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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 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: Temperate and Boreal Grassland and Shrubland Subclass (2.B)
• Formation: Temperate Grassland and Shrubland Formation (2.B.2)
• Division: Central North American and Shrubland Division (2.B.2.Nb)
o Macrogroup: Hesperostipa comata - Pascopyrum smithii - Festuca hallii Grassland Macrogroup (2.B.2.Nb.2)
Group: Hesperostipa comata - Bouteloua gracilis Dry Mixedgrass Prairie Group (2.B.2.Nb.2.b)
• Alliance: Hesperostipa comata Northwestern Great Plains Grassland Alliance
o Association: Hesperostipa comata - Carex filifolia Grassland
o Macrogroup: Andropogon hallii - Calamovilfa longifolia - Artemisia filifolia Great Plains Sand Grassland & Shrubland Macrogroup (2.B.2.Nb.4)
Group: Andropogon hallii - Calamovilfa longifolia - Hesperostipa comata Sand Grassland Group (2.B.2.Nb.4.b)
• Alliance: Calamovilfa longifolia Sand Prairie Alliance
o Association: Calamovilfa longifolia - Hesperostipa comata Grassland
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
This provisional ecological site is fairly common in MLRA 53A. Figure 1 illustrates the distribution of this ecological site based on current data. This map is approximate, is not intended to be definitive, and may be subject to change. Sandy is a moderately extensive ecological site that occurs on a variety of landscapes from nearly level to moderately steep. This site is characterized by coarse textured soils which typically fall within the coarse-loamy textural family in the upper 4 inches (Soil Survey Staff, 2014). Soils typically have a mollic epipedon and are deeper than 20 inches to a restrictive layer. Characteristic vegetation is needle and thread (Hesperostipa comata), threadleaf sedge (Carex filifolia), and prairie sandreed (Calamovilfa longifolia).
Associated sites
FX053A99X032 Loamy (Lo)
This site occurs adjacent to the Sandy ecological site on similar landforms. It generally occurs in similar landscape positions but occupies areas with fine-loamy textured soils (such as ground moraines) rather than kames or terraces.
FX053A99X040 Loamy Steep (LoStp)
This site occurs on moderate to steeply sloping hillslopes adjacent to or downslope from the Sandy ecological site. It is generally in backslope positions with linear or concave slope shapes and in areas of fine-loamy textured soils.
FX053A99X030 Limy (Ly)
This site occurs adjacent to the Sandy ecological site on similar landforms. It is generally in positions with convex slope shapes and occupies areas with fine-loamy textured soils (such as ground moraines) rather than kames or terraces.
Similar sites
FX053A99X032 Loamy (Lo)
This site differs from the Sandy ecological site in that soils contain more than 18 percent clay in the upper 4 inches. Prairie sandreed does not occur on this site.
FX053A99X030 Limy (Ly)
This site differs from the Sandy ecological site in that soils contain more than 18 percent clay in the upper 4 inches and have greater than 5 percent calcium carbonate in the upper 5 inches (as evidenced by strong or violet effervescence). Prairie sandreed does not occur on this site.
Table 1. Dominant plant species
Tree Not specified
Shrub Not specified
Herbaceous (1) Carex filifolia
(2) Calamovilfa longifoliaLegacy ID
R053AY715MT
Physiographic features
Sandy is an extensive ecological site occurring on a variety of landforms across MLRA 53A, largely in areas where glacial meltwater deposited large amounts of sand. It occurs on kames, moraines, and terraces and can occur on any slope shape or slope position. Slopes are typically less than 25 percent but may be as steep as 45 percent in some areas.
Figure 1. General distribution of the Sandy ecological site by map unit extent.
Table 2. Representative physiographic features
Landforms (1) Till plain > Kame
(2) Till plain > Moraine
(3) Terrace
Flooding frequency None Ponding frequency None Elevation 1800 – 3300 ft Slope 0 – 24 % Aspect Aspect is not a significant factor Table 3. Representative physiographic features (actual ranges)
Flooding frequency Not specified Ponding frequency Not specified Elevation 0 ft Slope 0 – 40 % Climatic features
The Northern Dark Brown Glaciated Plains is a semi-arid region with a temperate continental climate that is characterized by frigid winters and warm to hot summers (Coupland, 1958; Richardson and Hanson, 1977; Heidel et al., 2000). The majority of precipitation occurs as steady, soaking, frontal system rains in late spring to early summer. Summer rainfall comes mainly from convection thunderstorms that typically deliver scattered amounts of rain in intense bursts. These storms may be accompanied by damaging winds and large-diameter hail and result in flash flooding along low-order streams. Approximately 80 percent of the annual precipitation occurs during the growing season. June is the wettest month, followed by July and May (Richardson and Hanson, 1977; Heidel et al., 2000). Average annual precipitation ranges from 11 inches (280 mm) near Richey, Montana, to 15 inches (380 mm) in the Little Muddy drainage near Williston, North Dakota, but precipitation varies greatly from year to year. On average, severe drought and very wet years occur with the same frequency, which is 1 out of 10 years (Coupland, 1958; Heidel et al., 2000). Extreme climatic variations, especially droughts, have the greatest influence on species cover and production (Coupland, 1958, 1961; Biondini et al., 1998). The frost-free period for this ecological site ranges from 90 to 130 days, and the freeze-free period ranges from 115 to 155 days.
