State 1
Reference

The Reference state consists of three dominant plant communities: The mountain big sagebrush (Artemisia tridentata sp. vasayana)/little sagebrush (Artemisia arbuscula spp. Longiloba) dominated community, a mountain big sagebrush/bluebunch wheatgrass (Pseudoroegneria spicata) dominated community, and a community where the dominant overstory shrub is mountain big sagebrush, and the understory is a mix of bunchgrasses. The greatest difference between the three plant communities is composition and foliar cover of sagebrush (Artemisia) species and understory grass species. Generally, mountain big sagebrush foliar cover increases on sites that are closer to the higher end of the effective precipitation range (15 to 19 inch) or the calcium carbonate concentration in the soil is lower, closer to minimum 15 percent required in the site concept. This community also occurs more often when calcareous soil presence is deeper in the soil profile, closer to a depth of 20 inches (50cm). Processes (both natural and anthropogenic) that can result in state and community changes include fire, grazing, land use change, and establishment of invasive species (Davies et al., 2011).

Characteristics and indicators. The shift between states (and plant communities) at this site is generally driven by calcium carbonate concentration in soils, effective precipitation, and sagebrush killing disturbances or lack thereof. Historically, low to mixed severity fires occurred at relatively frequent fire return intervals of 10 to 25 years, limiting sagebrush canopy density and creating a mosaic of sagebrush stands and more open grasslands (Knick, Holmes, & Miller, 2005). Exclusion of fire (in conjunction with climate change) increases sagebrush canopy cover and can lead to more severe stand replacing fires, often times at more frequent intervals. These severe fires can drive shifts to grassland communities as well as create opportunities for invasive species establishment (Roadhouse, Irvine, & Bowerstock, 2020; Knick et al., 2005). Improper grazing practices can also lead to an increase in sagebrush canopy cover and increased risk of severe, stand replacing fire occurrence. Removal of understory grasses can lessen the opportunities for low severity fire occurrence which leads to increased canopy densities and increases potential for severe fire disturbance events (Knick et al., 2005).

Resilience management. This site has moderate resilience as a result of the cryic soil temperature regime and xeric soil moisture regime. Resistance and resilience of a specific site has been attributed with abiotic conditions favorable to plant growth and reproduction (Maestas et al. 2016). Soils that fall within the cryic (cold) temperature regime and xeric (wet) moisture regime tend to have higher diversity and production, and are therefore more resilient, specifically in terms of resisting or recovering from invasion post disturbance (Maestas et al., 2016). Although little sagebrush is susceptible to fire damage and usually killed by fire events, fire events within these communities are usually rare. These communities generally lack the fine fuels required to carry fire, promoting relatively infrequent fire return intervals (Steinberg, 2002). Mountain big sagebrush is also highly susceptible to damage and mortality from fire events. However, these communities tend to have higher fuel loading and carry fire more easily and frequently than in the little sagebrush communities (Innes, 2017).

Community 1.1
Mountain Big Sagebrush, Little Sagebrush, and Bluebunch Wheatgrass

Community 1.1 is well adapted to the abiotic conditions of the Lost River Mountain LRU. Little sagebrush (Artemisia arbuscula) and mountain big sagebrush are often able to coexist on the highly calcareous soils that form from limestone parent material. Little sagebrush more often dominates the canopy at this ecological site when concentrations of calcium carbonates are higher or exist closer to the surface; however, it is not uncommon for the percent composition between mountain big sagebrush and little sagebrush to be nearly equal. It is also possible that one of the two species is missing from the canopy completely. Mountain Big Sagebrush, Little Sagebrush, and Bluebunch Wheatgrass communities can form in a mosaic distribution with other communities in this state (1.2 & 1.3) across the range of relative effective annual precipitation. As effective precipitation increases, the understory of bluebunch wheatgrass (Pseudoroegneria spicata) decreases in percent canopy cover. Other bunchgrasses such as Idaho fescue (Festuca idahoensis) increase in canopy cover as available moisture increases. Production in this community ranges from 500 to 900 pounds per acre, averaging 700 pounds per acre. In this community, overstory shrubs and understory grasses contribute a nearly equal amount to overall production.

Resilience management. Resilience is moderate in Community 1.1. Mountain big sagebrush and little sagebrush are both drought tolerant species able to withstand periods of below average precipitation. Bluebunch wheatgrass is well suited to the variable climate experienced in the Lost River Mountains and is resilient towards many natural disturbances including drought and fire. Bluebunch wheatgrass has shown to recover to pre-fire disturbance population levels in 1 to 7 years post disturbance. Under certain conditions, canopy cover and production can exceed pre-fire values (Zlatnik, 1999). Bluebunch wheatgrass is a decreaser, reducing in canopy cover and production in relation to grazing pressure. Under heavy grazing pressure the species will shift towards areas such as under the canopy of shrubs, opening the canopy for the establishment of rhizomatous grass species, invasive species, or bare ground.

