State 1
Reference

The Reference State of this ecological site consists of two (2) potential plant communities: the 1.1 Mid-Statured Bunchgrass Community and the 1.2 Mixed Bluebunch Community. These are described below but are generally characterized by a mid-statured, cool-season grass community with limited shrub production. Community 1.1 is dominated by rough fescue and is considered the reference, while Community 1.2 has a codominance of rough fescue, bluebunch wheatgrass, green needlegrass, and western wheatgrass with a slight increase in yellow rabbitbrush and Wyoming big sagebrush. These communities may meld into each other due to the varying conditions that occur in Southwest Montana, particularly during dry cycles. Infrequent fire maintained these communities as open, treeless, seral stands of productive herbaceous species with patches of big sagebrush and assorted shrubs. As a result, the Reference State's core concept does not include coniferous trees; however, up to two (2) trees may exist on the landscape when closely situated to forested areas.

Community 1.1
Mid-Statured Bunchgrass Community

In the Mid-Statured Bunchgrass Community, rough fescue and bluebunch wheatgrass share dominance. Green needlegrass, Idaho fescue, needle and thread, and winterfat are subordinates in the community. Shrub species (big sagebrush, fringed sagewort, and broom snakeweed) remain a minor part of the community, by weight. Spineless horsebrush (Tetradymia canescens) and antelope bitterbrush (Purshia tridentata) may occupy a small niche. Sandberg bluegrass (Poa secunda) and dryland sedges are also common.

This state occurs on sites in areas with proper grazing pressure. Careful grazing management of this ecological site is necessary to maintain this deep-rooted bunchgrass community. Rough fescue tends to respond negatively to summer grazing, regardless of grazing intensity (King et al., 1998; Dormaar and Willms, January 1998), while bluebunch wheatgrass lacks resistance to grazing during the critical growing season (spring) and will decline in vigor and production if grazed in the critical growing season more than one year in three (Wilson et al., 1960). This evidence suggests that fall and dormant grazing in this community are most appropriate.

The Reference State is moderately resilient and will return to dynamic equilibrium following a relatively short period of stress (such as drought or short-term improper grazing), provided a return of favorable or normal growing conditions and properly managed grazing.

As discussed in the Ecological Dynamics section, the natural fire regime restricted shrubs to relatively small portions of the Mid-Statured Bunchgrass Community. Shrub species present may include Wyoming big sagebrush, spineless horsebrush, winterfat, tarragon (Artemisia drucunculus), and fringed sagewort. Infrequent fire probably maintained big sagebrush communities as open, treeless, seral stands of productive herbaceous species with patches of big sagebrush.

Community 1.2
Mixed Bluebunch Community

With proper grazing management over time, the Mixed Bluebunch Community (1.2) can come close to the diversity and complexity of the Mid-Statured Bunchgrass Community (1.1). Without active management the site is not likely to return the Reference Plant Community.

Western wheatgrass and needle and thread tolerate grazing pressure better than bluebunch wheatgrass and rough fescue. The growing points of tall, deep-rooted bunchgrasses are several inches above the ground, making them very susceptible to continued close grazing (Smoliack et al., 2006), while those of western wheatgrass and needle and thread plants tend to be near the plant base. These plants increase in composition when less palatable and less grazing-tolerant plants decrease due to improper grazing management. Bluebunch wheatgrass is dominant, with rough fescue, green needlegrass, and western wheatgrass sharing subdominance in the Mixed Bluebunch Community (1.2). Other grass species, which are more tolerant to grazing and are likely to increase in number compared to the Mid-Statured Bunchgrass Community, include Sandberg bluegrass (Poa secunda), prairie Junegrass, and blue grama (Bouteloua gracilis). Some increaser forb species include western yarrow, spiny phlox (Phlox hoodii), scarlet globemallow (Sphaeralcea coccinea), hairy goldenaster (Heterotheca villosa), and pussytoes (Antennaria spp.). Fringed sagewort (Artemisia frigida) is a shrub that also increases under prolonged drought or heavy grazing and can respond to precipitation that falls in July and August.

Heavy, continuous grazing will reduce plant cover, litter, and mulch. The timing of grazing is important on this site because of the moisture limitations beyond June, especially on the drier sites. Bare ground will increase, exposing the soil to erosion. Litter and mulch will be reduced as plant cover declines. As long as the production of rough fescue and bluebunch wheatgrass remains a significant portion of the total biomass production, the site can return to the Mid-Statured Bunchgrass Community (Pathway 1.2A) under proper grazing management and favorable growing conditions.

