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G301 Atriplex corrugata - Atriplex gardneri - Artemisia pedatifida Dwarf-Scrub Group
Type Concept Sentence: This dwarf-shrub scrub group occurs on gentle slopes and rolling plains in the Colorado Plateau and Uinta Basin on Mancos shale and arid, windswept basins and plains across parts of central Wyoming. It is characterized by an open canopy of dwarf-shrubs composed of relatively pure stands of Artemisia pedatifida, Atriplex corrugata, or Atriplex gardneri sometimes with Artemisia longifolia, Artemisia pygmaea, or Picrothamnus desertorum dominant or codominant.
Common (Translated Scientific) Name: Mat Saltbush - Gardner''s Saltbush - Birdfoot Sagebrush Dwarf-Scrub Group
Colloquial Name: Intermountain Dwarf Saltbush - Sagebrush Scrub
Hierarchy Level: Group
Type Concept: This semi-arid dwarf-shrub scrub group occurs in the interior western U.S. and is found on windswept basins and plains, often on marine shales. The vegetation is characterized by an open canopy of dwarf-shrubs composed of relatively pure stands of Artemisia pedatifida (important in Wyoming), Atriplex corrugata (western Colorado and Utah), or Atriplex gardneri (central Wyoming). Other dominant or codominant dwarf-shrubs may include Artemisia longifolia, Artemisia pygmaea, or Picrothamnus desertorum, sometimes with a mix of other low shrubs, such as Krascheninnikovia lanata or Tetradymia spinosa. Occasional individuals or small clumps of Atriplex confertifolia, Atriplex canescens, or Artemisia tridentata ssp. wyomingensis may be present in some stands within this group but do not codominate. The herbaceous layer is typically sparse. Scattered perennial forbs occur, such as Xylorhiza glabriuscula and Sphaeralcea grossulariifolia; perennial grasses Achnatherum hymenoides, Bouteloua gracilis (not in Wyoming), Elymus elymoides, Elymus lanceolatus ssp. lanceolatus, Pascopyrum smithii, Poa secunda, or Sporobolus airoides may dominate the herbaceous layer. In less saline areas, there may be inclusions of grasslands dominated by Hesperostipa comata, Leymus salinus, Pascopyrum smithii, or Pseudoroegneria spicata. Stands occur on gentle slopes and rolling plains. Substrates are shallow, typically saline, alkaline, fine-textured soils developed from shale or alluvium that may be associated with shale badlands. Infiltration rate is typically low. In Wyoming and possibly elsewhere, inclusions of non-saline, gravelly barrens or rock outcrops dominated by cushion plants such as Arenaria hookeri and Phlox hoodii without dwarf-shrubs may be present (these are not restricted to this group and larger patches would likely be classified in a sparse vegetation group).
Diagnostic Characteristics: This open dwarf-shrubland is typically dominated by relatively pure stands of Atriplex corrugata (in Colorado and Utah) or Atriplex gardneri (Wyoming). Other dominant or codominant dwarf-shrubs may include Artemisia longifolia, Artemisia pedatifida (very important in Wyoming, rare in Colorado stands), or Artemisia pygmaea, sometimes with a mix of other low shrubs, such as Krascheninnikovia lanata or Tetradymia spinosa. Occasional individuals or small clumps of Atriplex confertifolia, Atriplex canescens, or Artemisia tridentata ssp. wyomingensis may be present in some stands within this group but do not codominate.
Rationale for Nominal Species or Physiognomic Features: No Data Available
Classification Comments: This group is more broadly defined than just low, mat-forming saltbush on shaly sites (Atriplex corrugata, Atriplex gardneri), but includes few dwarf sagebrush species that occur with similar habits and in similar habitats. Generally, it does not include stands mixed with taller species of saltbush or sagebrush. Stands in this group may grade into sparse vegetation groups on shale barrens/badlands. Welsh (1957) observed that Atriplex corrugata stands were restricted to north and east aspects on Mancos shale, with south and west aspects nearly barren. In Montana, Atriplex gardneri also occurs associated with badlands, and determining which group it falls into may be difficult. Scrub stands dominated by Picrothamnus desertorum are placed in ~Intermountain Shadscale - Saltbush Scrub Group (G300)$$ because they often codominant with the widespread shrub Atriplex confertifolia. However, Picrothamnus desertorum is often short (10-25 cm tall) so it could also be classified as a dwarf-shrubland.
