Natural Resources
Conservation Service
Scenario model
Current ecosystem state
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Management practices/drivers
Select a transition or restoration pathway
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Transition T1A
Excessive grazing. Lack of fire.
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
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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
alderleaf mountain mahogany (Cercocarpus montanus), shrub
winterfat (Krascheninnikovia lanata), shrub
needle and thread (Hesperostipa comata), grass
little bluestem (Schizachyrium scoparium), grass
Submodel
Description
Species diversity and production have been significantly decreased due to the major reduction of mid- and tallgrass species and key shrubs. Energy flow, water cycle, and mineral cycle have been negatively affected. Litter levels are very low and unevenly distributed. Soil erosion may be a concern on steeper slopes and exposed areas. Greatly reduced infiltration and increased runoff typically cause off-site gully erosion and an ecological threshold has been crossed. Significant biotic and soil changes have negatively impacted energy flow and nutrient and hydrologic cycles. The loss of functional/structural groups such as warm-season midgrass reduces the biodiversity and productivity of this site.
Dominant plant species
soapweed yucca (Yucca glauca), shrub
broom snakeweed (Gutierrezia sarothrae), shrub
blue grama (Bouteloua gracilis), grass
threadleaf sedge (Carex filifolia), grass
Submodel
Description
Soil erosion can be highly variable depending on the amount of ground cover. Typically, there is a large amount of bare ground unless covered by annuals. Runoff is high and infiltration is low. An ecological threshold has been crossed. Erosion and loss of organic matter and carbon reserves are concerns.
Dominant plant species
soapweed yucca (Yucca glauca), shrub
broom snakeweed (Gutierrezia sarothrae), shrub
Fendler threeawn (Aristida purpurea var. longiseta), grass
threadleaf sedge (Carex filifolia), grass
blue grama (Bouteloua gracilis), 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 Sod-bound State. Biotic integrity and hydrologic function are impaired as a result of this transition.
Mechanism
Long-term heavy, continuous grazing without adequate recovery between grazing events and lack of fire cause a shift across an ecological threshold to the Increase Bare Ground State. Erosion and loss of organic matter and carbon reserves are concerns. Annual plants such as sixweeks fescue and cheatgrass are likely to increase or invade as a result of this transition.
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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