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Sandy (Sy) Wind River Basin Rim
Scenario model
Current ecosystem state
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Management practices/drivers
Select a transition or restoration pathway
- Transition T 1-2 More details
- Transition T 1-3 More details
- Restoration pathway R 2-1 More details
- Transition T 2-3 More details
- Transition T 2-4 More details
- Transition T 3-4 More details
- Restoration pathway R 4-5 More details
- Transition T 5-4 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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State 1
Bunchgrass/Sagebrush
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![10290](https://edit.jornada.nmsu.edu/uploads/thumb/es/pc/10290.jpg)
Description
Bunchgrass/Sagebrush State (State 1 - Reference) is characterized by the following key species: 10% or less composition by cover of Wyoming big sagebrush, with Needleandthread (15-30% composition), Indian ricegrass, and isolated areas of western wheatgrass and prairie sandreed. Minor component to the overall composition is made up of prairie junegrass, bottlebrush squirreltail, prairie sandreed, sand dropseed, threeawns, blue grama, and threadleaf sedge. Bluebunch wheatgrass is highlighted as a key species in the historic range site documentation, but is not found to be prevalent within the Wind River Basin.
Submodel
Description
Extended periods of drought across much of the Wind River Basin (as well as most of Wyoming) has taken a toll on many communities. Persistence of drought and/or frequent over use of the grasses leads to a decline of the herbaceous species, creating the Wyoming Big Sagebrush and Bare Ground state. Wyoming big sagebrush creates a zone of protection for herbaceous understory to persist and maintain vigor in difficult conditions, providing shade, moisture reserves, and protection from herbivory. This state can be exacerbated by insects and other human disturbances. The total woody canopy cover does not necessarily increase with this community, but the percent composition by cover and production is influenced by the decrease of herbaceous vegetation and the relative stability of the woody species production, creating the appearance of increased canopy cover of sagebrush.
Risk of wildfire 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 specific weather conditions. Depending on the prescription of use, trailing and other erosional patterns are highly visible in this state. The loose or coarser texture of these soils allows for increased wind scour and drifting/mounding to occur with more open ground between canopy “patches”, that further hinders fire movement.
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. The loss of herbaceous cover leads to increased bare ground and sagebrush cover. As the site continues to weaken, the sagebrush cover is susceptible to attack by insects, disease, and old age; which can remove it from the system increasing the risk of invasion or transition to a more degraded state. The level of variability of species in this state (State 2) remains abundant, however, only one well defined community will be provided, with discussion of transitions or variances from this community.
The overall arid nature of coarse textured soils exacerbates the impact of drought and reduces the resilience and resistance of this site during extended dry periods. Yucca’s presence on this site is not frequent, but when it does occur, it can easily become a concern, especially if grazed in the winter frequently. Its growth habits produce pedestalling and drift/scour patterns on the landscape.
Submodel
Description
Blue grama and threadleaf sedge are the dominant sod-forming grasses/grass-likes that currently exist within this LRU. Both species are a native component of the reference community. The general tendency is for these species to increase with prolonged drought or under grazing pressure, becoming dominant. 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 and funnels surface flow around the edge of the “clump”, concentrating flow into channel like patterns, creating a drier environment for native grass species and forbs to persist.
Submodel
Description
Cheatgrass or downy brome (Bromus tectorum) has quickly become the greatest threat to much of the rangelands across the west, including Wyoming. This annual 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. Cheatgrass’s ability to persist through the winter under a blanket of snow and grow early allow it to take advantage of early spring precipitation and snowmelt (winter annual). 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.
Although cheatgrass is the most prevalent large scale threat for rangeland managers, a variety of thistles and knapweeds, in combination with other aggressive invaders such as whitetop (hoary cress), black henbane, field bindweed, and leafy spurge are increasing in density and frequency, producing their own set of challenging management issues. As more species are found 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.
This state is characterized by the presence (not necessarily the dominance) of invasive/non-native species. Extended periods of drought alone or in combination with over utilization, 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.
