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CEGL001314 Atriplex confertifolia / Hesperostipa comata Shrubland
Type Concept Sentence: No Data Available
Common (Translated Scientific) Name: Shadscale Saltbush / Needle-and-Thread Shrubland
Colloquial Name: No Data Available
Hierarchy Level: Association
Type Concept: This shrubland association typically occurs at elevations between 1800 and 2195 m (5900-7200 feet) on nearly level to gently sloping low terraces, narrow valley floodplains, mesatops, flat ridgetops and plateaus. It is documented from northwestern Colorado, but it is predicted that this community also occurs in adjacent southwestern Wyoming and northeastern Utah. One site is on a sheltered badland slope of Mancos shale. It can occur on steeper surfaces, but slopes generally do not exceed 10%. Precipitation is usually less than 25.4 cm (10 inches) per year. Atriplex confertifolia is a xeric shrub associated with subdesert ecosystems. The soils that are commonly associated with this community are moderately coarse to fine, calcareous, and saline-alkaline with an average pH of 7.9. Bare soil covers much of the ground surface. The vegetation cover in this community is sparse, and the surface of the soil is often described as a gravel pavement due to the scouring action of the wind. This association has relatively low species diversity, with Atriplex confertifolia dominating the shrub layer with 4-20% cover. Other desert shrubs are usually present in low percentages. Hesperostipa comata dominates the herbaceous layer with 10-30% cover. Achnatherum hymenoides, Poa fendleriana, and Poa secunda are generally present with much lower cover. At lower elevations or warmer sites where Atriplex confertifolia is more abundant, there is more Pleuraphis jamesii, and Hesperostipa comata does not become abundant until further uphill where the Atriplex confertifolia decreases in cover.
Diagnostic Characteristics: No Data Available
Rationale for Nominal Species or Physiognomic Features: No Data Available
Classification Comments: No Data Available
Similar NVC Types: No Data Available
note: No Data Available
Physiognomy and Structure: No Data Available
Floristics: The vegetation cover in this community is sparse and the surface of the soil is often described as a gravel pavement due to the scouring action of the wind. This association has relatively low species diversity, with Atriplex confertifolia dominating the shrub layer with 4-20% cover. Other desert shrubs are usually present in low percentages. Hesperostipa comata (= Stipa comata) dominates the herbaceous layer with 10-30% cover. Achnatherum hymenoides (= Oryzopsis hymenoides), Poa fendleriana, and Poa secunda (= Poa sandbergii) are generally present with much lower cover. At lower elevations or warmer sites where Atriplex confertifolia is more abundant, there is more Pleuraphis jamesii (= Hilaria jamesii), and Hesperostipa comata does not become abundant until further uphill where the Atriplex confertifolia decreases in cover (P. Lyon pers. comm. 2005).
Dynamics: This association requires an unusual combination of site characteristics. The soils must be alkaline enough that Atriplex confertifolia has a competitive advantage over Artemisia tridentata ssp. wyomingensis, but coarse and deep enough to support Hesperostipa comata instead of the more typical Pleuraphis jamesii and Achnatherum hymenoides.
Environmental Description: This plant association typically occurs at elevations between 1800 and 2195 m (5900-7200 feet) on nearly level to gently sloping low terraces, narrow valley floodplains, mesatops, flat ridgetops and plateaus. One site is on a sheltered badland slope of Mancos shale. It can occur on steeper surfaces, but slopes generally do not exceed 10%. Precipitation is usually less than 25.4 cm (10 inches) per year. Atriplex confertifolia is a xeric shrub associated with subdesert ecosystems. The soils that are commonly associated with this community are moderately coarse to fine, calcareous, and saline-alkaline with an average pH of 7.9. Bare soil covers much of the ground surface.
Geographic Range: This shrubland has only been documented from Moffat County in northwestern Colorado, but it is predicted that this community also occurs in adjacent southwestern Wyoming and northeastern Utah.
Nations: US
States/Provinces: CO, UT?, WY?
Plot Analysis Summary:
http://vegbank.org/natureserve/ELEMENT_GLOBAL.2.686118
Confidence Level: Moderate
Confidence Level Comments: No Data Available
Grank: G2
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.5 Shadscale Saltbush - Fourwing Saltbush - Mat Saltbush Great Basin Scrub Macrogroup | M093 | 3.B.1.Ne.5 |
| Group | 3.B.1.Ne.5.b Shadscale Saltbush - Fourwing Saltbush - Spiny Hopsage Scrub Group | G300 | 3.B.1.Ne.5.b |
| Alliance | A0870 Shadscale Saltbush Scrub Alliance | A0870 | 3.B.1.Ne.5.b |
| Association | CEGL001314 Shadscale Saltbush / Needle-and-Thread Shrubland | CEGL001314 | 3.B.1.Ne.5.b |
Concept Lineage: No Data Available
Predecessors: No Data Available
Obsolete Names: No Data Available
Obsolete Parents: No Data Available
Synonomy: = Atriplex confertifolia / Stipa comata Association (Baker and Kennedy 1985)
- Baker, W. L. 1983c. Natural vegetation of part of northwestern Moffat County, Colorado. Unpublished report prepared for the State of Colorado Natural Areas Program, Department of Natural Resources, Denver by Colorado Natural Heritage Inventory, Denver.
- Baker, W. L., and S. C. Kennedy. 1985. Presettlement vegetation of part of northwestern Moffat County, Colorado, described from remnants. Great Basin Naturalist 45(4):747-777.
- Bourgeron, P. S., and L. D. Engelking, editors. 1994. A preliminary vegetation classification of the western United States. Unpublished report. The Nature Conservancy, Western Heritage Task Force, Boulder, CO. 175 pp. plus appendix.
- CNHP [Colorado Natural Heritage Program]. 2006-2017. Tracked natural plant communities. Colorado Natural Heritage Program, Colorado State University, Fort Collins. [https://cnhp.colostate.edu/ourdata/trackinglist/plant_communities/]
- Coles, J., D. Cogan, D. Salas, A. Wight, G. Wakefield, J. Von Loh, and A. Evenden. 2008a. Vegetation classification and mapping project report, Dinosaur National Monument. Natural Resource Technical Report NPS/NCPN/NRTR-2008/112. National Park Service, Fort Collins, CO. 814 pp.
- Lyon, Peggy. Personal communication. Botanist, Colorado Natural Heritage Program, Fort Collins, CO.
- WNDD [Wyoming Natural Diversity Database]. No date. Unpublished data on file. Wyoming Natural Diversity Database, University of Wyoming, Laramie, WY.
- Western Ecology Working Group of NatureServe. No date. International Ecological Classification Standard: International Vegetation Classification. Terrestrial Vegetation. NatureServe, Boulder, CO.