Community 1

Community 2

Community 3

Community 4

Community 5

State 6
Bunchgrasses/Sagebrush

The Reference State, Bunchgrasses/Sagebrush State, originated under moderate grazing by large ungulates. With continued grazing management, this community has persisted on the landscape. The State is characterized by a dominance of bluebunch wheatgrass and Wyoming big sagebrush. Occurrences of black sagebrush have been found, although not prevalent on this ecological site.

Characteristics and indicators. The reference state is characterized by the dominance of Wyoming big sagebrush, at 15 percent or less composition by weight, with bluebunch wheatgrass, at 40 percent or less composition by weight. But with these two dominant species, the site holds a healthy mix of rhizomatous wheatgrass, Western and Thickspike, as well as Indian ricegrass, needle and thread, and to a minor extent sod-formers such as threadleaf sedge.

Resilience management. These communities are drought tolerant and resistant to change unless under significant stress.

Community 6.1
Bluebunch Wheatgrass/Needleandthread/Sagebrush

Figure 8. Bluebunch wheatgrass, needle and thread, and a mixture of short-stature grasses with Wyoming big and black sagebrush dominate this community.

This plant community is extremely stable and well adapted to the climatic conditions of the Lower Foothills. The diversity in plant species allows for high drought tolerance. This is a sustainable plant community (site/soil stability, watershed function, and biologic integrity). This plant community is the interpretive plant community for this site and is considered to be the Reference Plant Community. This state evolved with grazing by large herbivores and periodic fires. The cyclical natural of the fire regime in this community prevented Wyoming big sagebrush from being the dominant landscape. This plant community can be found on areas that are properly managed with grazing and/or prescribed burning, and on areas receiving occasional short periods of rest. The potential vegetation is about 75 percent grasses or grass-like plants, 10 percent forbs, and 15 percent woody plants. This state is dominated by cool season mid-grasses. The major grasses include bluebunch wheatgrass, rhizomatous wheatgrasses (western and Montana), needle and thread, and Indian ricegrass. Other grasses occurring in this state include bottlebrush squirreltail, prairie junegrass, and Sandberg bluegrass. Wyoming big sagebrush is a conspicuous element of this state, occurring in a mosaic pattern, and making up 5 to 15 percent of the annual production. Winterfat is a common component found on this site. A variety of forbs also occurs in this state and plant diversity is high (see Plant Composition Table). The total annual production (air-dry weight) of this state is about 525 lbs./acre, but it can range from about 300 lbs./acre in unfavorable years to about 625 lbs./acre in above average years.

Resilience management. This plant community is resilient, but is subject to change. The herbaceous species present are well adapted to grazing; however, species composition can be altered through long-term overgrazing, lack of management or use causing decadence and decrease in vigor of the cover present or natural/man-made disturbance.

Community 6.2
Rhizomatous Wheatgrasses/Perennial Grasses/Sagebrush

Figure 11. Sagebrush has expanded in this community with rhizomatous wheatgrass and Sandberg bluegrass.

Historically, this plant community evolved under grazing and a low fire frequency. Currently, it is found under moderate, season-long grazing by livestock and will be exacerbated by prolonged drought conditions. In addition, the fire regime for this site has been modified and extended periods without fire is now common. This plant community is still dominated by cool-season grasses, while short warm-season grasses and miscellaneous forbs account for the balance of the understory. Wyoming big sagebrush is now a conspicuous part of the overall production and accounts for the majority of the over story. The dominant grasses include Bluebunch wheatgrass, rhizomatous wheatgrasses, and Needleandthread. Grasses and grass-like species of secondary importance include Prairie junegrass, Blue grama, Sandberg bluegrass, and Threadleaf sedge. Forbs commonly found in this plant community include Scarlet globemallow, Fringed sagewort, and Spiny phlox. Wyoming big sagebrush can make up to 25 percent of the annual production. The over story of sagebrush and understory of grasses and forbs provide a diverse plant community. When compared to the Reference Community 1.1, Wyoming big sagebrush, Blue grama, and Threadleaf sedge have increased. Plains prickly pear cactus will also have invaded, but occurs only in small patches. Indian ricegrass has decreased and may occur in only trace amounts under the sagebrush canopy or within the patches of prickly pear. In addition, the amount of Winterfat may or may not have changed depending on the season of use. The total annual production (air-dry weight) of this state is about 375 pounds per acre, but it can range from about 275 lbs./acre in unfavorable years to about 550 lbs./acre in above average years.

