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Ecological site R058AY719MT

Shallow to Gravel 10-14

Last updated: 8/29/2024
Accessed: 11/21/2024

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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: Xeromorphic Woodland, Scrub and Herb Vegetation Class (3)
• Subclass: Cool Semi-Desert Scrub and Grassland Subclass (3.B)
• Formation: Cool Semi-Desert Scrub and Grassland Formation (3.B.1)
• Division: Cool Semi-Desert Scrub and Grassland Division (3.B.1.Ne)
• Macrogroup: Artemisia tridentata - Artemisia tripartita ssp. tripartita - Purshia tridentata Steppe and Shrubland Macrogroup (3.B.1.Ne.3)
• Group: Artemisia tridentata ssp. wyomingensis - Artemisia tridentata ssp. tridentata Steppe and Shrubland Group (3.B.1.Ne.3.a)

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 on level to moderately steep terraces, hillslopes, stream terraces, and escarpments at elevations ranging from 1,900 to 3,500 feet and on slopes ranging from 0 to 15 percent. This site occurs on all aspects, although aspect is not a significant factor. The soils of this ecological site are 10 to 20 inches deep over sandy gravels and are excessively drained. Plant root penetration is limited to approximately 20 inches. The gravelly subsoil makes these soils moderately droughty. The soil textures are typically loam or gravelly loam at the surface and very gravelly sandy loam to extremely gravelly loamy sand at the subsurface.

Associated sites

R058AY708MT	Loamy 10-14 This site occurs on nearly level to moderately steep uplands that are adjacent to the Shallow to Gravel ecological site. It occurs on summit positions where slopes are less than 15 percent and coarse fragment content is less than 35 percent.
R058AY710MT	Loamy Steep 10-14 This site occurs on moderate to steeply sloping hillslopes adjacent to and downslope from the Shallow to Gravel ecological site. It occurs in backslope positions where slopes are 15 percent or greater and depth to coarse fragment content is less than 35 percent.
R058AY707MT	Gravelly 10-14 This site occurs adjacent to the Shallow to Gravel ecological site on similar landscapes and slope positions but where sandy-skeletal materials occur within 10 inches of the soil surface.

R058AY708MT

Loamy 10-14

This site occurs on nearly level to moderately steep uplands that are adjacent to the Shallow to Gravel ecological site. It occurs on summit positions where slopes are less than 15 percent and coarse fragment content is less than 35 percent.

R058AY710MT

Loamy Steep 10-14

This site occurs on moderate to steeply sloping hillslopes adjacent to and downslope from the Shallow to Gravel ecological site. It occurs in backslope positions where slopes are 15 percent or greater and depth to coarse fragment content is less than 35 percent.

R058AY707MT

Gravelly 10-14

This site occurs adjacent to the Shallow to Gravel ecological site on similar landscapes and slope positions but where sandy-skeletal materials occur within 10 inches of the soil surface.

Similar sites

R058AY707MT	Gravelly 10-14 This site differs from the Shallow to Gravel ecological site in that its soils have sandy-skeletal materials within 10 of the soil surface.
R058AY710MT	Loamy Steep 10-14 This site differs from the Shallow to Gravel ecological site in that that it contains less than 35 percent coarse fragments in the upper 20 inches of soil whereas the Shallow to Gravel ecological site contains 35 percent or more coarse fragments within 20 inches of the soil surface.
R058AY708MT	Loamy 10-14 This site differs from the Shallow to Gravel ecological site in that that it contains less than 35 percent coarse fragments in the upper 20 inches of soil whereas the Shallow to Gravel ecological site contains 35 percent or more coarse fragments within 20 inches of the soil surface.
R058AY709MT	Loamy Gravel 10-14 This site differs from the Shallow to Gravel ecological site in that its soils are loamy skeletal rather than sandy skeletal, meaning that fine-earth textures are finer than loamy fine sand. Percent clay in the fine-earth fraction is typically 18 to 34 percent.

Table 1. Dominant plant species

Tree	Not specified
Shrub	(1) Artemisia tridentata ssp. wyomingensis
Herbaceous	(1) Pseudoroegneria spicata (2) Pascopyrum smithii

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Physiographic features

This ecological site occurs on level to moderately steep terraces, hillslopes, stream terraces, and escarpments. Slopes typically range from 0 to 15 percent. This site occurs on all aspects. Aspect is not a significant factor.

