Natural Resources
Conservation Service
Loamy (Ly) Absaroka Lower Foothills
Scenario model
Current ecosystem state
Select a state
Management practices/drivers
Select a transition or restoration pathway
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Transition T1A
Loss of sagebrush occurs following prolonged drought with attacks by disease and/or insects, with wildfire or prescribed burns, or by chemical or mechanical removal. Slow recovery times of sagebrush allows for a grass dominated system to persist.
More details -
Transition T1B
Prolonged drought and severe grazing pressure reduces the bunchgrass component and encourages sod-forming species such as threadleaf sedge and blue grama. Loss of sagebrush aids in further transition to this sod community.
More details -
Transition T1C
Frequent or high intensity herbivory weakens the ability for native grasses to persist, especially during prolonged drought. Lack of fire allows sagebrush to become the majority of the composition in the community.
More details -
Transition T2A
Further disturbance of this community after the loss of sagebrush opens the potential for invasion by weedy species especially cheatgrass following a fire. Continued over use by large herbivores or continued drought will further stress the native grasses opening the canopy to the threat of invasive species.
More details - Transition T3A More details
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Restoration pathway R4A
Treatment to thin the canopy to allow the native vegetation to respond to improved moisture and sunlight followed by prescribed grazing to prevent overuse of the exposed grasses will help this community recover. Treatment will vary depending on the exact composition of grasses remaining and the potential threats to the location.
More details -
Transition T4A
Degraded communities with remnant native perennial grasses that loose the woody canopy to fire, drought or brush control measures may maintain or increase to a native perennial grass dominated community.
More details -
Transition T4B
Sagebrush removal in communities with an understory dominated by sod-formers will transition to state 3, especially with the stress on other perennial species during drought.
More details -
Transition T4C
Seed sources are abundant for cheatgrass, knapweed, and other invasive species. Drought stress, wildfire or prescribed burning, brush control, or ground/soil disturbance including impacts by grazing large herbivores or recreation create a niche for undesirable weeds to invade.
More details -
Transition T4D
Catastrophic or intense wildfires, prolonged drought with severe use by large herbivores, or large scale land disturbance where invasive species are present, creates the environment for invasive species to establish in mono-cultures with small isolated remnants of native species.
More details -
Transition T5A
Once a community is compromised by an invasive species, further impact can cause the invasive species to take over and dominate the community. Wildfire, extreme drought with disease and insect damage, and/or frequent and intense use by large herbivores with a seed source present are impacts most commonly seen to insight a weed infestation.
More details -
Restoration pathway R6A
Integrated pest management plan and intense weed control after and possibly before seedbed preparation will be necessary to overcome a severe weed infestation. Working a location and using either improved varieties, native seed, or in some cases an introduced species suited for the management use intended may be the only way to overcome some invasive species.
More details -
Transition T7A
Following reclamation, restoration, or after a land disturbance occurs, if no management is applied to prevent the re-occurrence of or a new infestation of weeds, the community will transition to an invaded state. Wildfire, prescribed burning, drought, or frequent and severe mis-use by large herbivores are a source disturbance.
More details -
No transition or restoration pathway between the selected states has been described
Target ecosystem state
Select a state
State 1
Reference
Reference
Description
State 1 is named the Bunchgrass/Sagebrush state, in response to the dominance of mid to tall stature cool-season bunchgrasses that are prominant in each community. Rhizomatous wheatgrasses and mid to short stature cool-season bunchgrasses are secondary in these communities. Sagebrush is present on the site, but is not the major cover class.
Characteristics and indicators
Bunchgrass/Sagebrush State (State 1 - Reference) is characterized by the key species including: 15% or less composition by cover of Wyoming big sagebrush, with Bluebunch wheatgrass (<30%), rhizomatous wheatgrasses (Western and Thickspike), Indian ricegrass, and Needleandthread. Minor component to the overall composition is made up of Cusick's bluegrass, Bottlebrush squirreltail, Sandberg bluegrass, Prairie junegrass, and Threadleaf sedge.
Green needlegrass is found in small isolated pockets throughout the land resource unit (LRU), on loamy soils. It is unclear if this is an effect of water catch areas, road drift influence, or management practices. Although intensive inventory data indicates no green needlegrass, it has been identified in ocular estimations, field notes and historic monitoring data collected by the Bureau of Land Management, within this LRU.