Rough fescue will continue to decrease, and bluebunch wheatgrass will decrease slightly, while needle-and-thread and Idaho fescue will increase until the species composition is nearly equal. Once rough fescue has been reduced to less than 10 percent by weight, it may be difficult for the site to recover to Mid-Statured Bunchgrass Community (1.1). The risk of soil erosion increases when canopy cover decreases below 50 percent. As soil conditions degrade, there will be a loss of organic matter, reduced litter, and reduced soil fertility. Degraded soil conditions increase the difficulty of reestablishing rough fescue and returning to the Mid-Statured Bunchgrass Community (1.1).

The Mixed Bluebunch Community (1.2) is the at-risk plant community for this ecological site. When overgrazing continues, increaser species such as western wheatgrass, needle and thread, and native forb species will become more dominant, and this triggers the change to the Altered State (2) or the Degraded State (3). Until the Mixed Bluebunch Community (1.2) crosses the threshold into another state, this community can be managed toward the Rough Fescue Community (1.1) using prescribed grazing and strategic weed control (if present). It may take several years to achieve this recovery, depending on growing conditions, the vigor of remnant rough fescue and bluebunch wheatgrass plants, and the aggressiveness of the weed treatments. Grazing management that benefits rough fescue tends to be a deferred or rest rotation (Fleenor, July 2011).

Pathway 1.1A
Community 1.1 to 1.2

Rough fescue and bluebunch wheatgrass lose vigor with improper grazing or extended drought. When vigor declines enough for plants to die or become smaller, species with higher grazing tolerance increase in vigor and production as they access the resources previously used by deep-rooted bunchgrass. The decrease in species composition by weight of rough fescue indicates that the plant community has shifted to the Mixed Bluebunch Community (1.2). The driver for community shift 1.1A is improper grazing management or prolonged drought. This shift is triggered by the loss of vigor of rough fescue, soil erosion, or prolonged drought coupled with improper grazing. Blaisdell (1958) stated that drought and warmer-than-normal temperatures are known to advance plant phenology by as much as one month. During drought years, plants may be especially sensitive or reach a critical stage of development earlier than expected.

Pathway 1.2A
Community 1.2 to 1.1

The Mixed Bluebunch Community (1.2) will return to the Mid-Statured Bunchgrass Community (1.1) with proper grazing management and appropriate grazing intensity. Favorable moisture conditions will facilitate or accelerate this transition. It may take several years of favorable conditions for the community to transition back to a rough fescue-dominated state. The driver for this community shift (1.2A) is the increased vigor of rough fescue to the point that it represents more than 50 percent of the weight of the grass community. The trigger for this shift is the change in grazing management, which favors rough fesuce. In general, conservative grazing management styles such as deferred or rest rotations utilizing light to moderate grazing (less than 50 percent use) coupled with favorable growing conditions like cool, wet springs are these triggers. These systems tend to promote increases in soil organic matter, which promotes microfauna and can increase infiltration rates. Inversely, long periods of rest at a time when this state is considered stable may not result in an increase in rough fescue, and it has been suggested (Noy-Meir 1975) that these long periods of rest or underutilization may actually drive the system to a lower level of stability by creating large amounts of standing biomass, dead plant caudex centers, and gaps in the plant canopy.

State 2
Altered

This state is characterized by having less than 10 percent mid-statured bunchgrasses. This state is represented by two (2) communities. Community 2.1 is a community dominated by Idaho fescue and needle and thread with small components of deep-rooted bunchgrasses such as rough fescue, bluebunch wheatgrass, and green needlegrass. Community 2.2 has a significantly reduced deep-rooted bunchgrass population that is restricted to protected areas under shrubs. Production in this state tends to be significantly lower than in the Reference State (1). Some native plants tend to increase under prolonged drought and/or heavy grazing practices. A few of these species may include western wheatgrass, needle and thread, Sandberg bluegrass, scarlet globemallow, hairy goldenaster, and fringed sagewort.

Community 2.1
Increaser Bunchgrass Community

Long-term grazing mismanagement with continuous growing-season pressure will reduce the total productivity of the site and lead to an increase in bare ground. Once plant cover is reduced, the site is more susceptible to erosion and degradation of soil properties. Soil erosion or reduced soil health will result in reduced plant production. This soil erosion or loss of soil fertility indicates the transition to the Altered State (2) because it creates a threshold requiring energy input to return to the Reference State (1). Transition to the Increaser Bunchgrass Community (2.1) may be exacerbated by extended drought conditions.

Needle and thread and rhizomatous wheatgrasses dominate this community (2.1). Rough fescue makes up less than 10 percent of species composition by dry weight, and the remaining deep-rooted bunchgrass plants tend to be scattered and low in vigor. Increaser and invader species will be more common and create more competition for deep-rooted bunchgrass. This makes it difficult for them to quickly respond to a change in grazing management alone. Therefore, an input of energy is required for the community to return to the Reference State (1). Wind and water erosion may be eroding soil from the plant interspaces. Soil fertility is reduced, and soil surface erosion resistance has declined compared to the Reference State (1).

