Natural Resources
Conservation Service
Ecological site BX012X02C068
Skeletal 15-19 Inch Precipitation Zone Lost River Mountains
Last updated: 5/19/2025
Accessed: 05/20/2025
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): 012X–Lost River Valleys and Mountains
Major Land Resource Area (MLRA) 012X, Lost River Valleys and Mountains, consists of approximately 4.85 million acres in Idaho. MLRA 012X is broken into two Land Resource Units (LRU) based on geology, landscape, common soils, water resources, and plant community potentials. The elevation ranges from approximately 3,600 feet (1,100 meters) in the valleys and extends to the highest point in Idaho, Mt. Borah, at 12,662 feet (3,869 meters). Annual precipitation has a significant range from six to 47 inches, the driest areas in the valley bottoms and the wettest areas on the mountain summits. This MLRA encompasses portions of the Salmon-Challis National Forest, small amounts of private land, as well as other public land managed by the State of Idaho and the Bureau of Land Management. The Continental Divide runs through the Beaverhead Mountain Range directly east of the MLRA and adjacent forests and parks include the Beaverhead National Forest, Custer Gallatin National Forest, Caribou-Targhee National Forest, and Craters of the Moon National Park.
LRU notes
The Lost River Mountain LRU is located on the Lemhi, Lost River, and White Knob Mountain Ranges. These mountain ranges extend from Salmon, Idaho to the north, Craters of the Moon National Monument to the south, the Beaverhead Mountain Range to the east, and the Sawtooth Mountains to the west. This LRU borders MLRA 043B - Central Rocky Mountains, and a small portion of MLRA 010X - Central Rocky Mountains and Foothills.
The geology of this LRU is comprised mostly of colluvium from the Challis Volcanic Group, limestone from the Permian to Mississippian Period, and till from Pleistocene glacial deposits. Additionally, metasedimentary formations from the Proterozoic dominate the Lemhi Range. The elevation range of this LRU is similar to that of the MLRA (approximately 4,000 to 12,500 feet). The boundary of the unit begins where the three mountain ranges meet the valley floor and extends to the mountain peaks. Effective precipitation (estimate of the moisture available for plant use and soil forming processes at a given site) generally ranges between 10 to greater than 36 inches. The soil temperature regimes present are frigid and cryic, and the soil moisture regimes include xeric and udic. The soils for the LRU are dominated by mollisols and inceptisols from limestone and quartzite parent material, as well as glacial till.
Classification relationships
Relationship to Other Established Classification Systems
National Vegetation Classification System (NVC):
3 Semi-Desert
3.B.1 Cool Semi-Desert Scrub & Grassland
3.B.1.Ne Western North American Cool Semi-Desert Scrub & Grassland Division
M170 Great Basin-Intermountain Dry Shrubland & Grassland Macrogroup
G304 Intermountain Mountain Big Sagebrush Steppe and Shrubland Group
A3208 Mountain Big Sagebrush - Mixed Steppe and Shrubland Alliance
CEGL001032 Mountain Big Sagebrush - Antelope Bitterbrush/Bluebunch Wheatgrass Shrubland Association
Ecoregions (EPA):
Level I: 10 Northwestern Forested Mountains
Level II: 10.1 Western Cordillera
Level III: 10.1.4 Middle Rockies
Ecological site concept
The Skeletal 15-19 inch precipitation zone ecological site (StSk 15-19") is an upland ecological site that primarily occurs on the mountain landscape, primarily on mountain slopes that are at a slope of 30 percent or less. This ecological site has a high volume of coarse fragments in the top 50cm of the soil profile (greater than 35 percent). This site is not limited by soil chemistry and does not receive additional water.
These soils:
o Are moderately deep to deep
o Are not saline, saline-sodic, sodic, or highly calcareous
o Have a high volume of coarse fragments in the top 50cm of the soil profile
o Occur on slopes less than or equal to 30 percent
Associated sites
| BX012X02C072 |
Steep Skeletal 15-19 Inch Precipitation Zone Lost River Mountains This site occurs in areas with high volumes of coarse fragments. |
|---|---|
| BX012X02C063 |
Shallow to Loamy, Calcareous 15-19 Inch Precipitation Zone Lost River Mountains This site can exist in areas with high volumes of coarse fragments. |
| BX012X02C034 |
Rocky Hills 15-19 Inch Precipitation Zone Lost River Mountains This site can occur adjacent on bedrock outcroppings. |
| BX012X02C026 |
Loamy, Calcareous 15-19 Inch Precipitation Zone Lost River Mountains This site can exist in areas with high volumes of coarse fragments. |
| BX012X02C022 |
Loamy 15 to 19 Inch Precipitation Zone Lost River Mountains This site can exist adjacent, where coarse fragments volume decreases. |
Similar sites
| BX012X02C072 |
Steep Skeletal 15-19 Inch Precipitation Zone Lost River Mountains This site is also skeletal (greater than 35 percent coarse fragments in the top 50cm), however it occurs on steep slopes. |
|---|---|
| BX012X02C022 |
Loamy 15 to 19 Inch Precipitation Zone Lost River Mountains This site occurs on slopes that are also not steep, but do not have a high volume of coarse fragments in the top 50cm. |
| BX012X02C063 |
Shallow to Loamy, Calcareous 15-19 Inch Precipitation Zone Lost River Mountains This site may also have a high volume of coarse fragments but is also highly calcareous in the 10-25cm portion of the soil profile. |
| BX012X02C026 |
Loamy, Calcareous 15-19 Inch Precipitation Zone Lost River Mountains This site may also have a high volume of coarse fragments but is also highly calcareous in the 25-50cm portion of the soil profile. |
Table 1. Dominant plant species
| Tree |
Not specified |
|---|---|
| Shrub |
(1) Artemisia tridentata ssp. vaseyana |
| Herbaceous |
(1) Festuca idahoensis |
Legacy ID
R012XC068ID
Physiographic features
This site can occur on mountain slopes, alluvial fans, and stream terraces within the mountain landscape. The site is not aspect-dependent. This site occurs on slopes less than 30 percent, with slopes averaging 14 percent. Elevation averages 7,134 feet, ranging from 4,914 feet to 7,649 feet. Runoff is generally low to medium and flooding and ponding do not occur.
Figure 1. Aspect and elevation of Skeletal 15-19 inch ecological sites surveyed.
Table 2. Representative physiographic features
| Landforms |
(1)
Mountains
> Mountain slope
(2) Mountains > Alluvial fan (3) Mountains > Stream terrace |
|---|---|
| Runoff class | Low to medium |
| Flooding frequency | None |
| Ponding frequency | None |
| Elevation | 6,620 – 7,134 ft |
| Slope | 5 – 22% |
| Aspect | W, NW, N, NE, E, SE, S, SW |
Table 3. Representative physiographic features (actual ranges)
| Runoff class | Not specified |
|---|---|
| Flooding frequency | None |
| Ponding frequency | None |
| Elevation | 5,730 – 8,121 ft |
| Slope | 3 – 26% |
Climatic features
In the Lost River Mountain LRU, both precipitation and temperatures fluctuate significantly throughout the seasons and year to year. Relative effective annual precipitation (estimate of the moisture available for plant use and soil forming processes at a given site) generally ranges between 10 to greater than 36 inches. Average daily temperatures during the growing season (April to August) range from 33 to 57 degrees Fahrenheit. These wide fluctuations in temperature and precipitation are largely due to elevation and aspect differences as well as lower relative humidity and drier air in the mountainous terrain of the LRU. The wettest months in terms of rainfall are May and June. The growing season varies across the LRU in relation to topographical and local conditions; however, generally ranges between 30 to 90 days. Most primary growth occurs from late April through June. Soil temperature regimes include cryic and frigid and soil moisture regimes include xeric and udic.
