State 1
Reference

Community 1.1
Alkali Sacaton/ Nuttall's Alkaligrass

Figure 8. Alkali sacaton and Nuttall's alkaligrass are prominent species within this Reference community.

Alkali Sacaton/Nuttall's Alkaligrass Community Phase (1.1) is the interpretive plant community for the Saline Subirrigated ecological site, and is also referred to as the Reference Community Phase. This community phase evolved with grazing by large herbivores, supplemental moisture, and saline and/or alkali soils. The major grasses include alkali sacaton, Nuttall’s alkaligrass, and basin wildrye. Grasses of lesser importance are Baltic rush, western wheatgrass, alkali cordgrass, inland saltgrass, and tufted hairgrass. Woody plants are minor in this community phase, and are primarily rubber rabbitbrush and greasewood. A variety of forbs also occurs in this state and plant diversity is high. The total annual production (air-dry weight) of this state is about 2400 pounds per acre, but it can range from about 1800 lbs./acre in unfavorable years to about 2800 lbs./acre in above average years.

Resilience management. The community phase is stable and well adapted to the Northern Plains climatic conditions. The diversity in plant species and the reliable water table allow for high drought resistance. This is a sustainable plant community (site/soil stability, watershed function, and biologic integrity).

Community 1.2
Alkali Sacaton/Inland Saltgrass/Mixed Shrub

Figure 11. Greasewood and other shrubs have increased with inland saltgrass, while basin big sagebrush and Nuttall's alkaligrass has decreased.

Historically, this plant community evolved under moderate grazing by domestic livestock. Currently, this site is normally found under a moderate, season-long grazing regime and in the absence of brush control. Prolonged drought can also play an important role and will exacerbate these conditions. Saline and flood tolerant perennial plants make up the dominant species in this plant community. Dominant grasses include alkali sacaton, inland saltgrass, western wheatgrass, alkali cordgrass, and Baltic rush. Forbs commonly found in this plant community include alkali seepweed, silverweed, American licorice, seaside arrowgrass, and smooth horsetail. Greasewood and rubber rabbitbrush comprises the majority of the woody species and make up less than 25% of the annual production. When compared to the Reference Community Phase, basin wildrye, Nuttall’s alkaligrass, and tufted hairgrass have decreased. Inland saltgrass, forbs, greasewood, and rubber rabbitbrush have increased. Annual herbaceous weedy plants have increased, but occur in small patches. The total annual production (air-dry weight) of this state is about 2000 pounds per acre, but it can range from about 1500 lbs./acre in unfavorable years to about 2500 lbs./acre in above average years.

Resilience management. This community phase is stable and protected from excessive erosion. The herbaceous component is mostly intact and plant vigor and replacement capabilities are sufficient. Only minimal occurrences of water flow patterns and litter movement is evident. Incidence of pedestalling is minimal. Soils are mostly stable and the surface shows minimum soil loss. The watershed is functioning and the biotic community is intact.

Pathway CP 1.1-1.2
Community 1.1 to 1.2

Alkali Sacaton/ Nuttall's Alkaligrass

Alkali Sacaton/Inland Saltgrass/Mixed Shrub

Continuous season-long grazing will convert this plant community to the Alkali Sacaton/Inland Saltgrass/Mixed Shrub Plant Community. Prolonged Drought will exacerbate this transition. Impacting the riparian species during the growing season without a chance for recovery will quickly weaken, and remove, the tall-stature and some mid-stature species. Drought will weaken and remove these species quickly when grazing continues.

Pathway CP 1.2-1.1
Community 1.2 to 1.1

Alkali Sacaton/Inland Saltgrass/Mixed Shrub

Alkali Sacaton/ Nuttall's Alkaligrass

Prescribed grazing and possible long-term prescribed grazing will result in a plant community very similar to the Reference Community Phase (1.1), except that greasewood will persist without some form of brush control. Greasewood and rubber rabbitbrush can prove difficult to remove from the system.

State 2
Sod-bound

Degradation of the tall- and mid-stature grasses by herbivory, drought, gullying, and other soils disturbances creates an opportunity for sod-forming (tillering) grasses to increase in the community. With time, the community shifts to a sod-dominant community.

Characteristics and indicators. Inland saltgrass is the major canopy cover in this system. Greasewood and rubber rabbitbrush will persist but is not able to develop into a monocultural stand of shrubs due to the integrity and density of inland saltgrass.

