Physiognomy and Structure: This group is characterized by widely spaced conifers forming open savannas (<25% cover) and a parklike understory strongly dominated by fire-resistant graminoids. Shrubs are few or absent from communities within this group. There may be a mid-level canopy of shrubs, copses of oaks, or even an occasional oak tree, but these are minor vegetation components.

Floristics: This group is dominated by well-spaced Pinus ponderosa with other conifers such as Pseudotsuga menziesii and Abies spp. sometimes present as canopy associates. Small trees and shrubs are poorly represented but can include scattered Juniperus spp., Quercus gambelii, Artemisia tridentata, and Chrysothamnus depressus. The understory is predominantly graminoid-dominated with species including Festuca arizonica, Muhlenbergia straminea (= Muhlenbergia virescens), Pseudoroegneria spicata, Andropogon gerardii, Carex rossii, Elymus elymoides, Koeleria macrantha, Poa fendleriana, Schizachyrium scoparium, Festuca idahoensis, Piptatheropsis micrantha (= Piptatherum micranthum), and Bouteloua gracilis.

Dynamics:  Fire is a key factor in maintaining the open canopies characteristic of these savannas. Historically, surface fires and drought were influential in maintaining open-canopy conditions in these savannas. With settlement and subsequent fire suppression, stands have become more dense. Presently, many 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 stand structures have affected fuel loads and altered 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 by Native Americans. With fire suppression and increased fuel loads, fires are now less frequent and often become intense crown fires which can kill mature Pinus ponderosa. 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 intervals have resulted in many stands having dense subcanopies of overstocked and unhealthy young Pinus ponderosa. Savage and Swetnam (1990) suggest that continuity of understory fuels, especially the grass layer, maintained high frequencies of low-intensity, surface fires along the entire gradient from ponderosa pine woodlands to spruce-fir forests. This hypothesis is supported by evidence that forests with grassy understories were once extensive and continuous over a large elevational range (Savage and Swetnam 1990, Moir et al. 1997). Descriptions of forests around the turn of the century noted open, large areas not confined to ponderosa pine forests. Most ecologists agree that hot, crown fires were not extensive in these open ponderosa pine savannas, although small thickets would have been destroyed by spot crown fires.