Semidesert Sand (Cutler Jointfir)

Description

This Reference State describes the natural range of variability as influenced by the ecological dynamics of this site. This state includes those biotic communities that will become established when all successional sequences are completed under a natural disturbance regime. This state has a well developed shrub layer with Cutler jointfir and fourwing saltbush dominating. A mixture of other shrubs including Mexican cliffrose, Torrey jointfir and green rabbitbrush are common. The herbaceous layer is composed of both warm and cool season grasses and a diverse forb community. Utah juniper has been known to invade this site when it is in close proximity to a seed source.

Primary disturbance mechanisms for this site include fire, grazing by native herbivores, prolonged rodent activity, insect herbivory, alluvial deposition and changes in the sites drainage patterns. These disturbances coupled with weather events dictate the dynamics that occur within the natural range of variability. The reference state is self sustaining and resistant to change due to high resistance to natural disturbances and high resilience after natural disturbances. When natural disturbances occur, the rate of recovery is relatively rapid due to niches being filled with highly adapted native vegetation.

Terminology:

Reference State: Community phases influenced by fire, native herbivore grazing, insect herbivory, alluvial deposits, time without disturbance, and climate.

Indicators: A well developed native perennial warm and cool season grass community with a diverse shrub overstory, when present.

Feedbacks: Establishment of non-native invasive species in the understory. Infrequent but regular fires that maintain the perennial grass understory and the establishment of shrubs.

At-risk Community Phase: All communities are at risk for invasion by non-native plants.

Trigger: Establishment of non-native plant species

Submodel

Description

The Current Potential State has invasive, non-native plant species present in all plant community phases. The primary disturbance mechanisms in this state can be natural or human induced. Events, such as improper livestock grazing, prolonged rodent activity, changes in historic fire regimes, improper OHV use, insect herbivory, or drought may influence this site. Any shift in species composition will affect nutrient cycling, soil-water relationships, hydrology, and soil stability.

Dominant grasses include both warm and cool season; however many times heavy spring grazing will remove the cool season grasses and heavy late summer and early fall grazing will remove the warm season grasses. Utah juniper is a common invader on this site potentially creating blowout areas and increasing erosion. This state is losing resistance to disturbances and resilience after disturbance. Invasive plants are beginning to fill the niches and establish on the site.

Terminology:

Current Potential State: Plant communities influenced by both natural and man influenced events, including rodent activity, improper OHV use, livestock grazing, insect herbivory, fire, time with out disturbances, and climatic fluctuations.

Indicators: A perennial cool and warm season grass understory with basin big sage or fourwing saltbush forming the dominant visual aspect, when present. Non-native species are now present in all plant communities.

Feedbacks: Extended drought, improper livestock grazing, or other disturbance that changes the ecological dynamics of the site. Infrequent but regular fires or properly managed domestic livestock grazing to maintain the understory and the establishment of shrubs.

At-risk Community Phase: All communities are at risk; however plant community 2.1 is most at risk due to its limited understory.

Trigger: Disturbance that facilitates the dominance of invasive forbs and/or grasses.

Submodel

Description

The Chained/Disked State of this ecological site has need mechanically altered to remove Utah juniper and or basin big sage. A significant portion of this site has been deep disked to remove all vegetation creating a fertile seedbed for invasive weeds to thrive.

Where chaining has occurred, dominant grasses include both warm and cool season may be recovering; careful livestock management is necessary for good recovery to occur. Where heavy spring grazing is allowed to occur, cool season grasses are removed, and heavy late summer and early fall grazing will remove the warm season grasses.

Following deep disking, all perennial vegetation is removed from the site. This site is then often completely dominated by aggressive invasive annuals.

This state has lost significant resistance to disturbances and resilience after disturbance.

Terminology:

Current Potential State: Plant communities influenced by both natural and man influenced events, including chaining, disking, rodent activity, improper OHV use, livestock grazing, insect herbivory, fire, time with out disturbances, and climatic fluctuations.

Indicators: Non-native species are now present in all plant communities.

Feedbacks: Extended drought, improper livestock grazing, or other disturbance that changes the ecological dynamics of the site.

At-risk Community Phase: All communities are at risk.

Trigger: Disturbance that facilitates the dominance of invasive forbs and/or grasses.

Submodel