Resilience management
This state occurs in areas that are grazed moderately with periods of rest by large ungulates include livestock (cattle and/or sheep) as well as antelope, deer, and elk.
Dominant plant species
Wyoming big sagebrush (Artemisia tridentata ssp. wyomingensis), shrub
green needlegrass (Nassella viridula), grass
bluebunch wheatgrass (Pseudoroegneria spicata), grass
western wheatgrass (Pascopyrum smithii), grass
Submodel
Description
Historically within the Big Horn Basin and the surrounding foothills, large landscapes were aerial sprayed for sagebrush control in the 1950’s and 1960's. Multiple large scale wildfires have occurred on the upper fringes of foothills. And in the more recent management strategies, various small scale sagebrush treatment methods have been completed for grazing improvements, large ungulate winter forage improvement projects, and for sage grouse habitat improvement projects. The removal of sagebrush has proven to be long term, with little to no woody vegetation recovery on many locations. This creates State 2, the Perennial Native Grasses State.
Characteristics and indicators
The dominant characteristic for this site is the complete lack of Wyoming big sagebrush, and in some instances all woody shrub cover. Fringed sagewort may be present or in abundance on these sites. Needleandthread and western wheatgrass are dominant with bluebunch wheatgrass, sandberg bluegrass, and threadleaf sedge common.
Resilience management
The scale and variability of sagebrush removal and conditions prior to treatment has led to a variable mixture of communities with one characteristic in common: the lack of sagebrush or other woody shrub structure (1-3 ft in height). Fringed sagewort and other sub-shrubs persist after fire, but do little to maintain or help recover the altered hydrologic function. This state is at-risk of further degradation due to drought, use, and fire.
Dominant plant species
needle and thread (Hesperostipa comata), grass
western wheatgrass (Pascopyrum smithii), grass
bluebunch wheatgrass (Pseudoroegneria spicata), grass
Submodel
State 3
Sod Bound
Sod Bound
Description
This state, State 3 - Sod-formers, is driven by low-stature sod-forming grasses. Although remnant populations of other desirable native grasses, threadleaf sedge, needleleaf sedge, and small areas of blue grama are the majority of the community composition.
Characteristics and indicators
The dominant sod-forming grass that currently exists within this LRU is threadleaf sedge with a mixture of needleleaf sedge and isolated occurrences of blue grama. Needleleaf sedge will form dense communities, but would not necessarily form a sod like threadleaf sedge.
Resilience management
These species occur naturally (in reference communities) within the ecological site. The general tendency is for these species to increase with prolonged drought or under grazing pressure, becoming dominant. Together as the dominant species, they alter the hydrology of the site by increasing the surface runoff from the dense shallow root system that inhibits the movement of water through or will direct surface flow around the edge of the map concentrating flow into channel like patterns, creating a difficult or hostile environment for native grass species and forbs to persist.
Dominant plant species
Wyoming big sagebrush (Artemisia tridentata ssp. wyomingensis), shrub
plains pricklypear (Opuntia polyacantha), shrub
threadleaf sedge (Carex filifolia), grass
needleleaf sedge (Carex duriuscula), grass
blue grama (Bouteloua gracilis), grass
Submodel
Description
Wyoming big sagebrush creates a niche for most herbaceous understory to persist and maintain some vigor in difficult conditions by utilizing the moisture and shelter provided by the canopy as well as protection from grazing. Persistence of drought and/or frequent over use by livestock and/or wildlife leads to a decline of the herbaceous species, creating the Wyoming Big Sagebrush and Bare Ground state. This state can be exacerbated by insects and other human disturbances.
Characteristics and indicators
There is a high level of variability of species in this State, that will shift in response to precipitation or that is in response to past management. Only one well defined community will be provided, with discussion of transitions or variances from this community. The total woody canopy cover does not necessarily always increase with this community, but the percent composition by cover and production is swayed by the decrease of herbaceous vegetation and the relative stability of production by the woody species, creating the appearance of increased canopy by sagebrush.
Resilience management
Risk of wildfire within this state is minimal due to the lack of fine fuels within the understory, but the canopy of the woody vegetation can easily carry a fire under certain climatic conditions. Depending on the prescription of use, trailing and other erosional patterns are highly visible in this state.
