Loamy 17-20" 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
- Transition T7A More details
- Restoration pathway R2A More details
- Transition T2A More details
- Transition T2B More details
- Transition T7A More details
- Restoration pathway R3A More details
- Transition T3A More details
- Transition T7A More details
- Transition T4A More details
- Transition T4B More details
- Transition T4C More details
- Transition T7A More details
- Transition T5A More details
- Transition T7A More details
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No transition or restoration pathway between the selected states has been described
Target ecosystem state
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Description
The Reference State represents the best estimate of the natural range of variability that dominated the dynamics in this ecological site prior to European settlement. This site in the Reference State (1.0) is dominated by cool-season grasses and subdominant warm-season grasses. Grazing or the lack of grazing, fire, and drought are the major drivers between plant communities. Continuous season-long grazing can push this State to a warm-season shortgrass-dominated State (2.0). Non-use, no fire, and invasion of non-native cool-season grasses will result in a transition to a Native/Invaded State (4.0).
Submodel
Description
The Shortgrass Sod State is dominated by shortgrass species and upland sedges. This State is the result of grazing patterns that did not provide adequate recovery time for cool-season wheat and needlegrasses. The hydrologic function of this site is dramatically altered. Runoff is high and infiltration is low. This State is very resistant to change through grazing management alone.
Historically, rangeland mechanical treatment of this site has been an option used to improve forage production and plant species composition on rangeland. These mechanical treatments include such things as contour furrowing, contour pitting, terracing, chiseling, and disking. The purpose of the practice is to mechanically break up a sod-bound vegetative condition or compacted soils, resulting in less runoff and better infiltration. Many of these treatments were implemented during the 1930s through the 1970s with mixed results. This is primarily due to improper grazing management following the renovation practice. Other drawbacks, in addition to the cost, is these practices result in a near-permanently roughed ground surface.
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 subdominant non-native cool-season grasses. It can be found on areas that are properly managed with grazing and possibly prescribed burning, and on areas receiving occasional short periods of rest. If the native cool-season species decline, a corresponding increase in non-native cool-season grasses can occur. The non-native cool-season grasses will include Kentucky bluegrass, smooth brome, cheatgrass, field brome, and possibly crested wheatgrass.
Submodel
Description
The Invaded State is the result of invasion and dominance of non-native cool-season grass species. This State is characterized by the dominance of smooth brome and Kentucky bluegrass. Heavy grazing or long-term light grazing (understocked) will tend to result in an increase of smooth bromegrass. Non-use and no fire will tend to benefit Kentucky bluegrass due to an increasing thatch layer that effectively blocks the introduction of other plants into the system.
Plant litter accumulation tends to favor the more shade-tolerant introduced grass species. The nutrient cycle is impaired, and the result is typically a higher level of nitrogen which also favors the introduced species. Increasing plant litter decreases the amount of sunlight reaching plant crowns, thereby shifting competitive advantage to shade-tolerant, introduced grass species. Studies indicate that soil biological activity is altered, and this shift apparently exploits the soil microclimate and encourages growth of the introduced grass species. Once the threshold is crossed, a change in grazing management alone cannot cause a reduction in the invasive grass dominance. Preliminary studies tend to indicate this threshold may exist when Kentucky bluegrass exceeds 30 percent of the plant community and native grasses represent less than 40 percent of the plant community composition. Plant communities dominated by Kentucky bluegrass have significantly less cover and diversity of native grasses and forb species (Toledo, D. et al., 2014).
Submodel
Description
The Disturbed State can be transitioned to from any plant community. The two separate vegetative plant communities, Go-back and Seeded, are highly variable in nature. They are derived through different management scenarios and are not related successionally. Infiltration, runoff, and soil erosion will vary depending upon the vegetation present on the site.
The Go-back Plant Community (6.1) was previously tilled for crop production and then abandoned. The plant community that develops on this site will be greatly influenced by the plant communities that are located on adjacent land. The Seeded Plant Community (6.2) was typically tilled and then seeded to a perennial forage species or mix of species.
Submodel
Mechanism
Continuous season-long grazing, continuous seasonal grazing, or heavy grazing in combination with drought will transition the Reference State to the Shortgrass Sod State (2.0). This transition is most likely to occur from the Blue Grama-Buffalograss-Western Wheatgrass Plant Community (1.2).
Mechanism
Heavy, continuous season-long grazing, frequent and severe defoliation, or heavy disturbance will transition the Reference State to the Early Successional State (3.0).
Mechanism
Continuous summer seasonal grazing, 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
Heavy disturbance including soil erosion, tillage, abandoned cropland, or seeding to improved pasture species result in a transition to the Disturbed State (6.0).
Mechanism
Long-term prescribed grazing may potentially convert the plant community to the Reference State (1.0), most probably to the Blue Grama-Buffalograss-Western Wheatgrass Plant Community (1.2), assuming adequate seed and vegetative sources are present. This could require significant time and inputs to achieve and, in the end, may not meet management objectives.
Mechanism
Heavy, continuous season-long grazing, frequent severe defoliation, or heavy disturbance will likely move this plant community to the Early Successional State (3.0).
Mechanism
Long-term prescribed grazing with change in season of use, adequate time for recovery, and a return to normal precipitation patterns will cause a transition. Due to the invasion of non-native cool-season perennial grasses the trajectory of this transition will be towards the Native/Invaded State (4.0). This transition may not be fast or feasible.
Mechanism
Heavy disturbance including soil erosion, tillage, abandoned cropland, or seeding to improved pasture species result in a transition to the Disturbed State (6.0).
Mechanism
Removal of management-induced disturbance coupled with long-term prescribed grazing with change in season of use, and adequate recovery time following grazing may return the Threeawn-Annual plant community 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.
Mechanism
Removal of management-induced disturbance and herbaceous weed control, followed by prescribed grazing that includes proper stocking, change in season of use, and deferment that provides time for adequate recovery will cause a transition. The invasion of non-native cool-season perennial grasses will likely transition this plant community to the Invaded State (5.0). This transition may not meet management objectives.
Mechanism
Heavy disturbance including soil erosion, tillage, abandoned cropland, or seeding to improved pasture species will result in a transition to the Disturbed State (6.0).
Mechanism
Continuous season-long grazing, continuous seasonal grazing, or heavy grazing in combination with drought will transition the Native/Invaded State to the Shortgrass Sod State (2.0).
Mechanism
Heavy, continuous season-long grazing, frequent and severe defoliation, or heavy disturbance will transition the Native/Invaded State to the Early Successional State (3.0).
Mechanism
Continuous seasonal grazing, heavy, continuous season-long grazing, or long-term light grazing will transition the Native/Invaded State to the Invaded State (5.0).
With extended periods of non-use and no fire, heavy litter layer build-up will favor cool-season non-native grasses such as Kentucky bluegrass and other non-native species, and will transition the Native/Invaded State to the Invaded State (5.0).
Mechanism
Heavy disturbance including soil erosion, tillage, abandoned cropland, or seeding to improved pasture species result in a transition to the Disturbed State (6.0).
Mechanism
Herbaceous weed control, followed by long-term prescribed grazing that includes proper stocking, change in season of use, and deferment that provides time for adequate recovery may transition this plant community to the Native/Invaded State (4.0). This transition could require significant time and input to achieve and, in the end, may not meet management objectives.
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.