Natural Resources
Conservation Service
Ecological site R046XS108MT
Subirrigated (Sb) RRU 46-S 15-19 PZ
Last updated: 7/19/2023
Accessed: 11/23/2024
General information
Provisional. A provisional ecological site description has undergone quality control and quality assurance review. It contains a working state and transition model and enough information to identify the ecological site.
Figure 1. Mapped extent
Areas shown in blue indicate the maximum mapped extent of this ecological site. Other ecological sites likely occur within the highlighted areas. It is also possible for this ecological site to occur outside of highlighted areas if detailed soil survey has not been completed or recently updated.
Associated sites
| R046XS104MT |
Silty (Si) RRU 46-S 13-19 PZ |
|---|---|
| R046XS105MT |
Clayey (Cy) RRU 46-S 13-19 PZ |
| R046XS107MT |
Wet Meadow (WM) RRU 46-S 15-19 PZ |
| R046XS109MT |
Overflow (Ov) RRU 46-S 13-19 PZ |
Similar sites
| R046XS109MT |
Overflow (Ov) RRU 46-S 13-19 PZ The Overflow site differs mainly by being associated with ephemeral streams and having no permanent water table. |
|---|---|
| R046XS118MT |
Riparian Subirrigated (RSb) RRU 46-S 13-19 PZ The Riparian Subirrigated site differs mainly by being adjacent to perennial or intermittent streams, being frequently flooded, and having a significant component of woody (willow) species. |
| R046XS107MT |
Wet Meadow (WM) RRU 46-S 15-19 PZ The Wet Meadow site differs mainly by being wet to at or near the surface for most of the growing season. |
Table 1. Dominant plant species
| Tree |
Not specified |
|---|---|
| Shrub |
Not specified |
| Herbaceous |
(1) Leymus cinereus |
Physiographic features
This ecological site occurs on terraces and high floodplain steppes, near springs or seeps, or other areas having a permanent water table close enough to the surface (typically within 3 feet) to influence plant composition and production. Slope is usually 0–2%, except it can be greater when this site occurs on hillslope near a spring/seep. These areas are rarely or non-flooded. Rare flooding indicates that flooding is unlikely, but possible under unusual weather conditions (0–5% chance in any year). These are also considered to be “lentic” (standing water) riparian/wetland areas.
Table 2. Representative physiographic features
| Landforms |
(1)
Terrace
(2) Hill (3) Flood-plain step |
|---|---|
| Flooding frequency | None to rare |
| Ponding frequency | None |
| Slope | 0 – 2% |
| Water table depth | 91 cm |
| Aspect | Aspect is not a significant factor |
Climatic features
See Climatic Data Sheet for more details (Section II of the Field Office Technical Guide) or reference the following climatic web site: http://www.wrcc.sage.dri.edu/ .
Table 3. Representative climatic features
| Frost-free period (characteristic range) | 49-96 days |
|---|---|
| Freeze-free period (characteristic range) | 105-122 days |
| Precipitation total (characteristic range) | 356-457 mm |
| Frost-free period (actual range) | 47-99 days |
| Freeze-free period (actual range) | 104-125 days |
| Precipitation total (actual range) | 330-457 mm |
| Frost-free period (average) | 76 days |
| Freeze-free period (average) | 114 days |
| Precipitation total (average) | 406 mm |
Figure 2. Monthly precipitation range
Figure 3. Monthly minimum temperature range
Figure 4. Monthly maximum temperature range
Figure 5. Monthly average minimum and maximum temperature
Figure 6. Annual precipitation pattern
Figure 7. Annual average temperature pattern
Climate stations used
-
(1) JOLIET [USC00244506], Joliet, MT
-
(2) COLUMBUS [USC00241938], Columbus, MT
-
(3) BIG TIMBER [USC00240780], Big Timber, MT
-
(4) MELVILLE 4 W [USC00245603], Big Timber, MT
-
(5) MARTINSDALE 3 NNW [USC00245387], Martinsdale, MT
-
(6) NYE 2 [USC00246190], Fishtail, MT
Influencing water features
Cowardin System:
Soil features
These soils are non-hydric. The soils associated with this ecological site are mainly deep to very deep with a permanent water table within about three feet of the surface. Free water occurs within about 36" of the surface. They are generally in the aquic moisture regime or aquic intergrade.