Community 1.2
Mountain Big Sagebrush and Bluebunch Wheatgrass

The Mountain Big Sagebrush and Mixed Bunchgrass community is well adapted to the abiotic conditions of the Lost River Mountain LRU. Mountain big sagebrush can occur on Mollisols, Aridisols, and Inceptisols, however, is most abundant on Mollisols (Innes, 2017). Mountain big sagebrush increases in canopy cover as highly calcareous soils are found deeper in the soil profile, which often coincides with a slight increase in relative effective annual precipitation. In this community, mountain big sagebrush has the ability to form dense monocultures with little competition from other shrub species. The understory is dominated by bunchgrasses, primarily bluebunch wheatgrass, and to a lesser extent at the higher end of the effective precipitation range, Idaho fescue (Festuca idahoensis). Plant diversity in mountain big sagebrush dominated communities is higher than with any other big sagebrush species. This primarily due to high diversity in forb and grass understory species (Innes, 2017). Total annual production of Community 1.3 ranges from 700 to 1,100 pounds per acre, averaging 970 pounds per acre. Shrub canopy cover can be as high as 40 percent, with 30 percent comprised of mountain big sagebrush. Grass canopy cover can also reach 40 percent, the majority consisting of bluebunch wheatgrass, Idaho fescue, and Sandberg bluegrass (Poa secunda).

Resilience management. This community has moderate. Mountain big sagebrush is the least drought tolerant of the big sagebrush species. Mountain big sagebrush is highly flammable and fire typically kills plants within the disturbance area. Because this species reproduces via seed that is dispersed through wind, water, and zoochory, distance from a viable source population plays a major role in post disturbance regeneration. When disturbance events cover a large area spatially, regeneration timespan increases and likelihood of transitioning to another state or community increases (Innes, 2017). Slow regeneration can open windows for erosion to occur and invasive species to establish. Post disturbance seeding and planting can increase restoration success. Bluebunch wheatgrass is a much more resilient species to the local disturbance regimes. The species is drought tolerant and usually is not killed except during the most severe wildfire events. During severe disturbances that remove the sagebrush overstory, bluebunch wheatgrass can persist as the dominant vegetation on this ecological site (Zlatnik, 1999).

Community 1.3
Mountain Big Sagebrush and Mixed Bunchgrass

The Mountain Big Sagebrush and Mixed Bunchgrass community is well adapted to the abiotic conditions of the Lost River Mountain LRU. Mountain big sagebrush can occur on Mollisols, Aridisols, and Inceptisols, however, is most abundant on Mollisols (Innes, 2017). Mountain big sagebrush increases in canopy cover as highly calcareous soils are found deeper in the soil profile, which often coincides with a slight increase in relative effective annual precipitation. In this community, mountain big sagebrush has the ability to form dense monocultures with little competition from other shrub species. The understory is dominated by bunchgrasses, primarily Idaho fescue, and to a lesser extent at the lower end of the effective precipitation range, bluebunch wheatgrass. Plant diversity in mountain big sagebrush dominated communities is higher than with any other big sagebrush species. This primarily due to high diversity in forb and grass understory species (Innes, 2017). Total annual production of Community 1.3 is high, ranging from 700 to 1,500 pounds per acre, averaging 1,100 pounds per acre. Production is generally split evenly between shrub and grass functional groups. Shrub canopy cover can be as high as 30 percent, while grass canopy cover can exceed 25 percent, the majority attributed to Idaho fescue, bluebunch wehatgrass, and Sandberg bluegrass (Poa secunda). Forb canopy cover can reach 22 percent, but is more often closer to 10 percent.

Resilience management. This community has moderately low resilience. Mountain big sagebrush is the least drought tolerant of the big sagebrush species. Mountain big sagebrush is highly flammable and fire typically kills plants within the disturbance area. Because this species reproduces via seed that is dispersed through wind, water, and zoochory, distance from a viable source population plays a major role in post disturbance regeneration. When disturbance events cover a large area spatially, regeneration timespan increases and likelihood of transitioning to another state or community increases (Innes, 2017). Slow regeneration can open windows for erosion to occur and invasive species to establish. Post disturbance seeding and planting can increase restoration success. When Idaho fescue is the dominant understory or shares dominance in the understory, fire return intervals can be as frequent as 10 to 15 years. Although Idaho fescue fares better than mountain big sagebrush during fire events, mortality averages between 20 and 50 percent and can exceed 75 percent after severe events (Zouhar, 2000). Severe fire events prompt a shift into the Disturbed State. The additional effective precipitation received at this site (20 to 24 inch) adds resilience. Available moisture has shown to be a key component of successful post disturbance recovery (Chamber et al., 2014).

