Natural Resources
Conservation Service
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. Lack of fire.
More details -
Transition T1B
Mechanical tillage.
More details -
Transition T2A
Excessive grazing. Lack of fire.
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 community phases. The plant communities and various successional stages between them represent the natural range of variability within the Reference state.
Dominant plant species
fourwing saltbush (Atriplex canescens), shrub
winterfat (Krascheninnikovia lanata), shrub
alkali sacaton (Sporobolus airoides), grass
western wheatgrass (Pascopyrum smithii), grass
Submodel
Description
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 edaphic (soil characteristic) changes have negatively impacted energy flow and nutrient and hydrologic cycles.
This is a very stable state, resistant to change due to the high tolerance of blue grama and buffalograss to grazing, the development of a shallow root system (aka rootpan), and subsequent changes in hydrology and nutrient cycling. The reduction of other functional/structural groups such as cool-season bunchgrasses, warm-season bunchgrasses, forbs, and shrubs, reduces the biodiversity and productivity of this site.
Dominant plant species
fourwing saltbush (Atriplex canescens), shrub
winterfat (Krascheninnikovia lanata), shrub
blue grama (Bouteloua gracilis), grass
buffalograss (Bouteloua dactyloides), grass
Submodel
Description
This state lacks stability, diversity, and productivity. Bare ground is a major concern, erosion potential is high, and soil loss can be severe. An ecological threshold has been crossed and it is in an extremely degraded condition.
Dominant plant species
plains pricklypear (Opuntia polyacantha), shrub
broom snakeweed (Gutierrezia sarothrae), shrub
Fendler threeawn (Aristida purpurea var. longiseta), grass
sand dropseed (Sporobolus cryptandrus), grass
burningbush (Bassia scoparia), grass
Russian thistle (Salsola), grass
Submodel
Description
The Tilled state is the result of the site being mechanically disturbed to facilitate conversion to production agriculture. An ecological threshold has been crossed due to the complete removal of vegetation and physical, chemical, and biological alterations of the soil.
Dominant plant species
cheatgrass (Bromus tectorum), grass
Fendler threeawn (Aristida purpurea var. longiseta), grass
burningbush (Bassia scoparia), grass
Russian thistle (Salsola), grass
Submodel
Mechanism
Continuous, heavy grazing without adequate recovery periods between grazing events and lack of fire shifts this plant community across an ecological threshold to the Warm-season Shortgrass Dominant State.
Mechanism
Tillage of this ecological site will cause an immediate transition across an ecological threshold to the Tilled State. This transition can occur from any plant community and it is irreversible.
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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