For this Skeletal ecological site, the effective precipitation is 15 to 19 inches. Precipitation and temperature data were taken from Snowtel stations located on the Lost River and Lemhi Range. Precipitation data was taken from Snowtel sites that record actual precipitation and sit at slightly higher elevations than where the Skeletal ecological site tends to be found. Therefore, values shown in the precipitation tables may be higher than the climatic subset of 15 to 19 inches.
Table 4. Representative climatic features
| Frost-free period (characteristic range) | 30-60 days |
|---|---|
| Freeze-free period (characteristic range) | 40-65 days |
| Precipitation total (characteristic range) | 18-27 in |
| Frost-free period (actual range) | 25-75 days |
| Freeze-free period (actual range) | 40-85 days |
| Precipitation total (actual range) | 14-31 in |
| Frost-free period (average) | 45 days |
| Freeze-free period (average) | 60 days |
| Precipitation total (average) | 21 in |
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
Influencing water features
This is an upland ecological site and is not influenced by additional water beyond the precipitation the site receives.
Wetland description
This ecological site is not associated with wetlands.
Soil features
The soils of this ecological site are very deep to bedrock. These soils have a high volume of coarse fragments (35 percent or greater weighted average) in the top 50cm of the soil profile. The soils are primarily loams and silt loams, often with gravelly or cobbly modifiers. The pH of these soils ranges from 5.3 to 7.6, averaging 6.2.
Figure 8. Profile by total fragment volume, Steep Skeletal 15-19 inch sites.
Figure 9. Profile by texture class, Steep Skeletal 15-19 inch sites.
Figure 10. Skeletal Ecological Site Soil Profile: Site ID 2021ID7031242
Table 5. Representative soil features
| Parent material |
(1)
Alluvium
–
igneous rock
(2) Slope alluvium – metasedimentary rock (3) Alluvium – metasedimentary rock (4) Slope alluvium – igneous rock (5) Outwash – igneous rock (6) Outwash – metasedimentary rock |
|---|---|
| Surface texture |
(1) Loam (2) Silt loam (3) Gravelly loam (4) Gravelly silt loam (5) Cobbly loam (6) Cobbly silt loam (7) Very gravelly loam (8) Extremely gravelly loam (9) Very gravelly silt loam (10) Extremely gravelly silt loam (11) Very cobbly silt loam (12) Extremely cobbly silt loam (13) Very cobbly loam (14) Extremely cobbly loam |
| Family particle size |
(1) Loamy-skeletal (2) Sandy-skeletal |
| Drainage class | Well drained to somewhat excessively drained |
| Permeability class | Moderate to moderately rapid |
| Surface fragment cover <=3" | 5 – 29% |
| Surface fragment cover >3" | 6% |
| Available water capacity (0-20in) |
1.51 – 2.14 in |
| Soil reaction (1:1 water) (0-20in) |
5.8 – 6.7 |
| Subsurface fragment volume <=3" (0-20in) |
15 – 35% |
| Subsurface fragment volume >3" (0-20in) |
2 – 10% |
Table 6. Representative soil features (actual values)
| Drainage class | Not specified |
|---|---|
| Permeability class | Not specified |
| Surface fragment cover <=3" | 38% |
| Surface fragment cover >3" | 17% |
| Available water capacity (0-20in) |
1.4 – 2.3 in |
| Soil reaction (1:1 water) (0-20in) |
5.4 – 7.6 |
| Subsurface fragment volume <=3" (0-20in) |
5 – 45% |
| Subsurface fragment volume >3" (0-20in) |
17% |
Ecological dynamics
The Skeletal ecological site in the 15 to 19 inch climatic subset is a range ecological site existing within the greater sagebrush steppe ecosystem and often the transition to the forested ecosystem. The primary overstory species is mountain big sagebrush (Artemisia tridentata ssp. vaseyana), and although many different rhizomatous and bunchgrasses can exist in the understory, Idaho fescue is the primary species.
Transitions from the Reference state are driven by disturbances both natural and anthropogenic. The two primary disturbances likely to impact this ecological site are fire and herbivory. To a lesser extent, climate-driven disturbances such as drought can also instigate transitions within the site's range of variability. The steep slopes of this site can create frequent colluvial disturbances and promote establishment of invasive species.
A state-and-transition model (STM) diagram for this ecological site is depicted in this section. Thorough descriptions of each state, transition, plant community phase, and pathway are found after the state-and-transition model. This STM is based on available experimental research, field observations, professional consensus, and interpretations. While based on the best available information, the STM will change over time as knowledge of ecological processes increases.
Plant community composition within this ecological site has a natural range of variability across the LRU due to the natural variability in weather, soils, and aspect. The reference plant community may not fit management goals. Selection of other plant communities is valid if the identified range health attributes have none to slight or slight departures from the Reference state. The biological processes on this site are complex; therefore, representative values are presented in a land management context. The species lists are representative and are not botanical descriptions of all species potentially occurring on this site. They are not intended to cover every situation or the full range of conditions, species, and responses for the ecological site.
Both percent species composition by weight and percent cover are used in this ecological site description. Foliar cover is used to define plant community phases and states in the STM. Cover drives the transitions between communities and states because of the influence of shade and interception of rainfall.
Species composition by dry weight remains an important descriptor of the herbaceous community and of site productivity as a whole and includes both herbaceous and woody species. Calculating the similarity index requires data on species composition by dry weight.
Although there is considerable qualitative experience supporting the pathways and transitions within the state-and-transition model, no quantitative information exists that specifically identifies threshold parameters between reference states and degraded states in 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
State 1 submodel, plant communities
State 2 submodel, plant communities
State 3 submodel, plant communities
State 1
Reference
The Reference state consists of three plant communities: The Mountain Big Sagebrush and Idaho fescue community, the Mixed Sagebrush and Bluebunch Wheatgrass community, and the Mountain Big Sagebrush/Mixed Bunchgrass community. The Mixed Sagebrush community (1.2) includes mountain big sagebrush, Wyoming big sagebrush (Artemisia tridentata ssp. wyomingensis), black sagebrush (Artemisia nova), and little sagebrush (Artemisia arbuscula). The Mountain Big Sagebrush and Mixed Bunchgrass community consists of Idaho fescue, bluebunch wheatgrass, and Geyer's sedge (Carex geyeri) in the understory. The Mountain Big Sagebrush and Idaho Fescue community is the most common community in the Reference state, and canopy cover is generally balanced between the sagebrush overstory and the bunch grass understory. The Mixed Sagebrush community often occurs as a result of very localized site condition variation. Small changes in surface fragment composition, slope shape, and site-specific effective precipitation can allow for the establishment of several additional overstory shrub species outside of mountain big sagebrush. The composition and occurrence of shrub species in the mixed shrub community are variable and site-specific.
Characteristics and indicators. The indicators showing a shift between communities in the Reference state are driven by the composition and foliar cover of shrub and grass species. In the primary community, Idaho fescue is the most prominent understory grass species, both in foliar cover and contribution to annual production. Community 1.2 has a higher canopy cover of bluebunch wheatgrass, however Idaho fescue may still be present at varying extents. This community can also have a mix of sagebrush species in the overstory canopy. The understory of community 1.3 will have Geyer's sedge present, usually co-dominating the understory with Idaho fescue and bluebunch wheatgrass. Low-severity disturbances and slight differences in localized conditions are the primary drivers influencing the understory canopy cover of grass species. Severe or frequent fire disturbances at sites tend to shift towards more fire-resilient and resistant species such as Geyer's sedge and bluebunch wheatgrass. Sites found at the higher end of the effective precipitation range tend to favor communities 1.1 and 1.3.