Submodel
Description
Lack of season long, dependable water sources for irrigation has limited the cultivation use of this landscape. Isolated areas along the lower edge of the rim may have limited access for irrigation, but the larger land use (excluding livestock) is energy development and wildlife/recreation. The broken nature of the rim provides more topographic relief for movement of wild game, yet access is still easy to moderate for wheeled traffic. Although the disturbance footprints within this LRU are smaller scale, old homestead locations, abandoned crop fields, and energy development has left their mark.
Disturbance to these highly erodible soils (whether it was mechanical, cultural, or natural), changes soil structure, hydrologic function, and possibly stability. The loss of resilience or resistance to support native vegetation or the ability to respond to management the same as an undisturbed site, occurs as these factors are changed (structure, hydrology, stability). 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 as the Reference community will.
This state can be achieved with one disturbance of any state or community within the State and Transition Model or diagram. Once the site has experienced an event that has altered the soil properties (erosional, depositional, hydrological or chemical), the site potential is altered. The soils have not been altered to the extent that they are outside the site characteristics, but the potential has shifted enough that it is no longer truly comparable to the reference state. Location or site specific investigation may need to occur to determine if a disturbed/reclaimed area still meets site characteristics.
To illustrate this concept, visualize an area that was impacted by drought removing the native grasses leaving a dense and decadent stand of Wyoming big sagebrush. A few weak (low vigor) needleandthread and blue grama plants persist within the crown of the sagebrush, but are not able to repopulate the area in a reasonable time. The landowner decides to seed the site using a small rototiller behind a tractor to prepare small areas within the sagebrush to broadcast a native seed mix. He then hand-raked the seed and used a roller barrel to compact the seedbed. The species selection he used was an assortment of native grass seed collected from neighboring sites. The tillage was minimal, but broke up the structure of the soil, mixing the loose surface with the blocky and slightly heavier subsurface. The change is reflected in the available water capacity of the soil, increasing infiltration slightly, but creating a limitation in permeability with the “plow pan”. The exposure to air, dries the mixed zone rapidly, wicking salts and carbonates to the surface that were otherwise not prevalent in the soil. The site is prone to erosion during the establishment period, and experiences soil movement.
The time required to allow the re-development of structure and the cryptogrammic crust, as well as any impact to chemistry, is beyond the natural function of management. The initial flush of vegetation is kochia and Russian thistle and mustards, a successional plant community. So the site begins its own recovery, but the time required to return to the original conditions (pre-disturbance) is outside of feasible consideration. The site, however, may become similar in composition to reference, but the integrity of the soil is altered, changing potential of the site.
Submodel
Mechanism
Frequent and Severe Grazing (Year-long) or Drought with the absence of Brush Management or Wildfire - Frequent or high intensity herbivory weakens the ability for the grasses to persist, especially during prolonged drought. With the weakened herbaceous cover and with prevention or lack of fire, the composition will shift to predominantly Wyoming big sagebrush. Over extended periods of time, the sagebrush canopy 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 2 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. It is important to recognize that the number of actual sagebrush plants may not increase to cause this shift. Rather the loss of herbaceous composition and increase in the canopy cover of woody species is the larger factor (creates the illusion of increased number of plants when it is the size and age that is more likely to change).
Mechanism
Frequent Grazing (Yearlong), Brush Management or Fire with Drought – Severe and frequent grazing (by livestock or any other large ungulates) reduces vigor and presence of key species. As needleandthread and Indian ricegrass begin to decline, shorter statured grasses become dominant. Animal disturbance (hoof impact) caused with long duration, high intensity herbivory 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 trampling and that can utilize the small bursts of spring and summer moisture, these species are generally mat or sod-forming species such as blue grama and threadleaf sedge. Prolonged drought stresses the plants, and opens the canopy for these short stature grasses 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 community. 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. The reference state (1.1 and 1.2) is dominated by cool season species. Provided the area receives 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 rhizomatous 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.