This community crossed a threshold compared to the Mixed Bunchgrass Community (1.2) due to the erosion of soil, vegetation composition, loss of soil fertility, or degradation of soil conditions. This results in a critical shift in the ecology of the site. The effects of soil erosion can alter the hydrology, soil chemistry, soil microorganisms, and soil structure to the point where intensive restoration is required to restore the site to another state or community. Changing grazing management alone cannot create sufficient improvement to restore the site within a reasonable time frame. Dormaar (1997) stated that with decreased grazing pressure, a needle and thread/blue grama plant community did not change species composition, but the content of the soil carbon increased. It will require a considerable input of energy to move the site back to the Reference State (1). This state has lost soil or vegetation attributes to the point that recovery to the Reference State (1) will require reclamation efforts, i.e., soil rebuilding, intensive mechanical treatments, and/or reseeding.

The transition to this state could result from overgrazing, especially repeated early-season grazing coupled with extensive drought. If heavy grazing continues, plant cover, litter, and mulch will continue to decrease, and bare ground will increase, exposing the soil to accelerated erosion. Litter and mulch will move off-site as plant cover declines. The Increaser Bunchgrass Community will then shift to the Shortgrass Community (2.2) or the Degraded State, depending on the level of disturbance. Introduction or expansion of invasive species will further drive the plant community into the Invaded State (4).

Community 2.2
Shortgrass Community

With continued mismanagement of grazing, especially coupled with prolonged drought, needle and thread will decrease in vigor. The bunchgrasses will decline in production as plants die or become smaller, and species with higher grazing tolerance (such as western wheatgrass) will increase in vigor and production as they respond to resources previously used by the bunchgrasses. These less desirable, shallow-rooted species will become codominant in this community along with mid-statured bunchgrasses such as needle and thread and Idaho fescue. Shrubs will become more competitive for limited moisture as bare ground and soil erosion increase. Remaining deep-rooted bunchgrasses such as rough fescue and bluebunch wheatgrass are nearly absent in this community; however, remnant populations may exist under shrub canopy away from grazing pressure.

Pathway 2.1A
Community 2.1 to 2.2

The driver for community shift 2.1a is continued improper grazing management. This shift is triggered by the continued loss of bunchgrass vigor, especially the remaining trace amounts of rough fescue and bluebunch on the site. Shrubs will protect these less vigorous bunchgrasses. The mid- and short-statured grasses will become more competitive and will become co-dominant with the bunchgrasses. Shrubs will increase their canopy cover but stay at about 15 percent.

Pathway 2.2A
Community 2.2 to 2.1

If proper grazing management is implemented, needle and thread may regain its vigor and move towards the Increaser Bunchgrass Community (2.1). This will give grasses an advantage over invading shrubs before too much competition takes place. The advantage to grasses comes from following a conservative grazing plan where utilization is reduced and rest or deferment is incorporated since the transition from Plant Community 2.1 to Plant Community 2.2 is likely caused by repeated heavy utilization. Van Poolen and Lacey (1979) found that forage production increased by an average of 35 percent on western ranges when converting heavy to moderate utilization (less than 50 percent). Shrub removal and favorable growing conditions can accelerate this process. If the site contains Wyoming big sagebrush (<a class="species-link" href="https://plants.usda.gov/core/profile?symbol=ARTR2" target="_blank" title="Open in plants.usda.gov"><i>Artemisia tridentata</i></a> spp. wyomingensis), low-intensity fire or mechanical treatment (Wambolt 1986) could reduce shrub competition and allow for increased vigor and the reestablishment of grass species.

State 3
Degraded

Degraded State lacks mid-statured bunchgrasses. Sandberg bluegrass and prairie Junegrass are dominant grasses, and increaser shrubs nearly replace larger shrub species. Larger shrub species that remain are heavily hedged. Likely a terminal state (e.g., restoration will likely be impossible or unsuccessful and require major energy inputs).

Characteristics and indicators. increased bare ground (excess of 25 percent) annual grasses common complete removal of deep rooted tall bunchgrasses and replaced with sandberg bluegrass, western wheatgrass, and blue grama sagebrush nearly gone and replaced with cactus rabbitbrush and broom snakeweed

Community 3.1
Shrub/Shortgrass Community

Soil loss continues, and subsequent losses of soil organic matter create conditions where native perennial grasses are reduced to less than 50 percent of their total production. Grass and forb cover may be very sparse or clumped. Weeds, annual species, and shrubs dominate the plant community. Mid-statured bunchgrass species may exist, but only in small patches. This could occur due to a failure to adjust stocking rates for declining forage production due to increased invasive dominance.

