This state includes the biotic communities that become established on the ecological site if all successional sequences are completed under the natural disturbance regimes. The reference state is generally dominated by Utah juniper, and twoneedle pinyon, however depending on disturbance history, native grasses, forbs, or other shrubs may occupy significant composition in the plant community. The primary disturbance mechanism is climate fluctuation. During long periods of drought, this site may lose the two-needle pinyon (phase 1.2). The reference state is self sustaining and resistant to change due to high resistance to natural disturbances and high resilience following natural disturbances. When natural disturbances occur, the rate of recovery is variable. Typically, in the reference state this site will fluctuate between community phases 1.1 and 1.2; however once invasive plants establish, return to these community phases may not be possible.
Reference State: Plant communities influenced by insect herbivory, and climate fluctuations.
Indicators: A community dominated by Utah juniper, where twoneedle pinyon shrubs, and native perennial grasses and forbs may or may not be present.
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.
The current potential state is similar to the reference state; however invasive species are present in all community phases. This state is generally dominated by Utah juniper and twoneedle pinyon, however depending on disturbance history, native grasses, forbs, or other shrubs may dominate the site. Primary disturbance mechanisms include climate fluctuations, insect herbivory, domestic livestock grazing, and surface disturbances such as road and pipeline development and off road vehicle (OHV) use. Due to lack of disturbed areas, the community responses to such disturbances are not documented are not currently included in the state and transition model. The current potential state is still self sustaining; but is losing resistance to change due to lower resistance to disturbances and lower resilience following disturbances, and new drastic disturbances such as fire being more likely to occur. Typically in the current potential state this site will fluctuate between community phases 2.1 and 2.2.
Current Potential State: Plant communities influenced by insect herbivory, climate fluctuations, and surface disturbances.
Indicators: A community dominated by Utah juniper where twoneedle pinyon, shrubs and native perennial grasses and forbs may or may not be present. Invasive grasses and forbs are present.
This transition is from the native perennial warm and cool season grass understory in the reference state to a state that contains invasive species. Events include intense continuous grazing of perennial grasses, prolonged drought, and surface disturbances, etc. However invasive species such as cheatgrass have been known to invade intact perennial plant communities with little to no disturbances. Once invasive plants are found in the plant community a threshold has been crossed.
Model keys
Briefcase
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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.
) icon wherever it occurs. Drag and drop items to reorder. Cookies are used to store briefcase items between browsing sessions. Because of this, the number of items that can be added to your briefcase is limited, and briefcase items added on one device and browser cannot be accessed from another device or browser. Users who do not wish to place cookies on their devices should not use the briefcase tool. Briefcase cookies serve no other purpose than described here and are deleted whenever browsing history is cleared.