Table 2. Representative physiographic features

Landforms	(1) Terrace (2) Stream terrace (3) Hillslope (4) Escarpment
Runoff class	Medium
Flooding frequency	None to rare
Ponding frequency	None
Elevation	579 – 1,067 m
Slope	0 – 15%
Aspect	Aspect is not a significant factor

Climatic features

MLRA 058A is a semi-arid region and is considered to have a continental climate characterized by cold winters, hot summers, low humidity, light rainfall, and much sunshine. The climate is the result of the MLRA’s location in the geographic center of North America. Temperatures can be extreme. The average annual temperature is 41 to 49 degrees Fahrenheit. Summer daytime temperatures are typically quite warm, generally averaging in the lower to mid 80 degree range for July and August. Summertime temperatures will typically reach 100 degrees or more at some point during the summer and can reach 90 degrees during any month between May and September. Conversely, winter temperatures can be cold, averaging in the lower teens or less for December and January. There will typically be several days of below zero temperatures each winter. It is not uncommon for temperatures to reach 30 to 40 degrees below zero, or even colder, most any winter.

During an average year, 70 to 75 percent of the annual precipitation falls between April and September, which are the primary growing season months. Most of the rainfall occurs as frontal storms early in the growing season during the months of May and June. Some high-intensity, convective thunderstorms occur in July and August, and some rainfall occurs in autumn. Later summer precipitation is greater in the eastern portion of the MLRA, which effects plant community composition. Winter precipitation occurs as snow although snowfall is not heavy, averaging about 39 inches annually, and snow cover is typically 1 to 3 inches. Heavy snowfall occurs infrequently, usually late in the winter or early spring. The average annual precipitation ranges from 8 to 22 inches but is typically 11 to 17 inches throughout most of the area. This site occurs on the lower range of 10 to 14 inche of precipitation. Precipitation fluctuates widely from year to year and severe drought occurs 2 out of 10 years on average.

There are few natural barriers on the northern Great Plains and the winds move freely across the plains and account for rapid changes in temperature. Spring can be windy throughout the MLRA, with winds averaging over 10 mph about 15 percent of the time. Speeds of 50 mph or stronger can occasionally occur. During the winter months, the western half of the MLRA commonly experiences Chinook winds, which are strong west to southwest surface winds accompanied by abrupt increases in temperature. The Chinook winds are strongest on the western boundary of the MLRA near the Rocky Mountain foothills and decrease eastward. In addition to producing damaging winds, prolonged Chinook episodes can result in drought or vegetation kills due to a reaction of plants to a “false spring” (Oard, 1993).

For local climate station information, refer to https://wrcc.dri.edu/summary/Climsmemt.html.

Table 3. Representative climatic features

Frost-free period (characteristic range)	85-150 days
Freeze-free period (characteristic range)	115-170 days
Precipitation total (characteristic range)	254-356 mm
Frost-free period (average)	125 days
Freeze-free period (average)	145 days
Precipitation total (average)	330 mm

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Figure 1. Monthly precipitation range

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Figure 2. Monthly average minimum and maximum temperature

Figure 3. Annual precipitation pattern

Figure 4. Annual average temperature pattern

Climate stations used

(1) RAPELJE [USC00246862], Rapelje, MT
(2) HYSHAM 25 SSE [USC00244364], Bighorn, MT
(3) BRANDENBERG [USC00241084], Rosebud, MT
(4) TERRY 21 NNW [USC00248169], Terry, MT
(5) BLOOMFIELD 5 NNE [USC00240923], Bloomfield, MT
(6) GLENDIVE [USC00243581], Glendive, MT
(7) POWDERVILLE 8 NNE [USC00246691], Volborg, MT
(8) JORDAN 23 ENE [USC00244530], Jordan, MT
(9) FT PECK PWR PLT [USC00243176], Fort Peck, MT
(10) CIRCLE [USC00241758], Circle, MT
(11) BROCKWAY 3 WSW [USC00241169], Brockway, MT
(12) MILES CITY F WILEY FLD [USW00024037], Miles City, MT
(13) MIZPAH 4 NNW [USC00245754], Ismay, MT
(14) SAND CREEK [USC00247342], Roy, MT
(15) ROCK SPRINGS [USC00247136], Angela, MT
(16) COHAGEN [USC00241875], Cohagen, MT

Influencing water features

This is 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 normally contained within the soil pedon. Soil moisture is recharged by spring rains, but it but rarely exceeds field capacity in the upper 40 inches before being depleted by evapotranspiration. The high content of sand and coarse fragments results in a very high infiltration rate and this site delivers moisture to downslope sites via subsurface flow. During intense precipitation events, the site may also deliver moisture to downslope sites via surface runoff. 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.

