Natural Resources
Conservation Service
Ecological site R053AY703MT
Discharge Closed Depression (CdD)
Last updated: 11/22/2023
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): 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 to 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
NRCS Soil Geography Hierarchy
• Land Resource Region: Northern Great Plains
• Major Land Resource Area (MLRA): 053A Northern Dark Brown Glaciated Plains
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: Shrub and Herb Wetland Subclass (2.C)
• Formation: Salt Marsh Formation (2.C.5)
• Division: Distichlis spicata - Hordeum jubatum Great Plains Saline Marsh Division (2.C.5.Na)
• Macrogroup: Great Plains Saline Wet Meadow and Marsh Macrogroup (2.C.5.Na.1)
• Group: Distichlis spicata - Hordeum jubatum - Pascopyrum smithii Great Plains Saline Wet Meadow and Marsh Group (2.C.5.Na.1.a)
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)
USFWS (Cowardin et al., 1979)
• Palustrine Emergent Temporarily Flooded and Palustrine Emergent Seasonally Flooded
Classification of natural ponds and lakes in the Glaciated Prairie Region (Stewart and Kantrud, 1971)
• Ephemeral Pond, Temporary Pond, and Seasonal Pond
Ecological site concept
Discharge Closed Depression is a somewhat extensive ecological site occurring in depressions on till plains and moraines. The distinguishing characteristics of this ecological site are that it is located in closed depression landforms, receives groundwater discharge as well as surface runoff from adjacent uplands, and contains hydric soils. The ponding duration is typically temporary or seasonal, however, it is highly variable depending on catchment size and annual precipitation. Soils for this ecological site are typically very deep (more than 60 inches), poorly drained, derived from alluvium, and are frequently very slightly to slightly saline. Characteristic vegetation is western wheatgrass (Pascopyrum smithii), inland saltgrass (Distichlis spicata), and foxtail barley (Hordeum jubatum).
Associated sites
R053AY706MT |
Loamy (Lo) The Loamy ecological site is in uplands surrounding the Discharge Closed Depression ecological site on till plains and moraines. It contributes surface water to the Discharge Closed Depression ecological site. |
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R053AY708MT |
Loamy Steep (LoStp) The Loamy Steep ecological site is on slopes greater than 15 percent surrounding the Discharge Closed Depression ecological site on till plains and moraines. It contributes surface water to the Discharge Closed Depression ecological site. |
R053AY711MT |
Recharge Closed Depression (CdR) The Recharge Closed Depression ecological site is on similar landforms as the Discharge Closed Depression ecological site. It typically is found in higher topographic positions and is the primary source of groundwater for the Discharge Closed Depression ecological site. |
R053AY720MT |
Swale (Se) The Swale ecological site is in upland coulees and swales. It is typically upslope from the Discharge Closed Depression ecological site on till plains and moraines. It contributes surface water to the Discharge Closed Depression ecological site. |
Similar sites
R053AY718MT |
Slough (Sl) The Slough ecological site is on flood plains, usually in oxbows or channels where flooding is very frequent and a water table is shallow and persistant. Its hydroperiod is typically much longer than that of the Discharge Closed Depression ecological site. This site typically contains deep marsh vegetation. |
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R053AY709MT |
Overflow (Ov) The Overflow ecological site is on flood plains, usually on higher terraces that receive additional moisture from runoff and stream overflow. Vegetation is dominated by facultative upland species. |
R053AY711MT |
Recharge Closed Depression (CdR) The Recharge Closed Depression ecological site differs from the Discharge Closed Depression ecological site in that it receives its moisture primarily from surface runoff rather than groundwater discharge. Water and soils are typically non-saline and vegetation is more diverse. A wide variety of sedges, spikerushes, and grasses are present. |
Table 1. Dominant plant species
Tree |
Not specified |
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Shrub |
Not specified |
Herbaceous |
(1) Pascopyrum smithii |
Click on box and path labels to scroll to the respective text.
Ecosystem states
States 2, 5 and 6 (additional transitions)
T1A | - | Introduction of non-native invasive species such as introduced gasses, forbs, or noxious weeds. |
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T2C | - | Displacement of native species by invasive species (introduced grasses, noxious weeds, etc.) |
T2A | - | Tillage or herbicide application and seeding of annual crops |
T2B | - | Artificial impoundment of water |
T2D | - | Artificial drainage, tillage or herbicide application, and seeding of annual crops |
T3A | - | Tillage or herbicide application and seeding of annual crops |
T3B | - | Artificial impoundment of water |
R4B | - | Cessation of annual cropping combined with reestablishment of native species |
T4A | - | Cessation of annual cropping combined with introduction of invasive species |
R5A | - | Restoration of natural hydrology and reestablishment of native species (labor intensive and costly) |
R6A | - | Restoration of natural hydrology and reestablishment of native species (labor intensive and costly) |
State 1 submodel, plant communities
P1.1a | - | 2 to 3 consecutive years of above average precipitation. |
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P1.2a | - | Drought |
P1.2b | - | 2 to 3 consecutive years of above average precipitation: larger catchment area. |
P1.3a | - | Drought |
State 2 submodel, plant communities
P2.1a | - | 2 to 3 consecutive years of above average precipitation |
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P2.2a | - | Drought |
P2.2b | - | 2 to 3 consecutive years of above average precipitation: larger catchment area |
P2.3a | - | Drought |
State 3 submodel, plant communities
State 4 submodel, plant communities
P4.1a | - | 1 more years of above average precipitation. |
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P4.2a | - | Average or below average precipitation |