Resilience management. Rangeland Health Implications/Indicators: This plant community is resilient, but is subject to change. The herbaceous species present are well adapted to grazing; however, species composition can be altered through long-term overgrazing, lack of management or use causing decadence and decrease in vigor of the cover present or natural/man-made disturbance. The herbaceous component is mostly intact and plant vigor and replacement capabilities are sufficient. Water flow patterns and litter movement may be occurring but only on steeper slopes. 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.

Community 6.3
Bluebunch Wheatgrass/Perennial Grasses

Figure 14. Reference community is in tact with a few shifts, however sagebrush has been lost from this community.

This plant community is evolving with the hydrologic shift caused by the loss of the shrub component. Remnant sagebrush skeletons will help to hold a minor amount of moisture, but the site holds a reduced potential and vulnerability due to the loss of the structure component of the canopy. Currently, it is found under moderate, season-long grazing by livestock and will be exacerbated by prolonged drought conditions. In addition, the fire regime for this site has been modified. This site appears to respond with an exaggerated shift in production from wet, normal and dry seasons and thus the fire threat will vary drastically from one production cycle to the next. This plant community is still dominated by cool-season grasses, while short warm-season grasses and miscellaneous forbs account for the balance of the understory. Under continued drought or intense grazing, this community is at-risk, shifting to a sod-forming, warm-season dominated grass community. Wyoming big sagebrush is relic in small depressions on the landscape, or may be replaced with rabbitbrush species or broom snakeweed, but has little to no production and is not included as a component of the over story. The dominant grasses include bluebunch wheatgrass, rhizomatous wheatgrasses, and needleandthread. Grasses and grass-like species of secondary importance include prairie junegrass, Sandberg bluegrass, and threadleaf sedge. Forbs commonly found in this plant community include scarlet globemallow, milkvetches, and spiny phlox. This site can still provide a diverse plant community, but lacks the structure for cover and wildlife habitat. When compared to the Reference Community 1.1, Wyoming big sagebrush is absent, while Sandburg bluegrass and threadleaf sedge have increased. Plains pricklypear cactus will also have invaded. Indian ricegrass has decreased and may occur in only trace amounts within the patches of Plains pricklypear. Season of use and treatment type may have limited or removed winterfat from this site. The total annual production (air-dry weight) of this state is about __ pounds per acre, but it can range from about __ lbs./acre in unfavorable years to about __ lbs./acre in above average years.

Resilience management. Rangeland Health Implications/Indicators: This plant community is resistant to change. The herbaceous species present are well adapted to grazing; however, species composition can be altered through long-term overgrazing. The herbaceous component is mostly intact and plant vigor and replacement capabilities are sufficient. Water flow patterns and litter movement may be occurring but only on steeper slopes. Incidence of pedestalling is minimal. Soils are mostly stable and the surface shows minimum soil loss. The watershed is functioning, but has been altered or affected by the loss of snow catch by the sagebrush and ability to slow water movement over the surface; however, the biotic community is intact.

Pathway P1.1-1.2
Community 6.1 to 6.2

Bluebunch Wheatgrass/Needleandthread/Sagebrush

Rhizomatous Wheatgrasses/Perennial Grasses/Sagebrush

Moderate, continuous season-long grazing will convert the plant community to the Rhizomatous/Perennial Grass/Big Sagebrush Plant Community. Prolonged drought will exacerbate this transition. The stressers reduce the bunchgrasses such as Bluebunch Wheatgrass, Needleandthread, Indian ricegrass; allowing the solitary growth and sod-formers to increase in dominance in the community.

Pathway CP1.1-1.3
Community 6.1 to 6.3

Bluebunch Wheatgrass/Needleandthread/Sagebrush

Bluebunch Wheatgrass/Perennial Grasses

Extensive Brush Management or Fire with Drought, creates a shift in the hydrology of the site preventing the re-establishment of Wyoming big sagebrush on the site without extensive management changes. This transition has been seen to occur with sites that were treated with chemicals aerially in the late 1960’s, and in areas where wildfires burned hot or were fired with a period of extended drought inhibiting the seed bank or preventing the establishment of seedlings into the area.

Pathway P1.2-1.1
Community 6.2 to 6.1

Rhizomatous Wheatgrasses/Perennial Grasses/Sagebrush

Bluebunch Wheatgrass/Needleandthread/Sagebrush

Prescribed grazing or possibly long-term prescribed grazing, will allow recovery of this plant community to the Reference community. The probability of this occurring is high especially if rotational grazing along with short deferred grazing is implemented as part of prescribed method of use. In addition, the removal of fire suppression will allow a somewhat natural fire regime to reoccur to more easily transition between this plant community and the reference community. A prescribed fire treatment can be useful to hasten this transition, if desired and if invasive species risk is low. Other brush management techniques, such as mechanical or chemical are alterntives.