Wetland description

Not Applicable

Soil features

Soils for this ecological site are typically very deep (greater than 60 inches to bedrock), excessively drained, and derived from alluvium from mixed sand and gravel deposits. Soils typically consist of a loam or sandy loam surface over very gravelly or extremely gravelly subsurface layers. Surface horizon textures are typically loam, sandy loam, coarse sandy loam or loamy sand. The underlying horizons consist of stratified layers ranging from very gravelly loam to extremely gravelly coarse sand and content of coarse fragments is 35 percent or more in the 10 to 20 inch layer of soil. The soil temperature regime is primarily frigid, with smaller areas of mesic temperature regime present. The soil moisture regime is aridic ustic. Figure 5 shows a typical soil profile for this ecological site.

Figure 5. Typical Soil Profile

Table 4. Representative soil features

Parent material	(1) Alluvium
Surface texture	(1) Loam (2) Sandy loam (3) Coarse sandy loam (4) Loamy sand
Drainage class	Excessively drained
Permeability class	Rapid to very rapid
Depth to restrictive layer	152 – 183 cm
Soil depth	152 – 183 cm
Surface fragment cover <=3"	1 – 15%
Surface fragment cover >3"	1 – 3%
Available water capacity (0-152.4cm)	1.27 – 5.08 cm
Calcium carbonate equivalent (38.1-152.4cm)	5 – 15%
Electrical conductivity (0-152.4cm)	1 – 2 mmhos/cm
Sodium adsorption ratio (0-152.4cm)	0
Soil reaction (1:1 water) (12.7-152.4cm)	7 – 9
Subsurface fragment volume <=3" (12.7-152.4cm)	35 – 70%
Subsurface fragment volume >3" (0-101.6cm)	5 – 9%

Ecological dynamics

Interpretations are primarily based on the Reference state, which is used as a reference in order to understand the original potential of the site. This ecological site developed under the combined influences of climatic conditions, periodic fire activity, grazing by large herbivores, and impacts from small mammals and insects. Changes may occur to the Reference state due to management actions such as improper grazing management, climatic conditions such as drought, and natural events such as multiple fires in close succession. The Reference state is dominated by a diversity of medium height, cool-season and warm-season grasses, which are tightly intermixed and well distributed over the site. Various forbs, half-shrubs, and shrubs are common on this site. The Reference state is not necessarily the management goal, as other vegetative states may be considered desired plant communities as long as critical resource concerns are met.

In addition to the Reference state, other plant communities can occur on this site and are usually the result of historic management practices. Long term overgrazing on this ecological site results in a decrease of mid-grasses and more palatable forbs and in an increase of shortgrasses, sedges, and less palatable forbs. Half-shrubs and shrubs increase in the absence of prescribed fire and wildfire. More frequent fire intervals decreases the shrub component resulting in a site dominated by herbaceous species. There are various transitional stages which may occur on this ecological site.

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 text

Ecosystem states

T1A	-	Prolonged drought, improper grazing, or a combination of these factors
T1B	-	Introduction of non-native invasive species (annual bromes, crested wheatgrass, noxious weeds, etc.)
T1C	-	Conversion to cropland
R2A	-	Proper grazing management in combination with rangeland seeding, grazing land mechanical treatment, and timely moisture (management intensive and costly).
T2A	-	Introduction of non-native invasive species (annual bromes, crested wheatgrass, noxious weeds, etc.)
T2B	-	Conversion to cropland
T3A	-	Conversion to cropland
T4A	-	Cessation of annual cropping
T5A	-	Conversion to cropland

