Print Report
G302 Artemisia tridentata - Artemisia tripartita - Purshia tridentata Big Sagebrush Steppe & Shrubland Group
Type Concept Sentence: This widespread matrix-forming sagebrush steppe and shrubland group occurs throughout the interior western U.S., Wyoming and the northwestern Great Plains and is characterized by an open to sparse shrub layer of Artemisia tridentata (ssp. tridentata, ssp. xericensis) or Artemisia tripartita ssp. tripartita with an often dense herbaceous layer dominated by perennial bunchgrasses such as Achnatherum occidentale, Festuca campestris, Festuca idahoensis, Leymus cinereus, Poa secunda, and Pseudoroegneria spicata.
Common (Translated Scientific) Name: Basin Big Sagebrush - Threetip Sagebrush - Antelope Bitterbrush Big Sagebrush Steppe & Shrubland Group
Colloquial Name: Intermountain Mesic Tall Sagebrush Steppe & Shrubland
Hierarchy Level: Group
Type Concept: This widespread matrix-forming sagebrush steppe group occurs throughout much of the western U.S. in the Great Basin, Columbia Plateau, northwestern Great Plains, eastern Sierra Nevada, Wyoming Basins, Rocky Mountains, and Colorado Plateau between elevations of 1200 and 2400 m. Stands are characterized by open to sparse shrublands dominated by Artemisia tridentata (ssp. tridentata, ssp. xericensis) or Artemisia tripartita ssp. tripartita which tend to occupy more mesic sites with well-developed soil, and Purshia tridentata which tends to occupy drier, rockier soils and positions, as well as sandy dune areas. Some Artemisia tridentata ssp. wyomingensis associations are included here, where they occur in biophysical settings conducive to an abundant herbaceous layer, and more mesic-indicator species. Herbaceous layers are often dense and dominated by perennial bunchgrasses, especially as Festuca idahoensis and Pseudoroegneria spicata. Other common graminoids include Achnatherum hymenoides, Achnatherum occidentale, Carex pensylvanica, Festuca campestris, Hesperostipa comata, Leymus cinereus, Pascopyrum smithii, and Poa secunda. In some cases scattered trees may form an emergent layer of individual trees; species include Cercocarpus ledifolius, Juniperus occidentalis, Juniperus osteosperma, Juniperus scopulorum, or Pinus ponderosa. Many perennial forb species are important in these shrublands, and microphytic crust is very important in this group. This group may occur on stream terraces, point bars, valley floors, alluvial fans, floodplains, washes, gullies, stabilized dunes, swales, and rocky slopes. Soils vary from deep and well-developed to shallow, rocky and poorly developed sandy loams, loamy sands, sand, silt loams, and clay loams derived from alluvium, loess, shale, and sandstone.
Diagnostic Characteristics: Stands are characterized by open to sparse shrublands dominated by Artemisia tridentata (ssp. tridentata, ssp. xericensis) or Artemisia tripartita ssp. tripartita which tend to occupy more mesic sites with well-developed soil, and Purshia tridentata which tends to occupy drier, rockier soils and positions, as well as sandy dune areas. Herbaceous layers are often dense and dominated by perennial bunchgrasses and a significant perennial graminoid layer is diagnostic of this group. Common graminoids include Achnatherum hymenoides, Achnatherum occidentale, Achnatherum thurberianum, Carex pensylvanica, Elymus lanceolatus, Festuca campestris, Festuca idahoensis, Hesperostipa comata, Koeleria macrantha, Leymus cinereus, Pascopyrum smithii, Poa secunda, and Pseudoroegneria spicata.
Rationale for Nominal Species or Physiognomic Features: No Data Available
Classification Comments: This group is a solid concept at its core, although the associations considered "mesic tall sagebrush" probably need adjustment. These communities tend to occur in the northern Great Basin and Northern Rockies, or on somewhat more mesic settings than the dry tall sagebrush group. Slightly higher precipitation and less evapotranspiration stress combined with deeper soils allow for the significant bunchgrass and perennial forb component of the shrublands in this group.
Similar NVC Types: No Data Available
note: No Data Available
Physiognomy and Structure: These are microphyllous evergreen or deciduous scrublands, with a significant component of perennial grasses. The group is structurally characterized by open to dense sagebrush or bitterbrush with associated shrubs interspersed and/or a dense understory of perennial bunch grasses.
