Shallow Sandy-West (16-20" PZ)
Scenario model
Current ecosystem state
Select a state
Management practices/drivers
Select a transition or restoration pathway
- Transition T1B More details
- Transition T1C More details
- Transition T1A More details
- Restoration pathway R2A More details
- Transition T2B More details
- Transition T2A More details
- Restoration pathway R3A More details
- Transition T3A More details
- Transition T4A More details
- Transition T4B More details
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No transition or restoration pathway between the selected states has been described
Target ecosystem state
Select a state
Description
The Reference State represents what is believed to show the natural range of variability that dominated the dynamics of the ecological site prior to European settlement. This site in the Reference State (1.0) is dominated by warm-season grasses, with cool-season grasses being subdominant. In pre-European times, the primary disturbance mechanisms included frequent fire and grazing by large herding ungulates. Timing of fires and grazing coupled with weather events dictated the dynamics that occurred within the natural range of variability. Taller cool- and warm-season grasses would have declined and a corresponding increase in short statured grass and grass-like species would have occurred. Today, a similar state can be found on areas that are properly managed with grazing and prescribed burning and sometimes on areas receiving occasional short periods of rest. The Reference State is susceptible to invasion of non-native cool-season grasses and the encroachment of conifers from adjacent sites.
Submodel
Description
This state is a result of continuous season-long grazing, or continuous seasonal grazing, or heavy grazing during extended periods of drought. This type of grazing causes reduced vigor of the selected species (i.e., typically the most desired by grazing ungulates). As the photosynthetic area of these species is repeatedly removed, carbohydrate production needed for root respiration is inadequate and the root systems of these species begin to falter. The shorter, more grazing tolerant species are given the advantage and will dominate the site. In the early stages of this state, mid- and tall grass remnants may be present in sufficient quantities to allow for recovery to the Reference State (1.0). Over time, this recovery will become less likely due to higher runoff and reduced infiltration.
Submodel
Description
The Early Successional State is the result of very heavy, concentrated disturbance such as intense rodent activity, or livestock concentration areas. This State can also develop as a result of invasion by highly competitive or noxious weed species. Extended periods of drought accompanied by heavy grazing can also push an at-risk plant community phase to this state. In most cases, this phase is dominated by pioneer perennial and annual grass and forb species. Bare ground is also much higher than on any other plant community phase.
Submodel
Description
The Native/Invaded State is dominated by native cool- and warm-season grasses, and sub-dominant non-native cool-season grasses. It can be found on areas that would appear to be properly managed with grazing and possibly prescribed burning. Extended periods of non-use and no fire, or long-term light grazing can result in the invasion and establishment of non-native cool-season grasses onto this site. If the native cool-season grasses decline a corresponding increase of non-native cool-season grasses can occur. The non-native cool-season grasses will include, cheatgrass, field brome, Kentucky bluegrass, and smooth brome.
Submodel
Mechanism
Continuous grazing (stocking levels above carrying capacity for extended portions of the growing season); continuous seasonal grazing (spring or fall); or heavy grazing in combination with drought will result in a transition from the Reference State (1.0) to the Shortgrass Sod State (2.0). This transition will most likely occur from the Needle and Thread-Blue Grama/Sedge Plant Community (1.2).
Mechanism
Heavy, continuous season-long grazing; frequent and severe defoliation; or heavy disturbance will transition the Reference State (1.0) to the Early Successional State (3.0).
Mechanism
Continuous seasonal grazing (summer); long-term light grazing; or no use and no fire; and the invasion of non-native cool-season grasses will transition the Reference State (1.0) to the Native/Invaded State (4.0).
Mechanism
Long-term prescribed grazing including proper stocking rates, change in season of use, adequate time for plant recovery; and a return to normal precipitation patterns following drought will transition the Shortgrass Sod State (2.0) to the Reference State (1.0). This transition may not be fast or feasible.
Relevant conservation practices
| Practice | External resources |
|---|---|
|
Prescribed Grazing |
Mechanism
Heavy, continuous season-long grazing; or frequent and severe defoliation; or heavy disturbance will transition the Shortgrass Sod State (2.0) to the Early Successional State (3.0).
Mechanism
Invasion of non-native cool-season grasses combination with a grazing system that allows these non-native grass species to continue to invade and persist on the site will result in a transition from the Shortgrass Sod State (2.0) to the Native/Invaded State (4.0). Normal to above normal precipitation patterns may aid in this transition, especially if it is early spring or late fall precipitation.
Mechanism
Removal of disturbances coupled with long-term prescribed grazing with change in season of use, and adequate recovery time following grazing may return the Early Successional State (3.0) to the Shortgrass Sod State (2.0). Herbaceous weed control may also be needed. This transition could require significant time and input to achieve and, in the end, may not meet management objectives.
Relevant conservation practices
| Practice | External resources |
|---|---|
|
Prescribed Grazing |
|
|
Herbaceous Weed Control |
Mechanism
Removal of disturbances; herbaceous weed control; possibly seeding to native species; followed by prescribed grazing that includes proper stocking, change in season of use, and deferment that provides time for adequate recovery may transition the Early Successional State (3.0) to the Native/Invaded State (4.0). This transition may not be fast or meet management objectives.
Relevant conservation practices
| Practice | External resources |
|---|---|
|
Prescribed Grazing |
|
|
Herbaceous Weed Control |
Mechanism
Continuous grazing (stocking levels above carrying capacity for extended portions of the growing season); continuous seasonal grazing (spring or fall); or heavy grazing in combination with drought will result in a transition the Native/Invaded State (4.0) to the Shortgrass Sod State (2.0).
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.