Resilience management. The Reference state is overall moderately resilient. In well-established communities, resilience towards climatic disturbances such as drought is high. Existing in the upper end of the 15 to 19 inch effective precipitation range aids in resistance to drought conditions and communities 1.1 and 1.2 are comprised of many drought resistance species. Resilience to moderate or high severity fire is low. Mountain big sagebrush produces large quantities of fine fuel and is susceptible to stand destroying fires. If the disturbance is severe enough, this can initiate transition from the Reference state to the Disturbed state.
Community 1.1
Mountain Big Sagebrush and Idaho Fescue
Figure 11. Community 1.1
The Mountain Big Sagebrush and Idaho Fescue community is well adapted to the conditions present in the Skeletal ecological site within the 15 to 19 inch effective precipitation climatic subset. The overstory shrub canopy is dominated by mountain big sagebrush. Canopy density can vary by site, but can reach as high as 25 percent. Other shrubs that can be mixed within the canopy include mountain snowberry (Symphoricarpos oreophilus) and yellow rabbitbrush (Chrysothamnus viscidiflorus), usually at less than five percent. The grass understory can consist of many different species but is dominated by Idaho fescue. Idaho fescue canopy cover can be as high as 30 percent. Other species include bluebunch wheatgrass, Sandberg bluegrass (Poa secunda), needlegrass (Achnatherum spp.), squirreltail (Elymus elymoides), and timber oatgrass (Danthonia intermedia). Primary forb species include pussytoes (Antennaria spp.) and buckwheat (Eriogonum spp.). Production for this community can be high and often split evenly between shrub and grass functional groups. Production ranges from 750 to 1,500 pounds per acre, averaging 950 pounds per acre.
Resilience management. This community has moderate resilience. Although many of the species in this community are resistant to drought, resistance and resilience are much lower to frequent or severe fire occurrences. Sites with dense canopies of mountain big sagebrush are more apt to build up fine fuels which drive more severe or frequent fire events. Mountain big sagebrush is also the least resilient of the big sagebrush species to fire (Innes, 2017). Depending on how much of the overstory canopy is impacted, severe or frequent fire occurrences can prompt a shift to the Disturbed state.
Dominant plant species
-
mountain big sagebrush (Artemisia tridentata ssp. vaseyana), shrub
-
Idaho fescue (Festuca idahoensis), grass
-
sulphur-flower buckwheat (Eriogonum umbellatum), other herbaceous
-
pussytoes (Antennaria), other herbaceous
Figure 12. Annual production by plant type (representative values) or group (midpoint values)
Table 7. Annual production by plant type
| Plant type | Low (lb/acre) |
Representative value (lb/acre) |
High (lb/acre) |
|---|---|---|---|
| Grass/Grasslike | 250 | 450 | 650 |
| Shrub/Vine | 150 | 250 | 400 |
| Forb | 150 | 200 | 250 |
| Total | 550 | 900 | 1300 |
Table 8. Ground cover
| Tree foliar cover | 0% |
|---|---|
| Shrub/vine/liana foliar cover | 13-27% |
| Grass/grasslike foliar cover | 15-43% |
| Forb foliar cover | 8-15% |
| Non-vascular plants | 0% |
| Biological crusts | 0% |
| Litter | 12-45% |
| Surface fragments >0.25" and <=3" | 5-15% |
| Surface fragments >3" | 0-6% |
| Bedrock | 0% |
| Water | 0% |
| Bare ground | 2-9% |
Table 9. Soil surface cover
| Tree basal cover | 0% |
|---|---|
| Shrub/vine/liana basal cover | 2-5% |
| Grass/grasslike basal cover | 3-8% |
| Forb basal cover | 1-3% |
| Non-vascular plants | 0% |
| Biological crusts | 0% |
| Litter | 0% |
| Surface fragments >0.25" and <=3" | 17-30% |
| Surface fragments >3" | 1-8% |
| Bedrock | 0% |
| Water | 0% |
| Bare ground | 35-60% |
Figure 13. Plant community growth curve (percent production by month). ID0705, ARTRV–PSSPS-FEID. State 1.
| 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 | 25 | 35 | 30 | 5 | 0 | 0 | 5 | 0 | 0 |
Community 1.2
Mixed Sagebrush and Bluebunch Wheatgrass
Community 1.2 has a shift in overstory vegetation, primarily seen through an increase in diversity and canopy cover of shrubs. In this community, bluebunch wheatgrass will be the dominant understory vegetation in both canopy cover and contribution to annual production. Idaho fescue can still be present on sites but in lesser volumes than community 1.1. Mountain big sagebrush remains the dominant overstory vegetation, however, other shrubs can include Wyoming big sagebrush (Artemisia tridentata ssp. wyomingensis), mountain snowberry (Symphoricarpos oreophilus), black and little sagebrush (Artemisia nova and Artemisia arbuscula), and yellow rabbitbrush (Chrysothamnus viscidiflorus). This community is most likely to occur at the lower end of the effective precipitation range. These conditions favor bluebunch wheatgrass establishment and reproductive success as the species thrives when annual precipitation is less than 17 inches (Zlatnick, 1999). Lower effective precipitation values also favor the low sagebrush species and Wyoming big sagebrush. Production in this community is moderate and is split relatively evenly between the shrub and grass functional groups. Production ranges between 500 to 1,000 pounds per acre, averaging 700 pounds per acre.
Resilience management. This community has moderate resilience. The overall diversity of this community increases resilience. Increased diversity can dilute the effect of many disturbances. Although many of the species in this community are resistant to drought, resistance and resilience are lower towards severe or frequent fire events. Sites with dense canopies of mountain big sagebrush are more apt to build up fine fuels which drive more severe or frequent fire events. Mountain big sagebrush is also the least resilient of the big sagebrush species to fire (Innes, 2017). Bluebunch wheatgrass has moderate to high resilience towards severe or frequent fire events, resulting from protected root systems (Zlatnick, 1999). Depending on how much of the overstory canopy is impacted, severe or frequent fire occurrences can prompt a shift to the Disturbed state.
Dominant plant species
-
mountain big sagebrush (Artemisia tridentata ssp. vaseyana), shrub
-
Wyoming big sagebrush (Artemisia tridentata ssp. wyomingensis), shrub
-
black sagebrush (Artemisia nova), shrub
-
little sagebrush (Artemisia arbuscula ssp. longiloba), shrub
-
mountain snowberry (Symphoricarpos oreophilus), shrub
-
yellow rabbitbrush (Chrysothamnus viscidiflorus), shrub
-
bluebunch wheatgrass (Pseudoroegneria spicata), grass
-
pussytoes (Antennaria), other herbaceous
-
cushion buckwheat (Eriogonum ovalifolium), other herbaceous
Figure 14. Annual production by plant type (representative values) or group (midpoint values)
Table 10. Annual production by plant type
| Plant type | Low (lb/acre) |
Representative value (lb/acre) |
High (lb/acre) |
|---|---|---|---|
| Shrub/Vine | 225 | 300 | 450 |
| Grass/Grasslike | 200 | 275 | 375 |
| Forb | 75 | 125 | 175 |
| Total | 500 | 700 | 1000 |
Table 11. Ground cover
| Tree foliar cover | 0% |
|---|---|
| Shrub/vine/liana foliar cover | 17-38% |
| Grass/grasslike foliar cover | 15-30% |
| Forb foliar cover | 5-15% |
| Non-vascular plants | 0% |
| Biological crusts | 0% |
| Litter | 15-35% |
| Surface fragments >0.25" and <=3" | 10-30% |
| Surface fragments >3" | 0-8% |
| Bedrock | 0% |
| Water | 0% |
| Bare ground | 5-12% |
Table 12. Soil surface cover
| Tree basal cover | 0% |
|---|---|
| Shrub/vine/liana basal cover | 2-5% |
| Grass/grasslike basal cover | 2-6% |
| Forb basal cover | 1-2% |
| Non-vascular plants | 0% |
| Biological crusts | 0% |
| Litter | 0% |
| Surface fragments >0.25" and <=3" | 12-35% |
| Surface fragments >3" | 0-15% |
| Bedrock | 0% |
| Water | 0% |
| Bare ground | 35-65% |
Figure 15. Plant community growth curve (percent production by month). ID0807, ARTRW8/PSSPS.
| 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 | 30 | 35 | 25 | 5 | 0 | 0 | 5 | 0 | 0 |
Community 1.3
Mountain Big Sagebrush and Mixed Bunchgrass
Community 1.3 often exists at the transitions from rangeland to forest. In Community 1.3, mountain big sagebrush remains the dominant overstory. The significant difference between Community 1.3 and the other two communities within the Reference state is the presence of Geyer's sedge (Carex geyeri). In this community, Geyer's sedge is present and occupies at least 5 percent of the canopy. It can become co-dominant with Idaho fescue, or be the dominant understory grass species. This community is highly productive, with most of the biomass split between the shrub and grass functional groups. Annual production has a large range range, spanning 450 to 1,400 pounds per acre. The average production for this community is 750 pounds per acre.
