Loamy, South Aspect, Columbia Hills
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
Note: most Loamy sites on the south side of the Columbia Hills have already crossed the threshold into State 3
State 1 Narrative:
State 1 represents grassland steppe with no invasive or exotic weed species. Each functional, structural group would have one or more native species. The south side of the Columbia Hills has no sagebrush or bitterbrush, and except for a spot along the Columbia River, the south side of the Columbia Hills also has no rabbitbrush.
Reference State Community Phases:
1.1 Bunchgrass Bluebunch wheatgrass
Dominate Reference State Species: would be bluebunch wheatgrass
At-risk Communities:
• Any community in the reference state is at risk of moving to State 2. The seed source of cheatgrass is nearby and blowing onto most sites annually.
Submodel
Description
Note: most Loamy sites on the south side of the Columbia Hills have already crossed the threshold into State 3
State 2 Narrative:
State 2 represents native grassland steppe with minor inclusion of invasive annual grasses such as cheatgrass. All the native functional, structural groups would be represented by one or more species. Cheatgrass would be a minor component in State 2. Once a community has been invaded by cheatgrass the chance of going back to State 1 is small.
Community Phases for State 2:
2.1 Bunchgrass Bluebunch wheatgrass
Submodel
Description
Note: most Loamy sites on the south side of the Columbia Hills have already crossed the threshold into State 3
State 3 Narrative:
State 3 represents sites dominated by invasive annual species and has crossed a biological threshold. As State 1 or State 2 begins to 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 Annual Grass cheatgrass
Submodel
Description
State 4 Narrative:
State 4 represents a site that has been seeded to desirable grasses such as Secar Snake River wheatgrass, Sherman big bluegrass, or crested wheatgrass. State 4 is stable if 0.8 plant per sq. ft. or greater of the desired bunchgrasses is maintained.
Community Phases for State 4:
4.1 Seeded Grasses
Submodel
Mechanism
T1 Result: transition from Reference State to State 2 (grassland steppe w/ a few annuals). The Reference State does not have invasive species. State 2 is the same as Reference State but with minor addition of invasive annual grasses such as cheatgrass.
Primary Trigger: soil disturbances (rodents, badgers) create openings in the community or a high moisture year causes a micro-burst of cheatgrass and is the principle means of colonization. Loss of soil biological crusts contribute to the invasion.
Ecological process. Annually cheatgrass or other annual grass seed blows onto most Reference State sites. With seed-soil contact this seed germinates and competes with the native species for space, light and moisture. The loss of soil biological crusts also contributes to the invasion. Even pristine communities in the Reference State are susceptible to colonization by invasive annual grasses.
Indicators: The occurrence of annual grasses on sites where they had been absent.
Mechanism
T2 Result: shift from State 2 with a few annuals to State 3 which is dominated by annual grasses. This transition would occur once the cover of bluebunch wheatgrass declines to less than 10% and invasive species cover is greater than 40%.
Primary Trigger: Due to chronic heavy grazing, season-long grazing, or late spring grazing, dominant species are all but eliminated. Annuals such as cheatgrass have gained the competitive advantage. 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. Note: chronic season-long grazing in 1880s-1940s created thousands of acres of annual grass-sagebrush community, and then fire turned that into annual grasses.
Ecological process: the unraveling of the native plant community begins with consistent defoliation pressures to bluebunch wheatgrass. This causes poor vigor, shrinking crowns and plant mortality. With more and more of the soil surface and upper soil rooting surfaces open, opportunistic weeds that take advantage of the available niche space and expand. The invasive annual grasses in State 2 communities make a dramatic increase to dominate the community.
Secondary Trigger: Repeated fire does the same thing. In Washington, chronic season-long grazing caused more acres of State 2 than repeated fire. Repeated fire is a much more common event in south Central Washington than elsewhere in MLRA 8.
Indicators: Decreasing vigor and 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. Secar Snake River wheatgrass, thickspike wheatgrass, Sherman big bluegrass, Sandberg bluegrass, and intermediate wheatgrass are typical species seeded on Loamy 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
R2 Result: Shift from State 4 back to State 2. This restoration transition does not occur without a significant commitment of time & resource inputs to restore ecological processes, native bunchgrasses 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 Snake River 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 with 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. State 4 stand must be killed before proceeding. 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 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.
Mechanism
T3 Result: shift from seeded grass State 4 to State 3 which is dominated by invasive annual species. This transition occurs when the desirable seeded grasses become minor to the dominant annual grasses.
Primary Trigger: This transition occurs when chronic heavy grazing has removed too much of the perennial bunchgrass cover allowing invasive annual species to colonize the site. As this continues the competitive advantage goes to the exotic species which are opportunistic and take most of the site’s resources. Little of the resources remain for the desirable species.
Secondary Trigger: Frequent fires or a severe fire that removes too much of the perennial bunchgrass cover and gives the competitive advantage back to the invasive species.
Ecological process: the unraveling of the seeded grass community begins with consistent defoliation pressures to seeded grasses. This causes poor vigor, shrinking crowns and plant mortality. With more and more of the soil surface and upper soil rooting surfaces open, opportunistic weeds that take advantage of the available niche space and expand. The invasive annual grasses in State 2 communities make a dramatic increase to dominate the community.
Indicators: shrinking crowns and mortality of desirable species, increasing caps gaps between desirable perennial species, 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
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