In the most severe stages of degradation, there is a significant amount of bare ground, and large gaps occur between plants. Potential exists for soils to erode to the point that irreversible damage may occur. This is a critical shift in the ecology of the site. Soil erosion combined with a lack of organic matter deposition due to sparse vegetation creates changes to the hydrology, soil chemistry, soil microorganisms, and soil structure to the point where intensive restoration is required to restore the site to another state or community. Changing management (i.e., improving grazing management) cannot create sufficient change to restore the site within a reasonable time frame.

This state is characterized by soil surface degradation and little plant soil surface cover. The forb component changes to being dominated by spiny phlox (Phlox hoodii), and shrub canopy cover is usually greater than 20 percent. Big sagebrush is replaced with a dominant community of broom snakeweed, rubber rabbitbrush, fringed sagewort, and plains prickly pear cactus. This state has lost soil or vegetation attributes to the point that recovery to the Reference State will require reclamation efforts, i.e., soil rebuilding, intensive mechanical treatments, and/or reseeding.

This plant community may be in a terminal state and will not return to the reference state because of degraded soil conditions and the loss of higher successional native plant species.

Key factors in the approach to transition include: a decrease in grass canopy cover and production; an increase in shrub canopy cover; increases in mean bare patch size; increases in soil crusting; decreases in the cover of cryptobiotic crusts; decreases in soil aggregate stability; and/or evidence of erosion, including water flow patterns and litter movement.

State 4
Invaded

The Invaded State is identified as being in the exponential growth phase of invader abundance where control is a priority. Dominance (or relative dominance) of noxious or invasive species reduces species diversity, forage production, wildlife habitat, and site protection. A level of 15 percent invasive species composition by dry weight indicates that a substantial energy input will be required to create a shift to the grassland state (herbicide, mechanical treatment), even with a return to proper grazing management or favorable growing conditions. Prescriptive grazing can be used to manage invasive species. In some instances, carefully targeted grazing (sometimes in combination with other treatments) can reduce or maintain the species composition of invasive species.

These communities within this state will follow a pathway if the invasive or noxious species continue to thrive without mechanical, biological, or chemical control methods to exceed 50 percent of species composition by dry weight. The invasive nature of the weed outcompetes the present plant community. Once the weed reaches its maximum population level for this site, effective control is unlikely without massive resource inputs. Ecological processes at the site may change after invading species have established and spread (Walker and Smith 1997).

Community 4.1
Invaded Community

Communities in this state may be structurally indistinguishable from the Reference State except that invasive or noxious species exceed 15 percent of species composition by dry weight. This state may also include a community similar to the Degraded State (3) except that invasive or noxious species exceed 15 percent of species composition by dry weight. Although there is no research to document the level of 15 percent, this is estimated to be the point in the invasion process following the lag phase based on the interpretation of Masters and Sheley (2001). For aggressive invasive species (i.e., spotted knapweed), a 15 percent threshold could be less than 10 percent. Early in the invasion process, there is a lag phase where the invasive plant populations remain small and localized for long periods before expanding exponentially (Hobbs and Humphries 1995).

Production in the invaded community may vary greatly. A site dominated by Kentucky bluegrass or spotted knapweed, where soil fertility and chemistry remain near reference, may have production near that of the reference community. A site with degraded soils and an infestation of cheatgrass may produce only 10 to 20 percent of the reference community.

Once invasive species dominate the site, either in species composition by weight or in their impact on the community, the threshold has been crossed to the Invaded State (4). As invasive species such as spotted knapweed, cheatgrass, and leafy spurge become established, they become very difficult to eradicate. Therefore, considerable effort should be put into preventing plant communities from crossing a threshold into the Invaded State (4) through early detection and proper management. Preventing new invasions is by far the most cost-effective control strategy and typically places an emphasis on education. Control measures used on the noxious plant species impacting this ecological site include chemical, biological, and cultural control methods. The best success has been found with an integrated pest management (IPM) strategy that incorporates one or several of these options along with education and prevention efforts (DiTomaso 2000).

State 5
Conifer Encroached

Rocky Mountain juniper (Juniperus scopulorum), Douglas fir (Pseudotsuga menziesii), and ponderosa pine (Pinus ponderosa) encroachment is limited on this ecological site and is generally focused in areas where the mountains of MLRA 44B transition quickly to MLRA 43B. Under the Reference State, up to two (2) stem per acres of conifers may exist as part of long-term fire suppression; however the core concept of this ecological site is to express no coniferous trees. Conifer Encroached State consists of up to 4 potential phases. The Early Phase, Mid Phase, Late Phase, and Closed Phase are defined by the amount of encroachment and age class of the stand. This state typically occurs in response to a combination of long-term fire suppression, grazing history, and increased atmospheric carbon dioxide. The trigger for transition is a coniferous expansion of more than 2 stems per acre.