Resilience management. This community has moderate resilience. Although many of the species in this community are resistant to drought, resistance and resilience are lower to frequent or severe fire occurrences. Sites with dense canopies of mountain big sagebrush are more apt to build up fine fuels which drive more severe or frequent fire events. Mountain big sagebrush is also the least resilient of the big sagebrush species to fire (Innes, 2017). Depending on how much of the overstory canopy is impacted, severe or frequent fire occurrences can prompt a shift to the Disturbed state. Geyer's sedge, however, is resilient to mixed-severity or frequent wildfires. If present, Geyer's sedge is often the first species to recolonize after fire disturbance (Chadwick, 2002).
Dominant plant species
-
mountain big sagebrush (Artemisia tridentata ssp. vaseyana), shrub
-
Geyer's sedge (Carex geyeri), grass
-
Idaho fescue (Festuca idahoensis), grass
-
pussytoes (Antennaria), other herbaceous
-
buckwheat (Eriogonum), other herbaceous
-
lupine (Lupinus), other herbaceous
Figure 16. Annual production by plant type (representative values) or group (midpoint values)
Table 13. Annual production by plant type
| Plant type | Low (lb/acre) |
Representative value (lb/acre) |
High (lb/acre) |
|---|---|---|---|
| Grass/Grasslike | 200 | 375 | 650 |
| Shrub/Vine | 175 | 275 | 450 |
| Forb | 75 | 100 | 300 |
| Total | 450 | 750 | 1400 |
Table 14. Ground cover
| Tree foliar cover | 0% |
|---|---|
| Shrub/vine/liana foliar cover | 11-30% |
| Grass/grasslike foliar cover | 21-35% |
| Forb foliar cover | 4-15% |
| Non-vascular plants | 0% |
| Biological crusts | 0% |
| Litter | 7-18% |
| Surface fragments >0.25" and <=3" | 2-15% |
| Surface fragments >3" | 1-18% |
| Bedrock | 0% |
| Water | 0% |
| Bare ground | 4-25% |
Table 15. Soil surface cover
| Tree basal cover | 0% |
|---|---|
| Shrub/vine/liana basal cover | 2-6% |
| Grass/grasslike basal cover | 3-8% |
| Forb basal cover | 1-3% |
| Non-vascular plants | 0% |
| Biological crusts | 0% |
| Litter | 0% |
| Surface fragments >0.25" and <=3" | 5-20% |
| Surface fragments >3" | 1-20% |
| Bedrock | 0% |
| Water | 0% |
| Bare ground | 35-65% |
Figure 17. Plant community growth curve (percent production by month). ID0705, ARTRV–PSSPS-FEID. State 1.
| 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 | 25 | 35 | 30 | 5 | 0 | 0 | 5 | 0 | 0 |
Pathway 1.1A
Community 1.1 to 1.2
The transition from Community 1.1 to Community 1.2 is a result of site-specific, localized abiotic and biotic differences. Sites primarily or secondarily dominated by bluebunch wheatgrass tend to be on the drier Skeletal sites in the 15 to 19 inch effective precipitation range. These conditions tend to favor bluebunch wheatgrass establishment and recruitment. These drier conditions also favor Wyoming big sagebrush as well as black or little sagebrush. Natural succession and population dynamics also play a role in this transition.
Context dependence. The abiotic and biotic conditions that result in community transitions from Community 1.1 to 1.2 are site-specific and not directly influenced by anthropogenic interactions.
Pathway 1.1B
Community 1.1 to 1.3
The transition from Community 1.1 to Community 1.2 is a result of site-specific, localized abiotic and biotic differences. Sites primarily or secondarily dominated by Geyer's sedge tend to be on the wetter end of the Skeletal 15 to 19 inch effective precipitation range. These conditions tend to favor elk sedge and Idaho fescue establishment and recruitment. These communities often occur near transition areas from rangeland to forest. Natural succession and population dynamics also play a role in this transition.
Context dependence. The abiotic and biotic conditions that result in community transitions from Community 1.1 to 1.3 are site-specific and not directly influenced by anthropogenic interactions.
State 2
Grazed
The Grazed state of the Skeletal 15 to 19 inch ecological site has one major community. The Grazed state is a mechanism of chronic defoliation from grazing pressure by agricultural grazing, natural grazing, or a combination of the two. The transition from the Reference state to the Grazed state occurs when understory grasses of the Reference state, such as Idaho fescue and bluebunch wheatgrass experience chronic defoliation to the point that they are replaced by more grazing tolerant species such as Sandberg bluegrass (Poa secunda) and rhizomatous wheatgrasses. Without managed grazing and rest, it is difficult to restore this state to the reference. Production in this state is lower and shifts more towards the shrub functional group. This state is also more susceptible to invasive species establishment resulting from the removal of Reference state species competition and hoof disturbance to the soil.
Characteristics and indicators. The primary indicator of the Grazed state is a shift in the compositional structure of the understory grass species. The bunchgrasses found in the Reference state (bluebunch wheatgrass and Idaho fescue) are removed through chronic defoliation and replaced with more grazing tolerant species such as Sandberg bluegrass and rhizomatous wheatgrasses like slender wheatgrass (Elymus trachycaulus). There is often also an increase in invasive species in this state as opportunities for establishment are created as the native species decrease. Soil disturbance from hoof traffic can also increase invasive species recruitment.
Resilience management. The Grazed state is moderately resilient. Most species present in this state are drought tolerant and response to frequent or severe fire varies by plant. Replacement of native vegetation through chronic defoliation from grazing increases opportunities for invasive species to establish. The greater the canopy cover of invasive species, the lower the resilience of the site.
Dominant plant species
-
mountain big sagebrush (Artemisia tridentata ssp. vaseyana), shrub
-
Sandberg bluegrass (Poa secunda), grass
-
bluebunch wheatgrass (Pseudoroegneria spicata), grass
-
slender wheatgrass (Elymus trachycaulus), grass
-
lupine (Lupinus), other herbaceous
-
pussytoes (Antennaria), other herbaceous
Community 2.1
Big Sagebrush and Sandberg Bluegrass
The Big Sagebrush and Sandberg Bluegrass community is well adapted to the conditions present at this ecological site, as well as the pressures of more intensive grazing practices. The understory grass species prevalent in this community such as Sandberg bluegrass are grazing tolerant and even increase under grazing pressure to a certain extent (Howard, 1997). Bunchgrass species that are found in the Reference state (bluebunch wheatgrass and Idaho fescue) can still be found on site, but are usually concentrated under the canopy of overstory shrubs where they are more protected from grazing species. Annual production in this community is lower than the communities in the Reference state. Production also shifts to be more heavily weighted in the shrub functional group. The production for this community can range from 350 to 850 pounds per acre, averaging 600 pounds per acre.