Mechanism
Prescribed Grazing with Brush Management or Wildfire - Treatment to thin or rejuvenate the sagebrush canopy is needed to allow and encourage native perennial grasses 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 current 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 grass 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. Climate and treatment conditions during and following a fire has a larger impact on the community. It is crucial to investigate the immediate and surrounding areas of a treatment site to ensure no invasive species (cheatgrass) are present.
Relevant conservation practices
Practice | External resources |
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Brush Management |
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Prescribed Burning |
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Fence |
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Livestock Pipeline |
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Spring Development |
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Integrated Pest Management (IPM) |
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Watering Facility |
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Water Well |
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Upland Wildlife Habitat Management |
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Prescribed Grazing |
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Invasive Plant Species Control |
Mechanism
Drought, Disease or Insect Damage, Over-use, or Fire - Sod-forming species such as blue grama and threadleaf sedge are able to tolerate high levels of use and will maintain as other native species decline. Hoof action or compaction inhibits more desirable native species, allowing the sod-formers to become dominant. This decline creates a sagebrush/sod community that is resistant to change by grazing management. Impacts to sagebrush by disease or insect damage, as well as drought or herbivory, will shift this community to the secondary community phase with cactus as a subdominant cover with blue grama/threadleaf sedge.
Extended periods of drought in combination with a change in the amount and timing of precipitation and spring snowmelt has allowed the warm season grass, blue grama, to out-compete other cool season natives such as needleandthread. Climate change is widely debated and speculated; however, the documented shifts in climatic curves, as well as large scale transitions to this community under different management scenarios, highlights climate as a key player – not just use and management. Further research is needed to identify the factor for each site specific transition.
Mechanism
Fire (wild/prescribed), 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 by a disturbance (fire, drought, disease/insect damage to sagebrush, or ground/soil disturbance including impacts by grazing large herbivores or recreational activities) that opens the canopy and breaks the surface of the soil, creates a niche for invasion by undesirable weeds. Invasions start with one or two isolated plants, that if caught can be treated and an infestation avoided; however, when unseen or ignored, the population grows exponentially with time. In some cases once the invasive species are established, they can create their own habitat; reducing the ability for native species to compete for the limited resources. The open canopy of the Sagebrush/Bare Ground state is vulnerable to invasive species without further influence. With continued over-use, drought, or insect damage/disease, 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 native grasses, allowing them to persist.
Mechanism
Frequent and Severe Grazing, Drought, Disturbance with a seed source present - The chance of wildfire is minimal with the lack of fine fuels and reduced sagebrush canopy leading to the assumption this community/state is safe from invasion. The increased interspatial pattern of these communities leaves exposed soil that is vulnerable to invasion by undesirable species. Increased pressure from over use and drought work to weaken the sod or mat-like community of low stature grasses, opening more surface to invaders, such as cheatgrass and knapweeds. If a seed source is available, ground disturbance by herbivores or man-induced, allows invasive species to find a way into the community. Once established in the community, the extent of spread is limited, but it is still extremely difficult to manage and eradication is not feasible. Once the invasive species have become prevalent on the landscape (>5% composition), the community crosses the threshold into the Invaded/Sagebrush State (State 4).
Mechanism
Integrated Pest Management, with Seeding - Integrated pest management and intense weed control after and if possible before seedbed preparation will be necessary to overcome a severe weed infestation. Seedbed preparations of the target area 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. The limited success and difficulties in re-establishing sagebrush also limit the site potential. Due to the need to till/turn the soil for seedbed preparation 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 treatment area, prevents the soils from reacting the same to management and environmental changes as an undisturbed/native community and so remains in a reclaimed or altered state (State 5).
Relevant conservation practices
Practice | External resources |
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Prescribed Burning |
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Critical Area Planting |
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Fence |
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Livestock Pipeline |
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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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Spring Development |
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Integrated Pest Management (IPM) |
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Watering Facility |
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Water Well |
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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 |
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 reoccurrence 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 over utilization by 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 stand, with significant dead growth inhibiting the crown of the plants, reducing vigor and production. As die-back occurs, the community becomes vulnerable to weed invasions; as seen with the frequent or severe grazing, drought, or fire. This invasion triggers the transition to an invaded state.
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.