Resilience management. The channeling characteristic of sod-grasses creates open areas of bare ground that are prone to rills and erosion, but the integrity of the sod root structure creates a community resistant to change, as well as resilient to further disturbance. The bare ground does expose risk of invasion by undesirable weeds.

Community 2.1
Inland Saltgrass/Mixed Shrub

This plant community is the result of frequent and severe grazing with periodic overflows and no brush control. This plant community is dominated by a dense short-stature warm-season grass sod and includes a mosaic shrub overstory. Shrubs comprise less than 35 percent of the annual production, and are kept in check by the herbaceous sod understory. The dominant grasses are inland saltgrass, Alkali bluegrass, Baltic rush and Chairmaker's bulrush. Forbs such as seaside arrowgrass, American licorice, curly dock, and smooth horsetail are common. Greasewood and rubber rabbitbrush are the primary overstory species in this plant community. Plant diversity is moderate to poor. When compared to the Reference Community Phases (1.1 or 1.2), the tall- and mid-stature grasses are significantly reduced or absent. Short-stature warm-season grasses are dominant and weedy annuals are common. Shrubs will have increased as a percentage of the total production, but will not dominate as the sod prevents a homogeneous shrub cover. Areas of bare ground may have increased in patches, and total production has decreased as the short grasses have replaced the tall- and mid-stature grasses. The total annual production (air-dry weight) of this state is about 1200 pounds per acre, but it can range from about 800 pounds per acre in unfavorable years to about 1600 pounds per acre in above average years.

Resilience management. The sod component of this plant community is extremely resistant to change and continued frequent and severe grazing or the removal of grazing does not seem to affect the plant composition or structure of the plant community. The biotic integrity of this community phase is generally not functional as plant diversity is poor, especially the amount of herbaceous species. The vegetative structure has shifted as the shrubs and short grasses now occupy the majority of the site. This sod bound plant community is very resistant to water infiltration. While this sod protects the soil within the basal cover, excessive runoff increases erosion on bare ground and can cause rill channels and gully erosion. Water flow patterns are obvious in the bare ground areas and shrubs and sod patches are pedestalled. Rill channels are noticeable in the interspaces and gullies may be establishing where rills have concentrated. The watershed may not be functioning, as runoff is excessive and erosional processes are accelerated.

State 3
Invaded

Soil disturbance within this ecological site opens the soil and provides the opportunity for invasive species to establish. Woody invasive species are the most dominant invasive species for these communities.

Characteristics and indicators. The presence and dominance of Tamarisk (saltcedar), Russian olive, swainsonpea or Canada thistle is the key indicator of a transition to the Invaded State. Foxtail barley, curly dock, and Russian Thistle are also common weedy invaders that occur in this community.

Resilience management. The Invaded State is resilient following further major disturbances. The extensive seed bank that most invasive species develop makes eradication or maintenance of extent difficult. Degradation of the State will occur with expanding populations of invasive species, most prominently Russian olive and Tamarisk (saltcedar).

Community 3.1
Alkali Sacaton/Invasive Woody

This plant community occurs where saltcedar or Russian olive encroaches into a saline subirrigated ecological site and becomes established. This occurs with or without grazing and is the result of conditions conducive to the colonization of these two plants. Bare ground is likely to increase the potential for colonization. However, areas that have been deferred or removed from grazing and had a healthy stand of alkali sacaton can be infested. Saline and flood tolerant perennial plants make up the dominant understory species in this plant community. Dominant grasses include alkali sacaton, inland saltgrass, western wheatgrass, alkali cordgrass, and Baltic rush. Forbs commonly found in this plant community include alkali seepweed, silverweed, American licorice, seaside arrowgrass, and smooth horsetail. Saltcedar or Russian olive comprise the majority of the woody species and make up less than 35 percent of the annual production. Invasion of saltcedar or Russian olive should be considered serious and should be controlled. When compared to the Reference State, basin wildrye, Nuttall’s alkaligrass, and tufted hairgrass have decreased. Inland saltgrass, forbs, saltcedar and Russian olive have increased. Total production is similar to the Alkali Sacaton/Mixed Shrub community phase. The total annual production (air-dry weight) of this state is about 1200 pounds per acre, but it can range from about 800 pounds per acre in unfavorable years to about 1800 pounds per acre in above average years.

