Natural Resources
Conservation Service
Clayey (Cy) 10-14" PZ Frigid
Scenario model
Current ecosystem state
Select a state
Management practices/drivers
Select a transition or restoration pathway
- Transition T1A More details
- Transition T1C More details
- Transition T1B More details
- Transition T1D More details
- Restoration pathway R2A More details
- Transition T2A More details
- Transition T2B More details
- Transition T2C More details
- Restoration pathway R3B More details
- Restoration pathway R3A More details
- Transition T3A More details
- Transition T3B More details
- Restoration pathway R4C More details
- Restoration pathway R4B More details
- Restoration pathway R4A More details
- Transition T4A More details
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No transition or restoration pathway between the selected states has been described
Target ecosystem state
Select a state
Description
The Reference state of this ecological site consists of two known potential plant communities, the Bluebunch community and the Mixed Bunchgrass community. These are described below but are generally characterized by a mid-statured, cool season grass community with limited shrub production. The Bluebunch community is dominated by bluebunch wheatgrass and is considered the reference, while Community 1.2 has a codominance of bluebunch, needle and thread, and western wheatgrass with an increase in forbs and Wyoming big sagebrush.
Submodel
Description
This state is characterized by having less than 15 percent bluebunch wheatgrass by dry weight. This state is represented by two communities that differ in the percent composition of needle and thread, production, and soil degradation. Production in this state can be similar to that in the Reference state. Some native plants increase with prolonged drought, heavy grazing practices, or both. These species may include western wheatgrass, needle and thread, Sandberg bluegrass, scarlet globemallow, hairy false goldenaster, and prairie sagewort.
Characteristics and indicators
Less than 15 percent bluebunch wheatgrass; increase in short stature grasses; increase in bare ground.
Resilience management
Conservative grazing management; integrated pest management; time.
Dominant plant species
big sagebrush (Artemisia tridentata), shrub
yellow rabbitbrush (Chrysothamnus viscidiflorus), shrub
broom snakeweed (Gutierrezia sarothrae), shrub
rubber rabbitbrush (Ericameria nauseosa), shrub
needle and thread (Hesperostipa comata), grass
Sandberg bluegrass (Poa secunda), grass
prairie Junegrass (Koeleria macrantha), grass
bluebunch wheatgrass (Pseudoroegneria spicata), grass
Submodel
Description
The Degraded state lacks mid-statured bunchgrasses. Western wheatgrass, blue grama, Sandberg bluegrass, and prairie Junegrass are dominant grasses. Broom snakeweed and prickly pear cactus have nearly replaced larger shrub species. Larger shrub species that remain are heavily hedged. This condition is likely a terminal state (e.g., restoration will likely be impossible or require major energy inputs beyond feasibility).
Characteristics and indicators
25 to 50 percent bare ground, annual grasses, and cactus are common.
Complete removal of bluebunch wheatgrass and green needlegrass. Replaced with Sandberg bluegrass, western wheatgrass, and blue grama.
Sagebrush is hedged. Rabbitbrush and broom snakeweed remain un-browsed.
Resilience management
Prescribed grazing; range seeding; brush management; integrated pest management.
Dominant plant species
broom snakeweed (Gutierrezia sarothrae), shrub
yellow rabbitbrush (Chrysothamnus viscidiflorus), shrub
rubber rabbitbrush (Ericameria nauseosa), shrub
plains pricklypear (Opuntia polyacantha), shrub
Sandberg bluegrass (Poa secunda), grass
blue grama (Bouteloua gracilis), grass
prairie Junegrass (Koeleria macrantha), grass
sixweeks fescue (Vulpia octoflora), grass
needle and thread (Hesperostipa comata), grass
Submodel
Description
The Invaded state is identified as being in the exponential growth phase of invader abundance, where control is a priority. Dominance (or relative dominance) of noxious or invasive species reduces species diversity, forage production, wildlife habitat, and site protection. A level of 20 percent invasive species composition by dry weight indicates that a substantial energy input will be required to create a shift to the grassland state (herbicide, mechanical treatment), even with a return to proper grazing management or favorable growing conditions. Prescriptive grazing can be used to manage invasive species. In some instances, carefully targeted grazing (sometimes in combination with other treatments) can reduce or maintain the species composition of invasive species.
