State 1
Historic Reference

State 1 represents sagebrush steppe with no invasive or exotic weed species. All the functional, structural groups have one or more native species. A diverse native community is more resistant to invasive annual species such as cheatgrass.

Reference Community 1.1 is dominated by bluebunch wheatgrass with some sagebrush.
Community 1.2 is even more strongly bunchgrass dominated.
Community 1.3 has a heavy sage canopy but bluebunch wheatgrass remains a vital component in the community.

Communities 1.1, 1,2 and 1.3 have enough bluebunch wheatgrass to shift to the other two communities and back again. These three community phases have high amounts of bunchgrass cover and are at low risk of moving to State 3

Community 1.4, depauperate, is dominated by sagebrush with Sandberg bluegrass as co-dominant. There is not enough bluebunch wheatgrass remaining for community 1.4 to shift back to the other communities in the reference state.

Community 1.1
Bluebunch Wheatgrass and Wyoming Big Sagebrush

Community 1.2
Bunchgrass

Community 1.3
Heavy Sage

Community 1.4
Depauperate

Pathway 1.1A
Community 1.1 to 1.2

Result: Shift from reference community to bunchgrass community. Sagebrush cover is all but eliminated, while bluebunch wheatgrass has a moderate increase in cover. Primary Trigger: Moderate-severity fire is complete enough and hot enough to remove almost all sagebrush. Most areas burn complete while other areas are unburned to lightly burned. Fire is not hot enough to affect soil conditions. Fire removes surface vegetation but has no impact on the crown of bunchgrasses. So, bunchgrasses and forbs return post-fire with good vigor. Post-fire the bunchgrasses are now more susceptible to grazing damage. Burned rangeland pastures will need two growing seasons recovery prior to resuming grazing, or to be lightly grazed but only during dormant season the first two years post-fire. Beyond two years for the bunchgrasses to expand, the grazing plan must promote light to moderate grazing intensity, and both critical period & growing season deferments must be implemented on burned pastures. Ecological process: Fire kills sagebrush and it does not have any sprouting ability. A few sagebrush plants remain, but only in patches that did not burn. The reduction in sagebrush releases resources and increases light for grasses and forbs. Fire conditions and post-fire grazing management allows bluebunch wheatgrass and other bunchgrasses to thrive and expand.

Pathway 1.2B
Community 1.1 to 1.3

Result: shift from reference community to heavy sage community. There is a moderate increase in sagebrush while bluebunch wheatgrass has a corresponding moderate decrease. Primary Trigger: With excessive grazing pressure (heavy grazing intensity, season long grazing or frequent late spring grazing) and a period of no fire, sagebrush increases its cover while bluebunch wheatgrass suffers a big decline. Ecological process: With consistent defoliation pressures bluebunch wheatgrass experiences poor plant vigor to such a degree that grass roots begin to die. So, bluebunch wheatgrass experiences shrinking crowns and some mortality. This gives sagebrush the opportunity to set new seedlings and expand its cover. Increased shade from the new sagebrush plants also plays a role in this process.

Pathway 1.2A
Community 1.2 to 1.1

Result: Shift from bunchgrass community to reference community. There is a minor reduction of bluebunch wheatgrass cover and a corresponding increase of sagebrush. Primary Trigger: Over time with no fire, sagebrush will re-enter the community even with good bunchgrass vigor. For most locations it may take up to 10 years for sagebrush to re-enter the community. With a slight increase in shade and some grazing pressure, perennial bunchgrasses experience a slight decline. Ecological process: Spots with soil disturbance receive sagebrush seed from remnant plants in unburned patches or from adjacent sites, seed germinates in the spring and a few sagebrush seedlings establish. For most locations it may take up to 10 years for sagebrush to re-enter the community. With a slight increase in shade perennial bunchgrasses experience a slight decline.