Pathway CP1.2-1.3
Community 6.2 to 6.3

Rhizomatous Wheatgrasses/Perennial Grasses/Sagebrush

Bluebunch Wheatgrass/Perennial Grasses

Extensive Brush Management or Fire with Drought, creates a shift in the hydrology of the site preventing the re-establishment of Wyoming big sagebrush on the site without extensive management changes. This transition has been seen to occur with sites that were treated with chemicals aerially in the late 1960’s, and in areas where wildfires burned hot or were fired with a period of extended drought inhibiting the seed bank or preventing the establishment of seedlings into the area.

Community 7

Community 8

Community 9

State 10
Sagebrush/Bare Ground

If continued pressure or disturbance occurs on the vulnerable community within the reference state (State 1), it can be forced into the Sagebrush/Bare Ground State. This state name is somewhat misleading in the perception considering that bare ground may only increase slightly and in many cases there is no change or a light decrease in cover by sagebrush. Over time, drought or grazing pressures on this state will eventually drive the sagebrush/shrub canopy out or decrease the health and vigor of the plant to a non-sustainable level. The herbaceous plant production may remain only slightly decreased, but the thriving species usually occur under the canopy of Wyoming Big sagebrush or similar shrub species (rabbitbrush) and within the protection of pricklypear cactus.

Characteristics and indicators. The prominent cover of Wyoming big sagebrush and significant lichen cover or bare ground is the key indicator for this State and Community Phase. The loss of key herbaceous species is significant, although remnant populations will reside within the sagebrush crown or cactus clumps.

Resilience management. Brush management, followed by prescribed grazing, may return this plant community to a similar or near Reference Plant Community. If prescribed fire is used as a means to reduce or remove the shrubs, sufficient fine fuels will need to be present. This may require deferment from grazing prior to treatment. Post management is critical to ensure success. This can range from two or more years of rest to partial growing season deferment, depending on the condition of the understory at the time of treatment and the growing conditions following treatment. In the case of an intense wildfire that occurs when desirable plants are not completely dormant, the length of time required to reach a community within the Reference State may be increased and seeding of natives is recommended.

Community 10.1
Wyoming Big Sagebrush / Bare Ground Plant Community

This plant community is the result of frequent and severe grazing and protection from fire. Sagebrush dominates this plant community, as the annual production of sagebrush ranges from 10 to 25% or greater. Wyoming big sagebrush is a significant component of the plant community and the preferred cool season grasses have been greatly reduced. The dominant grasses are prairie junegrass, Sandberg bluegrass, and threadleaf sedge. Cactus and sageworts often invade. The interspaces between plants have expanded leaving the amount of bare ground more prevalent. As compared with the reference state and inclusive community, the annual production may show a decline, but initially the shrub production compensates for some of the decline in the herbaceous production. The open interspaces leave this site vulnerable to weedy annual species such as Cheatgrass to occupy the site if a seed source is available. If these species gain a foothold, they push the state across a threshold into an invaded or annual grass state. The total annual production (air-dry weight) of this state is about __ pounds per acre, but it can range from about __ lbs./acre in unfavorable years to about __ lbs./acre in above average years.

Resilience management. Rangeland Health Implications/Indicators: This plant community is resistant to change as the stand becomes more decadent. These areas may actually be more resistant to fire as less fine fuels are available and the bare ground between the sagebrush plants is increased. Continued frequent and severe grazing or the removal of grazing does not seem to affect the composition or structure of the plant community. Plant diversity is moderate to poor. The plant vigor is diminished and replacement capabilities are limited due to the reduced number of cool-season grasses. Plant litter is noticeably less when compared to reference communities. Soil erosion is 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 down slope.

Community 11

Community 12

Community 13

State 14
Sod-former

Threadleaf sedge is a sod-forming species that exist as a component of the perennial vegetation naturally (in reference communities) in the Loamy Calcareous ecological site. The general tendency of threadleaf sedge is to increase under grazing pressure, becoming dominant. The root-mat created as threadleaf sedge increases slows water infiltration, increasing runoff and reducing the hydrologic function of this community.

Characteristics and indicators. Threadleaf sedge will be the major soil cover of this community with a deteriorating component of sagebrush and cactus. As sagebrush declines, pricklypear cactus tends to increase in composition in the community.

Resilience management. Threadleaf sedge is extremely resilient and resistant to degradation once established. This creates a stable community.