Protection from wildfire and use, on a long-term perspective can aid in the transition of a reference community (1.1 or 1.2) to this state as sagebrush becomes dense and decadent reducing the ability for the herbaceous component to maintain vigor; leading to a high rate of bare ground and sagebrush cover. As the herbaceous cover declines and the site continues to weaken, the sagebrush cover is susceptible to attack by insects, disease, and general old age that can remove it from the system creating a system that is at risk of invasion or transition to a more degraded state.
Dominant plant species
Wyoming big sagebrush (Artemisia tridentata ssp. wyomingensis), shrub
Sandberg bluegrass (Poa secunda), grass
western wheatgrass (Pascopyrum smithii), grass
Submodel
Description
State 5, Invaded/Sagebrush State, is successional in nature in response to the introduction and increase of invasive/aggressive weeds. Primarily, cheatgrass is the identified threat to the Absaroka foothills at this time. This state has maintained the native species, but the presence and threat of invasive species has crossed a threshold, affecting the at-risk or management capabilities of the native species that remain.
Characteristics and indicators
This state is characterized by the presence of an invasive/non-native species. Extended periods of drought alone or in combination with misuse, insect damage or wildfire has weakened the native composition of the community opening the canopy for invasion. The competitive nature of annuals and other invasive species, creates a complex environment that inhibits control, and makes it implausible to attain complete eradication once an invasive species has established on the landscape.
Although cheatgrass is the threat most prevalent to rangelands on a large scale, a variety of thistles, knapweeds (namely spotted and Russian), and whitetop (hoary cress) are increasing in density and frequency, producing their own set of challenging management issues. As more species are found within the foothills region or as other species become more prevalent on a large scale, the community dynamics in this state will shift in response to the concerns of the identified species.
Resilience management
Cheatgrass or Downy brome (Bromus tectorum) is the invader that has the greatest concern for most land managers. This invader has an aggressive growth habit that creates a hostile environment for most native species, including sagebrush. Multiple growth cycles throughout a year leaves a thick litter (duff) layer and builds a significant seedbank; and the ability for this annual to persist through the winter under a blanket of snow and sprout early gives it the advantage of all early spring precipitation and snowmelt. Shifts in climatic patterns, changes in management, and exposure to human activity are a few of the explanations for the current flush and rapid expanse across the western United States.
Dominant plant species
Wyoming big sagebrush (Artemisia tridentata ssp. wyomingensis), shrub
Sandberg bluegrass (Poa secunda), grass
western wheatgrass (Pascopyrum smithii), grass
cheatgrass (Bromus tectorum), grass
Submodel
Description
The transition of an Invaded/Sagebrush community into the Invaded state, is typically a result of wildfire, a failed controlled burn or other event that removes the sagebrush from the site and allows a readily available seed bank or seed source of the undesirable species to flourish.
Characteristics and indicators
The most common community that is found in the foothills and through the Big Horn Basin and much of the surrounding regions is Cheatgrass. However, there are other threats present, such as knapweeds, thistles, and Whitetop, that can develop into near monoculture stands. The loss of diversity, changes to the potential of a site due to allelopathy or other deterrent characteristics of invasive species, and risks or land use capabilities associated with the various invasive species creates a hostile environment for both native species and grazers.
Resilience management
The resilience and resistance of the invaders create a management road block that is usually financially driven. Many times, once an invasion reaches this point, many land managers have no choice but to learn to utilize what they have rather than to try to treat or improve the site, specifically in relation to cheatgrass control.
Dominant plant species
cheatgrass (Bromus tectorum), grass
Submodel
Description
The arid nature of this region has played a major role in the development and transitions in land use over time. Landscapes accessible by irrigation water and equipment were farmed and many were later abandoned and left to return to rangeland. Other landscapes were treated with a variety of prescriptions to manage or eradicate sagebrush. Tillage of the soil, change in hydrology caused by the loss of vegetative structure, constant climatic fluctuations, and advancements in seed sources have created this altered state.
Resilience management
Once a soil has been disturbed, whether it was mechanical, cultural, or natural the change in soil structure, hydrologic function, and possibly stability prevent a site from supporting the native vegetation or responding to management the same as an undisturbed site. Reclamation or restoration of an area will not replace the original function and factors that made the original location respond as it did. So these "altered" lands may, after significant inputs and time, look similar to the Reference communities (1.1 or 1.2), but they will not be able to respond/function the same as the Reference community.