Pathway 1.1B
Community 1.3 to 1.1

Result: Shift from heavy sage community to reference community. There is a major decrease in sagebrush cover and a considerable increase in the cover of bluebunch wheatgrass. The community shift is from sagebrush dominance to bunchgrass dominance. Primary Trigger: Moderate-severity fire is patchy, dependent on temperature, wind, fuel load and fuel moisture. In areas that burn the fire is complete enough and hot enough to remove most sagebrush. Most areas burn complete while other areas are unburned to lightly burned and fire is not hot enough to affect soil conditions. Fire removes surface vegetation but has no impact on the root crown of bunchgrasses. So, bunchgrasses and forbs return post-fire with good vigor. Post-fire the bunchgrasses are now more susceptible to grazing damage. Burned rangeland pastures will need two growing seasons recovery prior to resuming grazing, or to be lightly grazed but only during dormant season the first two years post-fire. Beyond two years, for the bunchgrasses to expand, the grazing plan must moderate grazing intensity, and both critical period & growing season deferments must be implemented on burned pastures. Ecological process: Fire kills sagebrush and it does not have any sprouting ability. Some sagebrush remains, but only in patches that did not burn. The reduction in sagebrush releases resources and, increases light for grasses and forbs. Fire conditions and post-fire grazing management allows bluebunch wheatgrass and other bunchgrasses to thrive and expand via tillering and new seedlings.

Pathway 1.2C
Community 1.3 to 1.4

Result: Shift from heavy sage community to depauperate community. Sagebrush has a moderate increase while bluebunch is all but eliminated from the community. Invasive annual grasses have not invaded, but Community 1.4 is most at risk to invasion and is the segue between States 1 & 2, and States 1 & 3. Pathway 1.2c is a continuation of the process that started with Pathway 1.2b. Primary Trigger: With excessive grazing pressure (heavy grazing intensity, season long grazing or frequent late spring grazing) and a period of no fire, sagebrush increases its cover while bluebunch wheatgrass bunchgrasses suffers a big decline. Grazing animals selectively target the remaining bluebunch wheatgrass plants eliminating most of the bluebunch wheatgrass plants from the community. Ecological process: With consistent defoliation pressure bluebunch wheatgrass has low vigor, shrinking crowns and a lot of mortality. This gives sagebrush opportunity to set new seedlings and expand its cover. A few bluebunch wheatgrass plants may survive.

State 2
Current Potential

State 2 represents a gradation along the transition between Reference State and State 3. State 2 is sagebrush steppe with the inclusion of invasive annual grasses such as cheatgrass. All the native functional, structural groups are still represented by one or more species.

Cheatgrass seed blows onto most sites annually seeking an opportunity to invade and colonize. With each loss of a native perennial plant, the site becomes less and less resistant to invasion. When cheatgrass makes seed for the next generation, the site has been colonized and will likely remain a component of the community. The loss of biological soil crusts is also contributes to invasion by cheatgrass.

For communities 2.1, 2.2, and 2.3 the amount of cheatgrass is minor. Cheatgrass is more prominent in community 1.4. Once a community has been invaded by cheatgrass the chance of going back to State 1 is small. This state can occur with or without sagebrush.

Community 2.1
Bluebunch Wheatgrass and Wyoming Big Sagebrush with Invasives

Community 2.2
Bunchgrass with Invasives

Community 2.3
Heavy Sage with Invasives

Community 2.4
Depauperate with Invasives

Pathway 2.1A
Community 2.1 to 2.2

Pathway 2.2B
Community 2.1 to 2.3

Pathway 2.2A
Community 2.2 to 2.1

Pathway 2.1B
Community 2.3 to 2.1

Pathway 2.2C
Community 2.3 to 2.4

State 3
Invaded

State 3 is represented by invasive annual grasses with cheatgrass as the main culprit. Virtually all the native functional, structural groups are missing. This state can occur with or without sagebrush.

Community 3.1
Wyoming Big Sagebrush and Cheatgrass

Community 3.2
Cheatgrass

Pathway 3.1A
Community 3.1 to 3.2

Result: shift from shrub-cheatgrass to cheatgrass. Primary Trigger: Moderate intensity fire kills most or all sagebrush. Cheatgrass and other invasive species fully occupy the site.

State 4
Seeded

State 4 represents a site that has been seeded to desirable grasses such as Secar Snake River wheatgrass, Sherman big bluegrass, crested wheatgrass or Siberian wheatgrass. State 4 has two community phases that are stable if they maintain 0.8 plant / sq. ft. or greater of the desired bunchgrasses.