Table 4 Representative climatic features
Frost-free period (characteristic range) 90-130 days Freeze-free period (characteristic range) 120-160 days Precipitation total (characteristic range) 10-20 in Frost-free period (average) 110 days Freeze-free period (average) 140 days Precipitation total (average) 10 in BarLineFigure 2. Monthly precipitation range
BarLineFigure 3. Monthly average minimum and maximum temperature
Figure 4. Annual precipitation pattern
Figure 5 Annual average temperature pattern
Climate stations used
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(1) CULBERTSON [USC00242122], Culbertson, MT
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(2) OPHEIM 10 N [USC00246236], Opheim, MT
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(3) OPHEIM 12 SSE [USC00246238], Opheim, MT
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(4) PLENTYWOOD [USC00246586], Plentywood, MT
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(5) SCOBEY 4 NW [USC00247425], Scobey, MT
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(6) SIDNEY [USC00247560], Sidney, MT
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(7) VIDA 6 NE [USC00248569], Vida, MT
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(8) WILLISTON SLOULIN INTL AP [USW00094014], Williston, ND
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(9) BREDETTE [USC00241088], Poplar, MT
">Influencing water features
This is an upland ecological site and is not influenced by a water table or run in from adjacent sites. Due to the semi-arid climate in which it occurs, the water budget is contained within the soil profile for the majority of the year; however, the site does function as a recharge site during the spring. Soil moisture is recharged by spring rains, and recharge of the localized area occurs via deep percolation or surface runoff. For the remainder of the year, soil moisture rarely exceeds field capacity in the upper 40 inches before being depleted by evapotranspiration. Moisture loss through evapotranspiration exceeds precipitation for the majority of the growing season, and soil moisture is the primary limiting factor for plant production on this ecological site.
Soil features
The soil series that best represent the central concept of this ecological site are Dooley and Tally. The Dooley soil is in the Argiustolls great group and is characterized by a relatively dark mollic epipedon and by an underlying argillic horizon where clay has accumulated through weathering. The Tally soil is in the Haplustolls great group and is characterized by a relatively dark mollic epipedon and an underlying cambic horizon where pedogenic development is present but minimal. The parent material for both of these soils is typically alluvium or glaciofluvial deposits, and they both have mixed minerology. The Dooley soil is in the fine-loamy family, meaning that it contains between 18 and 35 percent clay in the particle-size control section; the Tally soil is in the coarse-loamy family, meaning that it contains 15 percent or more fine sand and less than 18 percent clay. The soil moisture regime for all soils in this ecological site concept is typic ustic, which means that the soils are moist in some or all parts for either 180 cumulative days or 90 consecutive days during the growing season but are dry in some or all parts for over 90 cumulative days. These soils have a frigid soil temperature regime (Soil Survey Staff, 2014).
Surface horizon textures in this site are typically sandy loam or fine sandy loam and contain less than 18 percent clay and less than 70 percent sand. Some sites may have a higher sand content and have textures of loamy sand or loamy fine sand. The underlying horizons typically have loamy fine sand, fine sandy loam, or sandy clay loam textures and contain 10 to 30 percent clay and 55 to 70 percent sand. Organic matter content in the surface horizon typically ranges from 0.25 to 1.25 percent, and moist colors vary from olive brown (2.5Y 4/3) to very dark grayish brown (10YR 3/2). The upper 5 inches of these soils sometimes reacts strongly or violently with hydrochloric acid. The calcium carbonate equivalent in the upper 5 inches is typically 5 percent or less but may be as high as 10 percent in some areas. Soil pH classes are neutral to slightly alkaline in the surface horizon and neutral to moderately alkaline in the subsurface horizons. The soil depth class for this site can be moderately deep (between 20 to 40 inches to bedrock) where bedrock is present but is typically very deep. The upper 20 inches of soil generally does not contain coarse fragments.Table 5. Representative soil features
Parent material (1) Alluvium
(2) Glaciofluvial deposits
Surface texture (1) Sandy loam
(2) Fine sandy loam
Drainage class Well drained Soil depth 20 – 72 in Available water capacity
(0-40in)4.9 – 6.6 in Calcium carbonate equivalent
(0-5in)0 – 10 % Electrical conductivity
(0-20in)0 – 3 mmhos/cm Sodium adsorption ratio
(0-20in)0 – 12 Soil reaction (1:1 water)
(0-40in)6.6 – 8.4 Subsurface fragment volume <=3"
(0-20in)0 – 34 % Subsurface fragment volume >3"
(0-20in)0 – 34 % Ecological dynamics
The information in this ecological site description, including the state-and-transition model (STM), was developed based on historical data, current field data, professional experience, and a review of the scientific literature. As a result, all possible scenarios or plant species may not be included. Key indicator plant species, disturbances, and ecological processes are described to inform land management decisions.
The Sandy provisional ecological site in MLRA 53A consists of six states: the Historic Reference state (1), the Current Potential state (2), the Shortgrass state (3), the Invaded state (4), the Cropland state (5), and the Post Cropland state (6). Plant communities associated with this ecological site evolved under the combined influences of climate, grazing, and fire. Extreme climatic variability results in frequent droughts, which have the greatest influence on the relative contribution of species cover and production (Coupland, 1958, 1961; Biondini et al., 1998). Due to the dominance of cool-season graminoids, annual production is highly dependent upon mid- to late-spring precipitation (Heitschmidt and Vermeire, 2005; Anderson, 2006).
The historic ecosystem experienced periodic lightning-caused fires with estimated fire return intervals of 6 to 25 years (Bragg, 1995). Historically, Native Americans also set periodic fires. The majority of lightning-caused fires occurred in July and August, whereas Native Americans typically set fires during spring and fall to correspond with the movement of bison (Higgins, 1986). The precise effects of the historic fire return interval are not definitive, but in general the mixed-grass ecosystem was resilient to fire. Potential effects are generally temporary and may include reduction of litter, fluctuations in production, and changes in species composition (Vermeire et al., 2011, 2014).
Native grazers also shaped these plant communities. American bison (Bison bison) were the dominant historic grazer, but pronghorn (Antilocapra americana), elk (Cervus canadensis), and deer (Odocoileus spp.) were also common. Additionally, small mammals such as prairie dogs (Cynomys spp.) and ground squirrels (Urocitellus spp.) influenced this plant community (Salo et al., 2004). Grasshoppers and periodic outbreaks of Rocky Mountain locusts (Melanoplus spretus) also played an important role in the ecology of these communities (Lockwood, 2004). The mixed-grass ecosystem was resilient to grazing, although localized areas could experience shifts in species composition due to heavy grazing.