Community 14.1
Threadleaf Sedge/Wyoming Big Sagebrush

Figure 15. Threadleaf sedge and black sagebrush are the dominant canopy within this community.

This plant community is the result of frequent and severe year-long grazing, which has adversely affected the perennial grasses as well as impacted the shrub component. Other factors that can affect the shrubs include drought, heavy browsing, wildfires, and/or human brush control measures. A dense sod of threadleaf sedge dominates this state. Prickly pear cactus can become dense enough in patches so that livestock cannot graze forage growing within the cactus clumps. Wyoming big sagebrush has been reduced to small patches or in some cases removed. Rubber rabbitbrush may be the sole remaining shrub on the site. When compared to the Reference State, threadleaf sedge, have increased. Pricklypear cactus has invaded. All cool-season mid-grasses, forbs, and most shrubs have been greatly reduced. Production has been significantly decreased. The total annual production (air-dry weight) of this state is about __ pounds per acre, but it can range from about __ lbs./acre in unfavorable years to about __ lbs./acre in above average years.

Resilience management. This community is at risk of transition to a completely sod-bound community as explained above, as the sod 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 sod-formers, but it will eventually remove the shrub component from the plant community. The biotic integrity of this state is not functional and plant diversity is extremely low. The plant vigor is significantly weakened and replacement capabilities are limited due to the reduced number of cool-season grasses. This sod-bound plant community is very resistant to water infiltration. While this sod protects the site itself, off-site areas are affected by excessive runoff that can cause rills and gully erosion. Water flow patterns are obvious in areas of bare ground and pedestalling is apparent along the sod edges. Rill channels are noticeable in the interspaces and down slope. The watershed may or may not be functioning, as runoff may affect adjoining sites.

Community 14.2
Threadleaf Sedge/Cactus Plant Community

Figure 16. The sagebrush cover was removed in the 1960s with no recovery, but broom snakeweed and threadleaf sedge are strong in this community.

This plant community can occur fairly easily through drought, wildfire or continued pressure on the remaining shrubs. A dense sod of threadleaf sedge dominates this state. Prickly pear cactus can become dense enough in patches so that livestock cannot graze forage growing within the cactus clumps. Wyoming big sagebrush has been generally removed from the site with only isolated occurrences. Rubber rabbitbrush is significantly reduced, but is the remaining shrub on the site. When compared to the Reference Community 1.1, threadleaf sedge has increased. Prickly pear cactus has invaded. All cool-season mid-grasses, forbs, and most shrubs have been greatly reduced or removed. Production has been significantly decreased. The total annual production (air-dry weight) of this state is about __ pounds per acre, but it can range from about __ lbs./acre in unfavorable years to about __ lbs./acre in above average years.

Resilience management. Rangeland Health Implications/Indicators: This sod bound 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 state is not functional and plant diversity is extremely low. The plant vigor is significantly weakened and replacement capabilities are limited due to the reduced number of cool-season grasses. This sod bound plant community is very resistant to water infiltration. While this sod protects the site itself, off-site areas are affected by excessive runoff that can cause rills and gully erosion. Water flow patterns are obvious in the bare ground areas and pedestalling is apparent along the sod edges. Rill channels are noticeable in the interspaces and down slope. The watershed may or may not be functioning, as runoff may affect adjoining sites.

Pathway P3.1-3.2
Community 14.1 to 14.2

Threadleaf Sedge/Wyoming Big Sagebrush

Threadleaf Sedge/Cactus Plant Community

Frequent or Severe Grazing, Drought/Insect Damage, Fire/Wildfire – The Wyoming big sagebrush component of this community is the at risk species. Sagebrush will decrease under drought, and if grazing pressures persist through season or year-long patterns, becoming decadent and then dying. The sod dominated community reduces the ability for sagebrush to propagate, also leading to a recession of sagebrush. Although rare in occurrence, due to lack of fine fuels and canopy cover, fire will remove the shrub canopy as well. In some cases on the edge of the precipitation break, Rubber rabbitbrush will dominate a site as sagebrush diminishes. It is also noted that with periods of drought that have occurred in the past ten years, there is a noted decrease in the health and vigor of Blue grama and Threadleaf sedge. The dense root structure of the sod-former plants is reduced allowing other species to establish. The spring of 2014 has shown a flush of Sandberg bluegrass occupying Blue grama communities, and in some instances appear to be the dominant production for that community.