Pathway 1.1A
Community 1.1 to 1.2

Mountain Big Sagebrush, Little Sagebrush, and Bluebunch Wheatgrass

Mountain Big Sagebrush and Bluebunch Wheatgrass

Transition from community 1.1 to 1.2 is a product of slightly higher effective precipitation and slight changes in soil characteristics. Of all the big sagebrush species, mountain big sagebrush prefers sites with higher available moisture. Mountain big sagebrush thrives in deep soils that lack shallow concentrations of calcium carbonates (Innes, 2017). As carbonates are pushed deeper into the soil profile (which tends to occurs as effective precipitation increases), conditions become more ideal for mountain big sagebrush dominance.

Context dependence. The abiotic conditions that result in community transitions from Community 1.1 to 1.2 are site specific and not directly influenced by anthropogenic or biotic interactions.

Pathway 1.1B
Community 1.1 to 1.3

Mountain Big Sagebrush, Little Sagebrush, and Bluebunch Wheatgrass

Mountain Big Sagebrush and Mixed Bunchgrass

The primary drive that differentiates community 1.3 and community 1.2 is a slight increase in relative effective annual precipitation (REAP). When a Loamy Calcareous Ecological Site exists at the upper end of the 15 to 19 inch climatic subset, mountain big sagebrush and Idaho fescue are more likely to occupy a significant portion of the understory canopy. Idaho fescue prefers slightly higher volumes of effective precipitation and increases in canopy cover and production values accordingly (Zouhar, 2000).

Context dependence. The abiotic conditions that result in community transitions from Community 1.1 to 1.3 are site specific and not directly influenced by anthropogenic or biotic interactions.

Pathway 1.2A
Community 1.2 to 1.3

Mountain Big Sagebrush and Bluebunch Wheatgrass

Mountain Big Sagebrush and Mixed Bunchgrass

The primary driver that differentiates community 1.2 and community 1.3 is a slight increase in relative effective annual precipitation (REAP). When a Loamy Calcareous Ecological Site exists at the upper end of the 15 to 19 inch climatic subset, Idaho fescue is more likely to occupy a significant portion of the understory canopy. Idaho fescue prefers slightly higher volumes of effective precipitation and increases in canopy cover and production values accordingly (Zouhar, 2000).

Context dependence. The abiotic conditions that result in community transitions from Community 1.1 to 1.2 are site specific and not directly influenced by anthropogenic or biotic interactions.

State 2
Grazed

The Grazed state of the Loamy, Calcareous 20-24 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. 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 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 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.

Community 2.1
Shrub and Low Stature Bunchgrass

Figure 15. Community 2.1

The Shrub and Low Stature Bunchgrass 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. Grazing or disturbance tolerant forb species such as phlox (Phlox sp.) and pussytoes (Antennaria sp.) will become more prevalent. 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 - 850 lbs/acre, averaging 600 lbs/acre.

Resilience management. The Big Sagebrush and 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.

State 3
Disturbed

The Disturbed state is a result of both natural and anthropogenic disturbance events that result in widespread sagebrush mortality at a given site. The primary natural disturbance resulting in sagebrush mortality at this ecological site is wildfire; however, flooding, intense freeze events, and insect and disease can also occur. Mountain big sagebrush is highly susceptible to stand replacing fires and often experiences complete canopy loss during moderate and severe wildfire events (Innes, 2017 & Tirmenstein, 1999). Because this LRU exists primarily on publicly managed lands (US Forest Service, Bureau of Land Management, and State), widespread anthropogenic disturbance events are infrequent. Examples of anthropogenic disturbance events include brush management through sagebrush mowing or removal treatments, chemical treatments, or improper grazing techniques that result in high intensity hoof disturbance. A combination of natural and anthropogenic disturbance is possible and can result in increased severity of disturbance, decreased resilience, and greater difficulty returning to the Reference State. For example, improper grazing practices post fire disturbance can increase bare ground cover, increase erosion potential, and slow the reestablishment of grass species that preclude the return of overstory sagebrush canopy (Zlatnik, 1999).

Characteristics and indicators. The primary indicator of the Disturbed state is a near complete loss of overstory sagebrush species, often replaced by shrub species that are able to take advantage of the local disturbance regime. Common replacement species include Artemisia tripartita (threetip sagebrush) and Chrysothamnus viscidiflorus (yellow rabbitbrush). A shift towards an increase in native and disturbance tolerant grasses and forbs is likely with the removal of resource competition associated with the sagebrush overstory presence. Severe disturbance events also increase the opportunity for invasion of annual grasses and weeds such as cheatgrass (Bromus tectorum) and thistle species. The canopy cover percentage of these species is usually dependent on distance of a seed source post disturbance, but mostly stays under five percent (Zlatnik, 1999).