Table 4. Representative soil features
| Surface texture |
(1) Loam (2) Sandy loam (3) Clay loam |
|---|---|
| Drainage class | Somewhat poorly drained |
| Permeability class | Moderate |
| Soil depth | 102 cm |
| Electrical conductivity (0-101.6cm) |
0 mmhos/cm |
| Soil reaction (1:1 water) (0-101.6cm) |
6.6 – 8.4 |
Ecological dynamics
This site developed under Northern Rocky Mountain foothills climatic conditions, which included the natural influence of large herbivores and occasional fire. The plant community upon which interpretations are primarily based is the Historic Climax Plant Community (HCPC). This community is described as a reference to understand the original potential of this site, and is not always considered to be the management goal for every acre of rangeland. The following descriptions should enable the landowner or manager to better understand which plant communities occupy their land, and assist with setting goals for vegetation management. It can also be useful to understand the environmental and economic values of each plant community.
This site is considered resilient to disturbance as it has essentially no limitations for plant growth, except for the growing season. Changes may occur to the Historic Climax Plant Community due to management actions and/or climatic conditions, such as a drop in water table level due to prolonged drought conditions. Under continued adverse impacts, a moderate decline in vegetative vigor and composition will occur. Under favorable vegetative management treatments, this site can readily return to the Historic Climax Plant Community (HCPC).
Continual adverse impacts to the site over a period of years results in a departure from the HCPC, with a decrease of the taller, more palatable species such as basin wildrye, prairie cordgrass, bearded/slender wheatgrass, tufted hairgrass, bluejoint and slimstem reedgrass, and Nebraska, sedge will occur. These plants will be replaced by a mixture of medium and short grasses, sedges, and rushes including western wheatgrass, meadow barley, mat muhly, clustered field sedge, and Baltic rush as well as several species of non-palatable forbs. Shrubs such as shrubby cinquefoil, snowberry, or rose will also increase.
Continued deterioration results in an abundance of short grasses and short sedges, non-native grasses and forbs, and annuals. A lowering of the water table can also cause a significant change in the plant community. Plants that are not a part of the Historic Climax Plant Community that are most likely to invade are Kentucky, fowl, and Canada bluegrass, timothy, quackgrass, smooth brome, redtop, Canada thistle, dandelion, leafy spurge, sulfur cinquefoil, annuals, and other weedy species. Purple loosestrife is potentially a serious invader on this site.
Long-term non-use (>3 years) combined with the absence of fire will result in excessive litter and decadent plants.
State and transition model
Figure 8. State and Transition Model
More interactive model formats are also available.
View Interactive Models
More interactive model formats are also available.
View Interactive Models
Click on state and transition labels to scroll to the respective text
State 1 submodel, plant communities
State 2 submodel, plant communities
State 3 submodel, plant communities
State 4 submodel, plant communities
State 1
Tall and Medium Grasses, Sedges, Forbs
Community 1.1
Tall and Medium Grasses, Sedges, Forbs
This is the interpretive plant community and is considered to be the Historic Climax Plant Community (HCPC for this site. The major species include basin wildrye, bluejoint and slimstem reedgrass, prairie cordgrass, slender and bearded wheatgrass, tufted hairgrass, Nebraska sedge, and various rush species. There are several forbs that will occur in small amounts, including Northwest cinquefoil, leafy aster, and blue-eyed grass. This plant community is well adapted to the Northern Rocky Mountain foothills climatic conditions as well as the presence of a permanent water table. The diversity in plant species allows for drought tolerance. Individual species can vary greatly in production depending on growing conditions (timing and amount of precipitation, depth to the water table, and temperature). Plants on this site have strong, healthy root systems that allow production to increase significantly with favorable moisture conditions. Abundant plant litter is available for soil building and moisture retention. Plant litter is properly distributed with very little movement off-site and natural plant mortality is very low. The presence of available water throughout the growing season provides a very favorable soil-water-plant relationship. This plant community provides for soil stability and a properly functioning hydrologic cycle.