State 15
Invaded

Invasive plant species are a permanent concern with rangelands and management. Each year new species are discovered and will alter this section as they are. Currently within the Big Horn Basin there are several varieties of thistles, knapweeds, milkweeds, mustards and others that create a management issue for livestock and ecology. In areas where there has been a disturbance, natural or man-made, these species can gain a place in the landscape and are difficult to impossible to eradicate. Because of this it becomes a battle to maintain control with annual or prolonged management of the weed species, and preventing further shifts or changes to the native composition.

Characteristics and indicators. The presence of an invasive weed in a community warrants the transition to the Invaded State once it is at least 5 percent of the canopy cover or composition by weight in the community.

Resilience management. Treatment of many of the common invasive species is difficult and requires continual maintenance. Eradication, in many situations, has not been achieved. This leaves invaded communities open to further degradation, but resistant to improvement.

Community 15.1
Perennial Grasses/Invasive Species/Sagebrush

Figure 17. Cheatgrass is a significant factor of this community, however, the native population is persisting within the cheatgrass.

The Perennial Grasses/Invasive Species/Sagebrush community phase has maintained a representative sample of the perennial grasses and forbs that are typical of the site with the accompanying Wyoming big sagebrush composition. The invasive species are present and hold a significant (10% or greater) composition of the landscape, and are prominent on the site (referring to a more wide scale composition, not one isolated patch in an isolated portion of the landscape). Production of the desired perennial species of this site is generally reduced but the total production is maintained or elevated due to the production potential of many of the annual or invasive species.

Resilience management. Rangeland Health Implications/Indicators: This plant community is resistant to change. These areas may be more prone to fire as fine fuels are more available and the bare ground between the sagebrush plants is decreased. Plant diversity is moderate to poor. The plant vigor is diminished and replacement capabilities are limited due to the reduced number of cool-season grasses. Plant litter is noticeably more when compared to reference communities due to the potential biomass produced by the invasive species (species dependent). Soil erosion is variable depending on the species of invasion and the litter accumulation thus associated, this variability also applies to water flow patterns and pedestalling. Infiltration is reduced and runoff is increased due to loss of perennial vegetation and root density.

Community 15.2
Invasive Species/Sagebrush

This community phase is the at-risk community. As the native populations of perennial grasses and forbs become weakened, the site becomes invader driven, and irreversible. If environmental or management stressors or disturbances occur to remove the shrub component, the site crosses to community phase 4.3, Annual Grasses. Wyoming big sagebrush is able to compete and maintain a strong community under a heavy infestation level unless fire or disturbance of any nature weakens the plant. The canopy of the sagebrush serves as a protected niche in the system that can hold native grass species and help them to persist. But the system is low in resistance and even lower in resilience.

Resilience management. Rangeland Health Implications/Indicators: This plant community is resistant to change as the stand becomes more decadent. These areas may be more prone to fire as fine fuels are more available and the bare ground between the sagebrush plants is decreased. Plant diversity is poor. The plant vigor is diminished and replacement capabilities are limited due to the reduced number of cool-season grasses. Plant litter is noticeably more when compared to reference communities due to the potential biomass produced by the invasive species (species dependent). Soil erosion is variable depending on the species of invasion and the litter accumulation thus associated. The variability of the water flow and pedestalling as well as infiltration and runoff is determined again by the species that establishes on this site.

Community 15.3
Annual Grasses

Downy Brome, better known as Cheatgrass or Bromus tectorum, is able to green up and grow late into the fall taking advantage of the fall moisture. Seed lays dormant until conditions are positive, allowing growth before most native species. The plant’s ability to grow quickly utilizes the minimal available resources before the native species can begin to break dormancy for the season. The ability for Cheatgrass to produce a large quantity of seed quickly, and in poor conditions, as well as the morphology of the seed allowing easy dispersal creates a wide spread seed bank that is unmanageable. These traits create a management challenge that has not been successfully met at this time. Once this species has a niche on a landscape it is resistant and resilient to all changes. There may be native species that will persist in small scattered populations and under certain climatic conditions can show their resiliency and respond to the available resources, but generally found unable to out-compete the annual invader.

Resilience management. Rangeland Health Implications/Indicators: This plant community is resistant to change. These areas are extremely prone to fire fueled by the high fine fuels load associated with the Cheatgrass litter. Plant diversity is poor. The plant vigor is diminished and replacement capabilities are non-existent due to the loss of cool-season grasses. Plant litter is noticeably more when compared to reference communities in response to the dense duff layer created by Cheatgrass. Soil erosion is generally reduced in response to the litter accumulation; however, the annual nature of this plant accentuates the water flow patterns and pedestalling. Infiltration is reduced and runoff is increased with the loss of perennial vegetation and root depth and density.