The Disturbed or degraded state could be drafted as a stand-alone box within the state and transition model diagram. No matter what state a location is classified, once the site has experience an event that has altered the soil properties (erosional, depositional, hydrological or chemical), the site potential is altered. 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 soils have not been altered out of the current site characteristics, but the potential has shifted enough that it is no longer truly comparable to the reference state. The loss of soil structure, degredation of soil biota, loss of argillics or clay illuviation, and minor chemistry changes, alter water and nutrient movement in the soil profile and reduces the water holding capacity. The time required to rebuild structure and have further soil formation, and recovery of biota and vegetation are highly variable depending on the climatic conditions following the event. The initial flush of vegetation is kochia and Russian thistle and mustards. Although they provide organic material, nutrient flow and erosional protection, they lack the structure and root system to fully stabilize the site. The site may become similar in composition to reference, but the integrity of the soil is altered, changing potential of the site. So a dynamic state was captured to detail the altered communities that exist on the landscape.
Submodel
Transition T1A
Loss of sagebrush occurs following prolonged drought with attacks by disease and/or insects, with wildfire or prescribed burns, or by chemical or mechanical removal. Slow recovery times of sagebrush allows for a grass dominated system to persist.
Mechanism
Drought, Fire (Wild or Prescribed), Disease/Insect Damage - Damage leading to death of sagebrush occurs following prolonged drought that weakens the plants, allowing attacks by disease and/or insects. Across much of the Sagebrush Steppe, brush management was a common practice that historically resulted in complete eradication of sagebrush. Removal of sagebrush by fire, whether wild or prescribed, is most common, however chemical removal has occurred historically and is still a practice used today. Although new methods have improved and reduced the large scale approach, the scars remain on the landscape. Wildfire, insects, and disease damage have aided in the decline and removal of sagebrush from the system as well. Shrubs rely on their own structure to capture and hold moisture received through winter precipitation until the plant can utilize it for growth. The loss of structure alters the hydrology of the site, causing a perpetual drought cycle on the landscape reducing the ability for sagebrush to propagate. Unless methods of re-introducing sagebrush or other shrubs to provide the woody structure, very little to no re-establishment is possible. Slow recovery times of sagebrush allows for a grass dominated system to persist.
Constraints to recovery
Slow or the inability of sagebrush to recover is a response to the shift in the hydrologic processes within a location. This shift in hydrology is the constraint to recovery. Sagebrush provides a catchment for snow in the winter allowing for slower infiltration of spring melt. These small catchments help feed moisture or hold moisture on the site. The loss of sagebrush canopy also allows for higher solar radiation and greater wind stress on plants, creating drought conditions.
Transition T1B
Prolonged drought and severe grazing pressure reduces the bunchgrass component and encourages sod-forming species such as threadleaf sedge and blue grama. Loss of sagebrush aids in further transition to this sod community.
Mechanism
Frequent Grazing (Yearlong), Brush Management or Fire with Drought – Severe and frequent grazing reduces vigor and presence of key species. As bluebunch wheatgrass, needleandthread, and the rhizomatous wheatgrass begin to decline, shorter statured grasses become dominant. Animal disturbance (hoof impact) caused with long duration, high intensity grazing reduces the bunchgrass component by allowing repeated defoliation of the desirable species, reducing recovery potential and ground cover for insulation and snow catch, as well as physical damage to the crown and growth points of the plants; weakening and over time removing select species. The open canopy and hoof impact encourages species that are tolerant to high traffic and that can utilize the small shots of spring moisture, these species are generally mat or sod-forming species such as threadleaf sedge and blue grama. Prolonged drought stresses the plants, and opens the canopy for these two quick responding plants to fill in the interspaces. The shallow, dense root mats will continue to spread over time. The added removal of sagebrush with animal impacts, fire or brush management may open the canopy more and aid in establishing this sod-form community. A combination of needleleaf and threadleaf sedge and isolated areas of blue grama persist as the wheatgrasses are reduced. When the sagebrush component of this community has been degraded or removed, by drought or heavy use, the transition has a high probability of occurrence on the landscape. Season of use and intensity of grazing (time and timing) is a trigger that can reduce the risk of transitioning, or if done poorly can force the transition to occur rapidly. This community is dominated by cool season species, providing good spring moisture, growth and maturity of these plants can happen quickly within the first two weeks of June, while blue grama is just beginning. By alternating when the community is grazed providing periods of rest during the critical initial green up and growth in the spring, and allowing recovery time before the community is grazed again within the year, allows the bunchgrasses and more solitary grasses to maintain vigor and production. This also allows for summer use when the warm season grasses are growing (blue grama) which will help to utilize this species and maintain a low cover.
