Loamy Bottom
Scenario model
Current ecosystem state
Select a state
Management practices/drivers
Select a transition or restoration pathway
-
Transition T1a
grazing pressure
More details -
Restoration pathway R2a
restoration
More details -
Restoration pathway R2b
restoration
More details -
Transition T3a
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 grassland steppe with none to minor amounts of invasive or exotic weed species. All the functional, structural groups have one or more native species.
Reference State Community Phases:
1.1 Reference Basin wildrye – Basin &/or Wyoming big sagebrush
1.2 Bunchgrass Basin wildrye
1.3 Heavy Sage Basin &/or Wyoming big sagebrush – Basin Wildrye
Dominate Reference State Species: Basin wildrye, Wyoming and/or basin big sagebrush
At-risk Communities:
• All communities in the reference state are at risk of invasion by exotic species. Annual or biennial weeds and annual grass seeds blow onto most sites annually
• Community Phase 1.3, the heavy shrub community, has the highest risk of moving to State 2 because it has low cover of basin wildrye and high cover of shrubs
• Any Loamy Bottom community with high shrub cover and low cover of basin wildrye will also have invasive weeds, and thus, no longer be in the Reference State
• To seed or not to seed is the question after a fire. Community 1.3 and State 2 should be seeded to basin wildrye to minimize weed infestation. Any site with low cover of basin wildrye and any site with low to moderate cover of weeds should be seeded after a fire.
Submodel
Description
State 2 Narrative:
State 2 represents invasive species communities that have crossed a biological threshold. Virtually all the native functional, structural groups are missing. This state can occur with or without sagebrush.
Community Phases for State 2:
Can have several variations:
1. Invasive annual or biennial weeds (mustard, prickly lettuce, perennial pepperweed)
1. Invasive annual grasses (field brome, ventenata, medusahead)
2. Shrubs (basin big sagebrush, threetip sage, or rabbitbrush) with invasive weeds or annual grasses
Dominate State 2 Species:
Invasive weeds: mustard, prickly lettuce, perennial pepperweed, knapweeds
Invasive annual grasses: field brome, cheatgrass, medusahead, ventenata
Sagebrush, rabbitbrush, snowberry or rose
Submodel
Description
State 3 Narrative:
State 3 represents a site that has been seeded to desirable grasses such as basin wildrye or intermediate wheatgrass.
Community Phases for State 3:
3.1 Seeded Grasses
3.2 Shrub / Invasive Weeds – Seeded Grasses
Submodel
Mechanism
T1a Result: Shift from Reference State (native grassland with no invasive species) to State 2 which is dominated by invasive weeds or annual grasses.
The transition from State 1 to State 2 occurs as Community 1.3 declines until it crosses the biological threshold. This transition occurs once the cover of basin wildrye drops significantly and invasive species are co-dominant to dominant.
Primary Trigger: grazing pressure (heavy grazing intensity, season-long grazing, or frequent late spring grazing) to basin wildrye.
Ecological process: with consistent defoliation pressure basin wildrye and other palatable species exhibit poor vigor, shrinking crowns and plant mortality. This releases resources and niche space for invasive species. Weed seeds from invasive species blow onto the site or are carried in with runoff water. On most sites weed seeds are waiting for an opportunity to colonize the site. In a series of retrogressions basin wildrye cover continues to decline while invasive species increase accordingly until invasive species are dominant.
Indicators: Decreasing cover of basin wildrye and increasing cover of invasive species. Increasing canopy gaps between basin wildrye plants.
Mechanism
R2a Result: Shift from invasive species in State 2 back to Reference State. This restoration transition does not occur without a significant commitment of time & resource inputs to restore ecological processes, native bunchgrasses, sagebrush and native forb species.
TWO OPTIONS:
Option#1: Step 1 seed to introduced grasses; Step 2 seed to native species
Step 1 shifting from State 2 to State 3: It will take two years or longer to kill annual species and to exhaust the seedbank of invasive weed seed. Site will then need to be seeded to introduced perennial species such as crested 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, improved pore spaces and increased soil moisture within the soil profile. The site would also need several years of no significant fires and proper grazing management as well. See narrative for R1 recovery above.
Step 2 shifting from State 3 to State 1: This assumes that the shift from State 2 to State 3 has been successful. Introduced grasses and any remaining weeds must be killed while maintaining soil structure to ensure a proper seedbed (cloddy, a little rough and trashy to provide safe sites for the seed). A pulverized dust mulch must be avoided at all costs. The seeding of native species could occur in two steps: (1) first year, use a seed mix to duplicate the Reference Community – mostly basin wildrye with other native bunchgrasses so that broadleaf weeds may be controlled, and (2) second year re-introduce sagebrush and native forbs. Plugs may be used for sagebrush and native forbs rather than seed. Post-seeding the site would also need several years with no significant fires and proper grazing management as well to ensure plant establishment and vigor.
Option #2: seed directly to native species
Take two years or more to kill weeds and to exhaust the weed seedbank while maintaining soil structure. As in Option 1 above, the seeding of native species could occur in two steps: (1) first year, use a seed mix to duplicate the Reference Community – mostly basin wildrye with other native bunchgrasses so that broadleaf weeds may be controlled, and (2) second year re-introduce sagebrush and native forbs. Plugs may be used for sagebrush and native forbs rather than seed. Post-seeding the site would also need several years with no significant fires and proper grazing management as well to ensure plant establishment and vigor.
Mechanism
R2b Transition from State 2 (a community dominated by invasive annual species) to State 3, which can be to basin wildrye or to introduced grasses such as intermediate wheatgrass.
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 can require 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 1/8-1/4 inch is desired). Proper grazing management is essential to maintain the stand post-seeding. Intermediate wheatgrass is highly adapted to the Loamy Bottom 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
T3a Result: Shift from State 3 (seeded grasses) to State 2 which dominated by invasive weeds or annual grasses.
Primary Trigger: grazing pressure (heavy grazing intensity, 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 for invasive species to colonize the site. The competitive advantage goes to the exotic species which are opportunistic and take most of the site’s resources. In a series of retrogressions seeded grasses continue to decline while invasive species increase accordingly until invasive species are dominant.
Indicators: shrinking crowns and mortality of desirable species, increasing gaps between seeded grasses, and increasing cover of invasive annual 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
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