Floristics: This shrub and shrub herbaceous group is characterized by communities dominated by Artemisia tridentata ssp. tridentata, Artemisia tridentata ssp. xericensis, Artemisia tridentata ssp. wyomingensis, Artemisia tripartita ssp. tripartita, and Purshia tridentata. Other associated shrubs and dwarf-shrubs may include Arctostaphylos uva-ursi, Artemisia frigida, Chrysothamnus viscidiflorus, Ericameria spp., Peraphyllum ramosissimum, Philadelphus lewisii, Prunus virginiana, Ribes cereum, Symphoricarpos longiflorus, and Symphoricarpos rotundifolius. Herbaceous layers are often dense and dominated by perennial bunchgrasses. Common graminoids include Achnatherum hymenoides, Achnatherum nelsonii, Achnatherum occidentale, Achnatherum thurberianum, Carex pensylvanica, Elymus lanceolatus, Festuca campestris, Festuca idahoensis, Hesperostipa comata, Koeleria macrantha, Leymus cinereus, Muhlenbergia montana, Pascopyrum smithii, Poa secunda, and Pseudoroegneria spicata. Forbs are often diverse and have moderate to low cover. Species may include Balsamorhiza sagittata, Eriogonum umbellatum, or Penstemon deustus. In some cases scattered trees may form an emergent layer of individual trees; species include Cercocarpus ledifolius, Juniperus occidentalis, Juniperus osteosperma, Juniperus scopulorum, or Pinus ponderosa.
Dynamics: The natural fire regime of this group 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 this group. Microphytic crust is very important in this group.
Environmental Description: This widespread matrix-forming group occurs throughout much of the western U.S. between elevations of 600 m in the northern extents to 2500 m in southern range limits. This group may occur on stream terraces, point bars, valley floors, alluvial fans, floodplains, washes, gullies, stabilized dunes, mesic uplands, swales, and rocky slopes. Slopes are variable from gentle to very steep. Climate: The climate where this group occurs is semi-arid with annual precipitation ranging from 18-40 cm and high inter-annual variation. Much of the precipitation falls as snow, and growing-season drought is characteristic. Temperatures are continental with large annual and diurnal variations. Soil/substrate/hydrology: Soils vary from deep and well-developed to rocky and poorly developed sandy loams, loamy sands, sand, silt loams, and clay loams derived from alluvium, loess, shale, and sandstone. In drier regions, these shrublands are usually associated with perennial or ephemeral stream drainages with water tables less than 3 m from the soil surface.
Geographic Range: This widespread matrix-forming sagebrush steppe group occurs throughout much of the western U.S. in the Columbia Plateau, Great Basin, eastern Sierra Nevada, Colorado Plateau, Wyoming Basins, Rocky Mountains, and northwestern Great Plains.
Nations: CA,US
States/Provinces: AB?, AZ?, BC, CA, CO, ID, MT, NM, NV, OR, UT, WA, WY
Plot Analysis Summary:
http://vegbank.org/natureserve/ELEMENT_GLOBAL.2.837794
Confidence Level: Low
Confidence Level Comments: No Data Available
Grank: GNR
Greasons: No Data Available
| Type | Name | Database Code | Classification Code |
|---|---|---|---|
| Class | 3 Desert & Semi-Desert Class | C03 | 3 |
| Subclass | 3.B Cool Semi-Desert Scrub & Grassland Subclass | S11 | 3.B |
| Formation | 3.B.1 Cool Semi-Desert Scrub & Grassland Formation | F033 | 3.B.1 |
| Division | 3.B.1.Ne Western North American Cool Semi-Desert Scrub & Grassland Division | D040 | 3.B.1.Ne |
| Macrogroup | 3.B.1.Ne.3 Big Sagebrush - Threetip Sagebrush - Antelope Bitterbrush Steppe & Shrubland Macrogroup | M169 | 3.B.1.Ne.3 |
| Group | 3.B.1.Ne.3.b Basin Big Sagebrush - Threetip Sagebrush - Antelope Bitterbrush Big Sagebrush Steppe & Shrubland Group | G302 | 3.B.1.Ne.3.b |
| Alliance | A1528 Threetip Sagebrush - Big Sagebrush Mesic Steppe & Shrubland Alliance | A1528 | 3.B.1.Ne.3.b |
| Alliance | A3179 Antelope Bitterbrush - Big Sagebrush Mesic Steppe & Shrubland Alliance | A3179 | 3.B.1.Ne.3.b |
| Alliance | A3182 Wyoming Big Sagebrush Mesic Steppe & Shrubland Alliance | A3182 | 3.B.1.Ne.3.b |
| Alliance | A3183 Basin Big Sagebrush - Foothill Big Sagebrush Mesic Steppe & Shrubland Alliance | A3183 | 3.B.1.Ne.3.b |
Concept Lineage: No Data Available
Predecessors: No Data Available
Obsolete Names: No Data Available
Obsolete Parents: No Data Available
Synonomy: = Western Intermountain sagebrush steppe (West 1983c)
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