Upland Alkali Loam (Wyoming Big Sagebrush)
Scenario model
Current ecosystem state
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Management practices/drivers
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- Transition T1A More details
- Transition T2A More details
- Transition T2B More details
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No transition or restoration pathway between the selected states has been described
Target ecosystem state
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Description
The reference state represents the plant communities and ecological dynamics of the Upland Alkali Loam (Wyoming big sage/black greasewood/bottlebrush squirreltail) site. This state includes the biotic communities that become established on this ecological site when all successional sequences are completed under the natural disturbance regime. The reference state generally has co-dominate shrubs composed of Wyoming big sagbrush and black greasewood. Bottlebrush squirreltail and Indian ricegrass dominate the hergaceous layer.
The reference state is self sustaining and resistant to change due to high resistance to natural disturbances and high resilience following natural disturbances. When natural disturbances occur, the rate of recovery is variable due to disturbance intensity. Once invasive plants become established, return to the reference state may not be possible.
Reference State: Wyoming big sage/black greasewood/bottlebrush squirreltail state with natural fluctuations that allow either shrub species to dominate at any given location depending on the natural disturbance history.
Indicators: A healthy community dominated by Wyoming big sage, black greasewood and bottlebrush squirreltail.
Feedbacks: Improper livestock grazing of perennial grasses and/or other disturbances that may allow for the establishment of invasive species.
At-risk Community Phase: This state is at risk when native plants are stressed and nutrients become available for invasive plants to establish.
Trigger: The establishment of invasive plant species.
Submodel
Description
The current potential state is similar to the reference state, however invasive grasses and/ or forbs are now present in all community phases. This state is still dominated by a shrub canopy of Wyoming big sagebrush and black greasewood, however depending on disturbance history, green and/or rubber rabbitbrush may be prominent on the site. Bottlebrush squirreltail and Indian ricegrass are still the primary perennial grass species however, Sandberg bluegrass, western wheatgrass, cheatgrass and other less palatable species now make up a larger portion of the herbaceous layer.
Primary disturbance mechanisms include native herbivore grazing and domestic livestock grazing. Timing of these disturbances dictates the ecological dynamics that occur. The current potential state is still self sustaining; but is losing resistance to change due to lower resilience following disturbances. When disturbances occur, the rate of recovery is variable depending on severity.
Current Potential State: Wyoming big sagebrush/Black greasewood/ bottlebrush squirreltail state with variations of green and/or rubber rabbitbrush shrubs present. Invasive plants are present.
Indicators: A community dominated by a mixture of native perennial grassses, forbs and. Invasive grasses and/or forbs are also present.
Feedbacks: Frequent disturbances that may allow the dominance of annual invasive species such as cheatgrass to dominate.
At-risk Community Phase: As increased disturbance frequency allows for the dominance of annual grasses, such as cheatgrass, this community is at greater risk.
Trigger: Reoccurring disturbances that result in a dominance of annual grasses in the herbaceous layer.
Submodel
Description
This state occurs when the site is plowed or disked and planted to various rangeland grasses. Tall wheatgrass, crested wheatgrass and Russian wildrye are the most commonly seeded species. These seedings may be very clean and healthy or may have various amounts of non-native annuals including, but are not limited to Russian thistle, cheatgrass, tansy mustard, broom snakeweed, alyssum, 5-horned smotherweed and annual Cryptantha.
Invasive Forb State: Range seeding community phases influenced by livestock grazing practices and weather cycles.
Indicators: Perennial rangeland seeding with annual, invasive forbs and grasses present in various amounts.
Feedbacks: Livestock grazing practices and weather cycles that maintain or degrade the range seeding and suppress or increase the non-native annuals present in the community.
Trigger: An increase of cheatgrass and other annuals that may shorten the sites fire interval, decrease perennial seeding production and increase bare ground.
Submodel
Mechanism
This transition is from the native perennial warm and cool season grass and grasslike understory in the reference state to a state that contains non-native, invasive species. Events may include the establishment of invasive grasses and forbs, and an increase in black greasewood, basin big sagebrush and/or rubber rabbitbrush. Factors that drive such events include, improper livestock grazing of perennial grasses, prolonged drought, and the presence of a seed source for invasive species. Fire may also be a driver for this change in some instances. Invasive species such as cheatgrass however have been known to invade intact perennial plant communities with little to no disturbance. Once invasive species are found in the plant community a threshold has been crossed.
Mechanism
This transition is from the current potential state to a well established seeded rangeland community phase. Site is plowed, disked and/or burned, and seeded to adapted rangeland species including tall wheatgrass, crested wheatgrass or Russian wilrye. Factors that drive such events include, proper livestock grazing of perennial grasses, sufficient moisture for seeding establishment, and adequate control of unwanted invasive species.
Once site is converted, a threshold has been crossed.
Mechanism
This transition is from the current potential state to a failed seeded rangeland community phase. Site is plowed, disked and/or burned, and seeded to adapted rangeland species including tall wheatgrass, crested wheatgrass or Russian wilrye. Factors that drive such events include, improper livestock grazing of perennial grasses, prolonged drought for seeding establishment, and poor control of unwanted invasive species.
Once site is converted, a threshold has been crossed.
Model keys
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