Constraints to recovery
The altered hydrology that occurs with a transition to the dense, shallow root system of sod-formers coupled with the degraded or loss of sagebrush limits the ability of this community to recover. Sod-formers have proven difficult to reduce or remove from the system, which hinders the recovery or re-establishment of other perennial grasses.
Transition T1C
Frequent or high intensity herbivory weakens the ability for native grasses to persist, especially during prolonged drought. Lack of fire allows sagebrush to become the majority of the composition in the community.
Mechanism
Frequent and Severe Grazing (Year-long) or Drought with Brush Management or Wildfire - Frequent or high intensity herbivory on a community weakens the ability for the grasses to persist, especially during prolonged drought. With the weakened grasses and with prevention or lack of fire, the composition will shift to mostly sagebrush, and with time sagebrush will increase in density preventing the recovery without intervention. The conversion to a Wyoming Big Sagebrush/Bare Ground plant community is a response to extended periods of stress, both climate and/or human induced. Intensive grazing with minimal to no recovery period begins to transition the community. With added climatic stress, species diversity and productivity is lost, and the community crosses into the Sagebrush/Bare ground State. The illusion of crossing the threshold to State 4 is captured with fluctuating precipitation patterns affecting production of prominent plants within this system. The loss of species diversity and increased bare ground with lack of litter are the indicators that a true transition has occurred.
Constraints to recovery
The ability for the native perennial grasses to increase while reducing the canopy of sagebrush is the challenge for recovery for this community. With the reduction in sagebrush canopy, if precipitation and other climatic conditions are not favorable invasive species have an opportunity to establish preventing the native grasses from recovering.
Transition T2A
Further disturbance of this community after the loss of sagebrush opens the potential for invasion by weedy species especially cheatgrass following a fire. Continued over use by large herbivores or continued drought will further stress the native grasses opening the canopy to the threat of invasive species.
Mechanism
Frequent and severe Grazing, Drought, Wildfire, or Disturbances with a seed source present - Further disturbance of this community after the loss of sagebrush opens the potential for invasion by weedy species especially cheatgrass following a fire. The influence of fire and other disturbances in these communities opens the canopy allowing establishment of invasive non-native species such as cheatgrass (downy brome), thistles, knapweeds, and Whitetop. Drought alone, or in combination with fire, will create conditions prime for invasion. Photo and transect documentation shows that as the drought persists, Cheatgrass has increased exponentially each year, starting along roadways or disturbed areas and then radiating out from there. When compounded with or impacted solely by heavy grazing pressure or poor management, the risk of introducing invasive species in the system increases. Continued use or increased use post fire by large herbivores, elk specifically, with continued drought can weaken the native grasses opening the canopy to the threat of invasive species as well as be a seed source. Elk are carriers of many undesirable seeds into disturbed landscapes. Their ability to seek out the green patches of new growth, especially during drought, makes spring burns or summer burns with fall moisture susceptible as the moisture following the burn will create a green up of plants that entice the elk. This can have a positive impact by breaking up charred areas reducing hydrophobic tendencies, but it can also remove sensitive cover that could lead to erosion by wind and water, or could remove or hinder the native species that were trying to recover and allow an invasive species a niche to establish.
Constraints to recovery
The ability to control or eradicate cheatgrass and other major invasive species is the limiting factor of recovery for this transition.
Restoration pathway R4A
Treatment to thin the canopy to allow the native vegetation to respond to improved moisture and sunlight followed by prescribed grazing to prevent overuse of the exposed grasses will help this community recover. Treatment will vary depending on the exact composition of grasses remaining and the potential threats to the location.
Mechanism
Prescribed Grazing with Brush Management or Wildfire - Treatment to thin the canopy to allow the native vegetation to respond to improved moisture and sunlight followed by prescribed grazing to prevent overuse of the exposed grasses will help this community recover. Treatment will vary depending on the exact composition of grasses remaining and the potential threats to the location. Removal or thinning of the sagebrush within this community will help to reduce competition, encouraging grasses and forb recovery if the disturbance or over-use (recreational or grazing pressure) is reduced. Drought may prolong the time required for recovery. Mowing or mulching sagebrush trials have shown a strong response by grasses with little to no recovery time post treatment. The resulting community with these treatments is driven by the dominant species within the community pre-treatment or climatic and treatment conditions during and following the fire may sway the community. It is crucial to closely check the immediate and surrounding area around treatment site to ensure no invasive species (cheatgrass) is present.