Following European settlement, fire was largely eliminated, domestic livestock replaced native ungulates as the primary grazers, and non-native species were introduced to the ecosystem. Aside from drought, livestock grazing is now the principle disturbance on the landscape.
Improper grazing of this site can result in a reduction in the cover of the mid-statured grasses and an increase in shortgrasses such as blue grama (Bouteloua gracilis) (Smoliak et al., 1972; Smoliak, 1974). Eventually, improper grazing may also begin to reduce sedges. Improper grazing practices include any practices that do not allow sufficient opportunity for plants to physiologically recover from a grazing event or multiple grazing events within a given year and/or that do not provide adequate cover to prevent soil erosion over time. These practices may include, but are not limited to, overstocking, continuous grazing, and/or inadequate seasonal rotation moves over multiple years. Periods of extended drought (approximately 3 years or more) may have similar effects (Coupland, 1958, 1961). Further degradation of the site due to improper grazing can result in a community dominated by shortgrasses such as blue grama and prairie Junegrass (Koeleria cristata).
Most, if not all, extant examples of this site have some degree of invasion by non-native species. Non-native grasses, particularly crested wheatgrass (Agropyron cristatum), are the most common invasive species. Seeding of crested wheatgrass was a common practice on eroded and abandoned agricultural areas after the droughts of the 1930s (Rogler and Lorenz, 1983). It is a highly drought-tolerant and competitive cool-season, perennial bunchgrass that can invade relatively undisturbed grasslands (Lesica and DeLuca, 1996; Heidinga and Wilson, 2002; Henderson and Naeth, 2005). In most cases native ecological function is relatively intact, but in some cases non-native grasses will displace native species and dominate the ecological functions of the site.
The effects of an altered fire regime are not completely understood at the time of this writing, but evidence suggests that long-term fire suppression can result in accumulations of litter and may contribute to increased abundance of non-native grasses (Vermeire et al., 2011; Whisenant, 1990). Conversely, fire return intervals of less than 6 years, such as annual burning, can reduce productivity and shift species composition toward warm-season, short-statured grasses (Shay et al., 2001; Smith and McDermid, 2014).
Due to the coarse soil textures and the reduced water-holding capacity, this ecological site is not generally regarded as productive cropland. Regardless, many acres have been cultivated and planted to cereal grain crops, such as winter wheat, spring wheat, and barley. When taken out of production, this site is either allowed to revert back to perennial grassland or is seeded back to perennial grass. Such seedings may be comprised of introduced grasses and legumes or a mix of native species. Sites left to undergo natural plant succession after cultivation can, over several decades, support native vegetation similar to the Reference State (1) (Christian and Wilson, 1999) although it may take over 75 years for soil organic matter to return to its pre-disturbed state (Dormaar et al., 1990). Without vegetative cover, this ecological site is very susceptible to wind erosion and severe loss of topsoil is possible. Under such circumstances, a return to the reference conditions in a reasonable amount of time is unlikely. Sites seeded with non-native species may persist with this cover type indefinitely (Christian and Wilson, 1999). A mix of native species may also be seeded; however, a return to the Reference State (1) in a reasonable amount of time is unlikely.
The state-and-transition model (STM) (Figure 2) suggests possible pathways that plant communities on this site may follow as a result of a given set of ecological processes and management. The site may also support states not displayed in the STM diagram. Landowners and land managers should seek guidance from local professionals before prescribing a particular management or treatment scenario. Plant community responses vary across this MLRA due to variability in weather, soils, and aspect. The reference community phase may not necessarily be the management goal. The lists of plant species and species composition values are provisional and are not intended to cover the full range of conditions, species, and responses for the site. Species composition by dry weight is provided when available and is considered provisional based on the sources identified in the narratives associated with each community phase.State and transition model
More interactive model formats are also available. View Interactive Models
Click on state and transition labels to scroll to the respective textEcosystem states
States 2 and 5 (additional transitions)
T1A - Introduction of non-native grass species, such crested wheatgrass. 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.) T2C - Conversion to cropland R3A - Range seeding, grazing land mechanical treatment, timely moisture, proper grazing management (management intensive and costly) T3B - Conversion to cropland T4A - Conversion to cropland T5A - Cessation of annual cropping T6A - Conversion to cropland State 1 submodel, plant communities
State 2 submodel, plant communities
2.1A - Drought, improper grazing management 2.2A - Return to normal or above average precipitation, proper grazing management State 3 submodel, plant communities
State 4 submodel, plant communities
State 5 submodel, plant communities
State 6 submodel, plant communities
State 1
Historic ReferenceThe Historic Reference state (1) contains one community phase characterized by mid-statured bunchgrasses, sedges, and, in some areas, mid-statured, warm-season grasses. This state is considered extinct and is included here for historical reference purposes. It evolved under the combined influences of climate, grazing, and fire, with climatic variation having the greatest influence on cover and production. In general, this state was resilient to grazing; however, localized areas likely received heavy grazing, which resulted in the species composition shifting to short-statured species. Fire most likely resulted in short-term shifts in species composition to more warm-season grasses such as blue grama and fewer cool-season bunchgrasses.
Community 1.1
Mixedgrass CommunityThe Mixedgrass Community Phase (1.1) was characterized by mid-statured bunchgrasses, sedges, and, in some areas, mid-statured warm-season grasses. The predominant species were needle and thread and threadleaf sedge. Western wheatgrass (Pascopyrum smithii) was typically uncommon on coarser soil textures; however, it increased in abundance as soil textures became finer. Prairie sandreed became common with coarser soil textures, typically replacing western wheatgrass. The mat-forming, warm-season, perennial grass blue grama and prairie Junegrass were the predominant shortgrasses (Coupland, 1950, 1961). Forbs comprised about 10 percent of the cover, but shrubs were rare on this site.
