Loamy
Scenario model
Current ecosystem state
Select a state
Management practices/drivers
Select a transition or restoration pathway
- Transition T1A More details
- Transition T1B More details
- Transition T7A More details
- Transition T2A More details
- Transition T2B More details
- Transition T2C More details
- Transition T2D More details
- Transition T7A More details
- Restoration pathway R3A More details
- Transition T3A More details
- Transition T7A More details
- Restoration pathway R4A More details
- Restoration pathway R4B More details
- Transition T7A More details
- Restoration pathway R5A 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
This State represents what is believed to show the natural range of variability that dominated the dynamics in this ecological site prior to European settlement. This State was co-dominated by cool- and warm-season grasses. In pre-European times, the primary disturbance mechanisms for this site in the Reference condition 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. Cool-season and taller warm-season grasses would have declined and a corresponding increase in short, warm-season grasses would have occurred. The Reference State can be difficult to find in this MLRA with the introduction and spread of non-native cool-season grasses.
An alternate plant community phase dominated by tall and mid-warm-season grasses such as big bluestem, sideoats grama, and little bluestem may also have occurred in this State. This plant community phase could have occurred as a result of frequent spring fires or repeated high-intensity grazing in the early part of the growing season. As this community phase was not as common, it is not described in detail in this document.
Submodel
Description
This State represents the more common range of variability that exists with higher levels of grazing management, but in the absence of periodic fire followed by short-term intensive grazing. This State is dominated by native and non-native cool-season grasses, and native warm-season grasses. It can be found on areas that are properly managed with grazing and/or prescribed burning, and sometimes on areas receiving occasional short periods of rest. Native cool-season species can decline and a corresponding increase in short, warm-season grasses or non-native cool-season grasses will occur.
Submodel
Description
The Shortgrass Sod State is dominated by shortgrass species and upland sedges. This State is the result of grazing patterns that do not provide adequate recovery time for cool-season wheatgrasses 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.
Submodel
Description
This State is the result of very heavy concentrated disturbance such as concentrated rodent activity, or livestock concentration areas. This State can also develop as a result of invasion by highly competitive weed species such as Canada thistle, hound’s tongue, leafy spurge, or knapweeds. 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. The percentage of bare ground is also much higher than on any other plant community phase.
Submodel
Description
This 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/or Kentucky bluegrass. Heavy grazing or long-term light grazing (understocked) will tend to result in an increase of smooth bromegrass and or Kentucky bluegrass. 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 would 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
This 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.
The Go-Back (6.1) plant community 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 (6.2) plant community was typically tilled and then seeded to a perennial forage species or mix of species.
Infiltration, runoff, and soil erosion will vary depending on the vegetation present on the site.
Submodel
Mechanism
Invasion and spread of non-native cool-season grasses such as Kentucky bluegrass and smooth bromegrass, and disruption of natural disturbance regimes such as periodic fire followed by short-term high intensity grazing or long-term light grazing, will lead the Western Wheatgrass-Needlegrass-Bluestem Plant Community phase over a threshold to the Native/Invaded State (2.0).
Mechanism
Heavy, continuous seasonal grazing (stocking levels well above carrying capacity for extended portions of the growing season and at the same time of year each year, typically beginning early in the season) or heavy, continuous season-long grazing will convert the Reference State (1.0) to the Shortgrass Sod State (3.0). In addition, invasion of non-native grasses such as Kentucky bluegrass and smooth bromegrass, and disruption of natural disturbance regimes, such as periodic fire followed by short-term high intensity grazing, will exacerbate this transition.
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
Heavy, continuous seasonal grazing (stocking levels well above carrying capacity for extended portions of the growing season, and at the same time of year each year, typically beginning early in the season) or heavy, continuous season-long grazing will convert this plant community to the Shortgrass Sod State (3.0).
Mechanism
Heavy, continuous season-long grazing or a combination of disturbances such as extended periods of below-average precipitation coupled with frequent and severe defoliation will shift this community to the Early Seral State (4.0).
Mechanism
Heavy, continuous seasonal grazing (stocking levels well above carrying capacity for extended portions of the growing season, and at the same time of year each year, typically beginning after early cool-season grasses have reached boot stage), or heavy, continuous season-long grazing, or long-term light grazing will likely lead this State over a threshold to the Invaded State (5.0).
Mechanism
Non-use and no fire for extended periods of time (typically for 10 or more years) will likely lead this State over a threshold resulting in a shift to the Kentucky Bluegrass Plant Community (5.2).
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 (moderate stocking levels coupled with adequate recovery periods, or other grazing systems such as high- density, low-frequency intended to treat specific species dominance, or periodic light to moderate stocking levels, possibly including periodic rest) may lead this plant community over a threshold to the Native/Invaded State (2.0). This will likely take a long period of time, possibly up to 10 years or more, and recovery may not be attainable.
Mechanism
Heavy, continuous season-long grazing and/or frequent severe defoliation or grazing during extended periods of drought will likely move this plant community to the Early Seral 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
Removal of disturbance in combination with long-term prescribed grazing (moderate stocking levels coupled with adequate recovery periods, or other grazing systems such as high-density, low-frequency intended to treat specific species dominance, or periodic light to moderate stocking levels, possibly including periodic rest) and a return to normal precipitation patterns may lead this plant community over a threshold to the Native/Invaded State (2.0). This will likely take a long period of time, possibly up to 10 years or more, and recovery may not be attainable. Depending on the slope, aspect, and size, and if adequate perennial plants exist, this change can occur more rapidly.
Relevant conservation practices
| Practice | External resources |
|---|---|
|
Prescribed Grazing |
Mechanism
Removal of disturbance in combination with long-term prescribed grazing (moderate stocking levels coupled with adequate recovery periods, or other grazing systems such as high-density, low-frequency intended to treat specific species dominance, or periodic light to moderate stocking levels, possibly including periodic rest) and a return to normal precipitation patterns may lead this plant community over a threshold to the Shortgrass Sod State (3.0). This will likely take a long period of time, possibly up to 10 years or more, and recovery may not meet management goals.
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 (moderate stocking levels coupled with adequate recovery periods, or other grazing systems such as high- density, low-frequency intended to treat specific species dominance, or periodic light to moderate stocking levels, possibly including periodic rest) may lead this plant community over a threshold to the Native/Invaded State (2.0). Herbaceous weed control (i.e., herbicide) and or prescribed burning may also be needed to suppress cool-season invasive grasses. This will likely take a long period of time, possibly up to 10 years or more, and recovery may not be attainable. Success depends on whether native reproductive propagules remain intact on the site.
Relevant conservation practices
| Practice | External resources |
|---|---|
|
Prescribed Grazing |
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.