State 1
Mixed Grasses/Forbs

Mixed Bunchgrass/Forbs State (State 1 - Reference) evolved with grazing by large herbivores and is well suited for grazing by domestic livestock. Potential vegetation is estimated at 75% grasses or grass-like plants, 25% forbs, and no appreciable woody plants. Specific soil characteristics within the range of the site concept will result in a shift in the vigor and dominance of specific grass species, as well as the abundance of ground-covering forbs. In soils with a higher abundance of grus in the profile will have a higher ratio of mid-stature grasses than the modal concept for this site. There is also a higher occurrence of buckwheat and phlox species on these sites.

Characteristics and indicators. The community is characterized by the key species including: Columbia needlegrass, slender wheatgrass, needleleaf sedge, Idaho fescue, and bluebunch wheatgrass. Other grasses may include mutton and Cusick’s bluegrass, bentgrasses, prairie junegrass, onespike and timber oatgrass, thickspike wheatgrass, mountain brome and spike trisetum. Forbs include: cutleaf anemone and pale mountain dandelion. Increaser species are: bluegrasses, old man’s whiskers, rosy pussytoes, lupine, field chickweed, phlox and cinquefoil (herbaceous). Mountain and fringed sagewort have been found to occur in these communities but infrequently.

Resilience management. A shift that has been seen in this community is a variation between cattle grazing and sheep grazing over time. Those allotments reviewed with long-term sheep grazing had fewer forbs by production, but still maintained a strong diversity in the understory of a tall grass dominated system. As allotments with long-term cattle grazing were reviewed, the tall grasses persisted, but had a stronger undertone of more mid-stature grasses, and a higher prominence of all forbs within the community.

Community 1.1
Mixed Grasses/Forbs

The reference community (1.1) is declining in occurrence on the landscape. The introduction and creep of non-native species is a factor of change over time. Factors such as historic land uses (Sheep grazing to cattle grazing), to an overall increase of land use (increased access and recreational use), has allowed species such as smooth brome, common dandelion, Kentucky bluegrass, and others to become naturalized in the communities. Combined with the non-natives, the greater threat of invasive species has put the reference state and community at great risk. Granite based soils are generally lacking in the mountain big sagebrush component that is so prevelant on other sedimentary soils. These granitic soils do support low growing shrubs such as mountain sagewort and fringed sagewort. Other shrubs incidental to these sites are shrubby cinquefoil, snowberry, and wood's rose. Idaho fescue is a dominant component on these soils, while Columbia needlegrass and rhizomatous wheatgrasses will be prevelant as well. A variety of upland sedge species occupy this site, and will vary from area to area. Dense spikemoss may be present in this reference community, but comprises less than 10% of the ground cover. There is still open soil for seed establishment and typical infiltration of water. The weathered and decomposing granitic base to these soils allows for rapid infiltration even with heavier textures, and erosion is not present on stable sites (such as reference). The total annual production (air-dry weight) of this state is about 2200 lbs./acre, but it can range from about 1500 lbs./acre in unfavorable years to about 2600 lbs./acre in above average years. This production is based on the historic records used to write the initial Loamy 20”+ High Mountains ecological site.

Resilience management. This plant community is extremely stable and well adapted to the Central Rocky Mountain climatic conditions. The diversity in plant species allows for high drought tolerance. This is a sustainable plant community.

State 2
Forbs/Mixed Grasses

This state is prominent on granitic soils. Fringed sagewort and other low or dwarf shrubs found as a minor component in this community, but forbs and grasses are the dominant cover on the landscape. Grass species that remain are mid-stature bunchgrasses that still hold a significant composition in the community but are less conspicuous and lack the production and possibly palatability of other species.

Characteristics and indicators. Lupine, balsamroot, sandwarts and phlox are common components of this community with deathcamas, paintbrush and chickweed. Idaho fescue and timber and/or Parry's oatgrass are prominant, but are less vigorous or shorter in stature than in the reference community. An increase in Dense spikemoss is prevalent and can become a total ground cover in the interspaces of plants, restricting the propagation of new plants/species; which in turn lowers the resilience of this state.

Resilience management. Research has shown that attempts to understand and find management techniques for dense spikemoss have not provided an adequate solution. Trials within the Bighorn Mountains showed that after deep ripping a site, it was able to stabilize with significant vegetation and be a functional section of rangeland with improved production, but there are still significant remnants of the spikemoss that are evident in the trial. Disagreement on the cause and cure supported that this is a degraded state within the soil characteristics, that is a stable state to an extent, but that over time without some disturbance may loose all vigor and diversity. More research is warranted before any scientific statement can be made on the resiliency and management of a spikemoss driven community.

