Stony Upland (StU) Big Horn Basin Rim
Scenario model
Current ecosystem state
Select a state
Management practices/drivers
Select a transition or restoration pathway
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Transition T1-2
Frequent and severe grazing (yearlong grazing) or compaction from surface traffic, will weaken the mid-stature grasses and allow threadleaf sedge to increase.
More details -
Transition T1-3
Frequent and severe grazing as well as prolonged drought weakens the woody cover reducing the community to a grass dominated canopy.
More details -
Transition T2-4
Drought with or without hoof impact or mechanical soil impact to displace the sod opens the niche for invasive species to establish.
More details -
Transition T3-4
Disturbance to the soil surface provides the opportunity for invasive species to find their niche in a community.
More details -
Restoration pathway R4-5
Integrated weed management, seeding and grazing management will establish a community similar to Reference.
More details -
Transition T5-4
Any disturbance to or failure in reclaiming the community leaves this State at risk to invasion.
More details -
No transition or restoration pathway between the selected states has been described
Target ecosystem state
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Description
The Perennial Grasses/Sagebrush State (State 1) is the reference community for the Stony Upland ecological site. The prominent cover is bluebunch wheatgrass, needle and thread, and other mid-stature cool-season bunchgrasses with perennial forbs and a mix of Wyoming big sagebrush and fringed sagewort make for a productive and stable site.
Characteristics and indicators
Bluebunch wheatgrass is the dominant herbaceous species on this site with Wyoming big sagebrush as the dominant woody cover. Pincushion or low growing forbs are also prominent in the community. Purple prairie clover is a unique and very characteristic forb found on this ecological site within the Clark, WY area, marked by glacial deposits.
Resilience management
The hardiness of the vegetation that thrive within the Stony Upland ecological site create a plant community resistant to change. The community is drought tolerant and flexible to the variable climatic conditions. But once disturbed, the herbaceous component of this site is difficult to restore, reducing the resiliency of the community.
Submodel
Description
The Sod-former/Sagebrush ecological site is a short-stature community that has shifted from the cool-season bunchgrasses to tillering grass-likes (blue grama and threadleaf sedge). Fringed sagewort and prickly pear cactus are common.
Characteristics and indicators
Wyoming big sagebrush is present but in this State with an increase in fringed sagewort and rubber rabbitbrush. The sagebrush cover is dwarfed or droughty in appearance and generally has been reduced in vigor by the shift in hydrology of this community. Most other mid and short-stature cool-season bunchgrasses are limited to within the canopy of the sagebrush or within the protective cactus clumps.
Resilience management
The dense root map of blue grama and threadleaf sedge makes this community resistant to change. The doughtiness of the subset and high rock cover limits the resilience to disturbance. Although the establishment of tillering grasses is a slow process, it will recover with time.
Removal of grazing or disturbance does not provide a significant shift in the herbaceous cover within this community. However, the overall health and vigor of both the herbaceous and woody cover will improve with the removal of the grazing pressure or disturbance.
Submodel
Description
The loss of most of the woody understory in the Perennial Grasses State leaves a scabby (in appearance) cover of bunch grasses, generally bluebunch wheatgrass. The cover of pincushion or low growing forbs is similar to reference or has increased with the loss of other cover.
Characteristics and indicators
The dominance of mid-stature grass cover and the lack of most woody cover is the indication of the Perennial Grasses State. Remnant populations of other shrubs will occur in a scattered canopy usually on the edges of the landform.
Resilience management
The lack of native propagates and the droughty limitations created by the rock soil cover restricts the ability for sagebrush to recover, lowering the resiliency of this State.
Submodel
Description
The Invaded State has a range of variability that is distinguished by its population of invasive or introduced (non-native) species that has successful established and become significant within the composition of the community. A significant component of this community initially is native species common to the Stony Upland ecological site.
Characteristics and indicators
The composition by weight of five percent or more of an invasive species is the factor tipping a community over the threshold into the Invaded State. The community can be relatively intact, having a representative composition of native species similar to the Reference State, but with a significant composition (minimum of five percent) cover of an invasive species or mix of invasive species. Cheatgrass is the most significant threat at this time; however, there are other aggressive non-native species that pose a concern on this ecological site. These species include field cottonrose, mustards, thistle, and kochia.
