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Conservation Service

Ecological site R043BP804MT

Limy Grassland Group

Last updated: 3/01/2024
Accessed: 12/22/2024

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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): 043B–Central Rocky Mountains

The Central Rocky Mountains (MLRA 43B) of Montana occupy some 28,850 square miles and exist primarily in Central and SW portions of the state. The climate is extremely variable with precipitation lows of 9 to 100 inches per year and frost free days of less than 30 to over 110 days. The geology of the region is also highly variable. The combination of variable climate and geology create a complex relationship of plant communities. MLRA 43B elevations typically exist between 6000 and 12,799ft at Granite Peak (the highest point in Montana).

The Continental Divide runs through this MLRA effectively splitting its watershed to contribute to either the Missouri River to the East and the Columbia River to the West.

Ecological site concept

• Site does not receive any additional water
• Soils are
o Generally not saline or saline-sodic (limited extent)
o Moderately deep, deep, or very deep
o Typically less than 5% stone and boulder cover (<15% max)
o Strongly or violently effervescent within surface mineral 4”; calcium carbonates increase with depth
• Soil surface texture ranges from sandy loam to clay loam in surface mineral 4”
• Area of rugged mountain, hills, plateaus, and valleys of the Central Rocky Mountains in Southwest Montana
• Site Landform: fan remnants and hillslopes
• Moisture Regime: arid ustic to typic ustic
• Temperature Regime: cryic to frigid
• Dominant Cover: rangeland (grass dominated)
• Elevation Range: 3800-6700ft
• Slope range: 2-45% (typically less than 15%)

Site Development and Testing Plan
This Provisional Ecological Site Description was developed to meet the criteria as defined in Soil Survey National Instruction part 306 (430-306-NI, April 2015) as interpreted by Regional Ecological Site Specialist. Information in this description are first approximations based on broad groupings of soil properties and vegetation characteristics associated with those groupings. Although this description has been through the quality control and quality assurance review process it has not been certified for use in conservation planning.

Associated sites

R043BP810MT	Shallow Grassland Group Shallow Grassland is often located higher on the landscape; positioned on the shoulders of nearby hills. The Shallow Grassland has root restrictive layers (such as lithic and paralithic contact) at less than 20 inches below the soil surface.
R043BP811MT	Shallow Sagebrush Shrubland Group Shallow Sagebrush Shrubland is often located higher on the landscape; positioned on the shoulders of nearby hills. The Shallow Sagebrush Shrubland has root restrictive layers (such as lithic and paralithic contact) at less than 20 inches below the soil surface.
R043BP805MT	Limy Sagebrush Shrubland Group Limy Sagebrush Shrubland is often immediately adjacent to and intermixed with the Limy Grassland site as a complex. These sites share landscape position, hydrological processes, and often have the same soil components.

R043BP810MT

Shallow Grassland Group

Shallow Grassland is often located higher on the landscape; positioned on the shoulders of nearby hills. The Shallow Grassland has root restrictive layers (such as lithic and paralithic contact) at less than 20 inches below the soil surface.

R043BP811MT

Shallow Sagebrush Shrubland Group

Shallow Sagebrush Shrubland is often located higher on the landscape; positioned on the shoulders of nearby hills. The Shallow Sagebrush Shrubland has root restrictive layers (such as lithic and paralithic contact) at less than 20 inches below the soil surface.

R043BP805MT

Limy Sagebrush Shrubland Group

Limy Sagebrush Shrubland is often immediately adjacent to and intermixed with the Limy Grassland site as a complex. These sites share landscape position, hydrological processes, and often have the same soil components.

Similar sites

R043BP805MT	Limy Sagebrush Shrubland Group Limy Sagebrush Shrubland is often intermixed with the Limy Grassland site on a landscape level. These two sites share similar plant community species and have similar State and Transition Models. The Limy Sagebrush Shrubland will typically express a slightly lower overall production value
R043BP810MT	Shallow Grassland Group Shallow Grassland has a root restrictive layer less than 20 inches below soil surface. It shares similar plant community species and has similar State and Transition Models with the Limy Grassland. The Shallow Grassland will typically express lower overall production values.
R043BP811MT	Shallow Sagebrush Shrubland Group Shallow Sagebrush Shrubland has a root restrictive layer less than 20 inches below soil surface. It shares similar plant community species and has similar State and Transition Models with the Limy Grassland. The Shallow Sagebrush Shrubland will typically express lower overall production values.

