State and transition model
State 1
1 Reference State
The reference state includes the historic climax plant community that evolved with the soils and climate in the area. In this state, the plant communities are dominated by warm and cool season grasses with scattered shrubs and trees. With drought, long term winter dominated moisture patterns, grazing and other disturbances, perennial grasses will decrease and shrubs will increase on the site.
Introduced annuals are present in this common resource area, and very minor amounts of these may occur in the plant communities in this state.
Community 1.1
Reference Community
The reference community is dominated by mid and short warm and cool season grasses with a relatively small percentage of forbs and scattered shrubs and half shrubs. Plant species most likely to increase on this site when it is disturbed are broom snakeweed, rabbitbrush and annuals. There will be an increase in juniper on this site in the higher elevation and rainfall areas of this common resource area.
Community 1.2
1.2 Short Grasses/Snakeweed Community
This plant community is characterized by increase of shrubs such as broom snakeweed and Greeneās rabbitbrush. There is a decline of perennial grasses as shrubs increase. Other shrubs that increase include Wyoming big sagebrush at higher precipitation and/or mormon tea on dryer sites.
State 2
2 Natives with Introduced Annuals State
The plant communities in this state include the same species and plant community structures as the reference state. Introduced herbaceous species are now part of those plant communities and compete with native species for available moisture. Disturbances over time, such as fire, drought, and uncontrolled grazing, will now have the potential to allow an increase the introduced species on the site.
Community 2.1
2.1 Grassland/Shrub with Introduced Annuals Community
This plant community is very similar to the historic climax plant community, but it includes introduced exotic annual grasses and forbs that are affecting the biotic integrity of the site.
Community 2.2
2.2 Shortgrass/Snakeweed with Introduced Annuals Community
Introduced annual grasses and forbs are present in the plant community, but the amount and proportions of native plants is similar to that found in plant community 1.2, Shortgrass/Snakeweed.
Community 2.3
2.3 Sagebrush and Juniper with Introduced Annuals Community
This plant community is characterized by a dominance of shrubs and a increase of junipers. Introduced annual grasses and forbs are present in minor amounts in the plant community. Common shrubs include snakeweed, big sagebrush, rabbitbrush, mormon tea and yucca.
Pathway 2.1a
Community 2.1 to 2.2
Unmanaged grazing, drought
Pathway 2.1b
Community 2.1 to 2.3
Continuous improper grazing, drought
Pathway 2.2a
Community 2.2 to 2.1
Time without disturbance, well managed grazing, favorable moisture/climate
Pathway 2.2b
Community 2.2 to 2.3
Unmanaged grazing, soil surface disturbance, reduced perennial grass cover allows favors establishment of woody species, such as sagebrush and/or juniper.
Pathway 2.3a
Community 2.3 to 2.2
Reduction of woody canopy (Fire, prolonged drought), removal of soil disturbances, prescribed grazing.
State 3
3 Disturbed State
Shrubs such as snakeweed and/or rabbitbrush dominate the understory along with junipers. Wind and water caused soil erosion is prevalent creating rills and/or hummocks.
Community 3.1
3.1 Woody Dominated Community
Junipers and shrubs crowds and competes with understory species. Some grasses and forbs remain with annuals. Accelerated erosion occurs with Wind and water erosion is prevalent creating rills and/or hummocks.
Transition T1A
State 1 to 2
Introduction of non-native annuals species creates an irreversible change in the plant community
Transition T2A
State 2 to 3
Severe drought, unmanaged grazing, severe soil disturbances create areas of bare ground, increase erosion with rills and gullies.
Restoration pathway R3A
State 3 to 2
Removal of woody canopy with mechanical treatments or fire, prescribed grazing, seed source of grasses recovery, time without soil surface disturbance