Resilience management
The competitive edge of most invasive species makes this site resistant to change and resilient following disturbance. Cheatgrass has been seen to respond with a positive potential following disturbances (fire, mechanical).
Submodel
Description
The Degraded 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. The shift in potential and response to management makes it no longer similar to the reference community.
The potential shifts are highly variable, so a dynamic state was captured to highlight the altered communities that exist on the landscape. The amount of surface stone and boulder cover limits the extent of disturbances that may occur. Alteration of the community may be extensive enough (removal of the stones and boulders), that site potential has shifted to a different ecological site or so slight that it may be difficult to identify.
Characteristics and indicators
The soil disturbance and mechanical or physical removal of the vegetative canopy is the key characteristic of the Disturbed State. The initial indicators are the primary successional species that establish following a disturbance including kochia, six weeks fescue, and sunflowers. These initial colonizers will then be followed by any seeded species, or other species from within the locations seed bank.
Resilience management
The Disturbed State is highly variable and in a state of flux as the successional processes occur. Continued disturbance of these communities is a potential threat; and the communities are at-risk of transitioning to the Invaded State.
Submodel
Mechanism
Frequent and severe (year-long or continuous season-long ) grazing or compaction from surface traffic, will convert the plant community to a threadleaf sedge sod. The impact of frequent or repeated defoliation during grazing, hoof impact, and lack of rest for recovery weakens and removes the key grass species in the community. As the mid-stature grasses decline, threadleaf sedge is able to increase and alter the hydrology of the site.
Constraints to recovery
The dense root mat formed by threadleaf sedge alters the hydrology, effectively removing moisture from the site, limiting the available resources for other native species. The dense sod also limits the available soil space for seedling establishment. Interpspaces between sod patches are prone to erosion and runoff (limited infiltration of moisture).
Mechanism
Frequent and severe grazing begins the shift to the Perennial Grasses State. Drought, insect damage, and other natural disturbances to the woody vegetation (including wildfire) is a major factor in the transition to this grass dominated State.
Constraints to recovery
The lack of a seed bank and the droughty nature of the soils limits seedling establishment and survival. The unpredictable and variable spring precipitation also limits success of recovery for the Stony Upland ecological site.
Mechanism
Drought, Frequent or severe grazing, Disturbance – Drought alone, or with grazing intensity, weakens and eventually removes Wyoming big sagebrush on the landscape. Once sagebrush has been removed from a community, it is extremely difficult and input heavy to re-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 mechanical 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 dense sod of threadleaf sedge will continue to impact the hydrology and competition for limited resources in this community limiting the potential for recovery. The lack of other key herbaceous species also is a constraint on this site. The inability, at this time, to eradicate cheatgrass does not allow for a complete recovery of an invaded community.
Mechanism
Drought, soil disturbances, or high-intensity grazing with a seed source present can open the soil surface allowing invasive species to establish. Although not common, fire can provide the niche for cheatgrass to establish on this site.
Constraints to recovery
Once invasive species, especially cheatgrass, establish, it is costly and difficult (if even possible) to remove. The lack of the key grass species also limits recover of this site.
Mechanism
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 is one of the most invasive species for many ecological sites, although there are other challenges. With intensive weed control and inputs this community can resemble an at-risk community within the reference state, but it is not possible to reach the reference community condition once annuals have established.
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 |
Mechanism
Frequent or Severe Grazing, Disturbance with a seed Source, or Drought - Any disturbance that occurs or stress that is placed on the herbaceous cover, weakens the canopy and allows for invasive species to establish if a seed source is present. This State is at high risk of transitioning to an Invaded State. The limited abilities to complete a seeding on rocky soil opens the community to invasion.
Constraints to recovery
The challenge of eradicating or reducing invasive species such as cheatgrass prevents recovery of most invaded communities without significant inputs for weed control, seeding with long-term grazing management.
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.