R043BP805MT

Limy Sagebrush Shrubland Group

Limy Sagebrush Shrubland is often intermixed with the Limy Grassland site on a landscape level. These two sites share similar plant community species and have similar State and Transition Models. The Limy Sagebrush Shrubland will typically express a slightly lower overall production value

R043BP810MT

Shallow Grassland Group

Shallow Grassland has a root restrictive layer less than 20 inches below soil surface. It shares similar plant community species and has similar State and Transition Models with the Limy Grassland. The Shallow Grassland will typically express lower overall production values.

R043BP811MT

Shallow Sagebrush Shrubland Group

Shallow Sagebrush Shrubland has a root restrictive layer less than 20 inches below soil surface. It shares similar plant community species and has similar State and Transition Models with the Limy Grassland. The Shallow Sagebrush Shrubland will typically express lower overall production values.

Table 1. Dominant plant species

Tree	Not specified
Shrub	(1) Artemisia tridentata (2) Tetradymia canescens
Herbaceous	(1) Pseudoroegneria spicata (2) Hesperostipa comata

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Physiographic features

This ecological site occurs on slopes ranging from nearly level to 45 percent; however, the core concept is 4 to 15 percent slopes. Site exists on fan remnants, hillslopes, and mountain slopes.

Table 2. Representative physiographic features

Landforms	(1) Mountains > Hillslope (2) Mountains > Fan remnant (3) Mountains > Mountain slope
Runoff class	Low
Flooding frequency	None
Ponding frequency	None
Elevation	1,158 – 2,377 m
Slope	0 – 45%
Water table depth	254 cm
Aspect	Aspect is not a significant factor

Climatic features

The climate variable and receives 10 to 30 inches of precipitation with 50 to 130 frost-free days.

Table 3. Representative climatic features

Frost-free period (characteristic range)	20-102 days
Freeze-free period (characteristic range)	52-135 days
Precipitation total (characteristic range)	305-508 mm
Frost-free period (actual range)	8-114 days
Freeze-free period (actual range)	37-144 days
Precipitation total (actual range)	305-508 mm
Frost-free period (average)	61 days
Freeze-free period (average)	96 days
Precipitation total (average)	406 mm

Characteristic range

Actual range

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Figure 1. Monthly precipitation range

Characteristic range

Actual range

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Figure 2. Monthly minimum temperature range

Characteristic range

Actual range

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Figure 3. Monthly maximum temperature range

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Figure 4. Monthly average minimum and maximum temperature

Figure 5. Annual precipitation pattern

Figure 6. Annual average temperature pattern

Climate stations used

(1) DIVIDE [USC00242421], Wise River, MT
(2) WISE RIVER 3 WNW [USC00249082], Wise River, MT
(3) BIG SKY 2WNW [USC00240775], Gallatin Gateway, MT
(4) WILSALL 8 ENE [USC00249023], Wilsall, MT
(5) AUSTIN 1 W [USC00240375], Helena, MT
(6) CANYON FERRY DAM [USC00241470], Helena, MT
(7) NORRIS MADISON PH [USC00246157], Ennis, MT

Soil features

Soils of this site are moderately deep to deep and are strong or violently effervescent within the surface 4 inches of mineral soil. Typically calcium carbonates increase with depth. Soil textures vary from sandy loam to clay loam. Parent material is alluvium, slope alluvium and colluvium. Site typically exists on calcareous sedimentary rock.

Table 4. Representative soil features

Parent material	(1) Alluvium – sedimentary rock (2) Colluvium – sedimentary rock (3) Slope alluvium – sedimentary rock
Surface texture	(1) Sandy loam (2) Loam (3) Clay loam
Drainage class	Moderately well drained to well drained
Permeability class	Moderate to moderately rapid
Depth to restrictive layer	51 – 254 cm
Soil depth	51 – 254 cm
Surface fragment cover <=3"	0 – 25%
Surface fragment cover >3"	0 – 12%
Available water capacity (0-101.6cm)	13.97 – 17.02 cm
Calcium carbonate equivalent (0-50.8cm)	15%
Soil reaction (1:1 water) (0-10.2cm)	7.9 – 8.4
Subsurface fragment volume <=3" (25.4cm)	0 – 20%
Subsurface fragment volume >3" (25.4-50.8cm)	0 – 10%

Ecological dynamics

1 - Reference State - Bunchgrasses
1.1 Mid-statured bunchgrasses dominant (bluebunch wheatgrass or rough fescue), Shrubs are a relatively small component.