Pathway P4.1-4.2
Community 15.1 to 15.2

Frequent or Severe Grazing, Drought, Disturbances (mechancial) and Wildfire – Drought, wildfire, or other climatic stresses on the system can continue to stress the native species reducing their ability to maintain their footprint in the plant community. This continued stress or the complication with mechanical disturbances or, frequent or severe grazing or pressure from wildlife and livestock can reduce the natives to an unviable or unsustainable population and allow the invasive species to dominate the site. This is more typical in species such as knapweeds, Canada or Bull thistle, and specifically Cheatgrass (Downy brome).

Pathway CP4.1-4.3
Community 15.1 to 15.3

Fire or extended periods of drought can lead to the die back of sagebrush within this community. Mechanical or chemical removal of sagebrush will impact the native grasses and leave the community at threat of complete dominance of cheatgrass. Once cheatgrass forms a monoculture, the risk of fire is high and the ability for recovery is minimal

Pathway CP4.2-4.1
Community 15.2 to 15.1

With intensive weed control efforts and rest, native species have an opportunity to recover in this community. The prescription of a rest rotation with continued weed management can maintain a native community with the invasive species.

Pathway CP4.2-4.3
Community 15.2 to 15.3

Fire or extended periods of drought can lead to the die back of sagebrush within this community. Mechanical or chemical removal of sagebrush will impact the native grasses and leave the community at threat of complete dominance of cheatgrass. Once cheatgrass forms a monoculture, the risk of fire is high and the ability for recovery is minimal

State 16
Disturbed

The Disturbed state could be drafted as a stand-alone box within the state and transition model diagram. No matter what state a site originally is ranked in, once the site is mechanically disturbed, or suffers a catastrophic or significant natural disaster that alters the soil properties (erosional, depositional, hydrological or chemical), the site potential is altered.

Characteristics and indicators. To consider this as an alternate ecological site would not be unreasonable. In some cases (site by site consideration), a re-correlation of a location may be the best solution. But in many cases, the site has not been altered out of the current site, but the potential has shifted enough that it is no longer truly comparable to the reference community. So a dynamic state was captured to detail the altered communities that exist on the landscape.

Resilience management. The response to management varies with the specific form of disturbance, the stage or level of restoration attempted or the age of the community post disturbance. These communities are in a state of flux and are sensitive to further disturbance.

Community 16.1
Disturbed Lands Plant Communities

The title Disturbed Lands is encompassing three broad classifications of these land types. Go-back fields are referring to sites that were once cultivated or have had minor surface disturbance, and have since been left to natural processes. Homestead and abandoned farming sites can be identified on the landscape (through photo-tone shifts in aerial photographs) and are generally a mix of natives that have moved into disturbed sites or a co-mingling of introduced species and natives. These sites are difficult to reclaim, generally due to the introduced species that persist on the landscape. And once reclaimed, do not tend to respond to the natural disturbance regimes in the same manner that a native, mechanically undisturbed site would respond. In a similar process, mined lands or lands affected by energy development including transmission corridors, transportation corridors and development sites provide a host of successional processes. Many times, these locations are re-exposed to disturbance frequently by mechanical means leaving annual weeds and primary successional species as the dominate canopy. Older, established sites or abandoned locations, have established communities similar to those expected on go-back fields and may be stable in nature. The last type of Disturbed lands is the “introduced grass plantings”. Although this could be considered reclaimed or restored, there are sites that were seeded to introduced or improved species, such as crested wheatgrass, smooth brome, or tall wheatgrass in a monoculture. These communities will transition or mature as the stand density declines with lack of management or inputs, the canopy opens and allows natives, if present, to begin to establish. Although each planting is highly variable on the exact composition that will be present, they appear to be stable and can be productive sites. The growth curve of this plant community will vary depending on the species that are selected for seeding. For a more accurate portrait of the growth curve for the seeded community, the species used and the climatic tendencies of the region must be considered. Rangeland Health Implications/Indicators: The plant community is variable and depending on the age of the stand and the stage of successional tendencies that the location is in will determine how stable (resilient/resistant) the community is. Plant diversity is generally strong, but is usually lacking in the structural groups that are desired on the site. Soil erosion is variable depending on the disturbance regime that is occurring on the site and again on the specific community that has established on a specific location. The variability of the water flow and pedestalling as well as infiltration and runoff is determined again by the species that establishes on this site.

