Sodic Plains
Scenario model
Current ecosystem state
Select a state
Management practices/drivers
Select a transition or restoration pathway
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Transition 1.2 to 2
Long-term, heavy, stocking rates.
More details -
Transition 1 to 3
Mechanical tillage
More details -
No transition or restoration pathway between the selected states has been described
Target ecosystem state
Select a state
Description
The Grassland State defines the ecological potential and natural range of variability resulting from the natural disturbance regime of the Sodic Plains ecological site. This state is supported by empirical data, historical data, local expertise, and photographs. It is defined by a suite of 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.
Characteristics and indicators
The Grassland State is made up of two native plant communities. The Reference Plant Community consists of warm-season mid- and shortgrasses, cool-season and sod-forming grasses, forbs, and shrubs. The shortgrass/midgrass community is made up primarily of warm-season shortgrasses, with an interspersed cool-season component and decreasing amounts of forbs and midgrasses.
Resilience management
This is a stable state when grazing is adequately managed. A prescribed grazing program that incorporates proper stocking rates during the growing season will maintain this state.
Submodel
Description
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.
Characteristics and indicators
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 have been documented. As plant community cover decreases from bunchgrasses to more of the sodgrasses, there is a decrease in infiltration and interception and an increase in surface runoff (Thurow T., 2003).
Resilience management
This is a stable state that can be maintained by providing a forage and animal balance during the growing season.
Submodel
Description
The Tillage State consists of abandoned cropland that has been naturally revegetated (go-back) or planted/seeded to grassland. Many reseeded plant communities were planted with a local seeding mix under the Conservation Reserve Program (CRP) or were planted to a monoculture of sideoats grama. Go-back communities are difficult to define due to the variability of plant communities that can exist. Many of these communities are represented by the genus Aristida (threeawns).
Characteristics and indicators
This is an alternative state since the energy, hydrologic, and nutrient cycles are altered to that of the Reference State in its natural disturbance regime. Bulk density, aggregate stability, soil structure, and plant functional and structural groups are not fully restored to that of the Reference State. Mechanical tillage can destroy soil aggregation. Soil aggregates are an example of dynamic soil property change. Aggregate stability is critical for infiltration, root growth, and resistance to water and wind erosion (Brady and Weil, 2008).
Resilience management
This state will not transition to other states due to the inherited soil properties from years of tillage.
Submodel
Mechanism
Long-term management (approximately 30 years) without a forage and animal balance and heavy, continuous grazing 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.
Mechanism
This transition is triggered by a management action as opposed to a natural event. Tillage, or breaking the ground with machinery for crop production, will move the Grassland State to a Tillage State.
Constraints to recovery
The resilience of the Reference State has been compromised by the fracturing and blending of the native virgin sod. The energy, hydrologic, and nutrient cycles are altered and vary from that of the Grassland State.
Model keys
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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.