1.1a extended drought, improper grazing, climate change, catastrophic fire (limited on this site)

1.2 Mid-statured bunchgrasses subdominant to increaser bunchgrasses such as needle and thread or Idaho fescue. Shrubs increasing, clubmoss possible (limited extent), mat forming forbs increasing

1.2a proper grazing management, favorable growing conditions, time

T1A poor post-settlement grazing (late 1800’s), drought with improper grazing, multiple spring grazing, fire suppression
T1B sod-busting, introduction of tame pasture species and other invasive plants, overgrazing, drought, heavy human disturbance, extreme fire (multiple years or very intense)
T1C poor post-settlement grazing (late 1800’s), drought with improper grazing, multiple spring grazing or long-term overgrazing, fire suppression

2 - Altered Bunchgrass State
2.1 Mixed grass dominated site (needle and thread or Idaho fescue), mid-statured bunchgrasses existent under shrub canopy, possible conifer encroachment, forbs (scarlet globemallow, hoods phlox, mat forming forbs) and shrubs increase (broom snakeweed, big sagebrush)

2.1a improper grazing management, drought, fire, climate change

2.2 Needle-and-thread or Idaho fescue losing dominance to Sandberg bluegrass and Junegrass. Decreaser bunchgrasses very rare and limited under shrub canopy. Broom snakeweed and fringed sagewort beginning to replace shrub component

2.2a proper grazing management, time, Integrated Pest Management (IPM), brush management
T2A overgrazing, introduction of weeds, drought, heavy human disturbance
R2A fire, range seeding, timely moisture, proper grazing management, IPM
T2B sod-busting, introduction of tame pasture species and other invasive plants, overgrazing, extended drought, adjacent to construction or disturbance event, extreme fire (multiple years or very intense)

3 - Degraded State - Short-statured Grass State
3.1 Shortgrass State lacks mid-statured bunchgrasses. Sandberg bluegrass and prairie Junegrass are the dominant grasses, increaser shrubs nearly replace larger shrub species. Remaining larger shrub species heavily hedged.

T3A sod-busting, invasive plants, overgrazing, extended drought, adjacent to construction or disturbance event
R3A range seeding, time, proper grazing management, IPM
R3B Possibly not feasible, range seeding, time, proper grazing management, IPM

4 - Invaded State
4.1 May resemble the Reference State; however, often contains noxious or invasive weeds such as cheatgrass or knapweed. Conifer encroachment common.

R4A IPM, timely moisture, grazing management, brush management, range seeding
R4B IPM, range seeding, timely moisture, grazing management, brush management, range seeding

State and transition model

Custom diagram

Standard diagram

More interactive model formats are also available. View Interactive Models

Interpretations

Animal community

The Limy Grassland ecological site grouping provides for a variety of wildlife habitat for an array of species. Prior to the settlement of this area, large herds of antelope, elk and bison roamed. Though the bison have been replaced, mostly with domesticated livestock, elk and antelope still frequently utilize this largely intact landscape for winter habitat in areas adjacent to forest.

The relatively high grass component of the Reference Community provides excellent nesting cover for multiple neotropical migratory birds that select for open grasslands such as the Long-billed curlew and McCown’s longspur.

Greater sage grouse may be present on sites with suitable habitat, typically requiring a minimum of 15 percent sagebrush canopy cover (Wallestad 1975). The Bunchgrass Community (1.1) is likely to have minimal use by sage grouse given its low sagebrush canopy cover. However, the potentially diverse forb component of the Reference State may provide important early-season (spring) foraging habitat for the Greater sage grouse. Other communities on the site with sufficient sagebrush cover may harbor sage grouse populations specifically Community 2.1 where big sagebrush populations are under a reduced fire regime. Also as sagebrush canopy cover increases under Altered States 2.1 and 2.2 and, to a limited extent, the Degraded State 3.1; Pygmy rabbit, Brewer’s sparrow, and mule deer use may increase.

Managed livestock grazing is suitable on this site due to the potential to produce an abundance of high quality forage. This is often a preferred site for grazing by livestock, and animals tend to congregate in these areas. To maintain the productivity of the Limy ecological site, grazing on adjoining sites with less production must be managed carefully to be sure utilization on this site is not excessive. Management objectives should include maintenance or improvement of the native plant community. Careful management of timing and duration of grazing is important. Shorter grazing periods and adequate deferment during the growing season are recommended for plant maintenance, health, and recovery. According to McLean et al, early season defoliation of bluebunch wheatgrass can result in high mortality and reduced vigor of plants. They also suggest, based on prior studies, that regrowth is necessary before dormancy to reduce injury to bluebunch wheatgrass.