Community 16.2
Reclaimed Lands Plant Communities

Reclamation practices have shifted greatly over the last several decades. Crested wheatgrass was a species used frequently for reclamation throughout Wyoming and many of these communities persist today. Although there are areas where native species from neighboring sites are starting to slowly extend into the crested wheatgrass stands, many times, these stands remain as a monoculture until a disturbance occurs to open the canopy slightly to provide a more tolerable niche. Bozosky Russian wildrye and varieties of rhizomatous and bunch-wheatgrasses have also been used in mixes to help compensate for the chemistry of these soils. Although the success of vegetative seedings are low in this LRU, due to the low precipitation and timing of precipitation events, there are limited areas along pipeline corridors, well sites or pad sites, and along transportation corridors where re-seeded sites have succeeded. As mentioned in the community phase above, as these seedings mature and the stands open, they can be characteristically similar to other disturbed sites. Where under the more current, and understood definition of reclaimed or restored, sites are planted to as close to a natural occurring plant community as possible. This excludes the use of non-native species and allows for a more similar ecological response than what is expected with non-native species. Again, these seedings will not replicate the reference community in response to management due to the change in soil dynamics with mechanical disturbance, seedbed preparation and seeding, but they can be very similar. The growth curve of this plant community will vary depending on the species that are selected as the reclamation seed mix. For a more accurate portrait of the growth curve for the seeded community, the species used and the climatic tendencies of the region must be considered. Rangeland Health Implications/Indicators: Seeding mixtures will determine the plant community resistant to change and resilience to threat of invasive species and to erosion. Many of the stands established during seeding are diversity poor, but are better than the monocultures that were planned historically. Many seeded sites may be prone to fire as they mature as many of the cultivated seeds produce more biomass (possibly more litter) and thus may create more fine fuels to fuel a fire. Soil erosion is variable depending on the establishment of the seeding, how it is seeded, and mechanical procedures put in place. The variability of the water flow and pedestalling as well as infiltration and runoff is determined again by the species that establishes on this site.

Pathway P5.1-5.2
Community 16.1 to 16.2

Seeding, Brush Management, Integrated Pest Management, Prescribed grazing management – With the proper mechanical improvements and the follow-up through establishment and then maintenance, a disturbed site can be improved and managed. However, climatic limitations and soil chemistry limit the success of seeding treatments. Depending on the site location, invasive species are a risk to most sites within the Basin and create a low success potential for this process.

Pathway P5.2-5.1
Community 16.2 to 16.1

No use, No Fire, Long Term Prescribed Grazing, Frequent or Severe Grazing. In general, if a site is not maintained with the conditions of which the species are adapted under, a decline in vigor will occur and then a shift in composition will occur. Since the site is altered from reference state in soils due to plowing, mining, or other similar disturbances, the plant community will not follow the same expected shifts of a native community and this will refer back to a community more reflective of a disturbed plant composition.

Pathway P4.1-4.2
Community 3 to 13

Frequent or Severe Grazing, Drought/Insect Damage, Fire/Wildfire – The Wyoming big sagebrush component of this community is the at risk species. Sagebrush will decrease under drought, and if grazing pressures persist through season or year-long patterns, becoming decadent and then dying. The sod dominated community reduces the ability for sagebrush to propagate, also leading to a recession of sagebrush. Although rare in occurrence, due to lack of fine fuels and canopy cover, fire will remove the shrub canopy as well. In some cases on the edge of the precipitation break, Rubber rabbitbrush will dominate a site as sagebrush diminishes. It is also noted that with periods of drought that have occurred in the past ten years, there is a noted decrease in the health and vigor of Blue grama and Threadleaf sedge. The dense root structure of the sod-former plants is reduced allowing other species to establish. The spring of 2014 has shown a flush of Sandberg bluegrass occupying Blue grama communities, and in some instances appear to be the dominant production for that community.

Pathway P5.1-5.2
Community 5 to 11

Frequent or Severe Grazing, Drought, Disturbances (mechancial) and Wildfire – Drought, wildfire, or other climatic stresses on the system can continue to stress the native species reducing their ability to maintain their footprint in the plant community. This continued stress or the complication with mechanical disturbances or, frequent or severe grazing or pressure from wildlife and livestock can reduce the natives to an unviable or unsustainable population and allow the invasive species to dominate the site. This is more typical in species such as knapweeds, Canada or Bull thistle, and specifically Cheatgrass (Downy brome).

Pathway P7.1-7.2
Community 8 to 9

Seeding, Brush Management, Integrated Pest Management, Prescribed grazing management – With the proper mechanical improvements and the follow-up through establishment and then maintenance, a disturbed site can be improved and managed. However, climatic limitations and soil chemistry limit the success of seeding treatments. Depending on the site location, invasive species are a risk to most sites within the Basin and create a low success potential for this process.

