Natural Resources
Conservation Service
Ecological site EX043B23A104
Clayey (Cy) Absaroka Lower Foothills
Last updated: 10/04/2019
Accessed: 11/13/2024
General information
Provisional. A provisional ecological site description has undergone quality control and quality assurance review. It contains a working state and transition model and enough information to identify the ecological site.
MLRA notes
Major Land Resource Area (MLRA): 043B–Central Rocky Mountains
43B – Central Rocky Mountains – The Central Rocky Mountains extends from northern Montana to southern extent of Wyoming and from Idaho to central Wyoming. The southern extent of 43B is comprised of a combination of metamorphic, igneous, and sedimentary mountains and foothills. Climatic changes across this extent are broad and create several unique breaks in the landscape.
Further information regarding MLRAs, refer to: United States Department of Agriculture, Natural Resources Conservation Service. 2006. Land Resource Regions and Major Land Resource Areas of the United States, the Caribbean, and the Pacific Basin. U.S. Department of Agriculture Handbook 296.
Available electronically at: http://www.nrcs.usda.gov/wps/portal/nrcs/detail/soils/ref/?cid=nrcs142p2_053624#handbook.
LRU notes
Land Resource Unit (LRU) 043B23A: Absaroka Lower Foothills
Based on the shifts in geology, precipitation patterns and other climatic factors, as well as elevations and vegetation, the Absaroka Range was divided into LRU 23. Further division of this LRU is necessary due to the gradient moving from the foothills to the summit, as well as aspect shifts (east face versus west face). Subset A is set for the lower elevations within the foothills with 10 to 14 inches of precipitation. To verify or identify the LRU A (the referenced LRU for this ecological site), refer to the Wyoming LRU matrix key contained within the Ecological Site Key. This particular LRU occurs along the eastern lower foothills of the Absaroka Range. This LRU starts north of Clark, WY and runs to the Thermopolis, WY area. Once the foothills cross into the Northern Beartooth Range, the climatic patterns and elevational changes shifts the plant community and allows for a break in LRU's near the Montana state line. As the LRU follows to the south and tracks east with the intersection of the Absaroka and Owl Creek Ranges, the face changes aspect and geology creating a shift in plant dynamics and a break in the LRU. The extent of soils currently correlated to this ecological site does not fit within the digitized boundary. Many of the noted soils are provisional and will be reviewed and corrected in mapping update projects. Other map units are correlated as small inclusions within other MLRA’s/LRU’s based on elevation, landform, and biological references.
Moisture Regime: Aridic Ustic or Ustic Aridic – Progressive Initial mapping has shown that soil correlations completed prior to 2014 were identified as ustic aridic, after further evaluation of climatic and soil taxonomy information the proper moisture regime is aridic ustic. Both are recorded here until an update project is completed to correct the previous correlations.
Temperature Regime: Frigid
Dominant Cover: Rangeland – Sagebrush Steppe (major species is Wyoming Big Sagebrush)
Representative Value (RV) Effective Precipitation: 10-14 inches (254 – 355 mm)
RV Frost-Free Days: 80-110 days
Classification relationships
Relationship to Other Established Classification Systems:
National Vegetation Classification System (NVC):
3 Xeromorphic Woodland, Scrub & Herb Vegetation Class
3.B Cool Semi-Desert Scrub & Grassland Subclass
3.B.1 Cool Semi-Desert Scrub & Grassland formation
3.B.1.NE Western North American Cool Semi-Desert Scrub & Grassland Division
M169 Great Basin & Intermountain Tall Sagebrush Shrubland & Steppe Macrogroup
G302 Artemisia Tridentata - Artemisia tripartita - Purshia tridentata Big Sagebrush Steppe Group
CEGL001535 - Artemisia tridentata ssp. wyomingensis/Pseudoroegneria spicata Herbaceous Vegetation or
CEGL001009 - Artemisia tridentata ssp. wyomingensis/Pseudoroegneria spicata Shrubland
Ecoregions (EPA):
Level I: 10 North American Deserts
Level II: 10.1 Cold Deserts
Level III: 10.1.18 Wyoming Basin
Level IV: 10.1.18.b Big Horn Basin and
10.1.18.d Foothills and Low Mountains
Ecological site concept
• Site receives no additional water.
