Physiognomy and Structure: This microphyllous-leaved evergreen and broad-leaved, cold-deciduous macrogroup is structurally characterized by open to dense sagebrush with associated shrubs interspersed. A sparse to dense perennial herbaceous understory dominated by bunchgrasses is common. Scattered forbs may be present, but typically are not.

Floristics: This sagebrush shrubland and shrub-steppe macrogroup is characterized by an open to dense (10-80% cover) short-shrub canopy (<2 m tall) that is dominated by Artemisia tridentata. Purshia tridentata frequently dominates or codominates with Artemisia tridentata. The subspecies of Artemisia tridentata have diagnostic value for community classification and vary by habitat and geographic range. Artemisia tridentata ssp. wyomingensis and Artemisia tridentata ssp. tridentata are the most widespread taxa and dominate throughout much of range of this macrogroup. They may be codominated by associated shrub species such as Atriplex canescens, Chrysothamnus viscidiflorus, Ephedra nevadensis, Ephedra viridis, Ericameria nauseosa, or Sarcobatus vermiculatus. Artemisia tridentata ssp. tridentata, Artemisia tridentata ssp. xericensis, and Artemisia tripartita ssp. tripartita are characteristic of relatively mesic environments and may be codominated by Peraphyllum ramosissimum, Prunus virginiana, Ribes cereum, or Symphoricarpos spp. At montane elevations, Artemisia tridentata ssp. vaseyana, related taxa Artemisia tridentata ssp. spiciformis, and Artemisia cana ssp. viscidula are the dominant taxa. Purshia tridentata may also dominate or codominate montane stands. Common montane associates are Amelanchier utahensis and Symphoricarpos oreophilus. The understory is variable (5-50% cover) and dominated by a variety of perennial graminoid associates. On xeric sites Achnatherum hymenoides, Hesperostipa comata, Poa secunda, and other semi-desert associates are common. Montane and relatively mesic sites include Achnatherum occidentale, Bromus carinatus, Calamagrostis rubescens, Carex pensylvanica, Danthonia intermedia, Deschampsia cespitosa, Elymus trachycaulus, Festuca arizonica, Festuca campestris, Festuca idahoensis, Leucopoa kingii, Leymus cinereus, Poa fendleriana, and Pseudoroegneria spicata. Shrub-steppe with abundant native graminoid understory is more common in the less xeric northern extent and at montane elevations, as well as mesic microsites such as along drainages. Shrublands are more common in the drier southern extent with the core distribution in the Great Basin and Colorado Plateau.

Dynamics:  The natural fire regime of this macrogroup likely maintains a patchy distribution of shrubs so that the general aspect of the vegetation is a grassland. Shrubs may increase following heavy grazing and/or with fire suppression, particularly in moist portions in the northern Columbia Plateau where it forms a landscape mosaic pattern with shallow-soil scabland shrublands. Response to grazing can be variable depending on the type of grazer and the season in which grazing occurs. Hesperostipa comata can increase in abundance in response to either grazing or fire. In central and eastern Montana (and possibly elsewhere), complexes of prairie dog towns are common in instances of this macrogroup with low sagebrush density. Microphytic crust is very important for soil moisture retention, mitigating soil erosion, and seed germination in communities of this macrogroup.

Healthy montane sagebrush shrublands can be quite productive (roughly 100-150 gC m-2 year-1), though productivity is correlated with precipitation during the growing season. They are often grazed by domestic livestock, and are strongly preferred during the growing season (Padgett et al. 1989). Prolonged livestock use can cause a decrease in net primary productivity as well as the abundance of native bunchgrasses. It can also increase the canopy cover of shrubs and non-native grass species such as Bromus tectorum and Poa pratensis. Artemisia cana resprouts vigorously following spring fire, and prescribed burning may increase shrub cover. Conversely, fire in the fall may decrease shrub abundance (Hansen et al. 1995).

Artemisia tridentata is top-killed by fire and will not resprout Stands re-establish from seedbanks or from off-site sources depending on severity of burn and usually takes over ten years for it to form occurrences having 20% or more cover. However, a study on Wyoming big sagebrush shrub-steppe in central and southeast Montana stands where median time since fire was 22 years (ranging from 4 to 67 years) found no Wyoming big sagebrush canopy cover recovery for 17 of the 24 sites, and the oldest burn was only 8% recovered (Cooper et al. 2007). Lesica et al. (2005) did a similar study in southwest Montana with similar findings. Wyoming big sagebrush stands tend to occur on drier sites than the other subspecies and may be slower to recover on drier sites (Howard 1999). Tirmenstein (1999c) and Howard (1999) found sites with high-severity or repeated burns that kill the banked sagebrush seeds and mycorrhizal spores are slow to establish new shrubs so severity of fire and other fire characteristics, such as seasonality, size/extent, complexity, intensity, and type of fire as well as fire-return interval, influence post-fire recovery. According to Johnson (2000b), fire-return intervals of 30-70 years maintain perennial bunchgrasses and non-sprouting shrubs like sagebrush; fire-return intervals of 10-30 years eliminate short-lived, sprouting shrubs; and fire-return intervals of 2-5 years eliminate perennial grasses and non-sprouting shrubs leaving invasive annual grasses and forbs.

The condition of most sagebrush steppe has been degraded due to fire suppression, overgrazing by livestock, invasion by pinyon and juniper, and the invasion and subsequent domination of the herbaceous canopy by Bromus tectorum. It is unclear how long it will take to restore degraded occurrences.