Figure 9. Annual production by plant type (representative values) or group (midpoint values)
Table 5. Annual production by plant type
| Plant type | Low (kg/hectare) |
Representative value (kg/hectare) |
High (kg/hectare) |
|---|---|---|---|
| Grass/Grasslike | 3838 | 4599 | 5246 |
| Shrub/Vine | – | 269 | 583 |
| Forb | 48 | 161 | 291 |
| Total | 3886 | 5029 | 6120 |
Table 6. Ground cover
| Tree foliar cover | 0% |
|---|---|
| Shrub/vine/liana foliar cover | 5-10% |
| Grass/grasslike foliar cover | 85-95% |
| Forb foliar cover | 1-5% |
| Non-vascular plants | 0-1% |
| Biological crusts | 0% |
| Litter | 0% |
| Surface fragments >0.25" and <=3" | 0% |
| Surface fragments >3" | 0% |
| Bedrock | 0% |
| Water | 0% |
| Bare ground | 0% |
Table 7. Soil surface cover
| Tree basal cover | 0% |
|---|---|
| Shrub/vine/liana basal cover | 0-5% |
| Grass/grasslike basal cover | 36-41% |
| Forb basal cover | 0-2% |
| Non-vascular plants | 0-1% |
| Biological crusts | 0% |
| Litter | 50-60% |
| Surface fragments >0.25" and <=3" | 0% |
| Surface fragments >3" | 0-1% |
| Bedrock | 0% |
| Water | 0% |
| Bare ground | 0-1% |
Figure 10. Plant community growth curve (percent production by month). MT0816, Permanent water table. All sites with a permanent water table..
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|---|---|---|---|---|
| J | F | M | A | M | J | J | A | S | O | N | D |
| 0 | 0 | 0 | 5 | 20 | 25 | 20 | 20 | 10 | 0 | 0 | 0 |
State 2
Medium Grasses and Sedges, Rush, Forbs
Community 2.1
Medium Grasses and Sedges, Rush, Forbs
Early stages of degradation, including non-prescribed grazing, will tend to change the HCPC to a community dominated by medium height grasses (western wheatgrass, slimstem reedgrass, tufted hairgrass) and sedges (smallwing sedge, clustered field sedge). Most of the taller, more palatable grasses and sedges (basin wildrye, bluejoint reedgrass, prairie cordgrass, Nebraska sedge) will still be common, but in smaller percentages. Desirable and nutritious forbs will be replaced by less desirable and more aggressive species (Rocky Mountain iris, goldenpea). Short grasses and grasslikes such as Baltic rush, clustered field sedge, slender beaked sedge, meadow barley and mat muhly will become more common. Biomass production and litter become reduced on the site with as the taller grasses and sedges become replaced by shorter ones, especially the non-native grasses. Evapotranspiration tends to increase, moisture retention is reduced, and soil surface temperatures increase. Some natural ecological processes will be altered. These plant communities provide for moderate soil stability. Increased amounts of bare ground can result in undesirable species invading. Common invaders can include spotted knapweed, dalmation toadflax, sulphur cinquefoil, and leafy spurge. A key objective at this point is to implement a grazing strategy that prevents further degradation. This plant community will readily respond to improved grazing management, but a significant amount of time can be necessary to move it toward a higher successional stage and a more productive plant community similar to the HCPC.
State 3
Rush, Medium and Short Grasses and Sedges, Shrubs, Invasive Forbs
Community 3.1
Rush, Medium and Short Grasses and Sedges, Shrubs, Invasive Forbs
As disturbance to the site increases, the community will tend to become dominated by Baltic rush and western wheatgrass, meadow barley, mat muhly, clustered field sedge and other small sedges. Reed canarygrass often moves in and, if present, tends to form a monoculture. The taller grasses and sedges may still be present, but in much smaller amounts. Forbs such as Rocky Mountain iris, goldenpea, sow thistle, and silverweed cinquefoil become abundant. Shrubby cinquefoil, Wood’s rose and western snowberry also become more abundant. Non-native grasses (Kentucky or Canada bluegrass, timothy, redtop) and invasive forbs such as Canada thistle, common tansy, and dandelion often become more common. The non-native species will be benefitted, giving them a competitive advantage if the water table lowers, such as during a prolonged drought. This plant community is the result of long-term, heavy, continuous grazing and/or annual, early spring seasonal grazing, or sometimes a lowering of the water table. Repeated spring grazing depletes stored carbohydrates, resulting in weakening and eventual death of the cool season tall and medium grasses. This plant community can occur throughout the pasture, on spot grazed areas, and around water sources where season-long grazing patterns occur. This community has lost many of the attributes of a healthy rangeland. The loss of deep perennial root systems reduces total available moisture for plant growth. Invasive species are often aggressive and competitive with seedlings of native plants. This community can respond positively to improved grazing management but it usually requires additional time and inputs to move it towards a higher successional stage and a more productive plant community.
