Shallow Slopes 14-20 PZ
Scenario model
Current ecosystem state
Select a state
Management practices/drivers
Select a transition or restoration pathway
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Transition T1A
Introduction of invasive annual grasses
More details -
Transition T2A
Prolonged improper grazing management
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Transition T2B
Prolonged fire suppression
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Restoration pathway R3A
Restoration of native grasses
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Restoration pathway R4A
Reduction of juniper
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Transition T4A
Failed rehabilitation action, catastrophic fire
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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 grass-shrub site is characterized by a high cover of palatable perennial grasses and shrubs in the Reference State. Multiple communities may exist with varying compositions of grasses and shrubs driven by fire, climate cycles and ungulate grazing. A variety of forbs are common. No invasive annual grasses are present in this state.
Submodel
Description
This state is similar to the Reference State. Ecological function and structure has not changed fundamentally, however the resiliency of the site has been reduced by the presence of invasive plants. Non-native plant species may increase in abundance but will not become dominant or control ecological processes within this state.
Submodel
Description
Much of the perennial grasses have been lost and replaced by medusahead and cheatgrass. This may result in an increase in increase in fire frequency and size thereby maintaining the site in this state (Archer 2001, Zouhar 2003).
Mechanism
An introduction of invasive annual grasses due to factors such as overgrazing, recreational use, dispersal from invaded sites, or transport via mechanical means will alter the resilience and resistance of the site to disturbance (Archer 2001).
Mechanism
Prolonged improper grazing management leading to a loss of most perennial grasses and a widespread invasion of medusahead and cheatgrass. This may also occur following catastrophic fire if exotic annuals were high in cover before disturbance (Archer 2001).
Context dependence
A seed source of exotic annuals is required to be on site or adjacent sites for invasion to occur following these disturbances
Mechanism
With prolonged fire suppression, western juniper will continue to establish and recruit into the canopy.
Context dependence
This dynamic may be further accelerated by continued livestock grazing of herbaceous and shrub communities.
Mechanism
Restoration of native grasses on the site may be achieved in some cases. Techniques may include prescribed burning, mechanical treatment herbicide application and reseeding (Archer 2001). Steep slopes may restrict some activities.
Mechanism
Reduction of juniper is possible yet may be costly and time consuming at large scale. Mechanical reduction of juniper followed by prescribed fire may be effective on some sites.
Mechanism
Depending on site resiliency, treatment techniques used and the prior presence of exotic annual grasses, restoration actions may encourage exotic annual grass expansion. Catastrophic fire in the presence of significant cover of exotic annual grasses may also result in expansion of cover.
Model keys
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Ecological sites
Major Land Resource Areas
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.