Community 4.1
Seeded Grass

Community 4.2
Shrub and Seeded Grass

Pathway 4.1A
Community 4.1 to 4.2

Result: Shift from seeded grass to shrub – seeded grass community. Shrubs colonize the site and increase cover and density while seeded grasses decline. Primary Trigger: site has not burned. Heavy grazing pressure on seeded grasses reduce plant vigor. Grass root crowns shrink in size and some grasses die allowing shrubs to enter the site.

Pathway 4.2A
Community 4.2 to 4.1

Result: Shift from shrub-grass to seeded grass community. Shrubs are decreased to all but eliminated and grasses increase to dominate the community. Primary Trigger: community treatment activities. (1) For communities with fire sensitive shrubs (sagebrush, bitterbrush) and a good population of desirable grasses, the best course of action is to reduce the shrubs by fire, chemical or mechanical treatment, and use proper grazing management to ensure grasses recover. (2) For communities with fire tolerant shrubs (rabbitbrush, three-tip sage) and a good population of desirable grasses, the best course of action is to reduce the shrubs by chemical treatment and use proper grazing management to ensure grasses recover. (3) Communities that do not have much seeded grass remaining will need to be re-seeded, which requires existing stand to be killed and a proper seedbed to be prepared. Seedbed preparation can use a combination of fire, mechanical tillage and chemical application. Seeding operation should ensure very shallow seed-soil contact (1/8” depth). Post-seeding the site will need up to 2 years of rest while the seeded grasses are established. Broadleaf weed control may also be necessary. Afterward, proper grazing must be used to maintain the stand.

Transition T1A
State 1 to 2

Result: transition from Reference State to State 2 (Sagebrush Steppe with Invasive Species). The Reference State does not have invasive species. State 2 has the same communities but with minor additions of invasive annual grasses such as cheatgrass. Ecological process. Most sites in the Reference State have some scattered cheatgrass seed. This seed is waiting for enough moisture to germinate and to compete with the native species for space, light and moisture. When the right year happens even pristine communities in the Reference State are susceptible to colonization by cheatgrass. Primary Trigger: The transition occurs during a high moisture year that causes a micro-flush of cheatgrass and is the principle means of colonization. Indicators: The occurrence of annual grasses on sites where they had been absent.

Transition T2A
State 2 to 3

Result: Transition from State 2 to State 3, which is dominated by annuals. This transition occurs once the cover of bluebunch wheatgrass declines to less than 10 percent, while invasive species cover is at least 40 percent. This transition can occur with or without sagebrush in the community. Community 2.4 has limited amount of bluebunch wheatgrass and is the community most at risk. Community 2.4 is the segue between State 2 and State 3. Primary Trigger: Chronic heavy grazing, season-long grazing, or late spring grazing. Native species are all but eliminated. Note: chronic season-long grazing in 1880s to 1940s created thousands of acres of annual grass-sagebrush community, and then fire turned that into annual grasses. Annuals such as cheatgrass have 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. 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 7. Ecological Process: Consistent defoliation pressure to bluebunch wheatgrass causes poor vigor, shrinking crowns and plant mortality. With more and more of the soil surface and upper soil rooting surface open, opportunistic, exotic weeds take advantage of the available niche space to colonize and expand until the dominate the community. Indicators: Decreasing 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.

Restoration pathway R3A
State 3 to 4

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 crested 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.

Restoration pathway R4A
State 4 to 2

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, Wyoming big sagebrush, and native forb species. Shifting from State 3 to State 4: If the goal is to restore 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 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, 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 of 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. Introduced grasses must be killed before native species are seeded. 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 sagebrush and 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.

Transition T4A
State 4 to 3

Result: shift from seeded grasses of State 4 to State 3 which is dominated by invasive annual species. Primary Trigger: chronic grazing pressure has significantly reduced seeded grasses 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: A series of frequent fires or, a severe fire that burnt into the root crown of the seeded grasses and gives the competitive advantage to the invasive species. Ecological Process: Consistent defoliation pressure to seeded grasses cause poor vigor, shrinking crowns and plant mortality. With more and more of the soil surface and upper soil rooting surface open, opportunistic, exotic weeds that take advantage of the available niche space to colonize and expand until the dominate the community. Indicators: shrinking crowns and mortality of desirable species, increasing gaps between perennial species, and increasing cover by annual grasses.