Community 2.1
Forbs/Mixed Grasses

This plant community is the result of long-term season-long or severe grazing by livestock and large ungulates. A variety of forbs dominates the site, often exceeding 20-50% annual production and lowering grass/grass-like forage production. Bunchgrasses such as Idaho fescue, cusick’s and sandberg bluegrass, a variety of sedges and mountain brome are a major component of the understory. The total annual production (air-dry weight) of this community phase is about 1950 lbs./acre, but it can range from about 1100 lbs./acre in unfavorable years to about 2750 lbs./acre in above average years.

Resilience management. This plant community is resistant to change and is relatively stable. The site is protected from excessive erosion by the understory of dense spikemoss. The biotic integrity of this plant community is usually intact, however forage value will decrease and wildlife values will shift with the loss of higher quality grass species. The watershed is functioning, the hydrology varies from relatively unaltered to severely impacted depending on the extent of spikemoss in the community, as well as the forbs and grasses that persist. The variability of forb bloom and prominence on the landscape will provide a longer maturity period of the forbs, however, the risk to livestock has increased due to the reduced grass composition. Larkspur, death camas and locoweed are common threats that will vary from year to year depending on climatic patterns.

State 3
Non-Native/Invaded

This state is not easily divided into two distinct communities, nor is it possible to determine a typical composition of any one community. Unlike sedimentary soils, the encroachment of woody species (juniper/spruce) into the parks is not prevalent. However, dandelion, smooth brome, and Kentucky bluegrass, as well as invasive species do have opportunity for movement into degraded communities. There are instances where it is difficult to identify these communities on the landscape, especially when the community has transitioned to a high composition of forbs. The occurrence of these communities can be a process of time or of disturbance. Historic studies have shown the presence of non-natives such as Kentucky bluegrass and dandelions in a significant stature as early as 1940's and 50's. Other species such as creeping meadow foxtail, timonthy, and smooth brome are becoming more prevalent. Although it has not been documented for the purpose of ESD's at this time, large scale populations of invasive species are starting to develop on segments of the foothills of the Bighorn mountains. On an allotment basis, there are large patches of invasive species that are appearing, these areas are included in this state as a secondary community.

Characteristics and indicators. A dominant component of this state is comprised of a non-native or an invasive species. Dominant component is defined for this state as a composition of 5% or greater by weight. As species composition crosses this threshold it becomes difficult to ignore the impact on the site and is not easily or feasibly eradicated from the site. Woodland (tree) encroachment is also a component of this state, but would have to comprise at least 15% by canopy cover.

Resilience management. In this state, it is understood that the key to management of the site is finding the balance between grazing to reduce or maintain the current level of non-native or invasive species while maintaining and improving the native composition. Treatment with herbicides, biologicals, or mechanical means may be necessary to maintain current levels. The site is resilient in the sense, that once the non-native and invasive species are present, they are not eradicable.

Community 3.1
Non-Native Encroachment

Transitioning from the Forbs/Mixed Grasses community (2.1) to the non-native community phase is the result of a culmination of factors including land use, proximity to transportation routes, wildlife and livestock movement, and general shift in vegetation. Minor impacts or major disturbances allow small or isolated patches of non-native species to establish. From there, succession over time, drought, or other natural or man-driven disturbances allows the spread and eventual dominance of species such as smooth brome, timothy, dandelions, Kentucky bluegrass, field pennycress and others. Many of these species, once established, cannot be eliminated from the system. Unlike their invader cousins, these species will co-exist with most native species. They provide a desirable forage and can be managed with targeted livestock grazing. Research from the 1950’s using exclosures noted that dandelions did not seem to vary from grazed to non-grazed sites, and that they seemed to persist in undisturbed areas, reasoning that they were naturalized species. Although, many of these are naturalized, they are not native to the system and affect production and potential of a site if not managed. The total annual production (air-dry weight) of this state is about 2200 pounds per acre, but it can range from about 1250 lbs./acre in unfavorable years to about 3000 lbs./acre in above average years.

Resilience management. This community is at-risk of transitioning to the invaded state. The state overall is stable and protected from excessive erosion. The biotic integrity of this plant community is fractured, due to the increasing presence of non-native species. Forage value will decrease or the wildlife value will shift toward different species. Depending on the non-native species of threat in this community, will determine the departure from normal function on all levels. The watershed is functioning, but with the increase in woody species (conifers/junipers), the risk of fire could decrease the stability and watershed function of the site.