Resilience management. The Big Sagebrush/Sandberg Bluegrass community has moderate resilience. Many of the species found in this community are drought tolerant. Depending on grazing use, there may be increased resistance to severe or frequent fire resulting from the utilization and removal of fine fuels in the understory. This community has an increased risk of invasive species establishment as a result of grazing pressure and chronic defoliation of species present. This lowers the overall resilience of the community.
Dominant plant species
-
mountain big sagebrush (Artemisia tridentata ssp. vaseyana), shrub
-
Sandberg bluegrass (Poa secunda), grass
-
bluebunch wheatgrass (Pseudoroegneria spicata), grass
-
pussytoes (Antennaria), other herbaceous
-
lupine (Lupinus), other herbaceous
Figure 18. Annual production by plant type (representative values) or group (midpoint values)
Table 16. Annual production by plant type
| Plant type | Low (lb/acre) |
Representative value (lb/acre) |
High (lb/acre) |
|---|---|---|---|
| Shrub/Vine | 200 | 300 | 400 |
| Grass/Grasslike | 125 | 200 | 250 |
| Forb | 50 | 100 | 150 |
| Total | 375 | 600 | 800 |
Table 17. Ground cover
| Tree foliar cover | 0% |
|---|---|
| Shrub/vine/liana foliar cover | 15-40% |
| Grass/grasslike foliar cover | 10-25% |
| Forb foliar cover | 5-15% |
| Non-vascular plants | 0% |
| Biological crusts | 0% |
| Litter | 7-25% |
| Surface fragments >0.25" and <=3" | 5-25% |
| Surface fragments >3" | 0-9% |
| Bedrock | 0% |
| Water | 0% |
| Bare ground | 5-17% |
Table 18. Soil surface cover
| Tree basal cover | 0% |
|---|---|
| Shrub/vine/liana basal cover | 2-5% |
| Grass/grasslike basal cover | 2-6% |
| Forb basal cover | 1-3% |
| Non-vascular plants | 0% |
| Biological crusts | 0% |
| Litter | 0% |
| Surface fragments >0.25" and <=3" | 10-40% |
| Surface fragments >3" | 1-12% |
| Bedrock | 0% |
| Water | 0% |
| Bare ground | 20-45% |
Figure 19. Plant community growth curve (percent production by month). ID0209, ARTRV/POSE/ANNUALS. State 2.
| 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 | 25 | 40 | 15 | 10 | 0 | 5 | 5 | 0 | 0 |
State 3
Disturbed
The Disturbance state occurs when a natural or anthropogenic disturbance removes the overstory vegetation at a Skeletal 15 to 19 inch ecological site. These disturbances can include severe or frequent fire, flooding, prolonged periods of drought, intense grazing with hoof-related disturbance, insect and disease, and mechanical removal. The most common disturbance to impact this ecological site is severe or frequent fire. Fire removes the shrub overstory and the grass and forb functional groups become solely dominant. This can occur in small patches of a mosaic burn pattern, or in large spatial areas from severe fire events.
Characteristics and indicators. The Disturbance state is indicated by a lack of shrub overstory or a shrub overstory that consists of disturbance-tolerant species such as yellow rabbitbrush (Chrysothamnus viscidiflorus). The understory can maintain many of the bunchgrasses and forbs found in the Reference state such as Idaho fescue, bluebunch wheatgrass, and Geyer's sedge which can recover much more quickly following disturbance events. The composition of this state may also include invasive species as the disturbance opens opportunities for establishment.
Resilience management. This state is moderately resilient. Many species found in this state are drought tolerant. Continued disturbance can perpetuate this state, increasing time before the overstory can recover to pre-disturbance canopy structure and composition. This state loses resilience as a result of increased invasive species establishment following a disturbance.
Community 3.1
Bunchgrass and Forb
The Bunchgrass and Forb Community is easily identifiable by the lack of overstory shrub canopy cover that is present in the reference state. If a shrub canopy is present, it will be composed of more disturbance-tolerant shrubs such as yellow rabbitbrush or threetip sagebrush (Artemisia tripartita). The understory grass canopy is comprised mostly of bunchgrasses and forbs found in the reference state. Invasive species may be present in the overall site composition at less than five percent canopy cover. Production in this community can vary greatly based on the severity of the disturbance that caused the transition to this state/community and time since the disturbance. Production values range from 250 to 1,000 pounds per acre, averaging 750 pounds per acre.
Resilience management. This community is moderately resilient. Many of the species present in the canopy are drought-resistant. Continued fire disturbances will only perpetuate the community, while also increasing the probability of invasive species recruitment. Certain species such as yellow rabbitbrush and threetip sagebrush may also benefit from continued frequent disturbance. As the canopy cover of invasive species increase, resilience decreases as well.
Dominant plant species
-
yellow rabbitbrush (Chrysothamnus viscidiflorus), shrub
-
threetip sagebrush (Artemisia tripartita), shrub
-
bluebunch wheatgrass (Pseudoroegneria spicata), grass
-
Idaho fescue (Festuca idahoensis), grass
Figure 20. Annual production by plant type (representative values) or group (midpoint values)
Table 19. Annual production by plant type
| Plant type | Low (lb/acre) |
Representative value (lb/acre) |
High (lb/acre) |
|---|---|---|---|
| Grass/Grasslike | 150 | 500 | 700 |
| Forb | 50 | 175 | 200 |
| Shrub/Vine | 0 | 50 | 125 |
| Total | 200 | 725 | 1025 |
Table 20. Ground cover
| Tree foliar cover | 0% |
|---|---|
| Shrub/vine/liana foliar cover | 0-7% |
| Grass/grasslike foliar cover | 10-40% |
| Forb foliar cover | 3-15% |
| Non-vascular plants | 0% |
| Biological crusts | 0% |
| Litter | 2-18% |
| Surface fragments >0.25" and <=3" | 5-20% |
| Surface fragments >3" | 0-10% |
| Bedrock | 0% |
| Water | 0% |
| Bare ground | 7-30% |
Table 21. Soil surface cover
| Tree basal cover | 0% |
|---|---|
| Shrub/vine/liana basal cover | 0-2% |
| Grass/grasslike basal cover | 2-6% |
| Forb basal cover | 1-3% |
| Non-vascular plants | 0% |
| Biological crusts | 0% |
| Litter | 5-25% |
| Surface fragments >0.25" and <=3" | 8-35% |
| Surface fragments >3" | 1-13% |
| Bedrock | 0% |
| Water | 0% |
| Bare ground | 15-45% |
Figure 21. Plant community growth curve (percent production by month). ID1205, FEID-PSSPS. State 1.
| 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 | 5 | 25 | 30 | 25 | 5 | 5 | 0 | 5 | 0 | 0 |
Transition T1A
State 1 to 2
Transition from the Reference state to the Grazed state is a mechanism of intensive grazing practices that result in chronic defoliation of the understory vegetation. Over time, species like bluebunch wheatgrass and Idaho fescue are not able to recover from defoliation and the total canopy cover of that species will decrease on a site. In the absence of these species, grazing-tolerant plants such as Sandberg bluegrass will increase in canopy cover and production. The remaining bluebunch wheatgrass and Idaho Fescue will be concentrated under the overstory shrub cover.
Constraints to recovery. Constraints to recovery include: o Continued improper grazing techniques that result in chronic defoliation of vegetation o Prolonged periods of drought that diminish regeneration of desired species o Loss of nutrient-rich topsoil due to increased erosion o Establishment of invasive species
Context dependence. Restoration efforts can be greatly influenced by precipitation patterns. Successful regeneration of Reference state understory species is highly dependent on moisture received post-restoration efforts. Rates of successful establishment of Idaho fescue and bluebunch wheatgrass increase when available moisture is high during critical regeneration periods (Zlatnik, 1999; Howard, 1997).