State 1 submodel, plant communities

1.1. Wyoming Big Sagebrush, Bluebunch Wheatgrass, and Western Wheatgrass

1.2. Bluebunch Wheatgrass and Western Wheatgrass

1.3. Wyoming Big Sagebrush, Western Wheatgrass, and Blue Grama

1.4. Western Wheatgrass and Blue Grama

1.1A	-	Prescribed fire and wildfire, mechanical and chemical treatments, and biological processes
1.1B	-	Drought, improper grazing management
1.2A	-	Approximately 30 years post-fire regrowth
1.2B	-	Drought, improper grazing management, multiple fires in close succession
1.3B	-	Normal or above average precipitation, proper grazing management
1.3A	-	Prescribed fire and wildfire, mechanical and chemical treatments, and biological processes
1.4B	-	Normal or above average precipitation, proper grazing management
1.4A	-	Approximately 30 years post-fire regrowth

State 2 submodel, plant communities

2.1. Wyoming Big Sagebrush, Blue Grama, and Sandberg Bluegrass

2.2. Blue Grama and Sandberg Bluegrass

2.1A	-	Prescribed fire and wildfire, mechanical and chemical treatments, and biological processes
2.2A	-	Approximately 30 years post-fire regrowth

State 1
Reference

The Reference state for this ecological site consists of four communities and evolved under the combined influences of climatic conditions, periodic fire activity, grazing by large herbivores, and impacts from small mammals and insects. The Reference state is the plant community in which interpretations are primarily based and is used as a reference in order to understand the original potential of the site.

Dominant plant species

Wyoming big sagebrush (Artemisia tridentata ssp. wyomingensis), shrub
bluebunch wheatgrass (Pseudoroegneria spicata), grass
western wheatgrass (Pascopyrum smithii), grass
blue grama (Bouteloua gracilis), grass

Community 1.1
Wyoming Big Sagebrush, Bluebunch Wheatgrass, and Western Wheatgrass

This plant community is characterized by a bunchgrass community and Wyoming big sagebrush. The predominant species are cool-season and warm-season grasses such as bluebunch wheatgrass, western wheatgrass, needle and thread, little bluestem, sideoats grama, and plains muhly. Shortgrasses and sedges such as blue grama, prairie Junegrass, Sandberg bluegrass, and threadleaf sedge are present at low cover. Forbs such as American vetch, white prairie clover, purple prairie clover, black samson, hairy false goldenaster, spiny phlox, milkvetch, and scurfpea occur at approximately 5 percent canopy cover. Wyoming big sagebrush occurs at approximately 5 percent canopy cover.

Community 1.2
Bluebunch Wheatgrass and Western Wheatgrass

This plant community is characterized by a bunchgrass and rhizomatous wheatgrass community. The predominant species are cool-season and warm-season grasses such as bluebunch wheatgrass, western wheatgrass, needle and thread, little bluestem, sideoats grama, and plains muhly. Shortgrasses and sedges such as blue grama, prairie Junegrass, Sandberg bluegrass, and threadleaf sedge are present at low cover. Forbs such as American vetch, white prairie clover, purple prairie clover, black samson, hairy false goldenaster, spiny phlox, milkvetch, and scurfpea occur at approximately 5 percent canopy cover and Wyoming big sagebrush is absent to rare. This community occurs following sagebrush mortality due to wildfire, prescribed fire, mechanical and chemical treatments, or biological processes and may persist for 30 years or more thereafter (Watts and Wambolt, 1996; Wambolt et. al., 2001).

Community 1.3
Wyoming Big Sagebrush, Western Wheatgrass, and Blue Grama

This plant community is characterized by an increase in shortgrass species and sedges such as blue grama, and threadleaf sedge and a decrease in grazing sensitive bunchgrasses such as bluebunch wheatgrass. Prairie sagewort occurs at low to moderate canopy cover and Wyoming big sagebrush occurs at 1 to 5 percent canopy cover. This plant community occurs when site conditions decline due to long-term drought or improper grazing management, and major sagebrush mortality has not occurred for at least 30 years prior.

Community 1.4
Western Wheatgrass and Blue Grama

This plant community is characterized by an increase in shortgrass species and sedges such as blue grama, and threadleaf sedge and a decrease in grazing sensitive bunchgrasses such as bluebunch wheatgrass. Prairie sagewort occurs at low to moderate cover and Wyoming big sagebrush is absent to rare. This plant community occurs when site conditions decline due to long-term drought or improper grazing management, and sagebrush mortality due to wildfire, prescribed fire, mechanical and chemical treatments, or biological processes has occurred on the site less than 30 years prior.