Community 3.2
Invaded

The Invaded community phase has become an invader driven system. This community phase is characterized by a significant presence of non-native (> 25%) and/or invasive species (5% or greater) composition on the landscape, and are prominent on the site (referring to a wide scale composition, not one isolated patch in an isolated portion of the landscape). The diversity of species that are possible in this community and the wide array of growth forms, growth habits and plant characteristics make it difficult to determine or predict the limitations or risks of this site beyond those stated. The risks and limitations for this community will need to be addressed on an individual case basis. Production yields of the perennial grasses and forbs are reduced but the total production will maintain or may be slightly elevated due to the overall biomass and expanded growth potential of many of the annual or invasive species. A specific production range is not provided due to the variability of composition that will effect overall production.

Resilience management. When Invaded community phase has maintained a representative sample of native perennial grasses and forbs that are key to this particular ecological site. This community phase has, however, became an invader driven system. If native grasses can maintain at least a 15% composition, there is still a chance that the community can be improved, extent of improvement and costs required limit the economic feasibility. This plant community is prone to further invasion. Plant diversity is moderate, and plant vigor is diminished. Replacement capabilities are limited due to the reduced number of native grasses. Soil erosion is variable depending on the species of invasion and the litter accumulation thus associated.

Pathway CP 3.1-3.2
Community 3.1 to 3.2

The competition for limited resources is the driving factor for the transition to an invader driven system. As non-natives become prominent in the community, they are able to utilize resources quicker and slowly reduce the vigor and presence of most native grasses and forbs from the system. As invasive species are introduced into the system, they capitalize on small disturbed areas and open communities to establish and then spread. Drought stress, rodent activity, or grazing pressure will allow the invasive species to become dominant on the site, leaving only remnant populations of native perennial grasses.

State 4
Altered

Although more temperate in climate than the basin and foothills counter-parts, this high elevation site is arid in nature which has played a major role in the development and transitions in land use over time. Many landscapes were suppressed by fire management which has impacted forest health in general. While timber harvest has persisted on the landscape, the Bighorn Mountains provide a larger use as grazinglands. Historically, sheep were a major contributor on the range, but with time cattle are the most abundant user of this landscape. Farming (hayland) and general agricultural practices are not a threat to the higher elevations. However, development of summer working facilities, livestock handling facilities, quarries, recreational areas, trails, roads, and recreational camp sites have played a major role in transforming the landscape. Increased access to areas and more use by humans has fostered new challenges and disturbances to the open parks and sagebrush communities.

Characteristics and indicators. This state is characterized by active disturbance (erosion, development, shifts in use) or reclamation/restoration following a disturbance. This can include roads/access recovery post timber harvest, fire recovery, etc. The plant species and composition will vary with the age of the disturbance, the seed mixes used, or the post recovery characteristics.

Resilience management. Maintaining sites once reclaimed is dependent on access, the specific prescription used to treat the land and climatic factors during the establishment and succession of the community. Restoration or managing the disturb sites for natural recovery will vary depending on what successional species establish as well as the above mentioned variables. Site specific evaluations are needed to capture the resiliency and management needs of communities within this state.

Community 4.1
Disturbed/Degraded Lands

Disturbed or degraded lands are characterized by alteration of the soils to a degree that the functionality (erosional, depositional, hydrological or chemical) and potential of the site has been impacted. Site specific evaluations need to be completed to determine the level of effect. The method and severity of alternation, as well as the spatial extent of the disturbance will determine vegetation response and management needs. Linear disturbances, such as trails and roads, will hold a different risk than patchwork or polygonal disturbances, such as timber sites or parking areas. Small scale or isolated disturbances (spot fires, burrowing sites) can be just as significant of a risk as a large scale disturbance (mined-lands). The growth curve of this plant community will vary depending on the successional species that are able to establish in an area. Early successional community growth curves may be similar to the native community. For a more accurate growth curve, a site specific species inventory and documentation of the climatic tendencies should be collected.

Resilience management. 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 of these successional communities is generally strong, but is usually lacking in the structural groups that are desired on the site. The limited nature of the granitic loamy plant community will make it difficult to determine the successional transition from a degraded community (2.1), but the variety and nature of the forbs dominating the site will be a determining factor (Russian thistle compared to lupine, or mustards compared to bladderpods and phlox. In areas of new or frequent disturbance, annual weedy species or early successional plants will be the dominant cover, providing a strong diversity, but has minimal structural cover for some wildlife. As the site matures or as the period between disturbances is lengthened, perennial or taller statured, stronger rooted species will increase providing protection and help to improve hydrologic process and general cover for grasses and other perennial forbs to begin to establish. This flexibility and the natural stature of no large woody shrubs within the community creates a relatively stable level of biotic integrity. Soil erosion is dependent on the disturbance regime and the plant diversity of the community. The tendency for these communities to be high in dense spikemoss, limits erosion potential but will see an adverse effect to the water flow, infiltration, runoff, and pedestalling risk. Factors that are more prevalent or influential for these sites are surface roughness (tire tracks, hoof action, smoothed, denuded surfaces, trails that may focus the water).