Community 5.1
Conifer Encroachment Community

Restoration efforts may simply focus on the removal of coniferous trees and shrubs to restore the Conifer Encroached State (5) to the Reference State (1), depending on the level of conifer canopy cover and its impact on rangeland health.

If following and utilizing the phases established by Miller et al., management and restoration methods will vary. A majority of the conifer encroachment in MLRA 44B will fall into the early two phases of Miller's phases.

When conifers are removed through brush management and/or prescribed fire, Phase I may reveal none-to-slight to moderate deviations from rangeland health. If mechanical removal of conifers is utilized, no grazing management is needed, assuming relatively conservative management had been used prior to treatment. If prescribed fire is utilized, short-term grazing deferment and/or rest are suggested. In a short period of time, removing a Phase I encroachment will return the site to its original state. Proactive pest management is encouraged.

Phase II encroachment may require a more intensive mechanical removal of trees and shrubs, with prescribed fire not being a feasible method of control as this community may be at risk of catastrophic fire due to canopy density. Phase II displays a moderate departure from Reference, suggesting an overall instability of the site such as reduced herbaceous production, reduced functional and structural groups (e.g., reduced mid-statured bunchgrasses), increased rill frequency and length, and possibly more bare ground. Increased post-treatment grazing management may be necessary. Grazing management may be as simple as short-term growing season deferment; however, long-term rest may be necessary in the latter stages of Phase II encroachment. The latter stages of Phase II encroachment will likely require some short-term erosion mitigation, such as straw waddles, as well as range planting and/or critical area planting to re-establish any loss of native herbaceous plants, particularly mid-statured cool-season bunchgrasses.

Phase III encroachment canopy cover resembles forested sites with larger trees and shrubs. Prior to any prescribed burning, forest management-style tree removal (removal of woody debris and logs from the site) will be required to prevent the fire from burning too hot. The result of a prescribed fire on this site is typically unknown as seed sources of native herbaceous plants are usually limited to small patches. Since the Shallow Droughty ecological site for 44B LRU 01 Subset B is a dry site, herbaceous plants will likely have been depleted under a Phase III encroachment. This means there is an opportunity for large areas of bare ground, increased rills, and, in some cases, gully erosion. Post-treatment will require range planting and/or critical area seeding, erosion control, pest management, and possibly soil carbon amendments (biochar). Grazing management (primarily rest) will be required to ensure the establishment of any new seedlings.

Transition T1A
State 1 to 2

The Reference State (1) transitions to the Altered State (2) if mid-statured bunchgrasses, by dry weight, decreases to below 15 percent or if bare ground cover increases beyond 15 percent. The driver for this transition is the loss of taller bunchgrasses, which creates open areas in the plant canopy with bare soil. Soil erosion results in decreased soil fertility, driving transitions to the Altered State. There are several other key factors signaling the approach of transition T1A: increases in soil physical crusting, decreases in cover of cryptogamic crusts, decreases in soil surface aggregate stability, and/or evidence of erosion including water flow patterns, development of plant pedestals, and litter movement. The trigger for this transition is improper grazing management and/or long-term drought, leading to a decrease in rough fescue composition to less than 10 percent and a reduction in total plant canopy cover.

Transition T1B
State 1 to 3

The Reference State (1) transitions to the Degraded State (3) when rough fescue and bluebunch are removed from the plant community and needle and thread is subdominant over short-statured bunchgrasses such as Sandberg bluegrass. This transition differs from T1A in that it is generally a rapid transition and usually associated with disturbances such as repeated overgrazing or heavy human traffic. This rapid transition is generally realized where livestock are confined to small pastures for long periods of time, such as horse pastures and calving lots. The driver for this transition is the loss of taller bunchgrasses, which creates openings in the canopy and exposes bare soil. Soil erosion results in decreased soil health, driving transitions to the Degraded State. There are several other key factors signaling the approach of transition T1B: increases in soil physical crusting, decreases in cover of cryptogamic crusts, decreases in soil surface aggregate stability, and/or evidence of erosion including water flow patterns, development of plant pedestals, and litter movement. The trigger for this transition is improper grazing management, long term drought, and/or heavy human disturbance.

