Natural Resources
Conservation Service
Ecological site R058AY724MT
Clayey 15-19
Last updated: 8/29/2024
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): 058A–Northern Rolling High Plains, Northern Part
MLRA 058A, Northern Rolling High Plains (Northern Part), is an expansive and agriculturally and ecologically significant area encompassing 26 counties in southeast Montana (99 percent) and northeast Wyoming (1 percent). It stretches approximately 290 miles from east to west and 220 miles from north to south and comprises approximately 42,350 square miles (26,875,928 acres). The area is within the Missouri Plateau, Unglaciated, Section of the Great Plains Province of the Interior Plains. It is an area of old plateaus and terraces that have been eroded. Slopes generally are gently rolling to steep, and wide belts of steeply sloping badlands border a few of the larger river valleys. In some areas flat-topped, steep-sided buttes rise sharply above the general level of the plains. Elevations generally range from 2,950 to 3,280 feet, increasing from east to west and from north to south.
Tertiary continental shale, siltstone, and sandstone of the Fort Union Formation underlie the eastern one-third to one-half of this area. Marine and continental sediments of the Cretaceous Montana Group underlie the rest of the MLRA, generally at the higher elevations. There are also younger Cretaceous sediments of the Livingston Group occurring between the higher elevation Montana Group sediments and the lower elevation Tertiary sediments. The dominant soil orders in MLRA 058A are Entisols and Inceptisols. The soils in the area dominantly have a frigid soil temperature regime, an ustic soil moisture regime, and mixed or smectitic mineralogy. They range from shallow to very deep and are generally well drained and clayey or loamy.
The area primarily supports native prairie vegetation characterized by a variety of cool-season and warm-season graminoids, forbs, and shrubs. In the western portion of the area, cool-season grasses such as western wheatgrass and bluebunch wheatgrass are dominant but, in the eastern portion of the area, warm-season grasses such as little bluestem and sideoats grama become dominant. Wyoming big sagebrush, silver sagebrush, and fringed sagewort are common shrub species throughout the area. Forested areas occur in rough hilly areas and river breaks, particularly in areas with higher precipitation. Common tree species are ponderosa pine and Rocky Mountain juniper with scattered pockets of Douglas fir.
More than 75 percent of this MLRA is native rangeland utilized for livestock production and more than 50 percent of the MLRA consists of privately-owned ranches. Approximately 15 percent of the MLRA is used as cropland. Other land uses including forestland, urban development, water, and other uses combine for less than 10 percent of the total land use.
Classification relationships
NRCS Soil Geography Hierarchy
• Land Resource Region: Western Great Plains
• Major Land Resource Area (MLRA): 058A Northern Rolling High Plains, Northern Part
National Hierarchical Framework of Ecological Units (Cleland et al., 1997; McNab et al., 2007)
• Domain: Dry
• Division: Temperate Steppe
• Province: Great Plains-Palouse Dry Steppe Province (331)
• Section: North Central Highlands (331K) and Powder River Basin (331G)
National Vegetation Classification Standard (Federal Geographic Data Committee, 2008)
• Class: Xeromorphic Woodland, Scrub and Herb Vegetation Class (3)
• Subclass: Cool Semi-Desert Scrub and Grassland Subclass (3.B)
• Formation: Cool Semi-Desert Scrub and Grassland Formation (3.B.1)
• Division: Cool Semi-Desert Scrub and Grassland Division (3.B.1.Ne)
• Macrogroup: Artemisia tridentata - Artemisia tripartita ssp. tripartita - Purshia tridentata Steppe and Shrubland Macrogroup (3.B.1.Ne.3)
• Group: Artemisia tridentata ssp. wyomingensis - Artemisia tridentata ssp. tridentata Steppe and Shrubland Group (3.B.1.Ne.3.a)
EPA Ecoregions
• Level 1: Great Plains (9)
• Level 2: West-Central Semi-Arid Prairies (9.3)
• Level 3: Northwestern Great Plains (9.3.3)
• Level 4: Montana Central Grasslands (43n), River Breaks (43c), and Pine Scoria Hills (43p)
Ecological site concept
This ecological site occurs on nearly level to gently sloping sedimentary plains, terraces, and fans at elevations ranging from 1,900 to 3,500 feet. Slopes range from 0 to 15 percent but are generally less than 8 percent. This site occurs on all aspects, although aspect is not a significant factor. The soils of this ecological site are moderately deep to very deep and are well drained. The soil textures are typically clay, clay loam, silty clay loam, silty clay, or sandy clay.
Associated sites
R058AY727MT |
Loamy 15-19 This site is generally found is on similar landscapes and slope positions as the Clayey ecological site, but where clay content is 32 percent or less. |
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R058AY725MT |
Clayey Steep 15-19 This site occurs on moderate to steeply sloping hillslopes adjacent to and upslope from the Clayey ecological site. It occurs in lower backslope positions where slopes are 15 percent or greater and depth to bedrock is greater than 20 inches. |
R058AY734MT |
Shallow Clay 15-19 This site occurs on nearly level to steeply sloping uplands that are adjacent to or upslope from the Clayey ecological site. It occurs on upper backslope, crest, or summit positions where depth to bedrock is between 10 and 20 inches. |
Similar sites
R058AY727MT |
Loamy 15-19 This site differs from the Clayey ecological site in that soils contain 32 percent clay or less in the upper 4 inches. Surface textures are typically loam or silt loam. |
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R058AY734MT |
Shallow Clay 15-19 This site differs from the Clayey ecological site in that depth to bedrock or paralithic bedrock is 10 to 20 inches. |
R058AY725MT |
Clayey Steep 15-19 This site differs from the Clayey ecological site in that slopes are 15 percent or greater. |
Table 1. Dominant plant species
Tree |
Not specified |
---|---|
Shrub |
(1) Artemisia tridentata ssp. wyomingensis |
Herbaceous |
(1) Nassella viridula |
Click on box and path labels to scroll to the respective text.
Ecosystem states
T1A | - | Prolonged drought, improper grazing, or a combination of these factors |
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T1B | - | Introduction of non-native invasive species (annual bromes, crested wheatgrass, noxious weeds, etc.) |
T1C | - | Conversion to cropland |
R2A | - | Proper grazing management in combination with rangeland seeding, grazing land mechanical treatment, and timely moisture (management intensive and costly). |
T2A | - | Introduction of non-native invasive species (annual bromes, crested wheatgrass, noxious weeds, etc.) |
T2B | - | Conversion to cropland |
T3A | - | Conversion to cropland |
T4A | - | Cessation of annual cropping |
T5A | - | Conversion to cropland |
State 1 submodel, plant communities
1.1A | - | Prescribed fire and wildfire, mechanical and chemical treatments, and biological processes. |
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1.1B | - | Drought, improper grazing management |
1.2A | - | Approximately 30 years post-fire regrowth. |
1.2B | - | Drought, improper grazing management, multiple fires in close succession |
1.3B | - | Normal or above average precipitation, proper grazing management |
1.3A | - | Prescribed fire and wildfire, mechanical and chemical treatments, and biological processes. |
1.4B | - | Normal or above average precipitation, proper grazing management |
1.4A | - | Approximately 30 years post-fire regrowth |
State 2 submodel, plant communities
2.1A | - | Prescribed fire and wildfire, mechanical and chemical treatments, and biological processes. |
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2.2A | - | Approximately 30 years post-fire regrowth |