State 2
Current PotentialThe Current Potential state (2) contains two community phases characterized by mid-statured bunchgrasses, sedges, and, in some areas, mid-statured, warm-season grasses. It evolved under the combined influences of climate, grazing, and fire, with climatic variation having the greatest influence on cover and production. This state differs from the historical reference state in that it is influenced by introduced plant species and has altered fire and grazing regimes. In general, this state is resilient to grazing and fire, although these factors can influence species composition in localized areas. Lesser spikemoss, also known as dense clubmoss (Selaginella densa), is typically absent on this site but may occur in some areas; its dynamics on this site are not well understood.
Community 2.1
Mixedgrass – Introduced Grass CommunityThe Mixedgrass – Introduced Grass Community Phase (2.1) is predominantly native species, but it has some degree of non-native grass establishment. The predominant species are needle and thread and threadleaf sedge. Prairie sandreed is also common on coarse soil textures, but it is gradually replaced by rhizomatous wheatgrasses as soil textures become finer. Blue grama and prairie Junegrass are the predominant shorgrasses. Common forbs are spiny phlox (Phlox hoodii), scarlet globemallow (Sphaeralcea coccinea), and hairy false goldenaster (Heterotheca villosa). Shrubs and subshrubs are rare on this site. On finer textured soils, prairie sagewort (Artemisia frigida) can make up about 5 percent of the cover. However, coarser soil textures typically only support trace amounts of prairie rose (Rosa arkansana). Non-native species such as crested wheatgrass typically comprise 1 to 3 percent of the plant community. The approximate species composition of this plant community is as follows:
Percent composition by weight*
Needle and Thread - 25-35%
Threadleaf Sedge - 15-25%
Prairie Sandreed - 0-10%
Rhizomatous Wheatgrass - 5-15%
Blue Grama - 10-15%
Other Native Grasses - 10%
Perennial Forbs - 10%
Shrubs/Subshrubs - 1-5%
Non-native grasses - 1-3%
Estimated Total Annual Production (lbs./ac)*
Low - Insufficient data
Representative Value - 750
High - Insufficient data
*Estimated based on current data – subject to revisionCommunity 2.2
At-Risk CommunityThe At-Risk Community Phase (2.2) occurs when site conditions decline due to drought or improper grazing management. It is characterized by an increase in sedges, particularly threadleaf sedge, and a decline in needle and thread. Shortgrasses such as blue grama and prairie Junegrass are also increasing. When present, prairie sandreed may also increase in this phase. Mid-statured grasses are in decline and have been substantially reduced in both cover and vigor.
Pathway 2.1A
Community 2.1 to 2.2Drought, improper grazing management, or a combination of these factors can shift the Mixedgrass – Introduced Grass Community Phase (2.1) to the At-Risk Community Phase (2.2). These factors favor an increase in shortgrasses such as blue grama and a decrease in midgrasses (Coupland, 1961).
Key drivers
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Livestock grazing or browsing
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Precipitation (annual scale)
Pathway 2.2A
Community 2.2 to 2.1Normal or above-normal spring precipitation and proper grazing management transition the At-Risk Community (2.2) back to the Mixedgrass – Introduced Grass Community (2.1).
Key drivers
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Livestock grazing or browsing
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Precipitation (annual scale)
State 3
ShortgrassThe Shortgrass state (3) consists of one community phase. The dynamics of this state are driven by long-term drought, improper grazing management, or a combination of these factors. Shortgrasses increase with long-term improper grazing at the expense of cool-season midgrasses (Coupland, 1961; Biondini and Manske, 1996). In particular, communities of blue grama can alter soil properties, creating conditions that resist establishment of other grass species (Dormaar and Willms, 1990; Dormaar et al., 1994). Reductions in stocking rates can reduce shortgrass cover and increase the cover of cool-season midgrasses, although this recovery may take decades (Dormaar and Willms, 1990; Dormaar et al., 1994).
Community 3.1
Shortgrass-Sedge CommunityThe Shortgrass-Sedge Community Phase (3.1) occurs when site conditions decline due to long-term drought or improper grazing. Mid-statured grasses such as needle and thread and rhizomatous wheatgrasses have been largely eliminated. Short-statured species such as blue grama and prairie Junegrass dominate the plant community. Threadleaf sedge may persist due to its low stature and extensive root system; however, its vigor is declining due to grazing pressure. The subshrub prairie sagewort may also be common. Erosional patterns and plant pedestals are evident.
State 4
InvadedThe Invaded state (4) occurs when invasive plant species invade adjacent native grassland communities and displace the native species. Data suggest that native species diversity declines significantly when invasive species exceed 30 percent of the plant community. The non-native perennial grass crested wheatgrass is the greatest concern on this ecological site. Crested wheatgrass has been planted on an estimated 20 million acres in the western U.S. since the 1930s (Holechek, 1981). It is extremely drought tolerant, establishes readily on a variety of soil types, has high seedling vigor, and can dominate the seedbank of invaded grasslands (Rogler and Lorenz, 1983; Henderson and Naeth, 2005). Plant communities dominated by crested wheatgrass have significantly less cover of native grass and forb species (Heidinga and Wilson, 2002). Invasive grass species can invade relatively undisturbed grasslands, and it is not clear what triggers them to displace native species. Proximity to seeded areas is likely a major contributing factor as crested wheatgrass cover decreases with increasing distance from seeded areas (Heidinga and Wilson, 2002). Reduced plant species diversity, simplified structural complexity, and altered biologic processes result in a state that is substantially departed from both the Reference state (1) and the Current Potential state (2).