Since needle and thread normally matures earlier than bluebunch wheatgrass and produces a sharp awn, this species is usually avoided after seed set. Changing season of use will help utilize needle and thread more efficiently while preventing overuse of bluebunch wheatgrass.

Grazing season has more influence on winterfat than grazing intensity. Late winter or early spring grazing is detrimental. However, early winter grazing may actually be beneficial (Blaisdell 1984).

Continual non-prescribed grazing of this site will be detrimental, will alter the plant composition and production over time, and will result in transition to the Altered State. Transition to other states will depend on duration of poorly managed grazing as well as other circumstances such as weather conditions and fire frequency.

The Altered State is subject to further degradation to the Degraded Shortgrass State or Invaded State. Management should focus on grazing management strategies that will prevent further degradation, such as seasonal grazing deferment or winter grazing where feasible. Communities within this state are still stable and healthy under proper management. Forage quantity and quality may be substantially decreased from the Reference State.

Grazing is possible in the Invaded State. Invasive species are generally less palatable than native grasses. Forage production is typically greatly reduced in this state. Due to the aggressive nature of invasive species, sites in the Invaded State face increased risk for further degradation to the Invasive Dominated Communities. Grazing has to be carefully managed to avoid further soil loss and degradation and possible livestock health issues.

Prescriptive grazing can be used to manage invasive species. In some instances, carefully targeted grazing (sometimes in combination with other treatments) can reduce or maintain species composition of invasive species. In the Degraded Shortgrass State, grazing may be possible but is generally not economically or environmentally sustainable.

Hydrological functions

The hydrologic cycle functions best in the Bunchgrass State (1) with good infiltration and deep percolation of rainfall; however, the cycle degrades as the vegetation community declines. Rapid rainfall infiltration, high soil organic matter, good soil structure, and good porosity accompany high bunchgrass canopy cover (Thurow et al 1986). High ground cover reduces rain drop impact on the soil surface, which keeps erosion and sedimentation transport low. Water leaving the site will have minimal sediment load, which allows for high water quality in associated streams. High rates of infiltration will allow water to move below the rooting zone during periods of heavy rainfall. The Bluebunch Wheatgrass Community (1.1) should have no rills or gullies present and drainage ways should be vegetated and stable. Water flow patterns, if present, will be barely observable. Plant pedestals are essentially non-existent. Plant litter remains in place and is not moved by wind or water.

Improper grazing management results in a community shift to the Mixed Bunchgrass Community (1.2). This plant community has a similar canopy cover, but bare ground will be less than 15 percent. Therefore, the hydrologic cycle is functioning at a level like the water cycle in the Bluebunch Wheatgrass Community/Needle and thread (1.1). When the Mixed Bunchgrass Community (1.2) is compared to the Reference Community (1.1) infiltration rates are slightly reduced and surface runoff is slightly higher.

In the Shortgrass Community (2.2), Degraded Shortgrass State (3) and the Invaded State (4) canopy and ground cover are greatly reduced compared to the Bunchgrass State (1), which impedes the hydrologic cycle. Infiltration will decrease and runoff will increase due to reduced ground cover, presence of shallow-rooted species, rainfall splash, soil capping, reduced organic matter, and poor structure. Sparse ground cover and decreased infiltration can combine to increase frequency and severity of flooding within a watershed. Soil erosion is accelerated, quality of surface runoff is poor, and sedimentation increases. (McCalla et al 1984)

Improper grazing management results in a community shift to the Mixed Bunchgrass Community (1.2). This plant community has a similar canopy cover, but bare ground will be less than 15 percent. Therefore, the hydrologic cycle is functioning at a level similar to the water cycle in the Bluebunch Wheatgrass Community/Needle-and-thread (1.1). Compared to the Bluebunch Wheatgrass/Needle and thread Community (1.1) infiltration rates are slightly reduced and surface runoff is slightly higher.

In the Shortgrass Community (2.2), Degraded Shortgrass State (3) and the Invaded State (4) canopy and ground cover are greatly reduced compared to the Bunchgrass State (1), which impedes the hydrologic cycle. Infiltration will decrease and runoff will increase due to reduced ground cover, presence of shallow-rooted species, rainfall splash, soil capping, reduced organic matter, and poor structure. Sparse ground cover and decreased infiltration can combine to increase frequency and severity of flooding within a watershed. Soil erosion is accelerated, quality of surface runoff is poor, and sedimentation increases.