Transition T1C
State 1 to 4

Healthy plant communities are most resistant to invasion. However, regardless of grazing management, without some form of active weed management (chemical, mechanical, or biological control) and prevention, the Reference State (1) can transition to the Invaded State (4) in the presence of aggressive invasive species such as spotted knapweed, leafy spurge, and cheatgrass. This will occur even if the reference community is thriving. The Central Rocky Mountain Valleys tend to resist invasion by cheatgrass; however, repeated heavy grazing or intense human activities can open the interspaces of the bunchgrass community and allow for encroachment. Long-term stress conditions for native species (e.g., overgrazing, drought, and fire) accelerate this transition. If populations of invasive species reach critical levels, the site transitions to the Invaded State. The trigger for this transition is the presence of aggressive invasive species. The species composition by dry weight of invasive species approaches 10 percent.

Transition T1D
State 1 to 5

The transition from the Reference State (1) to the Conifer Encroached State (5) is driven primarily by long-term fire suppression, but heavy grazing may contribute to increased bare ground for seeding sites. Encroachment occurs most quickly within 200 feet of the seed source. The trigger for transition is a conifer stem count greater than two (2) per acre.

Restoration pathway R2A
State 2 to 1

The Altered State (2) has lost soil or vegetation attributes to the point that recovery to the Reference State (1) will require reclamation efforts such as soil rebuilding, intensive mechanical and cultural treatments, and/or revegetation. Examples of mechanical treatment may be brush control, while cultural treatments may include prescribed grazing, targeted brush browsing, or prescribed burning. Low intensity prescribed fires to reduce competitive increaser plants such as needle and thread and Sandberg bluegrass. A low-intensity fire will also reduce Wyoming big sagebrush densities. In areas with the potential for annual grass infestation, fire should be carefully planned or avoided. The drivers for this restoration pathway are reclamation efforts along with proper grazing management.

Transition T2A
State 2 to 3

As improper grazing management continues, the vigor of bunch grasses will decrease and the shorter grasses and shrubs will increase, leading to the Degraded Shortgrass State (3). Prolonged drought will provide a competitive advantage to shrubs, allowing them to become co-dominant with grasses. Shrub canopy will increase above 15 percent canopy cover. Key transition factors include: an increase in native shrub canopy cover; a reduction in bunchgrass production; a decrease in total plant canopy cover and production; increases in mean bare patch size; increases in soil crusting; decreases in the cover of cryptobiotic crusts; decreases in soil aggregate stability; and/or evidence of erosion, including water flow patterns and litter movement.

Transition T2B
State 2 to 4

Invasive species can occupy the Altered State (2) and drive it to the Invaded State (4). The Altered State is at risk if invasive seeds and/or other viable material are present. The driver for this transition is more than 10 percent dry weight of invasive species.

Transition T2C
State 2 to 5

The transition from the Altered State (2) to the Conifer Encroached State (5) is driven primarily by long-term fire suppression, but heavy grazing may contribute to increased bare ground for seeding sites. Encroachment occurs most quickly within 200 feet of the seed source. The trigger for transition is a conifer stem count greater than two (2) per acre.

Restoration pathway R3A
State 3 to 1

The Degraded State (3) has lost soil or vegetation attributes to the point that recovery to the Reference State (1) will require reclamation efforts, such as soil rebuilding, intensive mechanical treatments, and/or revegetation. Studies suggest (Whitford et al. 1989) that a mulch with a high carbon to nitrogen ratio, such as wood chips or bark, in low moisture scenarios can be beneficial for slow mobilization of plant-available nitrogen. Biochar may also be added to the system to improve Soil Organic Carbon (SOC) which should improve Cation Exchange Capacity (CEC), microbial activity, and hydrologic conductivity (Stavi 2012). The drivers for the restoration pathway are the removal of increaser species, restoration of native bunchgrass species, persistent management of invasives and shrubs, and proper grazing management. Without continued control, invasive and shrub species are likely to return (probably rapidly) due to the presence of seeds and/or other viable material in the soil and management-related increases in soil disturbance.

Restoration pathway R3B
State 3 to 2

Since the bunchgrass plant community has been significantly reduced, restoration to the Altered State (2) is unlikely unless a seed source is available. However, if a sufficient amount of grass remains on the site, chemical application and/or biological control, in conjunction with proper grazing management, can reduce the amount of shrubs and invasive species and restore the site to the Shortgrass Community (2.2). Low-intensity fire can be utilized to reduce Wyoming big sagebrush competition and allow the reestablishment of grass species. Caution must be used when considering fire as a management tool on sites with fire tolerant shrubs such as rubber rabbitbrush, as these shrubs will sprout after a burn. Broom snakeweed and fringed sagewort may or may not re-sprout depending on conditions (USDA Forest Service, 2011).

