Stony Foothills, bitterbrush
Scenario model
Current ecosystem state
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Management practices/drivers
Select a transition or restoration pathway
- Transition T1 More details
- Transition T2 More details
- Restoration pathway R1 More details
- Restoration pathway R2 More details
- Transition T3 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 Narrative:
State 1 represents shrub steppe with no invasive or exotic weed species. All the functional, structural groups are represented by one or more native species.
Reference State Community Phases:
1.1 Reference Idaho fescue-bluebunch wheatgrass – bitterbrush
1.2 Bunchgrass Idaho fescue-bluebunch wheatgrass.
1.3 Shrub Steppe Bitterbrush – Idaho fescue-bluebunch wheatgrass
1.4 Heavy Shrub Bitterbrush – needle and thread
Dominate Reference State Species:
Antelope bitterbrush – Idaho fescue – bluebunch wheatgrass
At-risk Communities:
• All communities in the reference state are at risk of moving to State 2. The seed source of cheatgrass is nearby and blowing onto most sites annually
• Community Phases 1.1, 1.2 and 1.3 have high amounts of Idaho fescue and bluebunch wheatgrass cover and are at low risk of moving to State 3
• Community Phase 1.4 is at-risk because of low density for Idaho fescue and bluebunch wheatgrass. Community 1.4 should be seeded after fire
• Communities with more than 40% bitterbrush cover
• When fire kills the Idaho fescue plants, these sites should be seeded after fire
• Community 1.4, and any site with low cover of Idaho fescue/bluebunch wheatgrass, and any site with moderate to heavy cover of cheatgrass should be seeded after fire
Submodel
Description
State 2 Narrative:
State 2 represents invasion by annual grasses and is the gradation between Reference State and State 3. State 2 is shrub steppe with the inclusion of invasive annual grasses such as cheatgrass. The loss of soil biological crusts and annual grass seed blowing onto the site annually contributes to the annual grass invasion. All the native functional, structural groups are still represented by one or more species.
Annual brome seed blows onto most sites annually seeking an opportunity to invade and colonize. With each loss of a native perennial plant, the site becomes less and less resistant to invasion. When the annual grasses make seed for the next generation, the site has been colonized and will likely remain a component of the community. The loss of biological soil crusts is also a contributing factor to the invasion.
For communities 2.1, 2.2, and 2.3 the amount of invasive annual grasses is minor. Annual grasses are more prominent in community 2.4. Once a community has been invaded by an annual brome the chance of going back to State 1 is small. This state can occur with or without bitterbrush.
Community Phases for State 2:
Same four communities as Reference State
Dominate Species for State 2:
Antelope bitterbrush, Idaho fescue and bluebunch wheatgrass
Pathways within State 2
The pathways in State 2 are basically the same as in the reference State. Community 2.4 is most at risk of transitioning to State 3.
Submodel
Description
State 3 Narrative:
State 3 represents communities dominated by invasive annual species and has crossed a biological threshold. Virtually all the native functional, structural groups are missing. This state can occur with or without shrubs.
Important species can include cheatgrass, Japanese brome, medusahead, ventenata, mustard, prickly lettuce and diffuse knapweed.
Community Phases for State 3:
3.1 Shrub – Annual Grass Bitterbrush – Annual bromes
3.2 Annual Grass Annual bromes
Dominate Species for State 3:
Cheatgrass or other annual grasses with bitterbrush
Submodel
Description
State 4 Narrative:
State 4 represents a site that has been seeded to desirable grasses such as Snake River wheatgrass, Sherman big bluegrass, or intermediate wheatgrass. State 4 has two community phases that are stable if they maintain 0.8 plant / sq. ft. or greater of the desired bunchgrasses
Community 4.1 is dominated by the desirable seeded species. State 4 has two community phases: Seeded grass phase and shrub – seeded grass phase.
Community 4.2 is a shrub-grass community.
Community Phases for State 4:
4.1 Seeded grasses
4.2 Shrub – Seeded Grasses
Dominate Species for State 4:
Desirable seeded grass and legume species with or without shrubs and legumes.
Submodel
Mechanism
T1 Result: Transition from Reference State to State 2 with a few annual grasses.
Primary trigger: Soil disturbances from rodent or badger activity provide great opportunity for invasive annual species. Fire, drought and grazing pressure can also create holes in the plant community. Loss of soil biological crusts also contributes.
Ecological process: Annual grass seeds blow onto the site awaiting an opportunity to colonize. Seeds germinate and have enough moisture to establish plants and seed for the next generation.
Indicators: A few annual grasses have colonized the site.
Mechanism
Result: Transition from State 2 with a few annuals to State 3 which is dominated by annual grasses. This transition occurs once the cover of bunchgrasses (Idaho fescue and bluebunch wheatgrass) declines to less than 10% and invasive species cover is greater than 40%.