• Slope is <20%
• Soils are:
o Textures range from loamy sand to very fine sandy loam in top 4” (10 cm) of mineral soil surface
o Clay content is ≥35% in top 4” (10 cm) of mineral soil surface
o All subsurface horizons in the particle size control section have a weighted average of ≥ 35% clay. (The particle size control section is the segment of the profile from either the start of an argillic horizon for 50 cm’s or from 25-100 cm’s).
o Moderately deep to very deep (20-80+ in. (50-200+ cm)
o <3% stone and boulder cover and 20% or less cobble and gravel cover
o Not skeletal (<35% rock fragments) within 20” (50 cm) of mineral soil surface
o None to Slightly effervescent throughout top 20” (50 cm) of mineral soil surface
o Non-saline, sodic, or saline-sodic
The Clayey ecological site concept is based on minimal (none to slight) influence from salts, carbonates, gypsum or other chemistry within the top 20 inches (50 cm) of the mineral soil surface. The main soil characteristic is a moderately deep to very deep soil that is fine textured with greater than or equal to 35% clay throughout the soil profile; the dominant soil textural classes are loamy sand to sandy loam in the subsurface.
The clayey site can be found occurring in a complex mosaic pattern where the geology is controlled by inter-bedded sandstone and shale. Locations controlled by primarily shale bedrock have pockets of saline upland, dense clay, and loamy sites intermixed with the clayey ecological site.
Associated sites
EX043B23A106 |
Clayey Overflow (CyO) Absaroka Lower Foothills Clayey Overflow sites are found in concave positions along slopes and will be similar to clayey sites, but receive additional extra moisture (with no water table) from upland runoff or overflow from intermittent streams. These sites are higher in productivity and have basin wildrye, slender wheatgrass, and snowberry. |
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EX043B23A109 |
Cobbly Upland (CoU) Absaroka Lower Foothills Dense Clay is similar in characteristics, however dense clay starts with a coarser textured soil surface texture and then has an abrupt increase in clay. This site is characterized by a birdfoot sagebrush dominated community. |
EX043B23A122 |
Loamy (Ly) Absaroka Lower Foothills Loamy sites are noted by slightly coarser in texture (>18% but < 35% clays), and have a mixture of needleandthread with rhizomatous wheatgrasses. Runoff is less of an issue on Loamy soils and plants tend to maintain a higher vigor with the increased ease of infiltration. |
EX043B23A150 |
Sandy (Sy) Absaroka Lower Foothills Sandy sites are found along the sandstone outcrops and in the same inter-bedded sedimentary uplifts. Sandy soils are dominated by Indian ricegrass and needleandthread. They tend to show drought stress quicker than clayey sites, but have similar production as the clayey site. |
EX043B23A158 |
Shallow Clayey (SwCy) Absaroka Lower Foothills Shallow Clayey soils are found along the outcrops and eroded slopes of shale (claystone) parent materials. These sites are lower in productivity with increased bare ground, but otherwise are very similar in characteristics. |
EX043B23A138 |
Saline Lowland (SL) Absaroka Lower Foothills Saline Lowlands are found as you move off of the upland clayey ecological site down along the riparian corridors and floodplains of the drainages/streams cutting through the foothills. |
EX043B23A144 |
Saline Upland (SU) Absaroka Lower Foothills Saline Upland sites may be very similar in texture, but have a significant content of salt that affects the plant community. |
Similar sites
R032XY104WY |
Clayey (Cy) 5-9” Big Horn Basin Precipitation Zone Clayey 5-9 |
---|---|
R032XY304WY |
Clayey (Cy) 10-14" East Precipitation Zone Clayey 10-14 |
R032XY204WY |
Clayey (Cy) 5-9” Wind River Basin Precipitation Zone Clayey 5-9 |
Table 1. Dominant plant species
Tree |
Not specified |
---|---|
Shrub |
(1) Artemisia tridentata ssp. wyomingensis |
Herbaceous |
(1) Achnatherum hymenoides |
Legacy ID
R043BX504WY
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