North aspect, Prairie
Scenario model
Current ecosystem state
Select a state
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 steppe with no invasive or exotic species. All the native functional, structural groups have one or more species.
Reference State Community Phases:
1.1 Reference Idaho fescue-bluebunch wheatgrass
1.2 Forb-Grass Unpalatable forbs-Idaho fescue-bluebunch wheatgrass
Reference Community is stable with a high cover of Idaho fescue and moderate cover of forbs. But when the dominant bunchgrasses exhibit low vigor and decline, unpalatable forbs increase.
Dominate Reference State Species: Idaho fescue, bluebunch wheatgrass.
At-risk Communities:
• 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 Transitional when cheatgrass 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 cheatgrass or broadleaf weeds have colonized the site
Submodel
Description
State 2 Narrative:
State 2 represents a moderate invasion by invasive species. Native species are present and dominant, but invasive species have gained a foothold that they do not relinquish. Grazing pressure weakens the stand of native species allowing the invasive species to colonize and establish themselves in the community. The invasion can be bulbous bluegrass, annual bromes or foxtail barley.
Dominate State 2 Species: unpalatable forbs and native bunchgrasses
Submodel
Description
State 3 Narrative:
State 3 represents sites dominated by invasive annual species and has crossed a biological threshold. As State 1 or State 2 unravels 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, 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 or smooth brome. 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: transition from Reference State (grassland with no invasive species) to Transitional State 2 (grassland with some invasive species). The Reference State does not have invasive species. State 2 has the same communities but with minor additions of invasive species such as bulbous bluegrass or annual bromes, or pioneering species such as foxtail barley.
Primary Trigger: improper grazing (heavy grazing intensity, season long grazing or frequent late spring grazing) to Idaho fescue and other palatable species
Ecological process: consistent defoliation pressure to Idaho fescue results in poor vigor, shrinking crowns and plant mortality. This releases resources and niche space. Unpalatable forbs and invasive species gain the competitive advantage. Forbs establish new seedlings. Invasive species colonize the site and increase cover.
Indicators: declining Idaho fescue cover and the occurrence of invasive species on sites where they had been absent.
Mechanism
T2 Result: Transition from Transitional State 2 to State 3 which is dominated by invasive species.
Primary Trigger: grazing pressure (heavy grazing intensity, season long grazing or frequent late spring grazing) to Idaho fescue and other palatable species. This transition occurs once the cover of Idaho fescue-bluebunch wheatgrass decline to less than 10% while invasive species cover is 40% or more.
Ecological process: consistent defoliation pressure to Idaho fescue results in poor vigor, shrinking crowns and plant mortality. This releases resources and niche space. In a series of retrogressions Idaho fescue and other native species are weakened, and the invasive species increase to fill the void. After each retrogression the stand stabilizes but at a lower ecological level. Finally, the stand is dominated by invasive species rather than natives.
Unpalatable forbs and invasive species gain the competitive advantage. Forbs establish new seedlings. Invasive species colonize the site and increase cover.
Indicators: decreasing cover of native species and increasing cover of invasive species
Mechanism
R1 Result: Shift 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 and smooth brome are typical species seeded on Prairie North Slope 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 State 4 seeded grass to State 3 which is dominated by invasive annual species.
Primary trigger: grazing pressure (heavy grazing intensity, season long grazing or frequent late spring grazing) to seeded grasses
Ecological Process: consistent defoliation pressure to seeded grasses results in poor vigor, shrinking crowns and plant mortality. Invasive species colonize the site and then expand to take advantage of released resources and niche space.
Indicators: decreasing cover of desirable grasses and increasing cover of 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. 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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