduous shrubs, such as Physocarpus malvaceus, Spiraea betulifolia, or Symphoricarpos albus, can be abundant in more northerly sites or more moist climates. Understory vegetation in the true savanna occurrences is predominantly fire-resistant grasses and forbs that resprout following surface fires; shrubs, understory trees and downed logs are uncommon. These more open stands support grasses such as Achnatherum spp., dry Carex species (Carex inops), Festuca campestris, Festuca idahoensis, Hesperostipa spp., or Pseudoroegneria spicata. The more mesic portions of this group may include Calamagrostis rubescens or Carex geyeri, species more typical of ~Central Rocky Mountain Douglas-fir - Pine Forest Group (G210)$$.

Dynamics:  Pinus ponderosa is a drought-resistant, shade-intolerant conifer which usually occurs at lower treeline in the major ranges of the western United States. Historically, surface fires and drought were influential in maintaining open-canopy conditions in these woodlands. With settlement and subsequent fire suppression, occurrences have become denser. Presently, some occurrences contain understories of more shade-tolerant species, such as Pseudotsuga menziesii and/or Abies spp., as well as younger cohorts of Pinus ponderosa. These altered structures have affected fuel loads and fire regimes. Presettlement fire regimes were primarily frequent (5- to 15-year return intervals), low-intensity surface fires triggered by lightning strikes or deliberately set fires by Native Americans. With fire suppression and increased fuel loads, fire regimes are now less frequent and often become intense crown fires, which can kill mature Pinus ponderosa (Reid et al. 1999). Establishment is erratic and believed to be linked to periods of adequate soil moisture and good seed crops as well as fire frequencies, which allow seedlings to reach sapling size. Longer fire-return intervals have resulted in many occurrences having dense subcanopies of overstocked and unhealthy young Pinus ponderosa, along with Pseudotsuga menziesii on moist sites (Reid et al. 1999).

Additional associations included in this group are subject to periodic drought that limits tree establishment. This climate-edaphic interaction results in widely scattered trees over "shrub-steppe" of sagebrush, bitterbrush, or sparsely distributed grasses. Tree growth is likely episodic, with regeneration episodes in years with available moisture. Tree density is limited in some areas by available growing space due to rocky conditions of the site. Hence the tree canopy in these associations will never reach woodland density or close due to the interaction of climate and edaphic factors, even in the absence of fire. They burn occasionally, but the vegetation is sparse enough that fires are typically not carried through the stand. Fire frequency is speculated to be 30-50 years. Some stands also occur on areas of sand dunes, scablands, and pumice where the edaphic conditions limit tree abundance.

A meeting of Pacific Northwest ecologists for Landfire concluded that the "true savannas" of high-frequency / low-intensity fires and grassy understories are now rare. Most areas that may have been savanna in the past are now more nearly closed-canopy woodlands/forests. Conclusion was that these true savannas should be included with this woodland group, along with the climatically-edaphically controlled "wooded steppes" which are also in this group. The wooded steppes included here are not fire-maintained; they occur on sites too droughty to support a closed tree canopy. They do burn with a high-frequency / low-intensity regime, but fire is not carried because of the sparse vegetation of the edaphically constrained sites (rock outcrops, dunes, super-dry, sparse trees over shrubs and sometimes grasses but widely spaced). Louisa Evers (pers. comm. 2006) notes that she has not found any evidence that ponderosa pine savanna existed historically in north-central and central Oregon. In north-central Oregon, the savanna would have been oak or pine-oak. In central Oregon, it may well have been western juniper. Condition surveys of the Cascades Forest Reserve and General Land Office survey notes suggest that ponderosa pine formed a woodland with grassy understories, but still was often referred to as open-parklike. Conversely pine-oak and Douglas-fir-oak savannas appeared to have once been quite common in the Willamette Valley.