Subirrigated
Scenario model
Current ecosystem state
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Management practices/drivers
Select a transition or restoration pathway
- Transition 1A 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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State 1
Reference State
Description
This State represents what is believed to show the natural range of variability that dominated the dynamics of the ecological site prior to European settlement. This site, in the Reference State, is dominated by native warm- and cool-season grasses, forbs, and shrubs. Trace amounts of non-native species, including Kentucky bluegrass and smooth brome, may be present but are not prevalent. During wet years the plant community will respond to a higher water table and grass-like species will increase. During drier years the plant community will be dominated by grasses. Grazing pressure on this site and surrounding sites also influence the plant community dynamics. Heavy grazing will reduce the amount of tall warm-season grasses and increase non-native cool-season grasses. Conversely no use and no fire will cause an increase in litter and potentially an increase in non-native cool-season grasses.
Submodel
Description
This state has been invaded and is dominated by non-native invasive cool-season species. Kentucky bluegrass occurs on this site and drives the successional process. Preliminary studies would indicate that a threshold may exist when Kentucky bluegrass exceeds 30 percent of the plant community and native grasses represent less than 40 percent of the plant community composition. Plant communities dominated by Kentucky bluegrass have significantly less cover and diversity of native grasses and forb species (Toledo, D. et al., 2014). Hoof action during wet periods can potentially cause soil compaction and reduce rooting depth and soil saturation levels. Heavy animal concentrations or cropping on the surrounding landscapes can increase runoff and sedimentation.
Once Kentucky bluegrass becomes established and dominates the ecological dynamics on this site it is unlikely that management alone will be able to provide a restoration pathway back to the Reference State (1.0).
Submodel
Mechanism
Invasion of non-native cool-season grasses in combination with heavy, continuous seasonal grazing will transition the Reference State (1.0) to the Invaded State (2.0). This transition is most likely to occur from PCP 1.2, however the transition could also occur through PCP 1.3 if Kentucky bluegrass invades the plant community.
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.