Transition T1B
State 1 to 3
The transition from the Reference state to the Disturbed state is a mechanism of frequent or severe disturbances that remove the overstory shrubs on a given site. The most common disturbance that results in the loss of the shrub overstory is high-intensity fire. Mountain big sagebrush is sensitive to all but the lowest severity fire, generally resulting in stand replacement. Since 1900, fire exclusion and removal of fine fuels through grazing have increased fire return intervals and increased the likelihood of more severe fire events that are often stand-destroying (Gucker, 2006).
Constraints to recovery. Constraints to recovery include: o Frequent disturbances before recovery has been completed o Prolonged periods of drought that diminish regeneration of desired species o Loss of nutrient-rich topsoil due to increased erosion o Establishment of invasive species o Distance from seed source
Restoration pathway R2A
State 2 to 1
The primary mechanism for restoration from the Grazed state to the Reference state is rest from grazing. Reference state grasses such as bluebunch wheatgrass and Idaho fescue will not be able to re-establish while grazing pressure continues. Seeding of desired species may speed up the restoration process.
Context dependence. The time frame for restoration is highly dependent on variations in localized weather patterns. Prolonged periods of drought can dramatically increase the time required to return to the Reference state, whereas periods of above-normal precipitation can decrease that time frame. Infrequent, light-intensity grazing events that mimic natural historic grazing patterns will not impact the restoration pathway. However, continuous early season grazing at moderate to high intensity resulting in significant defoliation will perpetuate the Grazed state.
Restoration pathway R3A
State 3 to 1
Restoration from the Disturbed state to the Reference state is a mechanism of time without stand-destroying disturbance. Once the shrub overstory has been removed, replacement seedlings will need to reach maturity without any further disturbances.
Context dependence. Restoration is highly dependent on time without disturbance. New sagebrush seedlings are moderately sensitive to disturbances such as flood, freeze, and insect and disease. They are highly sensitive to herbivory and even low-severity fire events (Fryer, 2009; Steinberg, 2002). Seeding and planting of desired species can speed up the restoration process, however; regeneration success with or without planting is highly dependent on localized weather patterns during the restoration period. Periods of drought will slow the process significantly, whereas periods of above-normal precipitation aid in sagebrush regeneration and establishment (Innes, 2017; Steinberg, 2002; Fryer, 2009).
Additional community tables
Table 22. Community 1.1 plant community composition
| Group | Common name | Symbol | Scientific name | Annual production (lb/acre) | Foliar cover (%) | |
|---|---|---|---|---|---|---|
|
Shrub/Vine
|
||||||
| 1 | 150–400 | |||||
| mountain big sagebrush | ARTRV | Artemisia tridentata ssp. vaseyana | 50–350 | 10–25 | ||
| yellow rabbitbrush | CHVI8 | Chrysothamnus viscidiflorus | 0–100 | 0–7 | ||
| mountain snowberry | SYOR2 | Symphoricarpos oreophilus | 0–100 | 0–7 | ||
|
Grass/Grasslike
|
||||||
| 2 | 250–650 | |||||
| Idaho fescue | FEID | Festuca idahoensis | 125–450 | 15–35 | ||
| bluebunch wheatgrass | PSSPS | Pseudoroegneria spicata ssp. spicata | 30–200 | 2–15 | ||
| Sandberg bluegrass | POSE | Poa secunda | 15–100 | 1–5 | ||
| sedge | CAREX | Carex | 0–40 | 0–2 | ||
| needlegrass | ACHNA | Achnatherum | 0–40 | 0–2 | ||
| Kentucky bluegrass | POPR | Poa pratensis | 0–35 | 0–3 | ||
| squirreltail | ELEL5 | Elymus elymoides | 0–35 | 0–2 | ||
| timber oatgrass | DAIN | Danthonia intermedia | 0–30 | 0–2 | ||
|
Forb
|
||||||
| 3 | 150–250 | |||||
| sulphur-flower buckwheat | ERUM | Eriogonum umbellatum | 10–40 | 2–7 | ||
| lupine | LUPIN | Lupinus | 0–30 | 0–3 | ||
| arrowleaf balsamroot | BASA3 | Balsamorhiza sagittata | 10–25 | 1–3 | ||
| pussytoes | ANTEN | Antennaria | 10–20 | 1–3 | ||
| agoseris | AGOSE | Agoseris | 0–20 | 0–3 | ||
| old man's whiskers | GETR | Geum triflorum | 0–20 | 0–3 | ||
| longleaf phlox | PHLO2 | Phlox longifolia | 5–20 | 1–3 | ||
| spiny phlox | PHHO | Phlox hoodii | 5–20 | 1–3 | ||
| Indian paintbrush | CASTI2 | Castilleja | 5–20 | 1–3 | ||
| stonecrop | SEDUM | Sedum | 0–15 | 0–2 | ||
| ballhead sandwort | ARCO5 | Arenaria congesta | 0–15 | 0–2 | ||
| western stoneseed | LIRU4 | Lithospermum ruderale | 0–15 | 0–2 | ||
| hawksbeard | CREPI | Crepis | 0–15 | 0–2 | ||
| common yarrow | ACMI2 | Achillea millefolium | 5–15 | 1–2 | ||
| agoseris | AGOSE | Agoseris | 0–15 | 0–2 | ||
| larkspur | DELPH | Delphinium | 0–10 | 0–1 | ||
| western daisy fleabane | ERBE2 | Erigeron bellidiastrum | 0–10 | 0–1 | ||
| cinquefoil | POTEN | Potentilla | 0–10 | 0–1 | ||
| onion | ALLIU | Allium | 0–10 | 0–1 | ||
| cushion buckwheat | EROV | Eriogonum ovalifolium | 0–10 | 0–1 | ||
| nineleaf biscuitroot | LOTR2 | Lomatium triternatum | 0–10 | 0–1 | ||
Table 23. Community 1.2 plant community composition
| Group | Common name | Symbol | Scientific name | Annual production (lb/acre) | Foliar cover (%) | |
|---|---|---|---|---|---|---|
|
Shrub/Vine
|
||||||
| 1 | 225–450 | |||||
| mountain big sagebrush | ARTRV | Artemisia tridentata ssp. vaseyana | 50–150 | 5–15 | ||
| Wyoming big sagebrush | ARTRW8 | Artemisia tridentata ssp. wyomingensis | 0–100 | 0–10 | ||
| black sagebrush | ARNO4 | Artemisia nova | 0–75 | 0–8 | ||
| mountain snowberry | SYOR2 | Symphoricarpos oreophilus | 0–75 | 0–5 | ||
| little sagebrush | ARARL | Artemisia arbuscula ssp. longiloba | 0–60 | 0–56 | ||
| yellow rabbitbrush | CHVI8 | Chrysothamnus viscidiflorus | 0–60 | 0–5 | ||
|
Grass/Grasslike
|
||||||
| 2 | 200–375 | |||||
| bluebunch wheatgrass | PSSP6 | Pseudoroegneria spicata | 50–200 | 5–15 | ||
| Idaho fescue | FEID | Festuca idahoensis | 20–125 | 2–10 | ||
| bluegrass | POA | Poa | 0–100 | 0–8 | ||
|
Forb
|
||||||
| 3 | 75–175 | |||||
| pussytoes | ANTEN | Antennaria | 10–50 | 0–5 | ||
| sulphur-flower buckwheat | ERUM | Eriogonum umbellatum | 0–50 | 0–4 | ||
| cushion buckwheat | EROV | Eriogonum ovalifolium | 0–40 | 0–4 | ||
| phlox | PHLOX | Phlox | 0–40 | 0–3 | ||
Table 24. Community 1.3 plant community composition
| Group | Common name | Symbol | Scientific name | Annual production (lb/acre) | Foliar cover (%) | |
|---|---|---|---|---|---|---|
|