Transition T3A
State 3 to 4

Invasive species can occupy the Degraded State (3) and drive it to the Invaded State (4). The Degraded State is at risk of this transition occurring if invasive seeds or viable material are present. The driver for this transition is the presence of critical population levels (more than 10 percent dry weight of invasive species). The trigger is the presence of seeds or viable material from invasive species. This state has sufficient bare ground that the transition could occur simply due to the presence or introduction of invasive seeds or viable material. This is particularly true of aggressive invasive species such as spotted knapweed. This transition could be assisted by overgrazing (failure to adjust stocking rate to declining forage production), a long-term lack of fire, or an extensive drought.

Transition T3B
State 3 to 5

The transition from the Degraded State (3) to the Conifer Encroached State (5) is driven primarily by heavy grazing; contributing to increased bare ground for seeding sites. Encroachment occurs most quickly within 200 feet of the seed source. The trigger for transition is a conifer stem count greater than two (2) per acre.

Restoration pathway R4A
State 4 to 1

If invasive species are removed before remnant populations of bunchgrass have been drastically reduced, the Invaded State (4) can return to the Reference State. The driver for the reclamation pathway is weed management with reseeding. Continued Integrated Pest Management (IPM) will be required as many of the invasive species that can occupy the Invaded State have extended dormant seed life.

Restoration pathway R4B
State 4 to 2

If invasive species are removed before remnant populations of bunchgrass have been drastically reduced, the Invaded State (4) can return to the Altered State. The driver for the reclamation pathway is weed management with reseeding. Continued Integrated Pest Management (IPM) will be required as many of the invasive species that can occupy the Invaded State have extended dormant seed life.

Restoration pathway R4C
State 4 to 3

If invasive species are removed before remnant populations of bunchgrass have been drastically reduced, the Invaded State (4) can return to the Degraded State. The driver for the reclamation pathway is weed management with reseeding. Continued Integrated Pest Management (IPM) will be required as many of the invasive species that can occupy the Invaded State have extended dormant seed life.

Transition T4A
State 4 to 5

The transition from the Invaded State (4) to the Conifer Encroached State (5) is driven primarily by heavy grazing; contributing to increased bare ground for seeding sites. Encroachment occurs most quickly within 200 feet of the seed source. The trigger for transition is a conifer stem count greater than two (2) per acre.

Restoration pathway R5A
State 5 to 1

Restoration efforts may simply focus on the removal of coniferous trees and shrubs to restore the Conifer Encroached State (5) to the Reference State (1), depending on the level of conifer canopy cover and its impact on rangeland health. If following and utilizing the phases established by Miller et al., management and restoration methods will vary. A majority of the conifer encroachment in MLRA 44B will fall into the early two phases of Miller's phases. When conifers are removed through brush management and/or prescribed fire, Phase I may reveal none-to-slight to moderate deviations from rangeland health. If mechanical removal of conifers is utilized, no grazing management is needed, assuming relatively conservative management had been used prior to treatment. If prescribed fire is utilized, short-term grazing deferment and/or rest are suggested. In a short period of time, removing a Phase I encroachment will return the site to its original state. Proactive pest management is encouraged. Phase II encroachment may require a more intensive mechanical removal of trees and shrubs, with prescribed fire not being a feasible method of control as this community may be at risk of catastrophic fire due to canopy density. Phase II displays a moderate departure from Reference, suggesting an overall instability of the site such as reduced herbaceous production, reduced functional and structural groups (e.g., reduced mid-statured bunchgrasses), increased rill frequency and length, and possibly more bare ground. Increased post-treatment grazing management may be necessary. Grazing management may be as simple as short-term growing season deferment; however, long-term rest may be necessary in the latter stages of Phase II encroachment. The latter stages of Phase II encroachment will likely require some short-term erosion mitigation, such as straw waddles, as well as range planting and/or critical area planting to re-establish any loss of native herbaceous plants, particularly mid-statured cool-season bunchgrasses. Phase III encroachment canopy cover resembles forested sites with larger trees and shrubs. Prior to any prescribed burning, forest management-style tree removal (removal of woody debris and logs from the site) will be required to prevent the fire from burning too hot. The result of a prescribed fire on this site is typically unknown as seed sources of native herbaceous plants are usually limited to small patches. Since the Shallow Droughty ecological site for 44B LRU 01 Subset B is a dry site, herbaceous plants will likely have been depleted under a Phase III encroachment. This means there is an opportunity for large areas of bare ground, increased rills, and, in some cases, gully erosion. Post-treatment will require range planting and/or critical area seeding, erosion control, pest management, and possibly soil carbon amendments (biochar). Grazing management (primarily rest) will be required to ensure the establishment of any new seedlings.