State 4
Rush, Non-Native Grasses, Invasive Forbs
Community 4.1
Rush, Non-Native Grasses, Invasive Forbs
Further deterioration results in a plant community dominated by Baltic rush. Non-native grasses and forbs (Kentucky/Canada bluegrass, redtop, smooth brome, Canada thistle, and dandelion) will become dominant especially if the water table has lowered. Reed canarygrass can create a monoculture if present. There may still be small, remnant amounts of the taller grasses and sedges present. Nebraska sedge can often be persistent because of its extensive system of roots and rhizomes. Shrubby cinquefoil, Wood’s rose and western snowberry will continue to be abundant. Plant community 4 produces less usable forage for wildlife and livestock. The continuation of the downward trend and degradation of this site has resulted in higher soil surface temperatures, reduced water infiltration, and higher evapotranspiration. This has resulted in plant species that are more adapted to drier conditions, such as Kentucky or Canada bluegrass and redtop. Most of the attributes of a healthy rangeland, including good infiltration, nutrient cycling and energy flow, have been lost. The objective at this point is to implement a grazing strategy that will restore the stability, health, and hydrology of the site. Communities 3 and 4 can respond positively to improved grazing management. However,grazing management alone typically will not be enough to restore the site to one that resembles the HCPC, Once plants such as Kentucky or Canada bluegrass, or timothy become established, they are very difficult to remove and replace by grazing management alone. Additionally, the chances for success are significantly reduced. Additional rest can sometimes help with re-establishment of the desired species, depending on the species composition at the time. It generally takes additional inputs, such as seeding, to move it towards communities similar in production and composition to the HCPC. This site is often seeded to introduced species for hay or pasture because of its productivity potential and level landscape. Reed canarygrass and “Garrison” creeping foxtail, often along with a legume such as clover or alfalfa, are common components. This plant community is often as productive as the HCPC but is no longer managed as rangeland. Once converted to introduced species, this community will take additional inputs (reseeding) to restore a community similar in composition to that of Plant Community 1 or 2.
Additional community tables
Table 8. Community 1.1 plant community composition
| Group | Common name | Symbol | Scientific name | Annual production (kg/hectare) | Foliar cover (%) | |
|---|---|---|---|---|---|---|
|
Shrub/Vine
|
||||||
| 0 | Shrubs and Half-shrubs | 0–583 | ||||
| Shrub, broadleaf | 2SB | Shrub, broadleaf | 0–291 | – | ||
| American plum | PRAM | Prunus americana | 0–291 | – | ||
| chokecherry | PRVI | Prunus virginiana | 0–291 | – | ||
| golden currant | RIAU | Ribes aureum | 0–291 | – | ||
| currant | RIBES | Ribes | 0–291 | – | ||
| Woods' rose | ROWO | Rosa woodsii | 1–291 | – | ||
| silver buffaloberry | SHAR | Shepherdia argentea | 0–291 | – | ||
| snowberry | SYMPH | Symphoricarpos | 1–291 | – | ||
|
Grass/Grasslike
|
||||||
| 0 | Grasses, Sedges, and Rushes | 3838–5246 | ||||
| basin wildrye | LECI4 | Leymus cinereus | 958–2040 | – | ||
| northern reedgrass | CASTI3 | Calamagrostis stricta ssp. inexpansa | 359–874 | – | ||
| prairie cordgrass | SPPE | Spartina pectinata | 0–874 | – | ||
| bluejoint | CACA4 | Calamagrostis canadensis | 359–874 | – | ||
| Nebraska sedge | CANE2 | Carex nebrascensis | 48–583 | – | ||
| slender wheatgrass | ELTR7 | Elymus trachycaulus | 241–583 | – | ||
| slender wheatgrass | ELTRS | Elymus trachycaulus ssp. subsecundus | 241–583 | – | ||
| meadow barley | HOBR2 | Hordeum brachyantherum | 0–291 | – | ||
| clustered field sedge | CAPR5 | Carex praegracilis | 0–291 | – | ||
| Grass-like (not a true grass) | 2GL | Grass-like (not a true grass) | 0–291 | – | ||
| Grass, perennial | 2GP | Grass, perennial | 0–291 | – | ||
| shortawn foxtail | ALAE | Alopecurus aequalis | 0–291 | – | ||
| Canada wildrye | ELCA4 | Elymus canadensis | 0–291 | – | ||
| mat muhly | MURI | Muhlenbergia richardsonis | 0–291 | – | ||
| western wheatgrass | PASM | Pascopyrum smithii | 48–291 | – | ||
| foxtail barley | HOJU | Hordeum jubatum | 0–1 | – | ||