Relevant conservation practices
| Practice | External resources |
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Brush Management |
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Grazing Land Mechanical Treatment |
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Range Planting |
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Heavy Use Area Protection |
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Upland Wildlife Habitat Management |
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Grazing Management Plan |
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Herbaceous Weed Control |
Transition T4A
Degraded communities with remnant native perennial grasses that loose the woody canopy to fire, drought or brush control measures may maintain or increase to a native perennial grass dominated community.
Mechanism
Drought and Disease/Insect Damage, Fire or Brush Management - Degraded communities with a perennial native grass component within the sagebrush that are exposed to fire or the drought stress and disease/insect damage will transition to a perennial grass dominant system, however, the composition and productivity is not the same as a reference community that transitions to this community. The community is highly variable, but with time and without weed infestation will become very similar with similar management.
Constraints to recovery
The length of time and difficulty to re-establish a strong population of sagebrush inhibits the recovery opportunities for this community.
Transition T4B
Sagebrush removal in communities with an understory dominated by sod-formers will transition to state 3, especially with the stress on other perennial species during drought.
Mechanism
Brush Treatment or Fire, Frequent Use - Removal or thinning of the sagebrush by mechanical, chemical or fire with an understory of Blue grama/Threadleaf sedge will lead to a threadleaf sedge or blue grama sod community, especially with the stress on other perennial species during drought. Frequent use of this community during dormant season will work to reduce the sagebrush through trampling and grazing, but will encourage the lower stature sod-formers in many instances. Within the Sagebrush/Bare Ground community, several native species can reside within the protective niche of the sagebrush canopy. Once that canopy is removed or opened, the management or level of disturbance will dictate which species will become dominant. If threadleaf or needleleaf sedge already have a strong presence, once the canopy is opened, they both can establish quickly in the right conditions driving the community into a sod dominant state (State 3).
Constraints to recovery
The time required and difficulty in recovering sagebrush with the difficulty in reducing sod-formers and encouraging mid to tall-stature cool-season grasses limits the ability for this community to recover.
Transition T4C
Seed sources are abundant for cheatgrass, knapweed, and other invasive species. Drought stress, wildfire or prescribed burning, brush control, or ground/soil disturbance including impacts by grazing large herbivores or recreation create a niche for undesirable weeds to invade.
Mechanism
Fire (wild), Frequent or severe grazing, Drought with Insect Damage/Brush Management – Throughout most of this LRU there is a seed source present for cheatgrass, knapweed, and other invasive species. Stress to the native community from drought; events such as wildfire or prescribed burning and other forms of brush management; or ground/soil disturbance including impacts by grazing large herbivores or recreation that open the canopy and break the surface of the soil, creates a niche for invasion by undesirable weeds. Documentation has shown that many times the invasion starts with one or two isolated plants, that if caught can be treated and a full infestation avoided; however, when unseen or ignored, the population soon grows exponentially as further stress or disturbance occurs. In some cases the invasive species once established can create it’s own habitat, forcing the weaker native species out. The open canopy of the Sagebrush/Bare Ground State is vulnerable to invasive species without further influence. With continued over-use, drought, insect damage or fire, the invasive species will establish and quickly dominate a location. The threshold species in this system is Wyoming big sagebrush, which protects the remnants of the perennial natives, allowing them to persist on the landscape.
Constraints to recovery
The lack of success in eradicating cheatgrass or other invasive species is the only constraint to recovery of this community.
Transition T4D
Catastrophic or intense wildfires, prolonged drought with severe use by large herbivores, or large scale land disturbance where invasive species are present, creates the environment for invasive species to establish in mono-cultures with small isolated remnants of native species.
Mechanism
Wildfire, Drought, Disease/Insects - With catastrophic or intense wildfires, prolonged drought with over use by large herbivores or large scale land disturbance occurs in areas where invasive species are present, the exposed soil and lack of native vegetation from already stressed communities creates the environment for the invasive species to establish as a mono-culture with possibly only small isolated remnants of native species. The canopy of Wyoming big sagebrush is the stabilizer for this community. Once it is removed from a community, it is extremely difficult to re-establish. Wyoming big sagebrush may require 25 years or greater to establish naturally, and in many cases will require outside assistance. The open raw landscape with minimal native species provides the perfect opportunity for invasive species, primarily Cheatgrass, to establish and take over a community. Drought or insects and disease serve to exacerbate the situation. Once the sagebrush is affected by the altered (shortened) fire frequency of this state due to the invasive species (primarily Cheatgrass), this community can be transitioned to the Invaded/Annuals state suddenly by prescribed burns or wildfire.