Characteristics and indicators
High amounts of invading species (both native and introduced).
Resilience management
Integrated pest management; prescribed grazing; brush management; prescribed fire; range seeding
Submodel
Description
Native rangeland has been converted for the production of forage crops or small grain products. This site often receives additional moisture from irrigation to increase production. Fertilizer and herbicides are frequently added to the Cultivated Cropland state to aid in crop production.
Submodel
Mechanism
The Reference state transitions to the Altered state if bluebunch wheatgrass, by dry weight, decreases to below 15 percent or if bare ground cover increases significantly. The driver for this transition is the loss of taller bunchgrasses, which creates open areas in the plant canopy with bare soil. Soil erosion results in decreased soil fertility, driving transitions to the Altered state. Several other key factors signal the approach of transition T1A: increases in soil physical crusting, decreases in cover of cryptogamic crusts, decreases in soil surface aggregate stability, or evidence of erosion including water flow patterns, development of plant pedestals, and litter movement. The trigger for this transition is improper grazing management, long-term drought, or both, leading to a decrease in bluebunch wheatgrass composition to less than 15 percent and a reduction in total plant canopy cover.
Mechanism
The Reference state transitions to the Degraded state when bluebunch wheatgrass is removed from the plant community and needle and thread is subdominant to short-statured bunchgrasses such as Sandberg bluegrass. The trigger for this transition is the loss of taller bunchgrasses, which creates open spaces with bare soil. Soil erosion results in decreased soil fertility, driving transitions to the Degraded state. Several other key factors signal the approach of transition T1C: increases in soil physical crusting, decreases in the cover of biological crusts, decreases in soil surface aggregate stability or evidence of erosion, including water flow patterns, the development of plant pedestals, and litter movement. The drivers for this transition are improper grazing management, intense or repeated fires, heavy human disturbance, or all three. Rapid transition is generally seen where livestock are confined to small pastures for long periods.
Mechanism
Healthy plant communities are most resistant to invasion. However, regardless of grazing management, without some form of active weed management (chemical, mechanical, or biological control) and without prevention, the Reference state can transition to the Invaded state in the presence of aggressive invasive species such as spotted knapweed, leafy spurge, and cheatgrass. The Central Rocky Mountain Valleys tend to resist invasion by cheatgrass; however, repeated heavy grazing or intense human activities can open the interspaces of the bunchgrass community and allow for establishment. Long-term stress conditions for native species (overgrazing, drought, and fire) accelerate this transition. If populations of invasive species reach critical levels, the site transitions to the Invaded state. The trigger for this transition is the presence of aggressive invasive species. The species composition by dry weight of invasive species approaches 10 percent.
Mechanism
Native rangeland has been converted for the production of forage crops or small grain products. This site often receives additional moisture from irrigation to increase production. Fertilizer and herbicides are frequently added to the Cultivated Cropland state to aid in crop production.
Mechanism
The Altered state has lost enough soil or vegetation attributes that recovery to the Reference state will require reclamation efforts such as soil rebuilding, intensive mechanical and cultural treatments, revegetation, or all three. Examples of mechanical treatment may be brush control, while cultural treatments may include prescribed grazing, targeted brush browsing, or prescribed burning. Low-intensity prescribed fires to reduce competitive increaser plants such as needle and thread and Sandberg bluegrass. A low-intensity fire will also reduce Wyoming big sagebrush densities. Fire should be carefully planned or avoided in areas prone to annual grass infestation. The drivers for this restoration pathway are reclamation efforts along with proper grazing management.
Mechanism
As improper grazing management continues, the vigor of bunchgrasses will decrease and the shorter grasses and shrubs will increase, leading to the Degraded state. Prolonged drought will provide a competitive advantage to shrubs, allowing them to co-dominate with grasses. The shrub canopy will increase. Key transition factors include: an increase in native shrub canopy cover; a reduction in bunchgrass production; a decrease in total plant canopy cover and production; increases in mean bare patch size; increases in soil crusting; decreases in the cover of biotic crusts; decreases in soil aggregate stability; and evidence of erosion, including water flow patterns and litter movement.
Mechanism
Invasive species can occupy the Altered state and drive it to the Invaded state. The Altered state is at risk if invasive seeds or other viable material are present. The driver for this transition is invasive species, which make up more than 20 percent of the dry weight. The trigger is the presence of seeds or other viable material from invasive species.
