State and transition model
State 1
State 1
Reference State
State 1
Reference State
The reference state includes the historic climax plant community that evolved over time with the soil forming process and long term changes in climatic conditions of the area. It is the native plant community that is best adapted to the unique combination of environmental factors associated with the site.
Community 1.1
Community 1.1
Shadscale saltbush/perennial warm and cool season grasses/native annuals
Community 1.1
Shadscale saltbush/perennial warm and cool season grasses/native annuals
The dominant aspect of this site is a shrub-grassland. Shadscale saltbush dominates both the visual aspect and the production in pounds of the site. Several other shrubs, including Ephedra and several cactus species are common, but make up only a small proportion of the aspect. Perennial grasses, both warm and cool season, are common, but sub-dominate to shadscale saltbush. Common warm season grasses include sand dropseed and galleta. Common cool season grasses include Indian ricegrass and squirreltail. The occurrence and production of sand dropseed may be expected to decrease in years of below average warm season precipitation and increase in years of above average warm season precipitation. The same can be expected of squirreltail except a decrease would be the result of below average cool season precipitation and an increase due to above average cool season precipitation. Cool season annuals may increase as a result of above average cool season precipitation and decrease as a result of below average cool season precipitation.
Community 1.2
Community 1.2
Shadscale saltbush/native annuals/perennial warm and cool season grasses
Community 1.2
Shadscale saltbush/native annuals/perennial warm and cool season grasses
The dominant aspect of this site is a shrub-grassland. Shadscale saltbush dominates both the visual aspect and the production in pounds of the site. Several other shrubs, including Ephedra and several cactus species are common, but make up only a small proportion of the aspect. Perennial grasses, both warm and cool season, are common, but sub-dominate to shadscale saltbush. Annuals and unpalatable perennial plants have become a major component, possibly more common than perennial grasses.
Pathway 1.1A
Community 1.1 to 1.2
Severe extended drought or/and extreme herbivory combined with severe soil surface disturbance weakens perennial plants providing annuals and unpalatable and drought tolerant perennial plants a competitive edge.
Pathway 1.2A
Community 1.2 to 1.1
Return to more normal precipitation amounts or/and removal of any extreme herbivory and severe soil surface disturbance allows perennial plant populations reduced due to drought or extreme herbivory to regain vigor and, over time, increase to "normal" amounts.
State 2
State 2
Natives / Introduced State
State 2
Natives / Introduced State
This state is very similar to the reference state, but exotic annuals have been introduced into the site. Observations to date indicate once these exotic annuals have been introduced into the plant community they cannot be removed completely, for an extended period of time, from the plant community.
Community 2.1
Community 2.1
Shadscale saltbush/perennial warm and cool season grasses/native and exotic annuals
Community 2.1
Shadscale saltbush/perennial warm and cool season grasses/native and exotic annuals
The dominant aspect of this site is a shrub-grassland. Shadscale saltbush dominates both the visual aspect and the production in pounds of the site. Several other shrubs, including Ephedra and several cactus species are common, but make up only a small proportion of the aspect. Perennial grasses, both warm and cool season, are common, but sub-dominate to shadscale saltbush. Common warm season grasses include sand dropseed and galleta. Common cool season grasses include Indian ricegrass and squirreltail. The occurrence and production of sand dropseed may be expected to decrease in years of below average warm season precipitation and increase in years of above average precipitation. The same can be expected of squirreltail except a decrease would be the result of below average cool season precipitation and an increase due to above average cool season precipitation. Exotic annuals occur in minor amounts. Cool season annuals, including exotic annuals, may increase as a result of above average cool season precipitation and decrease as a result of below average cool season precipitation.
Community 2.2
Community 2.2
Shadscale saltbush/exotic and native annuals/perennial warm and cool season grasses
Community 2.2
Shadscale saltbush/exotic and native annuals/perennial warm and cool season grasses
The dominant aspect of this site is a shrub-grassland. Shadscale saltbush dominates both the visual aspect and the production in pounds of the site. Several other shrubs, including Ephedra and several cactus species are common, but make up only a small proportion of the aspect. Perennial grasses, both warm and cool season, are common, but sub-dominate to shadscale saltbush. Annuals, including exotic annuals, and unpalatable perennial plants have become a major component, possibly more common than perennial grasses.
Community 2.3
Community 2.3
Globemallow/shadscale saltbush/perennial warm and cool season grasses/native and exotic annuals
Community 2.3
Globemallow/shadscale saltbush/perennial warm and cool season grasses/native and exotic annuals
Globemallow, acting as a pioneer plant, has filled the void left by the shrubs and perennial warm and cool season grasses killed by prolonged drought.
Pathway 2.1A
Community 2.1 to 2.2
Severe extended drought or/and extreme herbivory combined with severe soil surface disturbance weakens perennial plants providing annuals and unpalatable and drought tolerant perennial plants a competitive edge.
Pathway 2.1B
Community 2.1 to 2.3
Severe, prolonged drought results in substantial death of shrubs and perennial warm and cool season grasses, followed by normal or above normal precipitation that allows the pioneer plant globemallow to establish.
Pathway 2.2A
Community 2.2 to 2.1
Return to more normal precipitation amounts or/and removal of any extreme herbivory and severe soil surface disturbance allows perennial plant populations reduced due to drought or extreme herbivory to regain vigor and, over time, increase to "normal" amounts.
Pathway 2.3A
Community 2.3 to 2.1
Return to normal precipitation in the absence of severe disturbance.
Transition T1A
State 1 to 2
Exotic annuals are introduced into the ecosystem.