Pinyon-Juniper Woodland - Code: Ne1K

Pinyon-juniper woodland is one of the major habitats of the Great Basin and broader intermountain West of the United States (and into Mexico). Occurring in a narrow elevational band at 5,000–8,000 ft. (1,500–2,400m) in dry mountains and foothills, this habitat experiences an extreme range of temperatures and receives little rainfall, just 12–16 in. (300–400mm) annually. This a short, shrublike woodland, with trees rarely taller than 25 ft. (7.5m). Tree density is variable, and canopy cover ranges from about 50% in the northwest to a savanna-like 15% in the southeast. Regardless, this habitat is open enough to move through easily and is readily explored.

The tree component of pinyon-juniper woodland consists almost entirely of pinyon pines and junipers. The species composition and structure vary throughout the range (mostly on a northwest–southeast gradient), but key tree species include Western (Juniperus occidentalis), Utah (Juniperus osteosperma), Single-seeded (Juniperus squamata), Alligator (Juniperus deppeana), and Rocky Mountain Junipers (Juniperus scopulorum) in association with Single-leaf (Pinus monophyla) or Two-needled Pinyons (Pinus edulis). In general, juniper species are dominant at lower elevations, while at the upper end of the elevational range the majority of the trees are pinyons. 

The understory component of pinyon-juniper woodland also varies along a northwest–southeast gradient and is strongly influenced by adjacent habitats. In the northwest, pinyon-juniper woodland takes on characteristics of sagebrush shrubland, with a dense understory of Big Sagebrush (Artemesia spp.), bitterbrush (Purshia spp.), rabbitbrush (Chrysothamnus spp.), and mountain mahoganies (Cercocarpus sp.), with scattered perennial tussock grasses. In the southeast, the understory is composed of warm-season grasses characteristic of shortgrass prairie and Chihuahuan desert grassland, such as Blue, Black, Hairy, and Side-oats Gramas (Bouteloua spp.). In the s. Rockies and on the Colorado Plateau, montane shrubs like Gambel Oak (Quercus gambelii) constitute a significant portion of the ground cover.
 
As a result of overgrazing and the suppression of high-frequency, low-intensity fires, pinyon-juniper woodlands have expanded rapidly over the past 150 years. They often invade the more open habitats at pinyon-juniper’s lower elevation limit. This expansion is a threat to more restricted habitats; in particular it is detrimental to Greater Sage-Grouse, and pinyon-juniper removal is actively taking place in many protected areas.