Resilience management. This plant community is mostly resistant to change, but species composition can be altered through long-term continuous year-long grazing, high utilization with no rest, and further encroachment of saltcedar and Russian olive. The herbaceous component is stable and plant vigor and replacement capabilities are sufficient. The biotic community is not intact due to the encroachment of these invasive species. Plant diversity is moderate. Soils are mostly stabilized. Only minimal occurrences of water flow patterns and litter movement is evident. Incidence of pedestalling is minimal. Soils are mostly stable and the surface shows minimal soil loss. The watershed may or may not be functional.

Community 3.2
Woody Invaded

This plant community evolved under frequent and severe grazing with the encroachment of saltcedar or Russian olive. Saltcedar and Russian olive will comingle or will individually dominate this plant community. Most of the tall- and mid-stature grasses are eliminated and an understory of weedy herbaceous plants are prevalent. The interspaces between woody plants have expanded leaving more bare ground and more soil surface exposed to erosive elements or invaders. The weedy plants, such as foxtail barley, curly dock, swainsonpea, whitetop, and Russian thistle make up the dominant understory. Saltcedar or Russian olive make up greater than 35 percent of the total annual production. When compared with the Reference State, the annual production is less due to the decrease of the perennial grasses and increase of bare ground. The increase in woody species, however, compensates for some of this loss. The total annual production (air-dry weight) of this state is about 1200 pounds per acre, but it can range from about 800 pounds per acre in unfavorable years to about 1600 pounds per acre in above average years.

Resilience management. This plant community is resistant to change as the stand becomes more dense. Continued frequent and severe grazing or the removal of grazing does not seem to affect the plant composition or structure of the plant community. Saltcedar, Russian olive, annual grasses, weedy species and bare ground compromise the biotic integrity. Plant diversity is poor and the potential for native grasses to reproduce is absent. The shift in the vegetative structure and function is extreme and the biotic integrity is lost. The soil of this community phase is not protected; erosion has accelerated because of increased bare ground. Water flow patterns and pedestalling are obvious. Infiltration is reduced and runoff is increased. Rill channels may be noticeable in the interspaces and gullies may be establishing where rills have concentrated. The watershed is not functional due to excessive runoff, erosion and bare ground.

Pathway CP 3.1-3.2
Community 3.1 to 3.2

Repeated continuous season-long or year-long grazing plus encroachment will convert this plant community to a Woody Invaded Community Phase. Invasion of saltcedar or Russian olive should be consider serious and should be controlled. Failure to do so, or failure to continue with control measures will allow the further encroachment of one or both of these species. Other disturbances of the understory or native species by flooding, fire, or soil disturbances will assist with this transition.

Pathway CP 3.2-3.1
Community 3.2 to 3.1

Brush management, weed control, and prescribed grazing aid in the recovery of the herbaceous understory and return to the Alkali sacaton/Woody invader Community Phase (3.1). An integrated approach to treat the overstory and understory invaders. Successional years of treatment is generally required to maintain cover of both saltcedar and Russian olive, as well as many of the herbaceous invader species. Responses to grazing management is more expedient due to the hydrology of the ecological site. Parent material or native seed sources must be available for natural recovery.

State 4
Altered

Mining, energy development, irrigation conveyance lines, irrigation, and livestock operating facilities are a few activities that have created a change to this ecological site. The soil disturbance, removal of greasewood and other vegetation, as well as impacts to the hydrology of this ecological site has left scars on the landscape.

Characteristics and indicators. Outside of the visible evidence of soil movement, seeding, or development the altered/disturbed community is comprised of non-native or improved varieties and varying successional species such as weedy annuals (Russian thistle, sunflower or other asters) and foxtail barley.

Resilience management. Frequency of disturbance, species established, level of management, and remaining hydrology determines the resistance and resiliency of the Altered State.

Community 4.1
Altered Lands

Altered lands have been impacted by human settlement and land use advancement. Many areas within the Wind River Basin were farmed during early settlement periods. Water collection structures and conveyance ditches were cut through the channel systems to move water across the landscape for irrigation. Diversion structures, culverts, and intensive use of the riparian systems impacted the water flow and channel stability, causing downcutting and other erosional processes to occur. These alterations with changes in the precipitation and runoff into the system had an impact on the system and over time many ditches and irrigation systems were abandoned. Remnants of old mining towns, farmsteads, and corrals are visible along sections of these drainages today. Mechanical alteration of these areas in conjunction with the introduction of species from hayfields and in attempts to stabilize areas created these altered lands.