Restoration pathway R5B
State 5 to 2

The Conifer Encroached State (5) Phases I and II will generally resemble the Altered State (2) on this site. If following and utilizing the phases established by Miller et al., management and restoration methods will vary. A majority of the conifer encroachment in MLRA 44B will fall into the early two phases of Miller's phases. When conifers are removed through brush management and/or prescribed fire, Phase I may show none-to-slight to moderate deviations from rangeland health. If mechanical removal of conifers is utilized, no grazing management is needed, assuming relatively conservative management had been used prior to treatment. If prescribed fire is utilized, short-term grazing deferment and/or rest are suggested. In a short period of time, removing a Phase I encroachment will return the site to its original state. Proactive pest management is encouraged. Phase II encroachment may require a more intensive mechanical removal of trees and shrubs, with prescribed fire not being a feasible method of control as this community may be at risk of catastrophic fire due to canopy density. Phase II displays a moderate departure from Reference, suggesting an overall instability of the site such as reduced herbaceous production, reduced functional and structural groups (e.g., reduced mid-statured bunchgrasses), increased rill frequency and length, and possibly more bare ground. Increased post-treatment grazing management may be necessary. Grazing management may be as simple as short-term growing season deferment; however, long-term rest may be necessary in the latter stages of Phase II encroachment. The latter stages of Phase II encroachment will likely require some short-term erosion mitigation such as straw waddles as well as range planting and/or critical area planting to re-establish any loss of native herbaceous plants, particularly mid-statured cool-season bunchgrasses. Phase III encroachment canopy cover resembles forested sites with larger trees and shrubs. Prior to any prescribed burning, forest management-style tree removal (removal of woody debris and logs from the site) will be required to prevent the fire from burning too hot. The result of a prescribed fire on this site is typically unknown as seed sources of native herbaceous plants are usually limited to small patches. Since the Shallow Droughty ecological site for 44B LRU 01 Subset B is a dry site, herbaceous plants will likely have been depleted under a Phase III encroachment. This means there is an opportunity for large areas of bare ground, increased rills, and, in some cases, gully erosion. Post-treatment will require range planting and/or critical area seeding, erosion control, pest management, and possibly soil carbon amendments (biochar). Grazing management (primarily rest) will be required to ensure the establishment of any new seedlings.

Restoration pathway R5C
State 5 to 3

The Conifer Encroached State (5) Phases II and III may resemble the Degraded State (3) on this site. If following and utilizing the phases established by Miller et al., management and restoration methods will vary. An overwhelming majority of the conifer encroachment in MLRA 44B will fall into the early two phases of Miller's phases. This restoration pathway is extremely rare because managing a degraded state is typically not cost-effective for land managers. When conifers are removed through brush management and/or prescribed fire, Phase I may show none-to-slight to moderate deviations from rangeland health. If mechanical removal of conifers is utilized, no grazing management is needed, assuming relatively conservative management had been used prior to treatment. If prescribed fire is utilized, short-term grazing deferment and/or rest are suggested. Given a short time removal of a Phase I encroachment will recover to Reference. Proactive pest management is encouraged. Phase II Encroachment may require a more intensive mechanical removal of trees and shrubs, with prescribed fire not being a feasible method of control as this community may be at risk of catastrophic fire due to canopy density. Phase II displays a moderate departure from Reference, suggesting an overall instability of the site such as reduced herbaceous production, reduced functional and structural groups (e.g., reduced mid-statured bunchgrasses), increased rill frequency and length, and possibly more bare ground. Increased post-treatment grazing management may be necessary. Grazing management may be as simple as short-term growing season deferment; however, long-term rest may be necessary in the latter stages of Phase II encroachment. The latter stages of Phase II encroachment will likely require some short-term erosion mitigation, such as straw waddles, as well as range planting and/or critical area planting to re-establish any loss of native herbaceous plants, particularly mid-statured cool-season bunchgrasses. Phase III Encroachment canopy cover resembles forested sites with larger trees and shrubs. Forest management style tree removal (woody debris and logs removed from the site) will be necessary prior to any prescribed burning as to prevent the fire from burning too hot. The results of a prescribed fire on this site are typically unknown as seed sources of native herbaceous plants are usually limited to small patches. Since the Shallow Droughty ecological site for 44B LRU 01 Subset B is a dry site, herbaceous plants will likely have been depleted under a Phase III encroachment. This means there is an opportunity for large areas of bare ground, increased rills, and, in some cases, gully erosion. Post-treatment will require range planting and/or critical area seeding, erosion control, pest management, and possibly soil carbon amendments (biochar). Grazing management (primarily rest) will be required to ensure the establishment of any new seedlings.