Loamy, Prairie
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
- Transition R1 More details
- Restoration pathway T3 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
State 1 Narrative:
State 1 represents grassland with no invasive or exotic weed species. Each native functional, structural group has one or more native species. The prairies of MLRA 6 have no sagebrush or bitterbrush, and no rabbitbrush.
Reference State Community Phases:
1.1 Reference Idaho fescue – bluebunch wheatgrass
1.2 Grass-Forb Bluebunch wheatgrass – Unpalatable Forbs
Dominate Reference State Species: Idaho fescue and bluebunch wheatgrass
At-risk Communities:
• Different communities have different degrees of risk
• All communities in the reference state are at risk of invasive species and moving to State 2. The seed source of invasive species is nearby and moving onto most sites annually.
• Any community is at risk when fire kills Idaho fescue plants. The holes could quickly be filled by invasive grass or weeds
• A community has moved to State 2 when annual grasses or broadleaf weeds have colonized the site
• Any community becomes at-risk of moving to State 3 when Idaho fescue and bluebunch have low cover and annual grasses or broadleaf weeds have colonized the site
Submodel
Description
State 2 Narrative:
State 2 represents the transition between State 1 and State 3. State 2 is grassland steppe with the inclusion of invasive species such as bulbous bluegrass, annual bromes or foxtail barley. Native species are present and dominant, but invasive species have gained a foothold that they do not easily relinquish. All the native functional, structural groups are still represented by one or more species. Grazing pressure weakens the stand of native species allowing the invasive species to colonize and establish themselves in the community.
Invasive species are a minor component in State 2. But once a community has been invaded by invasive species the chance of going back to State 1 is small.
Dominate State 2 Species: unpalatable native forbs and native bunchgrasses
Submodel
Description
State 3 represents sites dominated by invasive species and has crossed a biological threshold. As State 1 and State 2 unravel the dominant bunchgrasses decline while invasive grasses become more and more prominent. Virtually all the native functional, structural groups are missing in State 3.
Community Phases for State 3:
3.1 Invasive species bulbous bluegrass, annual bromes or foxtail barley
Dominate State 3 Species: bulbous bluegrass, annual bromes or foxtail barley
Submodel
Description
State 4 Narrative:
State 4 represents a site that has been seeded to desirable grasses such as intermediate wheatgrass, smooth brome or orchardgrass. State 4 is stable if 0.8 plant per sq. ft. or greater of the desired bunchgrasses is maintained.
Community Phases for State 4:
1.1 Seeded Grasses
Dominate State 4 Species: Desirable seeded grasses with or without legumes
Submodel
Mechanism
T1 Result: shift from Reference State to State 2 (grassland steppe w/ some annuals). State 2 has the same communities but with minor additions of invasive annual grasses such as annual bromes.
Primary Trigger: grazing pressure (heavy grazing intensity, season long grazing or frequent late spring grazing) to Idaho fescue, bluebunch wheatgrass and other palatable species. Soil disturbances (rodents, badgers) create openings in the community and encourage weed germination. Loss of soil biological crusts contributes to the invasion.
Ecological process: consistent grazing pressure to native bunchgrasses results in poor vigor, shrinking crowns and plant mortality. This releases resources and niche space. Most sites in the Reference State have some scattered annual grass seed that has moved onto the site. This seed is waiting for enough moisture to germinate and to compete with the native species for space, light and moisture.
Indicators: The occurrence of annual grasses on sites where they had been absent. Decreasing cover of Idaho fescue, bluebunch wheatgrass and other native species.
Mechanism
T2 Result: Transition from State 2 a native community with some invasive species to State 3 which is dominated by annuals. This transition occurs once the cover of bluebunch wheatgrass-Idaho fescue declines to less than 10% while invasive species cover is at least 40%.
Primary Trigger: grazing pressure (heavy grazing, season long grazing or frequent late spring grazing) to Idaho fescue, bluebunch wheatgrass and other palatable native species.
Ecological Process: consistent defoliation pressure to palatable species results in poor vigor, shrinking crowns and plant mortality. Native species are all, but eliminated and invasive species have the competitive advantage. In a series of retrogressions, the cover of native species declines while weeds take advantage of the release of resources and available niche space to colonize and expand. The site has lost its primary species that stabilize and protect the soil from wind and water erosion and has also lost the ability to retain sufficient soil moisture for many of the native perennial species.
Indicators: Decreasing cover of bluebunch wheatgrass and increasing cover of invasive annual species. Increasing distance between perennial species. Decreasing soil organic matter, soil water retention, limited water infiltration and percolation in the soil profile.
Mechanism
R1 Transition from State 3 (a community dominated by invasive annual species) to State 4, which is predominately desirable seeded grasses.
This restoration transition does not occur without significant time and inputs to control weeds, prepare a seedbed, seed desirable species, and post-seeding weed control and management. This requires a commitment of two years or more for weed control. Care must be taken to maintain soil structure so that the seedbed has many safe sites for the seed. Seed placement must be managed to achieve seed-soil contact at very shallow depth (about 1/8 inch is desired). Proper grazing management is essential to maintain the stand post-seeding. Intermediate wheatgrass, smooth brome, orchardgrass and meadow brome are well adapted to Loamy, Prairie ecological site.
The actual transition occurs when the seeded species have successfully established and are outcompeting the annual species for cover and dominance of resources.
Mechanism
T3 Result: shift from seeded grass State 4 to State 3 which is dominated by invasive annual species.
Primary Trigger: grazing pressure (heavy grazing, season long grazing or frequent late spring grazing) to seeded grasses.
Ecological Process: with consistent defoliation pressure seeded grasses exhibit poor vigor, shrinking crowns and plant mortality. This releases resources and niche space which opportunistic invasives take most of. Little of the resources remain for the desirable species.
Indicators: decreasing cover of seeded grasses, increasing caps gaps between seeded grasses, increasing cover by invasive species.
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.
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
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