Resilience management. The persistence of introduce non-native species is an indicator that identifies this community phase. These non-native species are not invasive, although they may be persistent and aggressive species. Smooth brome, orchardgrass, varieties of wildrye, and hybrid wheatgrasses are a few cultivars that have been planted that have persisted on the landscape. The preparation of the seedbed as well as any original soil disturbance have altered the soil function and site characteristics. In other instances, the encroachment of these species due to irrigation seepage, or broadcasting have forced the change with an unnatural water source and non-native species. Productivity varies greatly depending on the exact disturbance, age and successional stage of recovery from this disturbance, and what, if any, species were seeded into the site. Composition variability of this plant community limits the ability to provided accurate averages and growth curves, so no production values are provided for this community phase.

Transition T 1-2
State 1 to 2

Repeated year-long and season-long grazing weakens the tall- and mid-stature grasses providing an advantage for tillering species to establish and increase in dominance in the community. Drought exacerbates this transition. High traffic areas, compaction, aids the speed of the transition as well.

Constraints to recovery. The dense root structure alters the hydrology and increases the erosion potential between vegetative cover reducing the ability for other more preferred species from establishing in the community. The dense root structure also is resilient to continued disturbance as well as removal of pressure, so it is difficult to shift the community without major impacts.

Transition T 1-3
State 1 to 3

Increases in bare ground, drought, and soil disturbances provides a mechanism when invasive seed sources are present to allow weedy species to invade a community. Russian olive and saltcedar are both advantageous species that are quick to establish and out-compete native species for space and resources, as are herbaceous invaders. Soil disturbances by vehicles, animal hoof action, flooding, and other disasters provide opportunity and potential for transport of seed sources to the community. Drought weakens native competitors allowing establishment in the community.

Constraints to recovery. Invasive (noxious) weed control is difficult, time consuming, and costly. In several species, complete eradication and maintenance following removal inhibits the ability to fully recover a community. This inability to completely eradicate all invasive species is the major constraint to recovery. In some instances, the means to eradicate a species may require extensive soil disturbances and seeding of the community, leading to an Altered State.

Restoration pathway R 2-1
State 2 to 1

Reducing the use and pressure on the tall- and mid-stature grasses, allowing alkali sacaton and basin wildrye to recover, with the use of grazing management strategies begins the recovery for this community. incorporating periods of rest during the growing season will allow these species to respond and increase again, will also aid in the stabilization of the channel. Removal or thinning of greasewood and potentially rubber rabbitbrush furthers this process. Care to minimize soil disturbance in the removal of species and weed control is needed to prevent a further degradation of the community.

Transition T 2-3
State 2 to 3

The sod-bound community has increased bare ground and erosion between vegetative patches, increasing the risk for invasion by undesirable species. Intensive use by livestock or wildlife, as well as other soil disturbances including drought and flooding, will open this community further to the pressures of invasion. Animal movement through the community, flood water, wind, and human presence in area are all sources to carry in weedy and invasive species seed sources. Drought will exacerbate this process.

Constraints to recovery. The extreme difficulty, cost, and limitations of weed control, especially eradication, is the major constraint to recovery. Although this is very species specific, the general knowledge is that weed control is costly, requires long term commitment and awareness, and has a high failure rate.

Restoration pathway R 3-4
State 3 to 4

The process of treating or eradicating the invasive species, specifically Russian olive and saltcedar, will require the removal of woody debris and roots. This generally will create extensive soil disturbance, especially in extremely dense cover. The preparation of a seedbed, treatment and removal of invasive and undesirable herbaceous cover, and seeding will physically alter the upper portion of the soil profile and may require deeper ripping and tillage depending on invasive species being dealt with. Improved varieties of species provide the best defense for establishment and competition with weedy species, and offer the best success to outcompete and prevent a re-infestation. This process leads to an Altered State.

Transition T 4-3
State 4 to 3

Seeding failure, lack of post-establishment management, or a re-occurrence of a disturbance or on-going disturbances are mechanisms that trigger a re-infestation of invasive species. Although the Saline Subirrigated ecological site provides a better opportunity for successful seedings in this arid and challenging climate. There is an inherent risk, especially in the flood-zone of these riparian areas. When a seeding fails, the bare ground and exposure to possible seed sources (rather imported with equipment and seed, or lasting seedbanks from previous infestations), provides a great opportunity for invasive species to re-establish. If proper timing for establishment and hardening is not provided, grazing impacts can severely weaken or damage a newly established community.

Constraints to recovery. The constraint to recovery is directly associated with the ability to eradicate or out compete the invasive species that establish in the community. Eradication is difficult to unforeseeable. Maintenance length and cost are also inhibiting to this process.