Natural Resources
Conservation Service
Subirrigated (Sb) 10-17” PZ
Scenario model
Current ecosystem state
Select a state
Management practices/drivers
Select a transition or restoration pathway
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Transition T1A
Excessive grazing without adequate recovery periods, or frequent and severe defoliation
More details -
Transition T2A
Long-term excessive grazing, or frequent and severe defoliation without adequate recovery between grazing events, or heavy, excessive grazing with overstocking
More details -
No transition or restoration pathway between the selected states has been described
Target ecosystem state
Select a state
Description
The Reference state is characterized by three distinct plant communities. The plant communities, and various successional stages between them, represent the natural range of variability within the Reference state.
Submodel
Description
This state is characterized by the sod-bound plant community. An ecological threshold has been crossed and a significant amount of production and diversity has been lost when compared to the Reference state. Significant biotic and soil changes have negatively impacted energy flow and the nutrient and hydrologic cycles.
This is a very stable state, resistant to change due to the high tolerance of inland saltgrass to grazing, the development of a shallow root system (root pan), and subsequent changes in hydrology and nutrient cycling. The loss of other functional/structural groups such as cool-season bunch and rhizomatous grasses, forbs, and shrubs reduces the biodiversity productivity of this site.
Submodel
Description
The Increased Bare Ground State develops with heavy, excessive grazing or excessive defoliation. An ecological threshold has been crossed. The Increased Bare Ground State denotes changes in infiltration, runoff, aggregate stability, and species composition. The changes in water movement and the plant community affect changes in hydrologic functionality, biotic integrity, and soil and site stability. Infiltration, runoff, and soil erosion vary depending upon the vegetation present. Erosion and loss of organic matter and carbon reserves are resource concerns. Desertification is advanced.
This alternative state should be tested and refined in future updates through long-term observation of ecosystem behavior, and repeated application of conservation and restoration practices.
Submodel
Transition T1A
Excessive grazing without adequate recovery periods, or frequent and severe defoliation
Mechanism
Excessive grazing without adequate recovery periods, or frequent and severe defoliation, will shift this plant community across an ecological threshold toward the Sod Bound state. Biotic integrity and hydrologic function will be impaired because of this transition.
Transition T2A
Long-term excessive grazing, or frequent and severe defoliation without adequate recovery between grazing events, or heavy, excessive grazing with overstocking
Mechanism
Long-term excessive grazing, or frequent and severe defoliation without adequate recovery between grazing events, or heavy, excessive grazing with overstocking will cause a shift across an ecological threshold to the Increased Bare Ground state.
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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