Noxious weeds such as leafy spurge are not widespread in MLRA 53A, but they can be a concern in localized areas. These species are very aggressive perennials. They typically displace native species and dominate ecological function when they invade a site. In some cases, these species can be suppressed through intensive management (herbicide application, biological control, or intensive grazing management). Control efforts are unlikely to eliminate noxious weeds, but their density can be sufficiently suppressed so that species composition and structural complexity are similar to that of the Current Potential state (2). However, cessation of control methods will most likely result in recolonization of the site by the noxious species.Community 4.1
Invaded CommunityEncroachment by introduced grasses, noxious weeds, and other invasive species is common. Rangeland health attributes have departed substantially from both the Reference State (1) and the Contemporary Reference State (2).
State 5
CroplandThe Cropland State (5) occurs when land is put into cultivation. Major crops in MLRA 53A are small grains such as wheat.
Community 5.1
Cropland CommunityAnnual, cool-season cereal grains, such as spring wheat, winter wheat, and barley, are the most common crops.
State 6
Post CroplandThe Post Cropland state (6) occurs when cultivated cropland is abandoned and allowed to either revegetate naturally or is seeded back to perennial species for grazing or wildlife use. This state can transition back to the Cropland state (5) if the site is put back into cultivation.
Community 6.1
Abandoned Cropland CommunityThe Abandoned Cropland Community Phase (6.1) typically occurs when cropland is abandoned with no further management. It may also occur when cropland is abandoned and then seeded to perennial forage species and the reseeding fails. In the absence of active management, the site can revegetate naturally and, over time, potentially return to a perennial grassland community with needle and thread, blue grama, and possibly prairie sandreed. Shortly after cropland is abandoned, annual and biennial forbs and annual brome grasses invade the site (Samuel and Hart, 1994). The site is extremely susceptible to erosion due to the absence of perennial species and the coarse soil textures. Eventually, the pioneering annual species are replaced by perennial forbs and pioneering grasses such as blue grama and prairie sandreed. Depending on the historical management of the site, perennial bunchgrasses such as needle and thread may also return; however, species composition will depend upon the seed bank. Invasion of the site by exotic species, such as crested wheatgrass, will depend upon the site’s proximity to a seed source. Fifty or more years after cultivation, these sites may have species composition similar to phases in the Contemporary Reference State (2). However, soil quality is consistently lower than under conditions prior to cultivation and a shift to the Contemporary Reference State (2) is unlikely within a reasonable time frame (Dormaar and Smoliak, 1985; Christian and Wilson, 1999).
Community 6.2
Perennial Grass CommunityThe Perennial Grass Community Phase (6.2) occurs when the site is seeded to perennial species for livestock forage or wildlife cover. Seedings typically are comprised of introduced species such as intermediate wheatgrass (Thinopyrum intermedium) and alfalfa (Medicago sativa), which can persist for several decades. Aggressive species such as crested wheatgrass can form monocultures persisting for at least 60 years (Krzic et al., 2000; Henderson and Naeth, 2005) and can invade adjacent sites if conditions are favorable. A mixture of native species may also be seeded to provide species composition and structural complexity similar to those of the Contemporary Reference State (2). However, soil quality conditions have been substantially altered and will not return to pre-cultivation conditions within a reasonable time frame (Dormaar et al., 1990).
Transition T1A
State 1 to 2Introduction of non-native grass species occurred in the early 20th century. The naturalization of these species in relatively undisturbed grasslands, coupled with changes in fire and grazing regimes, transitions the Reference state (1) to the Current Potential state (2).
Key drivers
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Nonnative plant species presence and/or establishment
Transition T2A
State 2 to 3Prolonged drought, improper grazing practices, or a combination of these factors weaken the resilience of the Current Potential state (2) and drive its transition to the Shortgrass state (3). The Current Potential state (2) transitions to the Shortgrass state (3) when mid-statured grasses become rare and contribute little to production. Shortgrasses such as blue grama and prairie Junegrass dominate the plant community.
Key drivers
-
Precipitation (decadal scale)
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Livestock grazing or browsing
Transition T2B
State 2 to 4The Current Potential state (2) transitions to the Invaded state (4) when aggressive perennial grasses or noxious weeds displace native species. The most common concerns are crested wheatgrass and introduced bluegrasses, which are widespread invasive species in the Northern Great Plains (Henderson and Naeth, 2005; Toledo et al., 2014). The precise triggers of this transition are not clear, but data suggest that exclusion of grazing and fire may be a contributing factor in some cases (DeKeyser et al., 2013). In addition, other rangeland health attributes, such as reproductive capacity of native grasses and soil quality, have been substantially altered.
Key drivers
-
Nonnative plant species presence and/or establishment
Transition T2C
State 2 to 5Tillage or application of herbicide followed by seeding of cultivated crops, such as winter wheat, spring wheat, and barley, transitions the Current Potential state (2) to the Cropland state (5).
Restoration pathway R3A
State 3 to 2A reduction in livestock grazing pressure alone may not be sufficient to reduce the cover of shortgrasses in the Shortgrass state (3) (Dormaar and Willms, 1990). Blue grama, in particular, can resist displacement by other species (Dormaar and Willms, 1990; Laycock, 1991; Dormaar et al., 1994; Lacey et al., 1995). Intensive management treatments may be necessary (Hart et al., 1985), but practices such as mechanical treatment of grazing land and range seeding should be used with caution on this site due to its susceptibility to wind erosion. Therefore, returning the Shortgrass State (3) to the Contemporary Reference State (2) may require considerable energy and cost, and may not be feasible within a reasonable amount of time.
Transition T3B
State 3 to 5Tillage or application of herbicide followed by seeding of cultivated crops, such as winter wheat, spring wheat, and barley, transitions the Shortgrass state (3) to the Cropland state (5).