Recreational uses

This site provides some limited recreational opportunities for hiking, horseback riding, big game and upland bird hunting. Some forbs have flowers that appeal to photographers. This site provides valuable open space.

Wood products

This site does not offer opportunity for wood products industry

Supporting information

Inventory data references

Site data sources from National Resources Inventory (NRI), BLM AIM, Field observations by NRCS, and professional knowledge/expertise by agency employees and partners.

Other references

• Barrett, H. 2007. Western Juniper Management: A Field Guide.
• Bestelmeyer, B., J.R. Brown, J.E. Herrick, D.A. Trujillo, and K.M. Havstad. 2004. Land Management in the American Southwest: a state-and-transition approach to ecosystem complexity. Environmental Management 34:38–51.
• Bestelmeyer, B. and J. Brown. 2005. State-and-Transition Models 101: A Fresh look at vegetation change.
• Blaisdell, J.P. 1958. Seasonal development and yield of native plants on the Upper Snake River Plains and their relation to certain climate factors.
• Colberg, T.J. and J.T. Romo. 2003. Clubmoss effects on plant water status and standing crop. Journal of Range Management 56:489–495.
• DiTomaso, J.M. 2000. Invasive weeds in Rangelands: Species, Impacts, and Management. Weed Science 48:255–265.
• Dormaar, J.F., B.W. Adams, and W.D. Willms. 1997. Impacts of rotational grazing on mixed prairie soils and vegetation. Journal of Range Management 50:647–651.
• Hobbs, J.R. and S.E. Humphries. 1995. An integrated approach to the ecology and management of plant invasions. Conservation Biology 9:761–770.
• Humphrey, L. David. 1984. Patterns and mechanisms of plant succession after fire on Artemisia-grass sites in southeastern Idaho Vegetation. 57: 91-101.
• Masters, R. and R. Sheley. 2001. Principles and practices for managing rangeland invasive plants. Journal of Range Management 38:21–26.
• McLean, A. and S. Wikeem. 1985. Influence of season and intensity of defoliation on bluebunch wheatgrass survival and vigor in southern British Columbia. Journal of Range Management 38:21–26.
• Miller, R.F., T.J. Svejcar, and J.A. Rose. 2000. Impacts of western juniper on plant community composition and structure. Journal of Range Management 53:574–585.
• Ross, R.L., E.P. Murray, and J.G. Haigh. July 1973. Soil and Vegetation of Near-pristine sites in Montana.
• Smoliak, S., R.L. Ditterlin, J.D. Scheetz, L.K. Holzworth, J.R. Sims, L.E. Wiesner, D.E. Baldridge, and G.L. Tibke. 2006. Montana Interagency Plant Materials Handbook.
• Stavi, I. 2012. The potential use of biochar in reclaiming degraded rangelands. Journal of Environmental Planning and Management 55:1–9.
• Stringham, T.K., W.C. Kreuger, and P.L. Shaver. 2003. State and Transition Modeling: an ecological process approach. Journal of Range Management 56:106–113.
• Stringham, T.K. and W.C. Krueger. 2001. States, Transitions, and Thresholds: Further refinement for rangeland applications.
• Tirmenstein, D. 1999. Gutierrezia sarothrae. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). https://www.fs.fed.us/database/feis/plants/shrub/gutsar/all.html [2022, March 30].
• Walker, L.R. and S.D. Smith. 1997. Impacts of invasive plants on community and ecosystem properties. Pages 69–86 in Assessment and management of plant invasions. Springer, New York, NY.
• Whitford, W.G., E.F. Aldon, D.W. Freckman, Y. Steinberger, and L.W. Parker. 1989. Effects of Organic Amendments on Soil Biota on a Degraded Rangeland. Journal of Range Management 41:56–60.
• Wilson, A.M., G.A. Harris, and D.H. Gates. 1966. Cumulative Effects of Clipping on Yield of Bluebunch wheatgrass. Journal of Range Management 19:90–91.

Contributors

Petersen, Grant

Approval

Kirt Walstad, 3/01/2024

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	12/22/2024
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:

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Natural ResourcesConservation Service

Ecological site R043BP804MT

Limy Grassland Group

Last updated: 3/01/2024 Accessed: 12/22/2024

General information

MLRA notes

Ecological site concept

Associated sites

Similar sites

Table 1. Dominant plant species

Natural Resources
Conservation Service

Last updated: 3/01/2024
Accessed: 12/22/2024