|
Forb
|
||||||
| 0 | Forbs | 48–291 | ||||
| Forb, perennial | 2FP | Forb, perennial | 0–291 | – | ||
| western yarrow | ACMIO | Achillea millefolium var. occidentalis | 0–291 | – | ||
| silverweed cinquefoil | ARAN7 | Argentina anserina | 0–291 | – | ||
| white sagebrush | ARLU | Artemisia ludoviciana | 0–291 | – | ||
| bedstraw | GALIU | Galium | 0–291 | – | ||
| American licorice | GLLE3 | Glycyrrhiza lepidota | 0–291 | – | ||
| common cowparsnip | HEMA80 | Heracleum maximum | 0–291 | – | ||
| Rocky Mountain iris | IRMI | Iris missouriensis | 0–291 | – | ||
| blue lettuce | LATA | Lactuca tatarica | 0–291 | – | ||
| wild mint | MEAR4 | Mentha arvensis | 0–291 | – | ||
| wild bergamot | MOFI | Monarda fistulosa | 0–291 | – | ||
| elephanthead lousewort | PEGR2 | Pedicularis groenlandica | 0–291 | – | ||
| slender cinquefoil | POGR9 | Potentilla gracilis | 0–291 | – | ||
| curly dock | RUCR | Rumex crispus | 0–291 | – | ||
| mountain blue-eyed grass | SISA4 | Sisyrinchium sarmentosum | 0–291 | – | ||
| goldenrod | SOLID | Solidago | 0–291 | – | ||
| alpine leafybract aster | SYFOF | Symphyotrichum foliaceum var. foliaceum | 0–291 | – | ||
| prairie thermopsis | THRH | Thermopsis rhombifolia | 0–291 | – | ||
Interpretations
Animal community
Livestock Grazing Interpretations: Managed livestock grazing is suitable on this site as it has the potential to produce an abundance of high quality forage. This is often a preferred site for grazing by livestock due to the succulent forage, and animals tend to congregate in these areas. In order to maintain the productivity of this site, stocking rates must be managed carefully on adjoining sites with less production to be sure livestock drift onto the Subirrigated site is not excessive. Management objectives should include maintenance or improvement of the plant community. Using shorter grazing periods and providing for adequate re-growth after grazing are recommended for plant maintenance, health, and recovery.
Heavy stocking and season-long use of this site can be detrimental and will alter the plant community composition and production over time. Continual non prescribed grazing of this site can be detrimental and will alter the plant composition and production over time. The result will be plant communities that resemble numbers 3 and 4, depending on how long this grazing management is used as well as other circumstances such as depth to the water table, weather conditions, and fire frequency.
Grazing this site when the upper part of the soil is wet can cause compaction. Hummocking (frost heaving) is sometimes a feature of this site. The hummocking can be exacerbated if grazing impact becomes excessive.
Whenever Plant Community 2 (medium and short grasses and sedges) occurs, grazing management strategies need to be implemented to avoid further deterioration. This community is still stable, productive, and healthy provided it receives proper management. This community will respond fairly quickly to improved grazing management including increased growing season rest of key forage plants. Grazing management alone can usually move this community back to one more similar to potential/historic climax community.
Plant community 3 is the result of long-term, heavy, continuous grazing and/or annual, early spring seasonal grazing. Repeated heavy early spring grazing, especially during stem elongation (generally mid May through mid June), can also have detrimental affects on the taller, key forage species. Repeated spring grazing depletes stored carbohydrates, resulting in weakening and eventual death of the cool season tall and medium grasses. This plant community can occur throughout the pasture, on spot grazed areas, and around water sources where season-long grazing patterns occur.
The management objective at this point to implement a grazing strategy that will restore the stability and health of the site. Additional growing season rest, often combined with other practices (e.g., seeding, fencing), is usually necessary for re-establishment of the desired native species and to restore the stability and health of the site.
Once established, plants such as Kentucky bluegrass, smooth brome, and Canada thistle are stable and very difficult to remove by grazing alone. The potential for using seeding or mechanical treatment to improve site health can be limited, depending on the depth to the water table.