Resilience management. Resilience in this state is moderate. Many of the post disturbance grasses and shrubs that are common in this state establish quickly and reach a representative canopy within 10 years post disturbance. Grasses and shrubs continue to increase until overstory canopy of sagebrush begins to return. However, local resilience in this state is highly dependent on current soil moisture availability, seed sources, timing and severity of the disturbance. In the instance of fire disturbance, bluebunch wheatgrass mortality can be significantly lower if the fire occurs in the spring as opposed to fall. Recovery can be impacted by quantity of immediate post fire precipitation (Zlatnik, 1999). More severe disturbances increase possibility of post disturbance invasion. The greater the establishment of invasives, the lower the site resilience becomes.

Community 3.1
Rabbitbrush and Bunchgrass

Figure 17. Rabbitbrush/Bunchgrass Community

The Rabbitbrush and Bunchgrass community is driven by the disturbance related removal of the primary overstory of sagebrush species. Both natural and anthropogenic disturbances that result in near complete removal of the sagebrush overstory create opportunities for increased establishment of both native and non-native grasses and forbs, as well as disturbance tolerant shrubs. In this community, the primary sagebrush removing disturbance at this ecological site is frequent or severe fire. The frequency and severity of these fire disturbances are highly influenced by the overstory composition of the specific site in the reference state, prior to disturbance. The composition and extent of the sagebrush species in the overstory impacts that respective fire regime. Communities in the Reference State with mountain big sagebrush overstory are highly susceptible to stand replacing fire events with fire return intervals ranging from 5 to 70 years (Innes, 2017 & Termenstein, 1999). This increases likelihood of transition from the Reference State to the Disturbed State (Community 2.1) following fire disturbances. In Community 3.1, the overstory is comprised of disturbance tolerant shrubs at a reduced canopy. The primary overstory species include yellow rabbitbrush (Chrysothamnus viscidiflorus) and threetip sagebrush (Artemisia tripartita). Bunchgrasses, primarily bluebunch wheatgrass (Pseudoroegneria spicata), Idaho fescue (Festuca idahoensis) and Sandberg bluegrass (Poa secunda) primarily occupy the understory. Canopy cover of bunchgrasses is often higher early in the successional period following a disturbance, decreasing as the yellow rabbitbrush or threetip sagebrush canopy increases. Production in community 3.1 ranges from 300 - 800 lbs/acre, averaging 550 lbs/acre.

Resilience management. This plant community is moderately resilient because the grasses and forbs that dominate the composition are resistant to a variety of disturbances and able to re-establish quickly in the event of more severe disturbances. Both bluebunch wheatgrass (Pseudoroegenaria spicata) and Sandberg bluegrass (Poa secunda) are rarely harmed by fire events except for in the most severe instances. Both plants are able to reduce the amount of heat transfer to the root systems, allowing successful regrowth (Zlatnik, 1999 & Howard, 1997). Studies show that in the absence of grazing, bluebunch wheatgrass dominated systems are able to return to pre-fire production levels eight years post disturbance (Zlatnick, 1999). Sandberg bluegrass has been shown to fully re-establish post plowing events in as little as 7 years (Howard, 1997). Idaho fescue (Festuca Idahoensis) is less resilient to both fires and grazing. Idaho fescue can often survive low severity fires, however, moderate to severe fires are more destructive, resulting in a 30 year return to pre-disturbance canopy cover (Zouhar, 2000). Both yellow rabbitbrush and threetip sagebrush are often the first shrub species to re-establish on this ecological site following a disturbance, and can increase in relation to the severity or frequency of the disturbance. Although yellow rabbitbrush can exist in relatively small numbers within the Reference State, it becomes the dominant shrub species in highly disturbed systems (Terminstein, 1999).

Transition T1A
State 1 to 2

Reference

Grazed

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. Overtime, species like bluebunch wheatgrass and Idaho fescue are not able to recover from defoliation and 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. 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 top soil 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

Reference

Disturbed

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 has 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 completed o Prolonged periods of drought that diminish regeneration of desired species o Loss of nutrient rich top soil due to increased erosion o Establishment of invasive species o Distance from seed source

Restoration pathway R2A
State 2 to 1

Grazed

Reference

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. Time frame for restoration is highly dependent on variations in localized weather patterns. Prolonged periods of drought can dramatically increase time required to return to the Reference State, whereas periods of above normal precipitation can decrease that time frame. Grazing practices that are infrequent and of light intensity, mimicking 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

Disturbed

Reference

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).