Semidesert Shallow Sandy Loam (Utah Juniper/Two-Needle Pinyon)
Scenario model
Current ecosystem state
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Management practices/drivers
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- Transition T1A More details
- Transition T2A More details
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No transition or restoration pathway between the selected states has been described
Target ecosystem state
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Description
This state describes the biotic communities that may become established on this ecological site if all successional sequences are completed under natural disturbance conditions. The reference state is generally dominated by an overstory canopy of Utah juniper with lesser amounts of two-needle-pinyon. Alderleaf mountain mahogany and black sagebrush are the dominate shrubs. Indian ricegrass and James galleta are the most common grasses. Other native grasses, forbs, and shrubs may produce significant composition in the plant community.
The primary disturbance mechanisms are overstory canopy density, weather fluctuation, and fire. The reference state is self sustaining and resistant to change due to a high resistance to natural disturbances and a high resilience following those disturbances. When natural disturbances occur, the rate of recovery can be quite variable. Typically in the reference state, this ecological site will fluctuate between community phases 1.1 and 1.2.
Reference State: Plant communities influenced by canopy density, long term weather fluctuations, and periodic fire.
Indicators: A community dominated by Utah juniper, two-needle-pinyon, alderleaf mountain mahogany and black sagebrush. The density of the overstory canopy determines the amount and composition of the other native perennial grasses and forbs that may be present.
Feedbacks: Natural fluctuations in weather patterns that allow for a self sustaining Utah juniper, two-needle-pinyon, alderleaf mountain mahogany, black sagebrush and native grass community. Insect herbivory, more frequent fires, or other disturbances that may allow for the establishment of invasive species.
At-risk Community Phase: All communities are at risk when native plants are stressed and nutrients become available for invasive plants to establish.
Trigger: The establishment of invasive plant species.
Submodel
Description
The current potential state is similar to the reference state, however invasive species are now present in all community phases. This state is generally dominated by Utah juniper with lesser amounts of two-needle pinyon present. Alderleaf mountain mahogany and black sagebrush are the most common shrubs. Depending on the sites disturbance history, native perennial grasses, forbs, or other shrubs may be common in the sites understory. Primary disturbance mechanisms are thought to include long-term weather fluctuations, insect herbivory, improper livestock grazing, fire interval and surface disturbances such as road and pipeline development and off road vehicle (OHV) use. Few disturbed sites have been located to date and so little data exists regarding them. The current potential state is still self sustaining but has less resistance to change due to lower resistance to disturbances and lower resilience following disturbances. This state will typically fluctuate between community phases 2.1 and 2.2.
Current Potential State: Plant communities influenced by livestock grazing, wildlife browsing, insect herbivory, weather fluctuations, fire periods and surface disturbances.
Indicators: A community dominated by Utah juniper, two-needle pinyon and black sagebrush where other shrubs and native perennial grasses and forbs may also be present. Invasive grasses and forbs are present.
Feedbacks: Natural fluctuations in weather that allow for a self sustaining Utah juniper, two-needle pinyon, black sagebrush and grass community.
Submodel
Description
This state occurs when the site is chained to remove Utah juniper and two-needle pinyon trees. Following the chaining this area may or may not be burned and then seeded to native or introduced species such as Indian ricegrass or crested wheatgrass. Where sufficient understory species are present, the site might be allowed to recover naturally following the chaining.
Submodel
Mechanism
This transitional pathway occurs when improper livestock grazing causes the perennial herbaceous community to become significantly reduced allowing non-native species such as cheatgrass, russian thistle and other invasive weeds to become established. Broom snakeweed may also increase during this time. Once invasive species occupy the site, a threshold has been crossed. Cheatgrass has been known to become established in healthy communities on this site, however.
Mechanism
This transitional pathway occurs when the site is chained and seeded to introduced species including creasted wheatgrass and intermediate wheatgrass. During seeding establishment non-native species such as cheatgrass, russian thistle and ragweed species may also become established. Broom snakeweed may increase during this time. Once introduced and invasive species occupy the site, a threshold has been crossed.
Model keys
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The Ecosystem Dynamics Interpretive Tool is an information system framework developed by the USDA-ARS Jornada Experimental Range, USDA Natural Resources Conservation Service, and New Mexico State University.