Plant Community 4 has a high percentage of aggressive, less-desirable species. It has lost most of the attributes of a healthy rangeland. Grazing management alone is seldom able to restore the site to one that resembles the HCPC once this plant community has become established. At this point, the primary objective should be to implement a grazing strategy that will restore the stability and health of the site. Additional rest is often a necessary component of this strategy. Seeding and/or mechanical treatment may be necessary, particularly since this community is predominantly non-native, highly competetive species.
Calculating Safe Stocking Rates: Proper stocking rates should be incorporated into a grazing management strategy that protects the resource, maintains or improves rangeland health, and is consistent with management objectives. Safe stocking rates will be based on useable forage production, and should consider ecological condition and trend of the site, and past grazing use history.
Calculations used to determine a safe stocking rate are based on the amount of useable forage available, taking into account the harvest efficiency of the animal and the grazing strategy to be implemented. Average annual production must be measured or estimated to properly assess useable forage production and stocking rates.
Stocking rates are calculated from average forage production values using a 25% Harvest Efficiency factor for preferred and desirable plants, and 10% Harvest Efficiency for less desirable species. AUM calculations are based on 915 pounds (air-dry) per animal unit month (AUM) for a 1,000-pound cow with calf up to 4 months. No adjustments have been made for site grazability factors, such as steep slopes, site inaccessibility, or distance to drinking water.
The following is an example of how to calculate the recommended stocking rate. This example does not use production estimates from this specific ecological site. You will need to adjust the annual production values and run the calculations using total annual production values from the ecological sites encountered on each individual ranch/pasture. Before making specific recommendations, an on-site evaluation must be made.
Example of total annual production amounts by type of year:
Favorable years = 2200 lbs/acre
Normal years = 1480 lbs/acre
Unfavorable years = 1200 lbs/acre
It is recommended that on slopes of 30% or less, stocking rate should be derived from the total annual production pounds minus 500 pounds for residual dry matter and 25% harvest efficiency. On slopes over 30%, stocking rate is derived from total annual production pounds minus 800 pounds for residual dry matter and 25% harvest efficiency. Refer to the NRCS National Range and Pasture Handbook for a list of Animal Unit Equivalents.
Sample Calculations using Favorable Year production amounts:
< 30% slopes: AUM/AC = [(2200-500)(0.25)]/915 lbs/month for one AU = 0.46 AUM/AC
AC/AUM = (1.0 AU)/(0.46AUM/AC) = 2.2 AC/AUM
> 30% slopes: AUM/AC = [(2200-800)(0.25)]/915 lbs/month for one AU = 0.38 AUM/AC
AC/AUM = (1.0 AU)/(0.38 AU! M/AC) = 2.6 AC/AUM
NOTE: 915 lbs/month for one Animal Unit is used as the baseline for maintenance requirements. This equates to 30 lbs/day of air-dry forage (1200 lb cow at 2.5% of body weight).
Hydrological functions
The runoff potential for this site is low. Runoff curve numbers generally range from 61 to 79. The soils associated with this ecological site are generally in Hydrologic Soil Group B. The infiltration rates for these soils will normally be moderate.
A drop in the water table elevation, such as a result of several years of drought conditions will result in a change in the plant community to more drought tolerant species (often non-native).
Good hydrologic conditions exist on rangelands if plant cover (grass, sedge, and litter) is greater than 70%. Fair conditions exist when cover is between 30 and 70%, and poor conditions exist when cover is less than 30%.
Sites in high similarity to HCPC (Plant Communities 1 and 2) generally have enough plant cover and litter to optimize infiltration, minimize runoff and erosion, and have a good hydrologic condition. The deep root systems of the potential vegetation help maintain or increase infiltration rates and reduce runoff.
Sites in low similarity (Plant Community 3 and 4) are generally considered to be in poor hydrologic condition as the majority of plant cover is from shallow-rooted species such as Kentucky bluegrass.
Erosion is minor for sites in high similarity. Rills and gullies should not be present. 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 erosion. Soil surfaces should not be compacted or crusted. Plant cover and litter helps retain soil moisture for use by the plants. Maintaining a healthy stand of perennial vegetation will optimize the amount of precipitation that is received. (Reference: Engineering Field Manual, Chapter 2 and Montana Supplement 4).
Recreational uses
Because of the biodiversity, varied structure and other features noted in the wildlife section, this site should provide some outstanding opportunities for recreation, such as bird watching. This site provides recreational opportunities for hiking, horseback riding, big game and upland bird hunting. The forbs have flowers that appeal to photographers. This site provides valuable open space and visual aesthetics. Caution should be used during wet weather
periods.
