The Intermountain Woodland Macrogroup [M896] occurs as a savanna to woodland on warm, dry, lower mountain slopes and plateaus at 1,800-2,600 m (5,910-8,530 ft) elevation in the Colorado Plateaus and Arizona/New Mexico Mountains ecoregions, and, to a lesser extent, in the Southern Rocky Mountains and mountains of the Chihuahuan Desert ecoregion. The tree canopy ranges from open to closed and is dominated by Utah juniper (Juniperus osteosperma) along with two-needle piñon (Pinus edulis). Shrub layers frequently are dominated by big sagebrush (Artemisia tridentata), which can form a moderately dense shrub canopy. Other common associated shrubs include yellow rabbitbrush (Chrysothamnus viscidiflorus), rubber rabbitbrush (Ericameria nauseosa), and Sonoran scrub oak (Quercus turbinella). The herbaceous layer ranges from sparse to dense and includes blue grama (Bouteloua gracilis), needle and thread (Hesperostipa comata), James’ galleta (Pleuraphis jamesii), Idaho fescue (Festuca idahoensis), and muttongrass (Poa fendleriana). Substrates are variable, but are generally shallow, cobbly, gravelly, or sandy to clay loam. Old-growth stands are largely restricted to rocky outcrops, upper slopes and ridges, and rims of mesas and canyons that are fire resistant. Younger seral stands have invaded adjacent shrublands and grasslands in recent times and now occur on lower slopes, valleys, and plains. In open savannas, periodic fire (at a 10 to 30 year interval) is important to maintaining the structure. Juniper trees less than 1.2 m (4 ft) tall are readily killed by fires.