Pathway 1.1A
Community 1.1 to 1.2

Community 1.1 will transition to community 1.2 through prescribed fire and wildfire, mechanical and chemical treatments, and biological processes. Wyoming big sagebrush is greatly reduced and perennial grasses will dominate the site.

Pathway 1.1B
Community 1.1 to 1.3

Drought, improper grazing management such as continuous season-long or year-long grazing, or a combination of these factors can shift community 1.1 to community 1.3. These factors favor an increase in blue grama and a decrease in cool-season mid-statured grasses (Coupland, 1961; Shay et al., 2001). Wyoming big sagebrush cover will be similar to community 1.1.

Pathway 1.2A
Community 1.2 to 1.1

Approximately 30 years or more of natural vegetative regrowth will shift community 1.2 to community 1.1. Approximately 30 years or more without major mortality permits Wyoming big sagebrush to recolonize the site.

Pathway 1.2B
Community 1.2 to 1.4

Drought, improper grazing practices such as continuous season-long or year-long grazing, multiple fires in close succession, or a combination of these factors can shift community 1.2 to community 1.3. These factors favor an increase in blue grama and a decrease in cool-season mid-statured grasses (Coupland, 1961; Shay et al., 2001). Wyoming big sagebrush cover will be similar to community 1.2.

Pathway 1.3B
Community 1.3 to 1.1

Approximately 30 years or more following mortality; normal or above-average precipitation and proper grazing management shifts community 1.3 to community 1.1.

Pathway 1.3A
Community 1.3 to 1.4

Community 1.3 will transition to community 1.4 through prescribed fire and wildfire, mechanical and chemical treatments, and biological processes. Wyoming big sagebrush is greatly reduced and perennial grasses will dominate the site.

Pathway 1.4B
Community 1.4 to 1.2

Less than approximately 30 years following mortality; normal or above-average precipitation and proper grazing management shifts community 1.4 to community 1.2.

Pathway 1.4A
Community 1.4 to 1.3

Approximately 30 years or more of natural vegetative regrowth will shift community 1.4 to community 1.3. Approximately 30 years or more without fire or similar mortality permits Wyoming big sagebrush to recolonize the site.

State 2
Shortgrass

The dynamics of the Shortgrass state are driven by long-term drought, improper grazing management such as continuous season-long or year-long grazing, or a combination of these factors. The Shortgrass state for this ecological site consists of two communities.

Dominant plant species

Wyoming big sagebrush (Artemisia tridentata ssp. wyomingensis), shrub
blue grama (Bouteloua gracilis), grass
Sandberg bluegrass (Poa secunda), grass

Community 2.1
Wyoming Big Sagebrush, Blue Grama, and Sandberg Bluegrass

This plant community is characterized by a dominance of short-statured grasses and sedges such as blue grama, prairie Junegrass, Sandberg bluegrass, and threadleaf sedge. Mid-statured grasses such as bluebunch wheatgrass, needle and thread, little bluestem, sideoats grama, and plains muhly are rare or absent. Prairie sagewort is common and Wyoming big sagebrush occurs at approximately 5 percent canopy cover. This community results in a reduction of soil surface litter, soil organic matter, and infiltration and an increase of soil surface runoff. This plant community is capable of tolerating season-long, heavy grazing and therefore is highly resistant to change.

Community 2.2
Blue Grama and Sandberg Bluegrass

This plant community is characterized by a complete dominance of short-statured grasses and sedges such as blue grama, prairie Junegrass, Sandberg bluegrass, and threadleaf sedge. Mid-statured grasses such as bluebunch wheatgrass, needle and thread, little bluestem, sideoats grama, and plains muhly are rare or absent. Prairie sagewort may be common and Wyoming big sagebrush is absent or rare. This plant community occurs when site conditions decline due to long-term drought or improper grazing management such as continuous season-long or year-long grazing, and sagebrush mortality due to wildfire, prescribed fire, mechanical and chemical treatments, or biological processes has occurred on the site less than 30 years prior.

Pathway 2.1A
Community 2.1 to 2.2

Community 2.1 will transition to community 2.2 through prescribed fire and wildfire, mechanical and chemical treatments, and biological processes. Wyoming big sagebrush is greatly reduced and perennial grasses will dominate the site.