Mechanism
Native rangeland has been converted for the production of forage crops or small grain products. This site often receives additional moisture from irrigation to increase production. Fertilizer and herbicides are frequently added to the Cultivated Cropland state to aid in crop production.
Mechanism
The Degraded state has lost enough soil or vegetation attributes that recovery to the Reference state will require reclamation efforts, such as soil rebuilding, intensive mechanical treatments, revegetation, or all three. Mulch with a high carbon to nitrogen ratio, such as wood chips or bark, in low moisture scenarios can be beneficial for slow mobilization of plant nitrogen (Whitford et al., 1989). Biochar may also be added to the system to improve soil organic carbon (SOC) which should improve cation exchange capacity (CEC), microbial activity, and hydrologic conductivity (Stavi, 2012). The drivers for the restoration pathway are the removal of increaser species, restoration of native bunchgrass species, persistent management of invasives and shrubs, and proper grazing management. Without continued control, invasive and shrub species are likely to return (probably rapidly) due to presence of seeds or other viable material in the soil and management related increases soil disturbance.
Mechanism
Since the bunchgrass plant community has been significantly reduced, restoration to the Altered state is unlikely unless a seed source is available. If enough grass remains on the site, chemical or biological control, combined with proper grazing management, can reduce the amount of shrubs and invasive species and restore the site to the Shortgrass community. Low-intensity fire can be utilized to reduce Wyoming big sagebrush competition and allow the reestablishment of grass species. Caution must be used when considering fire as a management tool on sites with fire tolerant shrubs, such as rubber rabbitbrush, as these shrubs will sprout after a burn. Broom snakeweed and prairie sagewort may or may not re-sprout depending on conditions.
Mechanism
Invasive species can occupy the Degraded state and drive it to the Invaded State. The Degraded state is at risk of this transition occurring if invasive seeds or viable material are present. The driver for this transition is the presence of critical population levels of invasive species. The trigger is the presence of seeds or viable material from invasive species. This state has sufficient bare ground that the transition could occur simply due to the presence or introduction of invasive seeds or viable material. This is particularly true of aggressive invasive species such as spotted knapweed and cheatgrass. This transition could be assisted by overgrazing (failure to adjust stocking rate to declining forage production), a long-term lack of fire, or an extensive drought.
Mechanism
Native rangeland has been converted for the production of forage crops or small grain products. This site often receives additional moisture from irrigation to increase production. Fertilizer and herbicides are frequently added to the Cultivated Cropland state to aid in crop production.
Mechanism
Restoration of the Invaded state to the Reference state requires substantial energy input. The drivers for the restoration pathway are the removal of invasive species, restoration of native bunchgrass species, persistent management of invasive species, and proper grazing management. Without continued control, invasive species are likely to return (probably rapidly) due to the presence of seeds or other viable material in the soil and management-related practices that increase soil disturbance. If invaded by conifer encroachment, treatment depends on the condition of the rangeland. Sites that have transitioned from the Degraded state to the Invaded state may be severely lacking in soil and vegetative properties that will allow for restoration to the Reference state. Hydrologic function damage may be irreversible especially with accelerated gully erosion.
Mechanism
If invasive species are removed before remnant populations of bunchgrass are drastically reduced, the Invaded state can revert to the Altered state. The driver for the reclamation pathway is weed management without reseeding. Continued integrated pest management (IPM) will be required as many of the invasive species that can occupy the Invaded State have extended dormant seed life. The trigger is invasive species control.
Mechanism
If invasive species are removed before remnant populations of bunchgrass are drastically reduced, the Invaded state can revert to the Degraded state. The driver for the reclamation pathway is weed management without reseeding. Continued integrated pest management (IPM) will be required as many of the invasive species that can occupy the Invaded State have extended dormant seed life. The trigger is invasive species control. Due to a lack of ground cover, the invading species cause a significant increase in soil loss (Lacey et al., 1989).
Mechanism
Native rangeland has been converted for the production of forage crops or small grain products. This site often receives additional moisture from irrigation to increase production. Fertilizer and herbicides are frequently added to the Cultivated Cropland state to aid in crop production.
Model keys
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