Transition T1-2
State 6 to 10

Frequent and severe grazing plus no fire on these droughty soils, will convert the plant community to the Big Sagebrush/Bare Ground Plant Community. The probability of this occurring is high. This is especially evident on areas with historically higher precipitation and the sagebrush stand is not adversely impacted by drought or heavy browsing.

Constraints to recovery. The calcic layer in these soils limits water and nutrients, making recovery difficult on this site.

Pathway P1.1-1.2
Community 4 to 12

Moderate, continuous season-long grazing will convert the plant community to the Rhizomatous/Perennial Grass/Big Sagebrush Plant Community. Prolonged drought will exacerbate this transition. The stressers reduce the bunchgrasses such as Bluebunch Wheatgrass, Needleandthread, Indian ricegrass; allowing the solitary growth and sod-formers to increase in dominance in the community.

Transition T1-3
State 6 to 14

Frequent and severe grazing (yearlong grazing) plus wildfire or brush control, will convert the plant community to the Blue Grama Sod Plant Community. The probability of this occurring is high, especially if the sagebrush stand has been severely affected by drought or heavy use or has been removed altogether.

Constraints to recovery. The dense root system and altered hydrology presented by threadleaf sedge limits the ability for this community to recover to Reference.

Restoration pathway R2-1
State 10 to 6

Prescribed Grazing with rest will allow remnant grass species to begin to recover. Time is the biggest component that is needed for this recover, with cooperative climatic conditions. Seeding of native species will assist the process with brush control may be needed to make this transition happen.

Pathway P7.2-7.1
Community 9 to 8

No use, No Fire, Long Term Prescribed Grazing, Frequent or Severe Grazing. In general, if a site is not maintained with the conditions of which the species are adapted under, a decline in vigor will occur and then a shift in composition will occur. Since the site is altered from reference state in soils due to plowing, mining, or other similar disturbances, the plant community will not follow the same expected shifts of a native community and this will refer back to a community more reflective of a disturbed plant composition.

Pathway P1.2-1.1
Community 12 to 4

Prescribed grazing or possibly long-term prescribed grazing, will allow recovery of this plant community to the Reference community. The probability of this occurring is high especially if rotational grazing along with short deferred grazing is implemented as part of prescribed method of use. In addition, the removal of fire suppression will allow a somewhat natural fire regime to reoccur to more easily transition between this plant community and the reference community. A prescribed fire treatment can be useful to hasten this transition, if desired and if invasive species risk is low. Other brush management techniques, such as mechanical or chemical are alternatives.

Transition T2-4
State 10 to 15

Frequent or Severe Grazing, Wildfire, Disturbance - The chance of wildfire is reduced with the loss of the fuels from sagebrush to help carry across large areas, however, in favorable production years areas can produce enough fine fuels to carry a wildfire which in turn opens the canopy and provides a niche for annual invaders such as Cheatgrass and knapweeds to take hold. If the seed source is available, fire is a well-known avenue to provide the conditions for annuals to flourish, as well as general disturbance whether from herbivores or man-induced.

Constraints to recovery. Once the seed source gains a place in the community, it is extremely difficult to manage and may not be feasible or possible to completely remove the invaders.

Transition T3-4
State 14 to 15

Drought, Frequent or severe grazing, Disturbance – Drought as the only factor or drought with grazing intensity together can work to weaken the native species on this site to allow invasive species to establish. Threadleaf sedge has been seen to die back or die out with prolonged drought opening the canopy and the community’s vulnerability to invasive species. Disturbance by mechancial means or human activities that break the root masses or disturb the soil surface open this closed community to potential invasive species, especially when there is a readily available seed source for those invasive species.

Constraints to recovery. The lack of tools to eradicate invasive species is the major constraint to recovery of this community.

Restoration pathway R4-5
State 15 to 16

Integrated Pest Management, with Seeding the site to a native mixture - Success is not known to have occurred, and is rated to be low and highly variable for the rate of control of most species. Cheatgrass and knapweeds are two of the most invasive species for many of these sites but there are many others, for example, Halogeton, that can dominate these sites. It is a consensus that the site can be brought to an at-risk community within the reference state, but that it is not possible to reach the reference community condition once annuals have established on a site.

Transition T5-4
State 16 to 15

Frequent or Severe Grazing, Disturbance with a seed Source, or Drought - Any stressor that is applied with the inherent seed source puts this state at risk to transitioning into an Annual Grass or Invaded State.

Constraints to recovery. The lack of control tools to eradicate cheatgrass and other invasive species, limit the ability for recovery of this community.