Natural Resources
Conservation Service
South Slopes 20-40 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 inappropriate grazing management, catastrophic fire in the presence of exotic annuals
More details -
Restoration pathway R3A
Restoration actions to reduce invasive species
More details -
No transition or restoration pathway between the selected states has been described
Target ecosystem state
Select a state
Description
Site characterized by bunchgrasses, with sparsely distributed shrubs and scrub oak. A disturbance regime of regular surface fire will maintain the community in this phase with white oak and bitterbrush able to resprout following low severity fire. The high precipitation that this site receives may increase site resilience to invasion relative to drier, low elevation sites.
Dominant plant species
Idaho fescue (Festuca idahoensis), grass
bluebunch wheatgrass (Pseudoroegneria spicata), grass
Sandberg bluegrass (Poa secunda), grass
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 exotic annual grasses. This may result in an increase in fire frequency and size thereby maintaining the site in this state (Archer 2001, Zouhar 2003).
Dominant plant species
cheatgrass (Bromus tectorum), grass
medusahead (Taeniatherum caput-medusae), grass
bulbous bluegrass (Poa bulbosa), grass
Submodel
Mechanism
An introduction of invasive annual grasses due to factors such as overgrazing, recreational use, or transport via mechanical means will alter the resilience and resistance of the site to disturbance (Archer 2001).
Transition T2A
Prolonged inappropriate grazing management, catastrophic fire in the presence of exotic annuals
Mechanism
Prolonged inappropriate grazing management leading to a loss of most perennial grasses and a widespread invasion of exotic annual grasses such as cheatgrass. This may also occur following catastrophic fire if exotic annuals were high in cover before disturbance (Archer 2001).
Mechanism
Reduction of invasive species may be possible yet will be time and labor intensive and require significant inputs. Techniques may include prescribed burning, mechanical treatment, herbicide application and reseeding (Archer 2001).
Context dependence
Steep slopes may restrict some activities.
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.
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