Transition T4A
State 4 to 5Tillage or application of herbicide followed by seeding of cultivated crops, such as winter wheat, spring wheat, and barley, transitions the Invaded state (4) to the Cropland state (5).
Transition T5A
State 5 to 6The transition from the Cropland state (5) to the Post Cropland state (6) occurs with the cessation of cultivation. The site may also be seeded to perennial forage species. Such seedings may be comprised of introduced grasses and legumes or a mix of native species.
Transition T6A
State 6 to 5Tillage or application of herbicide followed by seeding of cultivated crops, such as winter wheat, spring wheat, and barley, transitions the Post Cropland state (6) to the Cropland state (5).
Additional community tables
Table 6. Community 1.1 plant community composition
Group Common name Symbol Scientific name Annual production () Foliar cover (%) Table 7. Community 2.1 plant community composition
Group Common name Symbol Scientific name Annual production () Foliar cover (%) Table 8. Community 2.2 plant community composition
Group Common name Symbol Scientific name Annual production () Foliar cover (%) Table 9. Community 3.1 plant community composition
Group Common name Symbol Scientific name Annual production () Foliar cover (%) Table 10. Community 4.1 plant community composition
Group Common name Symbol Scientific name Annual production () Foliar cover (%) Table 11. Community 5.1 plant community composition
Group Common name Symbol Scientific name Annual production () Foliar cover (%) Table 12. Community 6.1 plant community composition
Group Common name Symbol Scientific name Annual production () Foliar cover (%) Table 13. Community 6.2 plant community composition
Group Common name Symbol Scientific name Annual production () Foliar cover (%) Interpretations
Supporting information
Inventory data references
Data for this provisional ecological site was obtained from two low-intensity plots and four medium-intensity plots representing the Contemporary Reference State (2). These plots were used in conjunction with a review of the scientific literature and professional experience to approximate the plant communities for this state. Information for remaining states was obtained from professional experience and a review of the scientific literature. All community phases are considered provisional based on these plots and the sources identified in this ecological site description.
Other references
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Biondini, M.E., and L. Manske. 1996. Grazing frequency and ecosystem processes in a northern mixed prairie, USA. Ecological Applications 6:239-256.
Biondini, M.E., B.D. Patton, and P.E. Nyren. 1998. Grazing intensity and ecosystem processes in a northern mixed-grass prairie, USA. Ecological Applications 8:469-479.
Bragg, T.B. 1995. The physical environment of the Great Plains grasslands. In: A. Joern and K.H. Keeler (eds.) The Changing Prairie, Oxford University Press, Oxford, pp. 49-81.
Christian, J.M., and S.D. Wilson. 1999. Long-term ecosystem impacts of an introduced grass in the Northern Great Plains. Ecology 80:2397-2407.
Clarke, S.E, E.W. Tisdale, and N.A. Skoglund. 1947. The effects of climate and grazing practices on short-grass prairie vegetation in southern Alberta and southwestern Saskatchewan. Canadian Department of Agriculture Technical Bulletin No. 46.
Cleland, D.T., et al. 1997. National hierarchical framework of ecological units. In: M.S. Boyce and A. Haney (eds.) Ecosystem Management Applications for Sustainable Forest and Wildlife Resources, Yale University Press, New Haven, CT.
Coupland, R.T. 1950. Ecology of the mixed prairie of Canada. Ecological Monographs 20:271-315.
Coupland, R.T. 1958. The effects of fluctuations in weather upon the grasslands of the Great Plains. Botanical Review 24:273-317.
Coupland, R.T. 1961. A reconsideration of grassland classification in the Northern Great Plains of North America. Journal of Ecology 49:135-167.
Coupland, R.T., and R.E. Johnson. 1965. Rooting characteristics of native grassland species in Saskatchewan. Journal of Ecology 53:475-507.
Derner, J.D., and R.H. Hart. 2007. Grazing-induced modifications to peak standing crop in northern mixed-grass prairie. Rangeland Ecology and Management 60:270-276.
Dix, R.L. 1960. The effects of burning on the mulch structure and species composition of grasslands in western North Dakota. Ecology 41:49-56.
Dormaar, J.F., and S. Smoliak. 1985. Recovery of vegetative cover and soil organic matter during revegetation of abandoned farmland in a semiarid climate. Journal of Range Management 38:487-491.
Dormaar, J.F., and W.D. Willms. 1990. Effect of grazing and cultivation on some chemical properties of soils in the mixed prairie. Journal of Range Management 43:456-460.
Dormaar, J.F., S. Smoliak, and W.D. Willms. 1990. Soil chemical properties during succession from abandoned cropland to native range. Journal of Range Management 43:260-265.
Dormaar, J.F., B.W. Adams, and W.D. Willms. 1994. Effect of grazing and abandoned cultivation on a Stipa-Bouteloua community. Journal of Range Management 47:28-32.
Dormaar, J.F., M.A. Naeth, W.D. Willms, and D.S. Chanasyk. 1995. Effect of native prairie, crested wheatgrass (Agropyron cristatum) and Russian wildrye (Elymus junceus) on soil chemical properties. Journal of Range Management 48:258-263.
Federal Geographic Data Committee. 2008. The National Vegetation Classification Standard, Version 2. FGDC Vegetation Subcommittee. FGDC-STD-005-2008 (Version 2), p. 126.
Fullerton, D.S., and R.B. Colton. 1986. Stratigraphy and correlation of the glacial deposits on the Montana Plains. U.S. Geological Survey.
Fullerton, D.S., R.B. Colton, C.A. Bush, and A.W. Straub. 2004. Map showing spatial and temporal relations of mountain and continental glaciations on the northern plains, primarily in northern Montana and northwestern North Dakota. U.S. Geologic Survey pamphlet accompanying Scientific Investigations Map 2843.
Hart, M., S.S. Waller, S.R. Lowry, and R.N. Gates. 1985. Disking and seeding effects on sod bound mixed prairie. Journal of Range Management 38:121-125.