Community 4.2
Reclaimed Lands

Shifts in reclamation practices over the last several decades have altered the success and stability of reclaiming a site. Crested wheatgrass and smooth brome were species used frequently for reclamation throughout Wyoming; many of these communities persist today. These stands are stable and generally persist as a monoculture until a disturbance creates a niche for native species to establish. Russian wildrye and varieties of rhizomatous and bunch-wheatgrasses are used in mixes to help increase establishment on many locations. Policies on federal lands, especially on forest lands, limits the use of non-native species and further limits where seed sources must be collected for use on these lands. Current interpretations of reclamation specifies the source of viable seed and the mix acceptable to achieve a composition as close to a natural (pre-disturbance) 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. These plantings 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 may be similar. The growth curve of this plant community is generally species dependent, but the climatic limitations are the major driver of this system. The short growing season with persistent snow cover through early fall to late spring and delayed warm up are the limitations to seedling establishment. For non-typical seed mixes and for project specific scenarios, the species used and the climatic tendencies of the site must be considered, and appropriate adjustments made to the growth curve provided below.

Resilience management. Seeding mixtures will determine the plant community's resistance to change and resilience against the threat of invasive species and to erosion. Many of the stands established during seeding are diversity poor, but are better than monocultures that were seeded historically. Soil erosion is variable depending on the establishment of the seeding, how it is seeded, and mechanical procedures used during the seeding. The variability of the water flow, infiltration and runoff is determined again by the species that comprise the community and the method of seeding (site preparation and seeding practice).

Pathway CP 4.1-4.2
Community 4.1 to 4.2

Completion of a re-vegetation project with seedbed preparation, re-seeding, integrated pest management, and long-term prescribed grazing or other managed use of the landscape is needed to shift a disturbed community back to a representative or functional plant community. However, climatic variability and topography limits the success of seeding projects (accessibility by equipment, lack of suitable seed sources, limited growing season, and timing of precipitation). The level of cover by dense spikemoss and topographical limitations can make ground preparations and weed/grazing management challenging as well.

Pathway CP 4.2-4.1
Community 4.2 to 4.1

If a reclaimed or restored site is not maintained or managed for the species implemented, whether with non-use or lack of a disturbance regime to maintain function of the system, the community will degrade over time. In the same, over-use of the system by livestock or wildlife can also shift the composition or revert the site back to a degraded phase. Since the soils are altered from reference state due to development, timber harvest/mining, or other similar disturbances, the plant community will not follow the same expected shifts as the native community. Monitoring and trend over time need to be recorded to determine if a location is degrading or adjusting with the climatic variables of the site. The initial establishment phase of a reclaimed site is crucial to determine success, but at any stage of a seeding, degradation or further disturbance can occur forcing the site to phase back to the disturbed community.

Transition T 1-2
State 1 to 2

Drought, season-long or severe grazing by livestock or large ungulates lowers the vigor of the perennial native grasses that dominate this site and encourage the native forbs to increase in prominence in the community. As more soil is exposed with the increased number of forbs, the dense spikemoss ground cover increases. Repeated early season grazing by cattle and elk, or by extended drought periods, grasses are reduced and forbs become the dominant cover, reducing the resiliency of this community. Seasonal fluctuations in moisture will affect the composition of species present and thus impact the grazers that can utilize the site. Larkspur is a major concern in years with a slow green up, as it will respond quickly while grasses may be slow with a slow warm up, increasing the risk of toxicity and poisoning in livestock. The same concern with lupine, in wet years, the abundance of lupine and groundsels can be significant, increasing the risk of toxicity; however, when abundant grass is present, the risk is manageable.

