Natural Resources
Conservation Service
Ecological site R058AY726MT
Woody Draw 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 1,950 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: Forest and Woodland Class (1)
• Subclass: Temperate and Boreal Forest and Woodland Subclass (1.B)
• Formation: Cool Temperate Forest and Woodland Formation (1.B.2)
• Division: North American Great Plains Forest and Woodland Division (1.B.2.Ne)
• Macrogroup: Great Plains Forest and Woodland Macrogroup (1.B.2.Ne.1)
• Group: Great Plains Mesic Forest and Woodland Group (1.B.2.Ne.1.b)
• Alliance: Great Plains Ash - Elm Ravine Forest
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 is an extensive site which occurs on moderately steep to very steep landscapes, typically where the landscape has been dissected by streams, rivers, or drainageways. This site generally occurs at elevations ranging from 1,900 to 3,500 feet and can occur on a wide range of slopes, although slopes ranging from 15 to 45 percent are most common. The site typically occurs in the narrowest, most sheltered swales and is most common on northerly aspects. The soils for this ecological site are typically very deep (greater than 60 inches), well drained, and derived from alluvium. The soil textures are typically loam, sandy loam, or silt loam.
Associated sites
R058AY727MT |
Loamy 15-19 This site occurs on nearly level to gently sloping positions upslope from and commonly surrounding the Woody Draw ecological site. It is typically found in summit positions where slopes are less than 15 percent and depth to bedrock is greater than 20 inches. |
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R058AY728MT |
Loamy Steep 15-19 This site is generally found is on moderately steep to steep positions adjacent to the Woody Draw ecological site, but in areas that are less sheltered and receive less effective moisture such as south facing slopes or broader, more gently sloped drainageways. |
Similar sites
R058AY720MT |
Swale 10-14 This site differs from the Woody Draw ecological site in that it receives less moisture and is dominated by herbaceous species. Bunchgrasses dominate the site in terms of cover and production. |
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R058AY736MT |
Riparian Woodland 10-19 This site differs from the Woody Draw ecological site in that it is on flood plains rather than upland swales. It generally is on stream terraces adjacent to a perennial stream reach and typically contains riparian species such as sandbar willow and plains cottonwood. |
R058AY727MT |
Loamy 15-19 This site differs from the Woody Draw ecological site in that it is in higher topographical positions that do not receive additional moisture and it does not support woody vegetation whereas the Woody Draw ecological site is in sheltered coulees or swales and supports woody vegetation. |
Table 1. Dominant plant species
Tree |
(1) Fraxinus pennsylvanica |
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Shrub |
(1) Prunus virginiana |
Herbaceous |
Not specified |
Click on box and path labels to scroll to the respective text.
Ecosystem states
T1A | - | Stand-replacing event in combination with prolonged improper grazing management |
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T1B | - | Prolonged improper grazing management |
R2A | - | Proper grazing management, tree/shrub planting, intensive weed management (management intensive and costly) |
R3A | - | Proper grazing management, tree/shrub planting, intensive weed management (management intensive and costly) |
State 1 submodel, plant communities
1.1A | - | Stand-replacing event (wildfire, prescribed fire, or biological processes) |
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1.1B | - | Improper grazing management |
1.2A | - | Lack of disturbance, tree regeneration, and woody plant regrowth |
1.3A | - | Proper grazing management |