Natural Resources
Conservation Service
Ecological site R058AY730MT
Ponderosa Pine 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: 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: Rocky Mountain Forest and Woodland Division (1.B.2.Nb)
• Macrogroup: Central Rocky Mountain Dry Lower Montane-Foothill Forest (1.B.2.Nb.2)
• Group: Black Hills-Northwestern Great Plains Ponderosa Pine Forest and Woodland (1.B.2.Nb.2.e)
• Alliance: Northwest Great Plains Ponderosa Pine Open Woodland
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 primarily on ridges, hills, and escarpments at elevations ranging from 1,900 to 3,500 feet and on slopes ranging from 5 to 60 percent. Occurrences are generally on east and north facing aspects, but aspect may vary. The soils of this ecological site range from shallow to very deep, but the majority are typically shallow to moderately deep. Soil textures on this ecological site vary widely and may range from loamy sands or sandy loams to clay loam or clay.
Associated sites
R058AY726MT |
Woody Draw 15-19 This site occurs on moderate to steeply sloping hillslopes adjacent to and downslope from the Ponderosa Pine ecological site. It occurs in steep, v-shaped swales that receive additional moisture from run-in. |
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R058AY733MT |
Shallow 15-19 This site occurs on nearly level to steeply sloping uplands that are adjacent to or upslope from the Ponderosa Pine ecological site. It occurs on upper backslope, crest, or summit positions where soils are 10 to 20 inches deep. |
R058AY735MT |
Very Shallow 15-19 This site occurs on nearly level to steeply sloping uplands that are adjacent to or upslope from the Ponderosa Pine ecological site. It occurs on upper backslope, crest, or summit positions where soils are less than 10 inches deep and is often associated with rock outcrops. |
Similar sites
R058AY701MT |
Clayey 10-14 This site differs from the Ponderosa Pine ecological site in that soils receive additional moisture from run-in and support primarily deciduous vegetation. |
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R058AY715MT |
Sandy 10-14 This site differs from the Ponderosa Pine ecological site in that it occurs where soils are drier and do not support on overstory of trees. It typically occurs on south and west aspects, but aspect may vary. |
Table 1. Dominant plant species
Tree |
(1) Pinus ponderosa |
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Shrub |
Not specified |
Herbaceous |
(1) Pseudoroegneria spicata |
Click on box and path labels to scroll to the respective text.
T1A | - | Intensive Fire Suppression |
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T1B | - | High Intensity, Stand Replacing Fire |
R2A | - | Aggressive thinning and removal of trees (Brush Management, harvesting, etc.), Prescribed Fire, Herbaceous Weed Control (management intensive and costly) |
T2A | - | High Intensity, Stand Replacing Fire |
T3C | - | Long-term tree regrowth and return to historic fire frequency/intensity |
T3A | - | Prolonged drought, Improper grazing management, or a combination of these factors |
T3B | - | Displacement of native species by non-native invasive species (Kentucky bluegrass, annual bromes, noxious weeds, etc.) |
R4A | - | Proper grazing management in combination with range planting, intensive weed management (management intensive and costly) |
State 1 submodel, plant communities
1.2A | - | Tree growth in combination with periodic low intensity fire |
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1.3A | - | Tree growth in combination with periodic low intensity fire |
State 2 submodel, plant communities
2.1A | - | Long term fire suppression, tree growth, and shrub encroachment |
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