Natural Resources
Conservation Service
Stony Foothills South Aspect, Bitterbrush, 2800-4000 feet
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
- Restoration pathway R1 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
Select a state
Description
State 1 Narrative:
State 1 represents shrub steppe with no invasive or exotic weed species. Each functional, structural group has one or more native species.
Reference State Community Phases:
1.1 Reference Bitterbrush – Bluebunch wheatgrass
1.2 Shrub–Grass–Forb Bitterbrush – Bluebunch Wheatgrass – Native Forbs
Dominate Reference State Species: Bluebunch wheatgrass, needle and thread, bitterbrush
At-risk Communities: Potentially every community is at risk as seeds of invasive move around by wind and animals.
Submodel
Description
State 2 Narrative:
State 2 represents a minor invasion by invasive species. All the native functional, structural groups are still represented by one or more 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. Once a community has been invaded by annual bromes or other invasive species the chance of going back to State 1 is small.
Dominate State 2 Species: Native forbs, shrubs and bunchgrasses are somewhat balanced in State 2 with the decline of the bunchgrasses.
Submodel
Description
State 3 Narrative:
State 3 represents sites dominated by invasive species and has crossed a biological threshold. As State 1 or State 2 unravels the dominant bunchgrasses decline while invasive species become more and more prominent. Virtually all the native functional, structural groups are missing in State 3.
Community Phases for State 3:
3.1 Annual Grass
Dominate State 3 Species: annual bromes or other invasive species
Submodel
Description
State 4 Narrative:
State 4 represents a stand of desirable introduced grasses such as intermediate wheatgrass or Secar Snake River wheatgrass. The State 3 community has been eliminated and the site seeded to desirable grasses such as intermediate wheatgrass. State 4 remains stable as long as a full stand is maintained (1.0 plant / sq. ft. or greater of the desired bunchgrasses)
Community Phases for State 4: Seeded Grasses
Dominate State 4 Species: Desirable seeded grasses with or without legumes
Submodel
Mechanism
T1 Result: transition from Reference State (shrub steppe with no invasive species) to Transitional State 2 (shrub steppe w/ some invasive species). State 2 has the same communities but with minor additions of invasive species such as annual bromes or bulbous bluegrass. This is a continuation of the degradation that started with Pathway 1.1a. Primary Trigger: grazing pressure (heavy grazing intensity, season long grazing or frequent late spring grazing) to bluebunch wheatgrass and other palatable species. Ecological process. Most sites in the Reference State have some scattered annual grass seed on site. This seed is waiting for enough moisture to germinate and to compete with the native species for space, light and moisture. Consistent defoliation pressure to bluebunch wheatgrass results in poor vigor, shrinking crowns and plant mortality. This releases resources and niche space which allows invasive species to colonize the site. Indicators: The occurrence of annual grasses on sites where they had been absent.
Mechanism
T2 Result: Transition from Transitional State 2 with some invasive species to State 3 which is dominated by annuals. This transition is a continuation of the degradation which started with Pathway 1.1a and Transition T2 and, occurs once the cover of bluebunch wheatgrass declines to less than 10% while invasive species cover is at least 40%. Primary Trigger: moderate severity fire and chronic grazing pressure (heavy grazing, season-long grazing, or late spring grazing) to bluebunch wheatgrass and other palatable species. Ecological Process: fire kills bitterbrush, but threetip sage sprouts. Defoliation pressure to bluebunch wheatgrass results in poor vigor, shrinking crowns and plant mortality. As bluebunch wheatgrass and other palatable species decline, and more and more of the soil surface and rooting surface become open to annual bromes and other opportunistic weeds. Invasive species take advantage of the released 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.
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. 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: chronic grazing pressure (heavy grazing intensity, season long grazing or frequent late spring grazing) to seeded grasses. Ecological process: defoliation pressure to seeded grasses results in poor vigor, shrinking crowns and plant mortality. As this continues invasive species have the competitive advantage and expand to a position of dominance. Little of the resources remain for the desirable species. Indicators: shrinking crowns and mortality of desirable species, increasing caps gaps between seeded plant crowns, 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. 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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Ecological site groups
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