Wood products
None.
Supporting information
Contributors
Robert L. Ross
Robert Leinard; Barbara Gibbons; Loretta Metz; Peter Husby, Jon Siddoway, Matt Ricketts
Approval
Kirt Walstad, 7/19/2023
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) | G. Petersen |
|---|---|
| Contact for lead author | grant.petersen@usda.gov |
| Date | 03/01/2020 |
| Approved by | Kirt Walstad |
| Approval date | |
| Composition (Indicators 10 and 12) based on | Annual Production |
Indicators
-
Number and extent of rills:
Rills are not present in the reference condition. -
Presence of water flow patterns:
Water flow patterns are not present in the reference condition. -
Number and height of erosional pedestals or terracettes:
Pedestals are not evident in the reference condition. -
Bare ground from Ecological Site Description or other studies (rock, litter, lichen, moss, plant canopy are not bare ground):
Bare ground is 0-5%. It consists of small, randomly scattered patches. -
Number of gullies and erosion associated with gullies:
Gullies are not present in the reference condition. -
Extent of wind scoured, blowouts and/or depositional areas:
Wind scoured, or depositional areas are not evident in the reference condition. -
Amount of litter movement (describe size and distance expected to travel):
Litter movement is not evident in the reference condition. -
Soil surface (top few mm) resistance to erosion (stability values are averages - most sites will show a range of values):
The average soil stability rating is 6 under plant canopies and plant interspaces. The A horizon is 15-20 inches thick. -
Soil surface structure and SOM content (include type of structure and A-horizon color and thickness):
Soil Structure at the surface is typically strong to medium fine granular. A Horizon should be 15-20 inches thick with color, when wet, typically ranging in Value of 3 or less and Chroma of 3 or less.
Local geology may affect color, it is important to reference the Official Series Description (OSD) for characteristic range. https://soilseries.sc.egov.usda.gov/osdname.aspx -
Effect of community phase composition (relative proportion of different functional groups) and spatial distribution on infiltration and runoff:
Infiltration of the Subirrigated ecological site is moderate to slow and is somewhat poorly drained. An even distribution of mid stature grasses (70-80%), cool season grasslikes/bunchgrasses (20-25%) along with rhizomatous grass (<5%), forbs (5-10%), and shrubs (3-5%) -
Presence and thickness of compaction layer (usually none; describe soil profile features which may be mistaken for compaction on this site):
A compaction layer is not present in the reference condition. Soil profile may contain an abrupt transition to an Argillic horizon which can be misinterpreted as compaction, however, the soil structure will be fine to medium subangular blocky, where a compaction layer will be platy or structureless (massive). -
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:
Mid-statured, cool season, perennial bunchgrasses (Primarily basin wildrye, tufted hairgrass, slender wheatgrass, bluejoint)Sub-dominant:
grasslikes/shortgrasses (Nebraska sedge, mountain rush) >> forbs > rhizomatous grasses ≥ ShrubsOther:
Additional:
-
Amount of plant mortality and decadence (include which functional groups are expected to show mortality or decadence):
Mortality in herbaceous species is not evident. Species with bunch growth forms may have some natural mortality in centers is 3% or less. -
Average percent litter cover (%) and depth ( in):
Total litter cover ranges from 55 to 65%. Most litter is irregularly distributed on the soil surface. -
Expected annual annual-production (this is TOTAL above-ground annual-production, not just forage annual-production):
Average annual production is 5000. Low: 4600 High 5200. Production varies based on effective precipitation and natural variability of soil properties for this ecological site. -
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:
Potential invasive (including noxious) species (native and non-native). Invasive species on this ecological site include (but not limited to) sulphur cinquefoil, houndstounge, whitetop, Canada thistle, Kentucky bluegrass, Canada bluegrass, Timothy, smooth brome, yellow toadflax, leafy spurge,
Native species such as Rocky Mountain juniper, Douglas fir, lupine, etc. when their populations are significant enough to affect ecological function, indicate site condition departure. -
Perennial plant reproductive capability:
In the reference condition, all plants are vigorous enough for reproduction either by seed or rhizomes in order to balance natural mortality with species recruitment.
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The Ecosystem Dynamics Interpretive Tool is an information system framework developed by the USDA-ARS Jornada Experimental Range, USDA Natural Resources Conservation Service, and New Mexico State University.
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