Pathway 2.2A
Community 2.2 to 2.1

It is estimated that approximately 30 years or more of natural vegetative regrowth could transition community 2.2 to community 2.1. It is possible that this transition could occur over time, however, the processes are not fully understood at this time. Therefore, this pathway is considered hypothetical until further investigation can be completed.

State 3
Invaded

The Invaded state occurs when invasive plant species invade native plant communities and displace the native species. The Invaded state consists of one community.

Dominant plant species

cheatgrass (Bromus tectorum), grass
field brome (Bromus arvensis), grass

Community 3.1
Cheatgrass and Field Brome

Observations suggest that native species diversity declines significantly when invasive or noxious species exceed approximately 30 percent of the plant community. Non-native, perennial, drought tolerant grasses such as crested wheatgrass, non-native, annual, invasive species such as cheatgrass and field brome, and noxious weed species can eventually dominate the seedbank of this site and displace native species. Reduced plant species diversity, simplified structural complexity, and altered ecological processes result in a state that is substantially departed from the Reference state. The dominance of annual, invasive grasses such as cheatgrass and field brome increases the fire cycle frequency.

State 4
Cropland

The Cropland state occurs when cultivation occurs to the land. The Cropland state consists of one community.

Community 4.1
Cropland

The land is cultivated and converted to crop production. Annual, cool-season cereal grains such as spring wheat, winter wheat, and barley are common crops which replace native plant communities.

State 5
Post Cropland

The Post Cropland state occurs when cultivated cropland is abandoned and allowed to either re-vegetate naturally or is seeded back to perennial species for livestock grazing or wildlife use. This state can transition back to the Cropland state if the site is returned to cultivation. No formal studies have been obtained regarding Wyoming big sagebrush recovery following cultivation and further investigation is needed to assess Wyoming big sagebrush recovery in the Post Cropland state. The Post Cropland state has two communities.

Community 5.1
Abandoned Cropland

In the absence of active management, the site can re-vegetate naturally and potentially return to a perennial grassland community over time. Shortly after cropland is abandoned, annual and biennial forbs and annual brome grasses invade the site. The site is highly susceptible to erosion due to the absence of perennial species. Eventually, these pioneering annual species are replaced by perennial forbs and perennial shortgrasses. Depending on the historical management of the site, mid-statured perennial grasses may also return; however, species composition will depend upon the seed bank. Invasion of the site by exotic species, such as crested wheatgrass and annual bromes, 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 communities in the Reference state. However, soil quality is consistently lower than conditions prior to cultivation and a shift to the Reference state is unlikely within a reasonable timeframe (Dormaar, J.F., and S. Smoliak. 1985).

Community 5.2
Perennial Grass

When the site is seeded to perennial forage species this community can persist for several decades. Introduced perennial grasses, in particular, may form monocultures that persist for 60 years or more (Samuel, M.J., and R.H. Hart. 1994). A mixture of native species may also be seeded to provide species composition and structural complexity similar to that of the Reference state. However, soil quality conditions have been substantially altered and will not return to pre-cultivation conditions within a reasonable timeframe.

Transition T1A
State 1 to 2

Prolonged drought, improper grazing management such as continuous season-long or year-long grazing, or a combination of these factors weaken the resilience of the Reference state and drive its transition to the Shortgrass state. The Reference state transitions to the Shortgrass state when mid-statured graminoids become rare and shortgrasses such as blue grama, Sandberg bluegrass, and prairie Junegrass dominate the plant community.

Transition T1B
State 1 to 3

The Reference state transitions to the Invaded state when non-native grasses or noxious weeds invade the plant community. Exotic plant species dominate the site in terms of cover and production and site resilience has been substantially reduced. In addition, other rangeland health attributes, such as reproductive capacity of native grasses and soil quality, have been substantially altered from the Reference state.

Transition T1C
State 1 to 4

Tillage or application of herbicide followed by seeding of cultivated crops, such as winter wheat, spring wheat, and barley, transitions the Reference state to the Cropland state.

Restoration pathway R2A
State 2 to 1

Blue grama can resist displacement by other species. A reduction in livestock grazing pressure alone may not be sufficient to reduce the cover of blue grama in the Shortgrass state and mechanical treatments may be necessary. Therefore, returning the Shortgrass state to the Reference state can require considerable cost, energy, and time.

