Cool Loamy, Channeled Scabland
Scenario model
Current ecosystem state
Select a state
Management practices/drivers
Select a transition or restoration pathway
-
Transition T1
Heavy grazing pressure
More details -
Restoration pathway R1
restoration
More details -
Transition T2
heavy grazing pressure
More details -
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 sagebrush steppe with no invasive or exotic species. All the functional, structural groups have one or more species.
Reference State Community Phases:
1.1 Reference Idaho fescue-bluebunch wheatgrass / threetip sagebrush
1.2 Shrub Steppe Threetip sage / Idaho fescue-bluebunch wheatgrass
Communities 1.1 and 1.2 are stable with a high cover of Idaho fescue/bluebunch wheatgrass and low to moderate cover of threetip sage. Both communities have a minor amount of threadleaf sedge which is native, but also rhizomatous. But when the dominant bunchgrasses exhibit low vigor and decline, threadleaf sedge and threetip sage increase and field brome colonizes the disturbed sites.
Dominant Reference State Species: Threetip sagebrush, Idaho fescue, bluebunch wheatgrass
At-risk Communities:
• All communities in the reference state are at risk of invasive species. The seed source for field brome or other invasive annual weeds move into most sites annually.
• Any community becomes at-risk of moving to State 3 when Idaho fescue and bluebunch have low vigor and the cover of threadleaf sedge is expanding
• Any community is at risk when fire kills the Idaho fescue plants. The holes could quickly be filled by threadleaf sedge or field brome. The site should be inter-seeded that fall or early the following spring.
Submodel
Description
State 2 Narrative:
State 2 represents a community dominated by threadleaf sedge and threetip sage. Many native functional, structural groups have been altered or are missing. Annual grasses such as field brome are present but secondary to the shrub and sedge components.
Community Phases for State 2:
2.1 Shrub-Sedge Threetip sage – Threadleaf sedge
Dominant Species in State 2: Threadleaf sedge, threetip sagebrush
Submodel
Description
Narrative for State 3:
State 3 represents sites that have been seeded. The site was no longer productive for intended uses so, a commitment was made to kill existing stand and seed more desirable species.
Community Phases for State 3:
3.1 Seeded grasses
3.2 Shrub – Seeded Grasses
Refer to narrative for R1.
Dominant Species in State 3: Desirable seeded grass species with or without legume
Submodel
Mechanism
T1 Transition from Reference State to State 2 (sedge-shrub). The Reference State has only a minor amount of threadleaf sedge and no invasive species. In State 2 threadleaf sedge makes a significant increase along with threetip sage and invasive species colonize the site.
Primary Trigger: Heavy grazing pressure (heavy grazing intensity, season long grazing or frequent late spring grazing) to Idaho fescue and bluebunch wheatgrass.
Ecological process. Consistent defoliation pressure to native bunchgrasses results in poor vigor, shrinking crowns and plant mortality. The cover of threadleaf sedge and threetip sagebrush increases as the cover of the dominant bunchgrasses decline. Soil disturbances by rodents and badgers enable seed-soil contact, for invasive weeds so they colonize the site and later, expand as opportunity presents itself.
Indicators: increasing gaps between dominant bunchgrasses (Idaho fescue and bluebunch wheatgrass). Expanding cover of threadleaf sedge and threetip sage, and the presence of invasive species where there has been none.
Mechanism
R1 Result: Transition from State 2 sedge-shrub. State 3 seeded grass
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 to kill threadleaf sedge and threetip sagebrush, and 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. Snake River wheatgrass, thickspike wheatgrass, Sherman big bluegrass, Sandberg bluegrass, crested or intermediate wheatgrass are typical species seeded on Cool Loamy ecological site.
The actual transition occurs when the seeded species have successfully established and are outcompeting the threadleaf sedge, shrubs and annual species for cover and dominance of resources.
Mechanism
T2 Transition from State 3 seeded grasses to State 2 threadleaf sedge – threetip sage. This transition occurs when the cover of dominant bunchgrasses drops to less than 10%, and threadleaf sedge has assumed a dominant position in the community.
Primary trigger: heavy grazing pressure (heavy grazing intensity, season long grazing or frequent late spring grazing) to the desirable seeded grasses.
Ecological process: consistent defoliation pressure to seeded grasses results in poor vigor, shrinking crowns and plant mortality. This releases resources and niche space to threadleaf sedge and threetip sage.
Indicators: Declining cover for the seeded species and increasing canopy gaps between seeded grass plants. Increasing cover of threadleaf sedge, threetip sage and 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, 1970
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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