Primary trigger: Grazing pressure (heavy grazing, season long grazing or frequent late spring grazing) causes low vigor and reduced cover of Idaho fescue and bluebunch wheatgrass. Initially both needleandthread and the annual grasses increase. As the grazing pressure continues, needleandthread will also decrease.
allowing the annual grasses to become dominate. Grazing pressure is defined as heavy grazing, season long grazing or frequent late spring grazing.
Secondary trigger would be a severe fire which can eliminate virtually every Idaho fescue plant from the community. This void is quickly filled by the annual grasses. Repeated fire which is not a common occurrence in MLRA 8 as another possibility.
Ecological process: With consistent defoliation pressures bluebunch wheatgrass, Idaho fescue and needleandthread experience poor plant vigor to such a degree that grass roots begin to die. So, bunchgrasses have shrinking crowns and some mortality. This gives invasive annual grasses opportunity to expand its cover to a position of dominance.
Indicators: Significant decline in vigor and cover of one or more of the dominant reference state species – Idaho fescue, bluebunch wheatgrass, bitterbrush. Increasing cover of annual grasses. Increasing canopy gaps between bunchgrasses (Idaho fescue & bluebunch).
Mechanism
Equipment limitations from surface rock and rock in the profile will cause issues and some treatment options may not be feasible on some sites.
R1 Result: Shift from State 3 dominated by annual grasses to State 4 seeded grasses.
This restoration transition is not likely to occur without significant time and inputs for weed control, seedbed preparation, seeding operation and post-seeding management & weed control. Two years of weed control, 1-2 years of deferment post-seeding, and proper grazing management afterward.
Mechanism
R2 Result: Shift from State 3 back to State 2.
This restoration transition does not occur without a significant commitment of time & resource inputs to restore ecological processes, native bunchgrasses, bitterbrush and native forb species. Attention needs to be paid to each step of the process: weed control, seedbed preparation, seeding and planting operations and post-seeding management.
Shifting from State 3 to State 4: If the goal is to restore back to a native plant community, State 3 must first be shifted to State 4. It will take two years or longer to kill annual species and to exhaust the seedbank of invasive species. Site will then need to be seeded to perennial species such as crested wheatgrass to restore soil properties before native species can survive and thrive on site. The seeded species rebuild some of the basic soil properties including increased soil organic matter, increased soil moisture, and likely would also require the soil’s pore spaces, bulk density and soil microorganisms to return before the native species that used to survive in this ecological site can return. The site would also need several years of no significant fires and proper grazing management as well. See narrative for R1 transition above.
Shifting from State 4 to State 2: This assumes that the shift from State 3 to State 4 has been successful. To make the switch from State 4 to state 2, all introduced grasses must be killed first. The seeding of native species should occur in two steps: (1) a seeding of native bunchgrasses so that broadleaf weeds may be controlled, (2) a re-introduction of sagebrush and native forbs. The site would also need several years of no significant fires and proper grazing management as well to ensure plant establishment and vigor. Shrubs and native forbs should not be planted until broadleaf weeds have been controlled.
Mechanism
T3 Result: Transition from State 4 seeded grass to State 3 annual grasses. This transition occurs when the desirable seeded grasses become minor to the dominant annual grasses.
Primary trigger: grazing pressure on the seeded grasses reduce the vigor and density of key bunchgrass species.
Ecological process: consistent defoliation pressure causes weakened vigor, roots dying and less cover for the seeded grasses. Invasive annual grasses colonize the site and become more and more common with the loss of each bunchgrass plant.
Indicators: shrinking crowns and mortality of desirable species, increasing caps gaps between seeded plants, increasing cover by annual grasses
References:
Boling M., Frazier B., Busacca, A., General Soil Map of Washington, Washington State University, 1998
Daubenmire, R., Steppe Vegetation of Washington, EB1446, March 1968
Davies, Kirk, Medusahead Dispersal and Establishment in Sagebrush Steppe Plant Communities, Rangeland Ecology & Management, 2008
Environmental Protection Agency, map of Level III and IV Ecoregions of Washington, June 2010
Miller, Baisan, Rose and Pacioretty, “Pre and Post Settlement Fire regimes in mountain Sagebrush communities: The Northern Intermountain Region
Natural Resources Conservation Service, map of Common Resource Areas of Washington, 2003
Rapid Assessment Reference Condition Model for Wyoming Sagebrush, LANDFIRE project, 2008
Rocchio, Joseph & Crawford, Rex C., Ecological Systems of Washington State. A Guide to Identification. Washington State Department of Natural Resources, October 2015. Pages 156-161 Inter-Mountain Basin Big Sagebrush.
Rouse, Gerald, MLRA 8 Ecological Sites as referenced from Natural Resources Conservation Service-Washington FOTG, 2004
Soil Conservation Service, Range Sites for MLRA 8 from 1980s and 1990s
Tart, D., Kelley, P., and Schlafly, P., Rangeland Vegetation of the Yakima Indian reservation, August 1987, YIN Soil and Vegetation Survey
Model keys
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