Conservation practices

Prescribed Grazing

Transition T2A
State 2 to 3

The Shortgrass state transitions to the Invaded state when non-native grasses, noxious weeds, and other invasive plants invade the Shortgrass state. Exotic plant species dominate the site in terms of cover and production. Site resilience has been substantially reduced.

Transition T2B
State 2 to 4

Tillage or application of herbicide followed by seeding of cultivated crops, such as winter wheat, spring wheat, and barley, transitions the Shortgrass state to the Cropland state.

Transition T3A
State 3 to 4

The Invaded state will transition to the Cropland state when the site is placed under cultivation.

Transition T4A
State 4 to 5

The transition from the Cropland state to the Post Cropland state occurs with the cessation of cultivation. The site may also be seeded to perennial forage species, such as crested wheatgrass and alfalfa, or a mix of native species.

Transition T5A
State 5 to 4

Tillage or application of herbicide followed by seeding of cultivated crops, such as winter wheat, spring wheat, and barley, transitions the Post Cropland state to the Cropland state.

Additional community tables

Supporting information

Inventory data references

Specific field data was not obtained for this provisional ecological site description. Existing field data were used in conjunction with a review of the scientific literature and professional experience to approximate the plant communities, states, and transitions. All community phases are considered provisional based on the sources identified in this ecological site description.

Other references

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Contributors

Jeff Fenton
Scott Brady
Maryjo Kimble
Brian Kloster

Approval

Kirt Walstad, 8/29/2024

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	11/21/2024
Approved by	Kirt Walstad
Approval date
Composition (Indicators 10 and 12) based on	Annual Production

Indicators

Number and extent of rills:
Presence of water flow patterns:
Number and height of erosional pedestals or terracettes:
Bare ground from Ecological Site Description or other studies (rock, litter, lichen, moss, plant canopy are not bare ground):
Number of gullies and erosion associated with gullies:
Extent of wind scoured, blowouts and/or depositional areas:
Amount of litter movement (describe size and distance expected to travel):
Soil surface (top few mm) resistance to erosion (stability values are averages - most sites will show a range of values):
Soil surface structure and SOM content (include type of structure and A-horizon color and thickness):
Effect of community phase composition (relative proportion of different functional groups) and spatial distribution on infiltration and runoff:
Presence and thickness of compaction layer (usually none; describe soil profile features which may be mistaken for compaction on this site):
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:
Amount of plant mortality and decadence (include which functional groups are expected to show mortality or decadence):
Average percent litter cover (%) and depth ( in):
Expected annual annual-production (this is TOTAL above-ground annual-production, not just forage annual-production):
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:
Perennial plant reproductive capability:

Download reference sheet

Click on box and path labels to scroll to the respective text.

Ecosystem states

T1A	-	Prolonged drought, improper grazing, or a combination of these factors
T1B	-	Introduction of non-native invasive species (annual bromes, crested wheatgrass, noxious weeds, etc.)
T1C	-	Conversion to cropland
R2A	-	Proper grazing management in combination with rangeland seeding, grazing land mechanical treatment, and timely moisture (management intensive and costly).
T2A	-	Introduction of non-native invasive species (annual bromes, crested wheatgrass, noxious weeds, etc.)
T2B	-	Conversion to cropland
T3A	-	Conversion to cropland
T4A	-	Cessation of annual cropping
T5A	-	Conversion to cropland

State 1 submodel, plant communities

1.1. Wyoming Big Sagebrush, Bluebunch Wheatgrass, and Western Wheatgrass

1.2. Bluebunch Wheatgrass and Western Wheatgrass

1.3. Wyoming Big Sagebrush, Western Wheatgrass, and Blue Grama

1.4. Western Wheatgrass and Blue Grama

1.1A	-	Prescribed fire and wildfire, mechanical and chemical treatments, and biological processes
1.1B	-	Drought, improper grazing management
1.2A	-	Approximately 30 years post-fire regrowth
1.2B	-	Drought, improper grazing management, multiple fires in close succession
1.3B	-	Normal or above average precipitation, proper grazing management
1.3A	-	Prescribed fire and wildfire, mechanical and chemical treatments, and biological processes
1.4B	-	Normal or above average precipitation, proper grazing management
1.4A	-	Approximately 30 years post-fire regrowth