The Grassland State defines the ecological potential and the natural range of variability resulting from the natural disturbance regime of the Shallow Red Plains ecological site. This state is supported by empirical data, historical data, local expertise, and photographs. It is defined by two native plant communities that are a result of periodic fire, drought, and grazing. These events are part of the natural disturbance regime and climatic process. The Reference Plant Community consists of warm-season mid-, tall- and shortgrasses, cool season, and sod-forming grasses, forbs, and shrubs. The Midgrass and Shortgrass Plant Community is made up primarily of warm-season mid- and shortgrasses.
Characteristics and indicators
Midgrasses account for greater than 40% by weight of the Grassland State. When shortgrasses become the dominant species this state has crossed a threshold into the Shortgrass State.
Resilience management
Managing for the midgrass (little bluestem and sideoats grama) key forage species by incorporating a forage and animal balance, will sustain the Grassland State and prevent a species composition change resulting in a transition to the Shortgrass State.
With heavy, continuous grazing, blue grama and buffalograss will become the dominant species and have a sod-bound appearance. Unable to withstand the grazing pressure, only a remnant population of western wheatgrass remains.
Species diversity has been reduced further. Water infiltration is reduced and runoff is increased due to the sod nature of the blue grama and buffalograss.
Specific dynamic soil property changes between the Grassland State and the Sod-bound State has been documented. As plant community cover decreases from bunchgrasses to more of the sod grasses there is a decrease in infiltration and interception and an increase in surface runoff (Thurow T., 2003).
Characteristics and indicators
Shortgrass species make up greater than 40 percent by weight of the plant community.
Resilience management
This state is stable and does not transition to another state.
Long-term management (approximately 30 years) without a forage and animal balance and heavy, stocking rates without adequate recovery periods between grazing events will convert the Grassland State to a Shortgrass State made up of blue grama and buffalograss sod. Drought, in combination with this type of management, will quicken the rate at which this transition occurs.
Constraints to recovery
The hydrologic and nutrient cycles are the ecological processes affected. There is an increase in evaporation rate, runoff, and in bulk density. There is a decrease in infiltration, a change in plant composition, and the functional and structural groups have changed dominance. These are all examples of the soil and vegetation properties that have compromised the resilience of the Grassland State, and therefore transitioned to a Shortgrass State.
Context dependence
The amount of time it takes for this transition to occur will vary.
Model keys
Briefcase
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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.
) icon wherever it occurs. Drag and drop items to reorder. Cookies are used to store briefcase items between browsing sessions. Because of this, the number of items that can be added to your briefcase is limited, and briefcase items added on one device and browser cannot be accessed from another device or browser. Users who do not wish to place cookies on their devices should not use the briefcase tool. Briefcase cookies serve no other purpose than described here and are deleted whenever browsing history is cleared.
