Natural Resources
Conservation Service
Ecological site R053AY712MT
Riparian Woodland (RW)
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 mixed grass 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 Tree Vegetation Class (1)
• Subclass: Temperate & Boreal Forest & Woodland Subclass (1.B)
• Formation: Temperate Flooded & Swamp Forest Formation (1.B.3)
• Division: Populus deltoides - Fraxinus pennsylvanica - Acer saccharinum Flooded & Swamp Forest Division (1.B.3.Na)
• Macrogroup: Populus deltoides - Fraxinus pennsylvanica / Salix spp. Flooded Forest Macrogroup (1.B.3.Na.4)
• Group: Populus deltoides - Fraxinus pennsylvanica / Pascopyrum smithii Floodplain Forest
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
Riparian Woodland is a common, extremely dynamic ecological site occurring flood plains and stream terraces. The distinguishing characteristics of this site are that it is located on flood plains and that it supports woody vegetation. Channel migration across the flood plain results in a continual cycle of erosion and deposition that drives soil development as well as plant succession. Flooding and sometimes ground water provide additional moisture for plant growth. Depth to a seasonal water table varies depending on the proximity to the channel. Soils for this ecological site are typically very deep (more than 60 inches), well drained, and derived from alluvium. Characteristic vegetation is plains cottonwood (Populus deltoides), redosier dogwood (Cornus sericea), western snowberry (Symphoricarpos occidentalis), and willow (Salix spp.). Green ash (Fraxinus pennsylvanica) and box elder (Acer negundo) may also be present in some areas.
Associated sites
R053AY719MT |
Subirrigated (Sb) The Subirrigated site is adjacent to the Riparian Woodland site, typically on lower terraces where ground water is closer to the surface and riparian woody plants are rare or absent. |
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R053AY718MT |
Slough (Sl) The Slough site is adjacent to the Riparian Woodland site, typically in oxbows or channels where flooding is very frequent and a water table is shallow and persistent. |
R053AY713MT |
Saline Lowland (SLL) The Saline Lowland site is adjacent to the Riparian Woodland site, typically on higher terraces and in areas where salts have accumulated due to geology, hydrology, or soil properties. |
R053AY709MT |
Overflow (Ov) The Overflow site is adjacent to the Riparian Woodland site, typically on higher terraces where flooding is less frequent and riparian woody plants are rare or absent. |
Similar sites
R053AY709MT |
Overflow (Ov) This site differs from the Riparian Woodland site in that it occupies higher terraces and is dominated by upland shrubs and herbaceous species. Trees are rare or absent. |
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R053AY719MT |
Subirrigated (Sb) This site differs from the Riparian Woodland site in that it occupies lower terraces. Depth to a water table is 24 to 40 inches. Trees and shrubs are rare or absent. |
R053AY723MT |
Woody Draw (WD) This site differs from the Riparian Woodland site in that it does not receive disturbance from flooding. It is located in upland swales rather than on flood plains, has a higher proportion of facultative shrubs, and typically does not support cottonwoods. |
Table 1. Dominant plant species
Tree |
(1) Populus deltoides ssp. monilifera |
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Shrub |
(1) Cornus sericea |
Herbaceous |
Not specified |
Click on box and path labels to scroll to the respective text.
Ecosystem states
T1A | - | Lack of flooding disturbance, lowered water table, prolonged improper grazing, or a combination of these factors |
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T1C | - | Establishment of invasive tree species (primarily Russian olive) |
T1B | - | Clear cutting, tillage or herbicide application, and seeding of cultivated crops (frequently combined with irrigation practices) |
R2C | - | Proper grazing management, tree/shrub planting, intensive weed management (management intensive and costly) |
T2A | - | Establishment of invasive tree species (primarily Russian olive) |
T2B | - | Clear cutting, tillage or herbicide application, and seeding of cultivated crops (frequently combined with irrigation practices) |
R3A | - | Removal of invasive tree species, sometimes combined with tree/shrub planting (management intensive and costly) |
T3B | - | Clear cutting, tillage or herbicide application, and seeding of cultivated crops (frequently combined with irrigation practices) |
State 1 submodel, plant communities
Communities 1 and 5 (additional pathways)
P1.1a | - | Lack of disturbance, natural plant growth, and bank building |
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P1.2a | - | Flooding, bank scouring, or a combination of these factors |
P1.2b | - | Lack of disturbance, bank building, and lowering of water table |
P1.3b | - | Major flooding or stand-replacing fire in combination with bank scouring/slumping |
P1.3a | - | Lack of disturbance, lowering of water table, cottonwood mortality |
P1.3c | - | Improper grazing management |
P1.4a | - | Major flooding or stand-replacing fire in combination with bank scouring/slumping |
P1.5b | - | Major flooding or stand-replacing fire in combination with bank scouring/slumping |
P1.5a | - | Proper grazing management |