Constraints to recovery
The slow recovery of sagebrush in perfect conditions, the increased risk of fire, and the inability to eradicate cheatgrass are the constraints to recovery.
Transition T5A
Once a community is compromised by an invasive species, further impact can cause the invasive species to take over and dominate the community. Wildfire, extreme drought with disease and insect damage, and/or frequent and intense use by large herbivores with a seed source present are impacts most commonly seen to insight a weed infestation.
Mechanism
Fire, Drought, Ground Disturbance, Over Use - Once a community has been compromised by a notable composition of an invasive species, stress or ground disturbance of any means can cause the invasive species to take over and dominate the site. Wildfire, extreme drought and the accompanying disease and insect damage, as well as frequent and intense use by large herbivores are the impacts most commonly seen to insight a weed infestation. Any action that reduces or damages the existing sagebrush canopy exposing the sensitive native grass population will start the transition. Drought, further disturbance or ill-planned grazing (grazing when the natives are trying to break boot and grow), will remove the competition and finish the transition.
Constraints to recovery
The difficulty to remove or eradicate, the aggressive nature, and competitive edge of cheatgrass with the added fire risk do to increasing fuel load are the constraints to recovery.
Restoration pathway R6A
Integrated pest management plan and intense weed control after and possibly before seedbed preparation will be necessary to overcome a severe weed infestation. Working a location and using either improved varieties, native seed, or in some cases an introduced species suited for the management use intended may be the only way to overcome some invasive species.
Mechanism
Integrated Pest Management, with Seeding - Integrated pest management plan and intense weed control after and possibly before seedbed preparation will be necessary to overcome a severe weed infestation. Working the soil and preparing a seedbed at a location and using either improved varieties, native seed, or in some cases an introduced species suited for the management use intended may be the only way to overcome some invasive species. Success of re-establishing a native or desired plant community on a large scale is not documented. Small scale attempts are rated to be low and highly variable for the rate of control of most species. It is a consensus that the site in theory could be brought to a community that looks similar 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. This is due to the need to work the soil or to do seedbed preparation to seed in the native species which reduces soil stability by breaking down soil structure, and alters the hydrologic cycle by changing the infiltration and percolation rates of the soil. The alteration of the soils, the change in the plant community and the risk of re-invasion of the site will never allow it to react the same to management and environmental changes the same as a truly native community and so remains in a reclaimed state.
Relevant conservation practices
| Practice | External resources |
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Critical Area Planting |
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Prescribed Grazing |
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Grazing Land Mechanical Treatment |
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Range Planting |
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Heavy Use Area Protection |
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Integrated Pest Management (IPM) |
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Upland Wildlife Habitat Management |
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Early Successional Habitat Development/Management |
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Native Plant Community Restoration and Management |
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Prescribed Grazing |
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Invasive Plant Species Control |
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Monitor key grazing areas to improve grazing management |
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Herbaceous Weed Control |
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Prescriptive grazing management system for grazed lands |
Transition T7A
Following reclamation, restoration, or after a land disturbance occurs, if no management is applied to prevent the re-occurrence of or a new infestation of weeds, the community will transition to an invaded state. Wildfire, prescribed burning, drought, or frequent and severe mis-use by large herbivores are a source disturbance.
Mechanism
No Use, Fire (wild or prescribed), Frequent or severe Grazing, Drought with seed source present – In the reclamation or restoration process, or after a land disturbance occurs, if no management is put into place to prevent a re-occurrence or a new infestation of weeds, the community will revert back or transition to an invaded state. Wildfire, prescribed burning, drought, or frequent and severe miss-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. Opposite of the non-use scenario, it has been found that frequent or severe grazing, drought, or fire can open the canopy to invasion as well. This invasion triggers the transition to an invaded state.
Constraints to recovery
The inability to eradicate or efficiently reduce the composition of cheatgrass and other aggressive invasive weed species.
Model keys
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The Ecosystem Dynamics Interpretive Tool is an information system framework developed by the USDA-ARS Jornada Experimental Range, USDA Natural Resources Conservation Service, and New Mexico State University.
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