Mound-Intermound Complex
Scenario model
Current ecosystem state
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Management practices/drivers
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- Transition T1A More details
- Transition T3A 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
State 1 for both components of this complex represents communities with no invasive species present. Very Shallow sites rarely burn, and in most cases, receives minimal grazing. So, these sites are mostly very stable, remaining in State 1 regardless of climate or management. Similarity Index scores are typically higher on Very Shallow than other ecological sites on the landscape. At-risk communities • All communities in the reference state for both Very Shallow and Loamy Mound are at risk of invasive species. The seed source for annual bromes or other invasive annual seed blows onto most sites annually. • Community 1.1 for Very Shallow and Community 1.1 for Loamy Mound have high bunchgrass cover and are at low risk of shifting to State 2 • Community 1.2 on both components – forb – low shrub on the Very Shallow component and heavy sagebrush on the Loamy Mound component are at high risk of shifting to State 2
Submodel
Description
Forbs & Annual Grasses for Very Shallow Very Shallow State 2 represents the rare situation where Very Shallow is dominated by forbs, or annual grasses. Invasive annual grasses, which are common & frequently dominant on Loamy ecological sites, do not compete as well on Very Shallow sites. In most instances the Very Shallow component remains virtually unchanged while the Loamy Mound may shift to Community Phases 1.2 or even to State 2. State 2: Annual Grasses for Loamy Mound Loamy Mound State 2 on Loamy Mound represents a highly disturbed community. Heavy soil disturbances from rodents or badgers, &/or heavy grazing pressure from rodents, rabbits or livestock (heavy to severe grazing intensity, chronic critical period grazing or season long grazing) causes mortality of bunchgrasses (basin wildrye, bluebunch wheatgrass and Idaho fescue. As bunchgrasses decline, annual grasses colonize and eventually become dominant. For mounds with sagebrush, shrubs will increase alongside the annual grasses.
Very Shallow Component Recovery from State 2 is considered non-reversible. Refer to Very Shallow PESD R008XY001WA for more narrative regarding recovery. Loamy Mound component While the restoration of Loamy Mounds is possible, treatment actions may be both impractical and costly. Each mound is spatially separated from other mounds and it is possible that different mounds could require different treatments.
Description
State 1 for both components of this complex represents communities with no invasive species present. Very Shallow sites rarely burn, and in most cases, receives minimal grazing. So, these sites are mostly very stable, remaining in State 1 regardless of climate or management. Similarity Index scores are typically higher on Very Shallow than other ecological sites on the landscape. At-risk communities • All communities in the reference state for both Very Shallow and Loamy Mound are at risk of invasive species. The seed source for annual bromes or other invasive annual seed blows onto most sites annually. • Community 1.1 for Very Shallow and Community 1.1 for Loamy Mound have high bunchgrass cover and are at low risk of shifting to State 2 • Community 1.2 on both components – forb – low shrub on the Very Shallow component and heavy sagebrush on the Loamy Mound component are at high risk of shifting to State 2
Submodel
Description
Forbs & Annual Grasses for Very Shallow Very Shallow State 2 represents the rare situation where Very Shallow is dominated by forbs, or annual grasses. Invasive annual grasses, which are common & frequently dominant on Loamy ecological sites, do not compete as well on Very Shallow sites. In most instances the Very Shallow component remains virtually unchanged while the Loamy Mound may shift to Community Phases 1.2 or even to State 2. State 2: Annual Grasses for Loamy Mound Loamy Mound State 2 on Loamy Mound represents a highly disturbed community. Heavy soil disturbances from rodents or badgers, &/or heavy grazing pressure from rodents, rabbits or livestock (heavy to severe grazing intensity, chronic critical period grazing or season long grazing) causes mortality of bunchgrasses (basin wildrye, bluebunch wheatgrass and Idaho fescue. As bunchgrasses decline, annual grasses colonize and eventually become dominant. For mounds with sagebrush, shrubs will increase alongside the annual grasses.
Very Shallow Component Recovery from State 2 is considered non-reversible. Refer to Very Shallow PESD R008XY001WA for more narrative regarding recovery. Loamy Mound component While the restoration of Loamy Mounds is possible, treatment actions may be both impractical and costly. Each mound is spatially separated from other mounds and it is possible that different mounds could require different treatments.
Mechanism
Result: Shift from Reference State Community Phase 1.1 to Community Phase 2.1, resulting in the shift of functional groups to forbs and/or invasive annual grasses. Primary Trigger: Extensive spring grazing with heavy use to Sandberg bluegrass. Plant vigor declines and most or all Sandberg bluegrass plants are lost from the community. The soil is more open to evaporation, to wind and water erosion, and facilitates plant community changes from Community 1.2 to Community 2.1. Secondary Triggers: a micro-burst of cheatgrass could put Community 1.2 at risk. The trampling of Very Shallow soils, displacing and disturbing the surface soil structure by grazing animals could also trigger transition to State 2. Ecological process: mortality of Sandberg bluegrass frees resources in the surface soils that allows native forbs to increase, while introduced annual species (forbs and grasses) colonize and expand. A micro-burst of annual grasses could allow even pristine sites to be invaded. Community 1.2 is the community most at risk and is also the pathway for crossing the threshold from State 1 to State 2. Indicators: Declining vigor and cover of Sandberg bluegrass, declining soil biotic crust and, increasing gaps between perennial bunchgrasses. Transitions for Loamy Mound component: T1 Result: Shift from Loamy Mound Community 1.2 across a threshold to Community 2.1, which is dominated by annual grasses. Ecological process: Generally, with grazing activity livestock trail across Very Shallow component to graze the Loamy Mound component. Very Shallow receives minimal grazing while the Loamy Mound can be grazed heavily. As grazing increases livestock trails are evident on the Very Shallow, but the Loamy Mounds are hammered. Primary trigger on Loamy Mound: heavy soil disturbances from rodents/rabbits &/or heavy grazing pressure from rodents, rabbits or livestock (heavy to severe grazing intensity, chronic critical period grazing or season long grazing). Mortality of bunchgrasses occur (basin wildrye, bluebunch wheatgrass and Idaho fescue. As bunchgrasses decline, annual grasses and tumble mustard or Russian thistle colonize and eventually become dominant. For mounds with sagebrush, shrubs will increase alongside the annual grasses. Secondary trigger on Loamy Mounds: Drought cycle coupled with heavy grazing. Indicators on Loamy Mound: Reduced vigor of bunchgrasses, colonization by annual grasses, increasing canopy gaps for perennials species, increasing sagebrush cover.
Model keys
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