Shrub/Vine
|
||||||
| 1 | 175–450 | |||||
| mountain big sagebrush | ARTRV | Artemisia tridentata ssp. vaseyana | 150–400 | 10–30 | ||
| little sagebrush | ARARL | Artemisia arbuscula ssp. longiloba | 0–150 | 0–5 | ||
| common juniper | JUCO6 | Juniperus communis | 0–100 | 0–3 | ||
|
Grass/Grasslike
|
||||||
| 2 | 200–650 | |||||
| Geyer's sedge | CAGE2 | Carex geyeri | 75–250 | 5–20 | ||
| Idaho fescue | FEID | Festuca idahoensis | 75–250 | 5–18 | ||
| bluebunch wheatgrass | PSSP6 | Pseudoroegneria spicata | 0–200 | 0–15 | ||
| bluegrass | POA | Poa | 0–40 | 0–3 | ||
| Sandberg bluegrass | POSE | Poa secunda | 0–40 | 0–3 | ||
| sedge | CAREX | Carex | 0–30 | 0–2 | ||
| timber oatgrass | DAIN | Danthonia intermedia | 0–20 | 0–1 | ||
| squirreltail | ELEL5 | Elymus elymoides | 0–20 | 0–1 | ||
| cheatgrass | BRTE | Bromus tectorum | 0–20 | 0–1 | ||
| Cusick's bluegrass | POCU3 | Poa cusickii | 0–20 | 0–1 | ||
|
Forb
|
||||||
| 3 | 75–300 | |||||
| buckwheat | ERIOG | Eriogonum | 10–50 | 1–5 | ||
| sulphur-flower buckwheat | ERUM | Eriogonum umbellatum | 0–50 | 0–5 | ||
| lesser spikemoss | SEDE2 | Selaginella densa | 0–50 | 0–5 | ||
| pussytoes | ANTEN | Antennaria | 10–35 | 1–4 | ||
| lupine | LUPIN | Lupinus | 10–35 | 1–3 | ||
| ballhead sandwort | ARCO5 | Arenaria congesta | 0–10 | 0–2 | ||
| granite prickly phlox | LIPU11 | Linanthus pungens | 0–10 | 0–2 | ||
| plains pricklypear | OPPO | Opuntia polyacantha | 0–10 | 0–2 | ||
| Indian paintbrush | CASTI2 | Castilleja | 0–5 | 0–1 | ||
| fireweed | CHAN9 | Chamerion angustifolium | 0–5 | 0–1 | ||
| cushion buckwheat | EROV | Eriogonum ovalifolium | 0–5 | 0–1 | ||
| spiny phlox | PHHO | Phlox hoodii | 0–5 | 0–1 | ||
| cinquefoil | POTEN | Potentilla | 0–5 | 0–1 | ||
Table 25. Community 2.1 plant community composition
| Group | Common name | Symbol | Scientific name | Annual production (lb/acre) | Foliar cover (%) | |
|---|---|---|---|---|---|---|
|
Shrub/Vine
|
||||||
| 1 | 200–400 | |||||
|
Grass/Grasslike
|
||||||
| 2 | 125–250 | |||||
| bluebunch wheatgrass | PSSP6 | Pseudoroegneria spicata | 40–175 | 3–15 | ||
| Sandberg bluegrass | POSE | Poa secunda | 75–150 | 5–12 | ||
| Idaho fescue | FEID | Festuca idahoensis | 0–100 | 0–7 | ||
| slender wheatgrass | ELTR7 | Elymus trachycaulus | 0–75 | 0–5 | ||
|
Forb
|
||||||
| 3 | 50–150 | |||||
| pussytoes | ANTEN | Antennaria | 15–70 | 2–7 | ||
| buckwheat | ERIOG | Eriogonum | 5–50 | 1–5 | ||
| lupine | LUPIN | Lupinus | 0–50 | 0–4 | ||
| milkvetch | ASTRA | Astragalus | 0–30 | 0–4 | ||
Table 26. Community 3.1 plant community composition
| Group | Common name | Symbol | Scientific name | Annual production (lb/acre) | Foliar cover (%) | |
|---|---|---|---|---|---|---|
|
Shrub/Vine
|
||||||
| 1 | 0–125 | |||||
| yellow rabbitbrush | CHVI8 | Chrysothamnus viscidiflorus | 25–100 | 3–10 | ||
| threetip sagebrush | ARTR4 | Artemisia tripartita | 0–100 | 0–8 | ||
|
Grass/Grasslike
|
||||||
| 2 | 150–750 | |||||
| bluebunch wheatgrass | PSSP6 | Pseudoroegneria spicata | 50–200 | 4–15 | ||
| Idaho fescue | FEID | Festuca idahoensis | 0–150 | 0–10 | ||
| Geyer's sedge | CAGE2 | Carex geyeri | 0–150 | 0–10 | ||
| Sandberg bluegrass | POSE | Poa secunda | 0–150 | 0–7 | ||
|
Forb
|
||||||
| 3 | 50–200 | |||||
| pussytoes | ANTEN | Antennaria | 20–100 | 2–8 | ||
| heartleaf arnica | ARCO9 | Arnica cordifolia | 0–100 | 0–6 | ||
| lupine | LUPIN | Lupinus | 10–100 | 1–3 | ||
| phlox | PHLOX | Phlox | 0–30 | 0–1 | ||
| buckwheat | ERIOG | Eriogonum | 0–20 | 0–1 | ||
| common yarrow | ACMI2 | Achillea millefolium | 0–20 | 0–1 | ||
| Indian paintbrush | CASTI2 | Castilleja | 0–10 | 0–1 | ||
Interpretations
Animal community
Listed below are production ranges for each community in the Skeletal ecological site within the 15 to 19 inch climatic subset. These values can be used to estimate stocking rates, however, community composition as listed in this ecological site description may not entirely match the current composition at a given site. Field visits to document actual plant composition and production should be conducted to calculate actual stocking rates at a location.
Communities and Production Ranges (in pounds per acre):
Reference State:
1.1 - 750 - 950 - 1500
1.2 - 500 - 700 - 1000
1.3 - 450 - 750 - 1400
Grazed:
2.1 - 350 - 600 - 850
Disturbed
3.1 - 200 - 750 - 1000
Wildlife Interpretations:
Sagebrush steppe ecosystems in the Western United States cover nearly 165 million acres and provide vital habitat for over 170 different species of birds and mammals (NWF, 2022).
The sagebrush grasslands in the Lost River Mountain LRU provide critical winter range for mule deer, elk, pronghorn and moose. The LRU also encompasses critical habitat for greater sage grouse populations in the Lemhi, Lost River, and White Knob Mountain mountain ranges. Sage grouse priority planning areas have been identified by the Challis Sage Grouse Local Working Group in Grouse and Morse Creek, the Upper Pahsimeroi north of Sawmill Canyon, Mackay Bar, and Barton Flats (CSLWG, 2007). According to Idaho Fish and Game Management spatial layers developed in conjunction with the Bureau of Land Management, US Forest Service, and US Fish and Wildlife Service, greater sage grouse general habitat exists on the northern end of the White Knob Mountain range, northern end of the Pahsimeroi Mountain range, and portions of the eastern side of the Lemhi and White Knob Mountain ranges. More importantly to the species, significant areas designated important and priority habitat have been identified across the entirety of the White Knob, Lost River, and Lemhi mountain ranges.
The following are dominant plant species within this ecological site and their associated value to wildlife present in the LRU:
Mountain big sagebrush (Artemisia tridentata spp. vaseyana) - Communities 1.1, 1.2, 1.3, 2.1:
Mountain big sagebrush is considered to be highly palatable by most wildlife browsers (Rosenstrater, 2005). Sage grouse, ungulates, and rodents browse mountain big sagebrush primarily during the winter when it becomes one of the more palatable available forages. However, seasonal snow levels can exclude many browsing species. Several studies have shown that Mountain big sagebrush is preferred forage by elk, mule deer, and sage grouse when compared to the other big sagebrush species (Innes, 2017). Sage grouse are considered obligate species of mountain big sagebrush and other big sagebrush varieties. These species are generally preferred over the low sagebrush species; Artemisia nova and Artemisia arbuscula (Dalke et al., 1963).