Similar NVC Types: No Data Available
note: No Data Available
Physiognomy and Structure: This group is a facultatively deciduous, subdesert dwarf-shrubland. It typically has an open woody canopy of clumps of low, mat-forming dwarf-shrubs and a sparse herbaceous layer.
Floristics: This dwarf-shrubland group is characterized by an open canopy of dwarf-shrubs typically composed of relatively pure stands of Atriplex spp., such as Atriplex corrugata (in Colorado and Utah), Atriplex gardneri (Wyoming and Montana into Canada), or Artemisia pedatifida (very important in Wyoming, rare in Colorado stands). Other dominant or codominant dwarf-shrubs may include Artemisia longifolia, Artemisia pygmaea, or Picrothamnus desertorum, sometimes with a mix of other low shrubs, such as Krascheninnikovia lanata or Tetradymia spinosa. Occasional individuals or small clumps of Atriplex confertifolia, Atriplex canescens, or Artemisia tridentata ssp. wyomingensis may be present in some stands within this group but do not codominate. The herbaceous layer is typically sparse. Scattered perennial forbs occur, such as Xylorhiza glabriuscula and Sphaeralcea grossulariifolia; perennial grasses Achnatherum hymenoides, Bouteloua gracilis (not in Wyoming), Elymus elymoides, Elymus lanceolatus ssp. lanceolatus, Pascopyrum smithii, Poa secunda, or Sporobolus airoides may dominate the herbaceous layer. In less saline areas, there may be inclusions of grasslands dominated by Hesperostipa comata, Leymus salinus, Pascopyrum smithii, or Pseudoroegneria spicata. In Wyoming and possibly elsewhere, inclusions of non-saline, gravelly barrens or rock outcrops dominated by cushion plants such as Arenaria hookeri and Phlox hoodii without dwarf-shrubs may be present (these are not restricted to this group and larger patches would likely be classified in a sparse vegetation group). Annuals are seasonally present and may include Eriogonum inflatum, Plantago tweedyi, Monolepis nuttalliana, and the introduced annual grass Bromus tectorum.
Dynamics: Atriplex corrugata-dominated shrublands are the most saline-tolerant of the Mancos shale plant communities studied by Branson et al. (1976). Atriplex corrugata can completely dominate these extremely saline sites (Branson et al. 1976). It is a true evergreen dwarf-shrub retaining leaves for several years, and branches are capable of rooting at the nodes. This plant utilizes winter soil moisture, beginning new growth in March when the soils are relatively warm and moist. It flowers in April, and by mid-July fruits are shattered (Branson et al. 1976). If the soils dry out in mid-summer, it can go dormant until the late-summer monsoon rains begin. Large areas of Atriplex corrugata died during the extreme drought of 2002 in the Four Corners area. By 2004, new seedlings were established and spreading; shrub cover recovered to approximately 50% of what it was before the drought. Atriplex gardneri-dominated vegetation is another saline/drought-tolerant example of the Mancos Shale plant communities studied by Branson et al. (1976). Although very slow-growing, it can completely dominate these extremely saline sites (Branson et al. 1976).
Environmental Description: This group occurs on gentle slopes and rolling plains in the northern Colorado Plateau and Uinta Basin on Mancos shale and arid, windswept plains and basins across parts of Wyoming. On Mancos shale (and possibly other saline marine shales), stands may be restricted to gentler slopes and cooler north and east aspects, with steeper south and west aspects nearly barren (Welsh 1957). Climate: Climate is temperate and semi-arid. Summers are generally hot, and freezing temperatures are common in the winter. Mean annual precipitation ranges from 13-33 cm. In Montana and Wyoming, approximately two-thirds of the annual precipitation falls in spring and early summer. In Colorado and Utah, over half the precipitation occurs in the late-summer monsoons as high-intensity thunderstorms. Soil/substrate/hydrology: Substrates are typically saline, alkaline, fine-textured soils developed from shale or alluvium and may be associated with shale badlands. Infiltration rate is typically low. In Wyoming and possibly elsewhere, inclusions of non-saline, gravelly barrens or rock outcrops may be present.
