Natural Resources
Conservation Service
Ecological site FX053A99X040
Loamy Steep (LoStp)
Last updated: 11/22/2023
Accessed: 11/21/2024
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): 053A–Northern Dark Brown Glaciated Plains
The Northern Dark Brown Glaciated Plains, MLRA 53A, is a large, agriculturally and ecologically significant area. It consists of approximately 6.1 million acres and stretches 140 miles from east to west and 120 miles from north to south, encompassing portions of 8 counties in northeastern Montana and northwestern North Dakota. This region represents part of the southern edge of the Laurentide Ice Sheet during maximum glaciation. It is one of the driest and westernmost areas within the vast network of glacially derived prairie pothole landforms of the Northern Great Plains and falls roughly between the Missouri Coteau to the east and the Brown Glaciated Plains to the west. Elevation ranges from 1,800 feet (550 meters) to 3,300 feet (1,005 meters).
Soils are primarily Mollisols, but Inceptisols and Entisols are also common. Till from continental glaciation is the predominant parent material, but alluvium and bedrock are also common. Till deposits are typically less than 50 feet thick (Soller, 2001). Underlying the till is sedimentary bedrock largely consisting of Cretaceous shale, sandstone, and mudstone (Vuke et al., 2007). The bedrock is commonly exposed on hillslopes, particularly along drainageways. Significant alluvial deposits occur in glacial outwash channels and along major drainages, including portions of the Missouri, Poplar, and Big Muddy Rivers. Large eolian deposits of sand occur in the vicinity of the ancestral Missouri River channel east of Medicine Lake (Fullerton et al., 2004). The northwestern portion of the MLRA contains a large unglaciated area containing paleoterraces and large deposits of sand and gravel known as the Flaxville gravel.
Much of this MLRA was glaciated towards the end of the Wisconsin age, and the maximum glacial extent occurred approximately 20,000 years ago (Fullerton and Colton, 1986; Fullerton et al., 2004). Subsequent erosion from major stream and river systems has created numerous drainageways throughout much of the MLRA. The result is a geologically young landscape that is predominantly a dissected till plain interspersed with alluvial deposits and dominated by soils in the Mollisol and Inceptisol orders. Much of this area is typic ustic, making these soils very productive and generally well suited to production agriculture.
Dryland farming is the predominant land use, and approximately 50 percent of the land area is used for cultivated crops. Winter, spring, and durum varieties of wheat are the major crops, with over 48 million bushels produced annually (USDA-NASS, 2017). Areas of rangeland typically are on steep hillslopes along drainages. The rangeland is mostly native mixedgrass prairie similar the Stipa-Agropyron, Stipa-Bouteloua-Agropyron, and Stipa-Bouteloua faciations (Coupland, 1950; 1961). Cool-season grasses dominate and include rhizomatous wheatgrasses, needle and thread, western porcupine grass, and green needlegrass. Woody species are generally rare; however, many of the steeper drainages support stands of trees and shrubs such as green ash and chokecherry. Seasonally ponded, prairie pothole wetlands may occur throughout the MLRA, but the greatest concentrations are in the east and northeast where receding glaciers stagnated and formed disintegration moraines with hummocky topography and numerous areas of poorly drained soils.
Classification relationships
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: Glaciated Northern Grasslands Section 331L
• Subsection: Glaciated Northern Grasslands Subsection 331La
• Landtype association/Landtype phase: N/A
National Vegetation Classification Standard (Federal Geographic Data Committee, 2008)
• Class: Mesomorphic Shrub and Herb Vegetation Class (2)
• Subclass: Temperate and Boreal Grassland and Shrubland Subclass (2.B)
• Formation: Temperate Grassland and Shrubland Formation (2.B.2)
• Division: Central North American Grassland and Shrubland Division (2.B.2.Nb)
• Macrogroup: Hesperostipa comata - Pascopyrum smithii - Festuca hallii Grassland Macrogroup (2.B.2.Nb.2)
• Group: Pascopyrum smithii - Hesperostipa comata - Schizachyrium scoparium Mixedgrass Prairie Group (2.B.2.Nb.2.c)
• Group: Needle-and-Thread - Blue Grama Dry Mixedgrass Prairie Group (2.B.2.Nb.2.b)
EPA Ecoregions
• Level 1: Great Plains (9)
• Level 2: West-Central Semi-Arid Prairies (9.3)
• Level 3: Northwestern Glaciated Plains (42)
• Level 4: Glaciated Dark Brown Prairie (42i)
Glaciated Northern Grasslands (42j)
Ecological site concept
Loamy Steep occurs on hillslopes, till plains, and bluffs where slopes are 15 percent or greater. This site is typically found on linear or concave backslopes. The distinguishing characteristics of this site are moderately steep to very steep slopes, a relatively well developed soil profile, surface textures within the fine-loamy textural family (18 to 35 percent clay), and less than 5 percent calcium carbonate (lime) concentration in the upper 5 inches of soil.
Associated sites
FX053A99X032 |
Loamy (Lo) This site is generally adjacent to the Loamy Steep ecological site. It is most commonly on summits where slopes are less than 15 percent and linear or concave in shape. |
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FX053A99X029 |
Limy Steep (LyStp) This site occurs on moderate to steeply sloping hillslopes adjacent to the Loamy Steep ecological site. It is generally in backslope positions with a convex slope shape rather than a linear or concave slope shape. |
FX053A99X030 |
Limy (Ly) This site occurs on gentler slopes (less than 15 percent) upslope from the Loamy Steep ecological site. It is generally on shoulders or crests with a convex slope shape whereas the Loamy Steep site is in backslope positions with a linear or concave slope shape. |
Similar sites
FX053A99X032 |
Loamy (Lo) This site differs from Loamy Steep in that slopes are less than 15 percent. |
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FX053A99X029 |
Limy Steep (LyStp) This site differs from Loamy Steep in that soils contain 5 percent or greater calcium carbonate in the upper 5 inches (as evidenced by strong or violent effervescence). |
Table 1. Dominant plant species
Tree |
Not specified |
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Shrub |
Not specified |
Herbaceous |
(1) Hesperostipa comata |
Legacy ID
R053AY708MT
Click on box and path labels to scroll to the respective text.
Ecosystem states
T1A | - | Introduction of non-native grass species, such as Kentucky bluegrass, smooth brome, and crested wheatgrass. |
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T2A | - | Prolonged drought, improper grazing management, or a combination of these factors |
T2B | - | Displacement of native species by non-native invasive species (Crested Wheatgrass, Kentucky bluegrass, noxious weeds, etc.) |
R3A | - | Range seeding, grazing land mechanical treatment, timely moisture, proper grazing management (management intensive and costly) |
State 1 submodel, plant communities
State 2 submodel, plant communities
P2.1a | - | Drought, improper grazing management |
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P2.2a | - | Return to normal or above average precipitation, proper grazing management |