Transition T 1-3
State 1 to 3

Drought, season-long or severe grazing by livestock or large ungulates weaken the perennial native vegetation that comprises this community, and provides an opening for non-native, invasive or aggressive species to encroach into the community. During dry, open winters, cold and exposure can weaken the prominent grasses within the community, and if there are seed-sources that have been carried in on livestock or wildlife, then these non-native or invasive species find a foothold to establish within the community. If the drought or use continues, and the encroached species is not addressed, it will continue to gain a hold in the community until it is unfeasible to control or eradicate it from the community. Conifer enroachment is thought to be driven more by melt off and dry down of soils during the germination and establishment of seedlings to maturity. Periods of or the cycle of drought and winter snow melt have the most significant influence with management factors serving only as a minor contribution to the soil attributes.

Constraints to recovery. The species that are moving into the reference system and the mechanism for encroachment are the two factors that will limit the ability for a site to maintain or recover. Site and time specific observations are necessary to understand the full potential of recovery for communities in this state.

Restoration pathway R 2-1
State 2 to 1

Recovery time will be necessary with a prescribed grazing system developed specific to the forb species that are dominant and the grass species that are lost. Not all sites will have the ability to recover without significant inputs of energy and resources. In extreme cases, chemical or mechanical methods of treating the forbs on the site as well as mechanical methods to break the significant ground cover of dense spikemoss cover to permit seedling establishment. Seeding may be necessary to help restore the grass and grass-like structure and to further aid the recovery of the hydrology lost with the increase in forbs and dense spikemoss ground cover.

Context dependence. Not all communities will be hindered by a significant understory of dense spikemoss. For those communities that are, the ability to enhance or improve the community without major soil disturbance is not possible at this time. For those without this understory, the ability to use natural process to improve this site are more feasible.

Transition T 2-3
State 2 to 3

Drought, continued season-long grazing or severe use provides the opportunity for aggressive species to establish in this community. The weakened plant structure leaves the community vulnerable to encroachment or species creep by non-native species such as Kentucky bluegrass, dandelions, smooth brome, and in some instances conifers. This also leaves the site vulnerable for invasive species such as toadflax, cheatgrass, thistles, and others to establish.

Constraints to recovery. The ability to eradicate or control non-native species without affecting the native composition is the only significant constraint of recovery to a native or less degraded plant community.

Context dependence. The specific limitations to recovery is based on which/what species are encroaching on the community and what other species are in the surrounding vicinity.

Restoration pathway R 2-4
State 2 to 4

In the case of significant ground cover by dense spikemoss, mechanical disturbance to break up or loosen the ground cover is necessary to allow desired grasses and forbs the ability to establish. Hoof action in high intensity may be an option, but no trials were found to determine the likelihood of success. With mechanical disturbance to break up the soil cover, restoring hydrology to the site, seeding will be necessary with integrated pest management to ensure that no undesirable species move into the community. The act of tilling or breaking the soil crust alters the site, so that even after re-vegetation, the soils and hydrology will not function as an undisturbed site. The potential for the site will be shifted from the reference and further recovery will require different mechanisms to allow the soil to redevelop. This prevents this community from being reference even though it may resemble reference.

Restoration pathway R 3-4
State 3 to 4

Significant treatments may be needed, including integrated pest management, soil disturbance or seeding, to eradicate the invasive species and to reclaim the community. The use of improved varieties, limited diversity in a seeding, as well as seed bed preparation and eradication processes alters the hydrology and compositional function of the system. Policy for federal and state lands sets parameters for species selection; however, a factor that determines reclamation options is limited more by the lack of seed availability for many of the native species.

Transition T 4-3
State 4 to 3

Following a ground disturbance, whether planned or incidental in nature, provides a niche for non-native species to establish. This same niche is an opportunity for non-typical natives (juniper/spruce) to encroach into the area. Disturbance by means of equipment, vehicles, or human activity, as well as domestic animals and wildlife provide a means for introducing seed sources for these undesirable species into the system. Planned disturbances, seeding or development activities provides the open niche for invasive species to establish in an area. Ground disturbances of any nature introduces seed sources from surrounding areas into a prime seedbed. In the reclamation or restoration process, if no management is put into place to prevent an infestation of weeds, the community will transition (or possibly revert back) to an invaded state. Wildfire, prescribed burning, drought, or frequent and severe over-use by large herbivores can be a source of the disturbance that either opens the canopy and/or introduces the species to the location. Extended periods of non-use creates a decadent community with a large proportion of dead growth persisting around the crown of the plants, reducing vigor and production. As the plants begin to die-back, the community becomes vulnerable to weed invasions. This invasion triggers the transition to an invaded state.

Context dependence. Once the soils of a community are mechanically altered, the community will no longer function or respond as an undisturbed soils. Although it may be very similar, there will be subtle differences. For this transition, soil disturbance has occurred, but the function or driver for State 3 is a response to the non-native or invasive species, not to the soil properties.