Geographic Range: This group occurs on gentle slopes and rolling plains in the Colorado Plateau and Uinta Basin on Mancos shale and arid, windswept basins and plains across parts of Wyoming and Montana, and into Canada.
Nations: CA,US
States/Provinces: AZ, CO, MT, NM, NV, UT, WY
Plot Analysis Summary:
http://vegbank.org/natureserve/ELEMENT_GLOBAL.2.835900
Confidence Level: Moderate
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.5 Shadscale Saltbush - Fourwing Saltbush - Mat Saltbush Great Basin Scrub Macrogroup | M093 | 3.B.1.Ne.5 |
| Group | 3.B.1.Ne.5.a Mat Saltbush - Gardner''s Saltbush - Birdfoot Sagebrush Dwarf-Scrub Group | G301 | 3.B.1.Ne.5.a |
| Alliance | A1106 Pygmy Sagebrush Low Scrub Alliance | A1106 | 3.B.1.Ne.5.a |
| Alliance | A1109 Mat Saltbush Low Scrub Alliance | A1109 | 3.B.1.Ne.5.a |
| Alliance | A1110 Gardner''s Saltbush Low Scrub Alliance | A1110 | 3.B.1.Ne.5.a |
| Alliance | A1127 Birdfoot Sagebrush Low Scrub Alliance | A1127 | 3.B.1.Ne.5.a |
Concept Lineage: No Data Available
Predecessors: No Data Available
Obsolete Names: No Data Available
Obsolete Parents: No Data Available
Synonomy: = Mat-Atriplex Association (Graham 1937)
>< Other Sagebrush Types (408) (Shiflet 1994)
>< Saltbush - Greasewood (501) (Shiflet 1994)
= Vegetation on Manco Shale (Welsh 1957)
>< Other Sagebrush Types (408) (Shiflet 1994)
>< Saltbush - Greasewood (501) (Shiflet 1994)
= Vegetation on Manco Shale (Welsh 1957)
- Branson, F. A., R. F. Miller, and I. S. McQueen. 1976. Moisture relationships in twelve northern desert shrub communities near Grand Junction, Colorado. Ecology 57:1104-1124.
- Faber-Langendoen, D., J. Drake, S. Gawler, M. Hall, C. Josse, G. Kittel, S. Menard, C. Nordman, M. Pyne, M. Reid, L. Sneddon, K. Schulz, J. Teague, M. Russo, K. Snow, and P. Comer, editors. 2010-2019a. Divisions, Macrogroups and Groups for the Revised U.S. National Vegetation Classification. NatureServe, Arlington, VA. plus appendices. [in preparation]
- Graham, E. H. 1937. Botanical studies in the Uinta Basin of Utah and Colorado. Annals of the Carnegie Museum 26:28-432.
- Knight, D. H. 1994. Mountains and plains: Ecology of Wyoming landscapes. Yale University Press, New Haven, MA. 338 pp.
- Knight, D. H., G. P. Jones, Y. Akashi, and R. W. Myers. 1987. Vegetation ecology in the Bighorn Canyon National Recreation Area. Unpublished report prepared for the USDI National Park Service and University of Wyoming-National Park Service Research.
- Potter, L. D., R. C. Reynolds, Jr., and E. T. Louderbough. 1985. Mancos shale and plant community relationships: Analysis of shale, soil, and vegetation transects. Journal of Arid Environments 9:147-165.
- Shiflet, T. N., editor. 1994. Rangeland cover types of the United States. Society for Range Management. Denver, CO. 152 pp.
- Welsh, S. L. 1957. An ecological survey of the vegetation of the Dinosaur National Monument, Utah. Unpublished thesis, Brigham Young University, Provo, UT. 86 pp.