Threetip sagebrush (Artemisia tridentata spp. tripartita) - Community 3.1:
Threetip sagebrush is not a preferred browse species for most wild ungulates. It can be used to a minor extent by mule deer in both the winter and summer and as emergency forage for other large ungulates (Tirmenstein, 1999.)
Bluebunch wheatgrass (Psuedoeogenaria spicata) - All states/communities:
Bluebunch wheatgrass is considered one of the most important forage species on Western rangelands for both livestock and wildlife (Sours, 1983). In Idaho, utilization of bluebunch wheatgrass by elk was medium-high, medium for mule deer, high for bighorn sheep, and low for pronghorn (Zlatnik, 1999).
Idaho fescue (Festuca idahoensis) - All States/ Communities
When available, Idaho fescue can be a dominant component to many wild ungulate diets, including pronghorn, deer, elk, and bighorn sheep. In some instances depending on other available forage, the species can be considered as valuable but not preferred forage for ungulates. The species is a valuable component to the diet of the Northern pocket gopher and grizzly bear when it is found within their range.
Sandberg bluegrass (Poa secunda) - Potentially all states/communities
Sandberg bluegrass is one of the earliest grasses to green up during the spring and become available forage for wildlife; however becomes less utilized during the later summer months. Degree of use for elk and pronghorn is good to poor, and good to fair for mule deer, small mammals, small nongame birds, and upland game birds. Usage is fair to poor by waterfowl (Howard, 1997).
Geyer's Sedge (Carex geyeri) - Potentially all states/ communities:
Geyer's sedge has fair nutritional value, providing decent forage for wildlife and livestock. This sedge is highly palatable to elk, and moderately palatable to other native ungulates. Black bear browse elk sedge extensively in the spring. Geyer's sedge often increases after disturbance and is highly drought resistant, making it a valuable forage during times following a fire disturbance or prolonged periods of low moisture availability (Chadwick, 2002).
Hydrological functions
Annual precipitation is the primary limiting factor of total plant production on this ecological site. Soils associated with this site are primarily associated with hydrologic group B. Runoff potential ranges from moderate to rapid and soil permeability is moderate. Water transmission through the soil is unimpeded.
Higher infiltration rates and lower runoff rates tend to coincide with ground cover percentage. Reduced infiltration and increased runoff have the greatest potential when ground cover is less than 50 percent.
Recreational uses
This ecological site provides hunting opportunities for upland game birds and large game animals including pronghorn, mule deer, elk, and moose. Many trails and campsites exist within the LRU and are maintained by public land management agencies.
The diverse plants that exist in this LRU and on this ecological site have an aesthetic value that appeals to recreationists.
Supporting information
Inventory data references
Site IDs and data collection intensity for each site used in the development of this ecological site description are listed below. Tier III data sets include five rangeland inventory protocols: Line point intercept, canopy/basal gap, production, continuous line intercept for overstory canopy, and soil stability. Tier II datasets include Line point intercept and at least one other survey. Tier I datasets include an ocular macroplot survey that involved a site plant census, canopy cover estimates, production by species estimates, and total site production estimates.
1.1
Tier I : 2021ID7200012,2021ID7200060
1.2
Tier I : 2021ID7033192, 2021ID7031242
1.3
Tier I : 2021ID7033192,2021ID7200090,2021ID7202009
2.1
Tier I : 2019ID7032062
Other references
Challis Sage-grouse Local Working Group (CSLWG). 2007. Challis Sage-grouse Conservation Plan.
Chadwick, Amy C. 2002. Carex geyeri. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Available: https://www.fs.usda.gov /database/feis/plants/graminoid/cargey/all.html
Howard, Janet L. 1997. Poa secunda. In: Fire Effects Information System, [Online].
U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station,
Fire Sciences Laboratory (Producer). Available:
https://www.fs.usda.gov/database/feis/plants/graminoid/poasec/all.html
Innes, Robin J. 2017. Artemisia tridentata subsp. vaseyana, mountain big sagebrush. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Missoula Fire Sciences Laboratory (Producer). Available:https://www.fs.usda.gov/database/feis/plants/shrub/arttriv/all.html
https://www.fs.usda.gov/database/feis/plants/shrub/chrvis/all.html
USNVC [United States National Vegetation Classification]. 2021. United States National Vegetation Classification Database, V2.031. Federal Geographic Data Committee, Vegetation Subcommittee, Washington DC. [usnvc.org]
Zlatnik, Elena. 1999. Pseudoroegneria spicata, bluebunch wheatgrass. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Available: https://www.fs.usda.gov /database/feis/plants/graminoid/psespi/all.html [2024, March 12].
Contributors
Zachary Van Abbema
Carla Rebernak
Grant Petersen
Kirt Walstad
Karen Clause
Approval
Kirt Walstad, 5/19/2025
Acknowledgments
Carla Rebernak
Katelyn Palmer
Nick Kozlowski
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) | Zach VanAbbema |
|---|---|
| Contact for lead author | zachary.vanabbema@usda.gov |
| Date | 03/05/2025 |
| 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 uncommon in the reference condition. When present, they usually occur on steeper slopes (greater than 15 percent) and are inconspicuous, disconnected, and very short in length. -
Number and height of erosional pedestals or terracettes:
Pedestals and/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 between two to 25 percent. This refers to exposed mineral soil not covered by litter, rock, basal cover, plant cover, standing dead, lichen and/or moss. -
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):
Movement of fine herbaceous litter may occur within less than a foot from where it originated. -
Soil surface (top few mm) resistance to erosion (stability values are averages - most sites will show a range of values):
Soil Surface Stable with Stability Ratings of 4-6 (both under canopy and bare). Abiotic crusts and or root mats may be present. -
Soil surface structure and SOM content (include type of structure and A-horizon color and thickness):
Soil surface structure is granular with the first A horizon ranging from 0 - 13cm thick. Predominant A horizon colors are 7.5YR 2.5/1-7.5YR 3/3 and 10YR 2/2-10YR 3/3. -
Effect of community phase composition (relative proportion of different functional groups) and spatial distribution on infiltration and runoff:
Plants are evenly distributed across the ecological site and the shrubs and bunchgrasses present improved infiltration as well as protect against runoff. -
Presence and thickness of compaction layer (usually none; describe soil profile features which may be mistaken for compaction on this site):
Not present. -
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:
Mountain big sagebrush > Idaho fescueSub-dominant:
Mixed shrubs>bluebunch wheatgrass/remaining grassesOther:
Pink pussytoes = cushion buckwheat = sulphur flower buckwheat = phlox spp.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. Sagebrush species will become decadent in the absence of historical fire return intervals. -
Average percent litter cover (%) and depth ( in):
Total ground litter cover varies but can range from 12 to 45 percent averaging 30 percent. Depth is usually shallow at less than 1/8 inch. -
Expected annual annual-production (this is TOTAL above-ground annual-production, not just forage annual-production):
Annual production ranges from 500 to 1500 lbs/acre, averaging 800 lbs/per acre. Production varies based on effective precipitation and the natural variability of soil properties for this ecological site. Total production is slightly higher for perennial grass species but tends to be slightly higher for shrubs than grasses. -
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 species include cheatgrass, spotted knapweed, toadflax, and crested wheatgrass. Native species such as yellow rabbitbrush or significant populations of Sandberg bluegrass or rhizomatous wheatgrasses can indicate a departure from the reference state. -
Perennial plant reproductive capability:
All functional groups have the potential to reproduce in most years. Bluebunch wheatgrass may not reproduce during extended periods of drought.
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