Heidel, B., S.V. Cooper, and C. Jean. 2000. Plant species of special concern and plant associations of Sheridan County, Montana. Report to U.S. Fish and Wildlife Service. Montana Natural Heritage Program, Helena, MT.
Heidinga, L., and S.D. Wilson. 2002. The impact of an invading alien grass (Agropyron cristatum) on species turnover in native prairie. Diversity and Distributions 8:249-258.
Heitschmidt, R.K., and L.T. Vermeire. 2005. An ecological and economic risk avoidance drought management decision support system. In: J.A. Milne (ed.) Pastoral Systems in Marginal Environments, XXth International Grasslands Congress, July 2005, p. 178.
Henderson, A.E., and S.K. Davis. 2014. Rangeland health assessment: A useful tool for linking range management and grassland bird conservation? Rangeland Ecology and Management 67:88-98.
Henderson, D.C., and M.A. Naeth. 2005. Multi-scale impacts of crested wheatgrass invasion in mixed-grass prairie. Biological Invasions 7:639-650.
Herrick, J.E., J.W. Van Zee, K.M. Havstad, L.M. Burkett, and W.G. Whitford. 2009. Monitoring manual for grassland, shrubland and savanna ecosystems. U.S. Department of Agriculture, Agricultural Research Service, Jornada Experimental Range, Las Cruces, NM.
Higgins, K.F. 1986. Interpretation and compendium of historical fire accounts in the Northern Great Plains. U.S. Fish and Wildlife Service Resource Publication 161.
Holechek, J.L. 1981. Crested wheatgrass. Rangelands 3:151-153.
Knopf, F.L. 1996. Prairie legacies—birds. In: F.B. Samson and F.L. Knopf (eds.) Prairie Conservation: Preserving North America’s Most Endangered Ecosystem, Island Press, Washington, DC, pp. 135-148.
Knopf, F.L., and F.B. Samson. 1997. Conservation of grassland vertebrates. In: F.B. Samson and F.L. Knopf (eds.) Ecology and Conservation of Great Plains Vertebrates: Ecological Studies 125, Springer-Verlag, New York, NY, pp. 273-289.
Krzic, M., K. Broersma, D.J. Thompson, and A.A. Bomke. 2000. Soil properties and species diversity of grazed crested wheatgrass and native rangelands. Journal of Range Management 53:353-358.
Lacey, J., R. Carlstrom, and K. Williams. 1995. Chiseling rangeland in Montana. Rangelands 17:164-166.
Laycock, W.A. 1991. Stable states and thresholds of range condition on North American rangelands. Journal of Range Management 44:427-433.
Lesica, P., and T.H. DeLuca. 1996. Long-term harmful effects of crested wheatgrass on Great Plains grassland ecosystems. Journal of Soil and Water Conservation 51:408-409.
Lockwood, J.A. 2004. Locust: The devastating rise and mysterious disappearance of the insect that shaped the American frontier. Basic Books, New York, NY.
McNab, W.H., et al. 2007. Description of ecological subregions: Sections of the conterminous United States [CD-ROM]. USDA Forest Service, General Technical Report WO-76B.
Montana State College. 1949. Similar vegetative rangeland types in Montana. Montana State College, Agricultural Experiment Station.
Nesser, J.A., G.L. Ford, C.L. Maynard, and D.S. Page-Dumroese. 1997. Ecological units of the Northern Region: Subsections. USDA Forest Service, Intermountain Research Station, General Technical Report INT-GTR-369.
Ogle, S.M., W.A. Reiners, and K.G. Gerow. 2003. Impacts of exotic annual brome grasses (Bromus spp.) on ecosystem properties of the northern mixed grass prairie. American Midland Naturalist 149:46-58.
Richardson, R.E., and L.T. Hanson. 1977. Soil survey of Sheridan County, Montana. USDA Soil Conservation Service, Bozeman, MT.
Rogler, G.A., and R.J. Lorenz. 1983. Crested wheatgrass: Early history in the United States. Journal of Range Management 36:91-93.
Romo, J.T. 2011. Clubmoss, precipitation, and microsite effects on emergence of graminoid and forb seedlings in the semiarid Northern Mixed Prairie of North America. Journal of Arid Environments 75:98-105.
Romo, J.T., and Y. Bai. 2004. Seedbank and plant community composition, Mixed Prairie of Saskatchewan. Journal of Range Management 57:300-304.
Rowe, J.S. 1969. Lightning fires in Saskatchewan grassland. Canadian Field Naturalist 83:317-327.
Salo, E.D., et al. 2004. Grazing intensity effects on vegetation, livestock and non-game birds in North Dakota mixed-grass prairie. Proceedings of the 19th North American Prairie Conference, Madison, WI.
Samuel, M.J., and R.H. Hart. 1994. Sixty-one years of secondary succession on rangelands of the Wyoming High Plains. Journal of Range Management 47:184-191.
Schoeneberger, P.J., D.A. Wysocki, E.C. Benham, and Soil Survey Staff. 2012. Field book for describing and sampling soils. Version 3.0. USDA Natural Resources Conservation Service, National Soil Survey Center, Lincoln, NE.
Shay, J., D. Kunec, and B. Dyck. 2001. Short-term effects of fire frequency on vegetation composition and biomass in mixed prairie in south-western Manitoba. Plant Ecology 155:157-167.
Smith, B., and G.J. McDermid. 2014. Examination of fire-related succession within the dry mixed-grass subregion of Alberta with the use of MODIS and Landsat. Rangeland Ecology and Management 67:307-317.
Smoliak, S. 1974. Range vegetation and sheep production at three stocking rates on Stipa-Bouteloua prairie. Journal of Range Management 27:23-26.
Smoliak, S., J.F. Dormaar, and A. Johnston. 1972. Long-term grazing effects on Stipa-Bouteloua prairie soils. Journal of Range Management 25:246-250.
Soil Survey Staff. 2014. Keys to Soil Taxonomy, 12th edition. USDA Natural Resources Conservation Service.
Soller, D.R. 2001. Map showing the thickness and character of Quaternary sediments in the glaciated United States east of the Rocky Mountains. U.S. Geological Survey Miscellaneous Investigations Series I-1970-E, scale 1:3,500,000.
Toledo, D., M. Sanderson, K. Spaeth, J. Hendrickson, and J. Printz. 2014. Extent of Kentucky bluegrass and its effect on native plant species diversity and ecosystem services in the Northern Great Plains of the United States. Invasive Plant Science and Management 7:543-552.
U.S. Department of Agriculture, National Agricultural Statistics Service. 2017. Montana Annual Bulletin, Volume LIV, Issue 1095-7278. https://www.nass.usda.gov/Statistics_by_State/Montana/Publications/Annual_Statistical_Bulletin/2017/Montana_Annual_Bulletin_2017.pdf (Accessed 14 February 2017).
U.S. Department of Agriculture, Natural Resources Conservation Service. Glossary of landform and geologic terms. National Soil Survey Handbook, Title 430-VI, Part 629.02c. http://www.nrcs.usda.gov/wps/portal/nrcs/detail/soils/ref/?cid=nrcs142p2_054242 (Accessed 13 April 2016).
Van Dyne, G.M., and W.G. Vogel. 1967. Relation of Selaginella densa to site, grazing, and climate. Ecology 48:438-444.
Vaness, B.M., and S.D. Wilson. 2007. Impact and management of crested wheatgrass (Agropyron cristatum) in the northern Great Plains. Canadian Journal of Plant Science 87:1023-1028.
Vermeire, L.T., J.L. Crowder, and D.B. Wester. 2011. Plant community and soil environment response to summer fire in the northern Great Plains. Rangeland Ecology and Management 64:37-46.
Vermeire, L.T., J.L. Crowder, and D.B. Wester. 2014. Semiarid rangeland is resilient to summer fire and postfire grazing utilization. Rangeland Ecology and Management 67:52-60.
Vuke, S.M., K.W. Porter, J.D. Lonn, and D.A. Lopez. 2007. Geologic map of Montana - information booklet: Montana Bureau of Mines and Geology Geologic Map 62-D.
Whisenant, S.G. 1990. Postfire population dynamics of Bromus japonicus. American Midland Naturalist 123:301-308.
Wilson, S.D., and J.M. Shay. 1990. Competition, fire, and nutrients in a mixed-grass prairie. Ecology 71:1959-1967.Contributors
Scott Brady
Stuart VeithApproval
Kirt Walstad, 4/25/2025
Acknowledgments
A number of USDA-NRCS staff supported this project. Staff contributions are as follows: Soil Concepts, Soils Information, and Field Descriptions Charlie French, USDA-NRCS (retired) Steve Sieler, USDA-NRCS NASIS Reports, Data Dumps, and Soil Sorts Bill Drummond, USDA-NRCS (retired) Pete Weikle, USDA-NRCS Peer Review Kirt Walstad, USDA-NRCS Mark Hayek, USDA-NRCS Kami Kilwine, USDA-NRCS Robert Mitchell, USDA-NRCS Quality Control Kirt Walstad, USDA-NRCS Quality Assurance Stacey Clark, USDA-NRCS Preceding Version: Lacey et al., 2005. Sandy 10 to 14 inch p.z. R053AE062MT. Field Office Technical Guide Section II. U.S. Department of Agriculture, Natural Resources Conservation Service - Montana.
Rangeland health reference sheet
Interpreting Indicators of Rangeland Health is a qualitative assessment protocol used to determine ecosystem condition based on benchmark characteristics described in the Reference Sheet. A suite of 17 (or more) indicators are typically considered in an assessment. The ecological site(s) representative of an assessment location must be known prior to applying the protocol and must be verified based on soils and climate. Current plant community cannot be used to identify the ecological site.
Author(s)/participant(s) Contact for lead author Date 04/24/2025 Approved by Approval date Composition (Indicators 10 and 12) based on Annual Production Indicators
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Number and extent of rills:
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Presence of water flow patterns:
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Number and height of erosional pedestals or terracettes:
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Bare ground from Ecological Site Description or other studies (rock, litter, lichen, moss, plant canopy are not bare ground):
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Number of gullies and erosion associated with gullies:
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Extent of wind scoured, blowouts and/or depositional areas:
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Amount of litter movement (describe size and distance expected to travel):
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Soil surface (top few mm) resistance to erosion (stability values are averages - most sites will show a range of values):
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Soil surface structure and SOM content (include type of structure and A-horizon color and thickness):
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Effect of community phase composition (relative proportion of different functional groups) and spatial distribution on infiltration and runoff:
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Presence and thickness of compaction layer (usually none; describe soil profile features which may be mistaken for compaction on this site):
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Functional/Structural Groups (list in order of descending dominance by above-ground annual-production or live foliar cover using symbols: >>, >, = to indicate much greater than, greater than, and equal to):
Dominant:
Sub-dominant:
Other:
Additional:
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Amount of plant mortality and decadence (include which functional groups are expected to show mortality or decadence):
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Average percent litter cover (%) and depth ( in):
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Expected annual annual-production (this is TOTAL above-ground annual-production, not just forage annual-production):
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Potential invasive (including noxious) species (native and non-native). List species which BOTH characterize degraded states and have the potential to become a dominant or co-dominant species on the ecological site if their future establishment and growth is not actively controlled by management interventions. Species that become dominant for only one to several years (e.g., short-term response to drought or wildfire) are not invasive plants. Note that unlike other indicators, we are describing what is NOT expected in the reference state for the ecological site:
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Perennial plant reproductive capability:
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