Shallow Clay
Scenario model
Current ecosystem state
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Management practices/drivers
Select a transition or restoration pathway
- Transition T1b More details
- Transition T1b More details
- Transition T1c More details
- Restoration pathway R2 More details
- Transition T2 More details
- Restoration pathway R3 More details
- Transition T3 More details
- Restoration pathway R4 More details
- Restoration pathway R4 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 the natural range of variability that dominates the dynamics of this ecological site (ES). This state is codominated 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. Today, this state 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. The dominant cool- and warm-season species can decline and a corresponding increase in short-statured species will occur.
Submodel
Description
This state consists of areas where tree canopy increases to a level that impedes the reproductive capability of the major native perennial grass species. The increase in tree canopy is a result of a disruption of the natural historic fire regime that kept the trees at an immature stage.
Submodel
Description
This state is the result of invasion and dominance of introduced species. This state is characterized by the dominance of Kentucky bluegrass and smooth bromegrass and an increasing thatch layer that effectively blocks introduction of other plants into the system. Plant litter accumulation tends to favor the more shade tolerant introduced grass species. The nutrient cycle is also 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.
Submodel
Mechanism
Prescribed grazing (alternating season of use and providing adequate recovery periods) or periodic light to moderate grazing possibly including periodic rest will convert this plant community to the 1.1 Needlegrass/Bluestem/Western Wheatgrass Plant Community Phase.
Mechanism
No fire for extended periods of time will lead the Reference State (State 1) across a threshold resulting in the Increased Tree Canopy State (State 3). This transition also requires the presence of eastern redcedar and/or Rocky Mountain juniper, or other trees that can increase on this site. It is a result of a disruption of the natural historic fire regime that occurred in the past.
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 the 4.1 Smooth Bromegrass/Kentucky Bluegrass Plant Community Phase within the Invaded State (State 4).
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 phase over a threshold to the Reference State (State 1). This will likely take a long period of time, possibly up to 10 years or more, and recovery may not be attainable. Under certain circumstances, the harsh conditions created by the shortgrass sod can lead to the elimination of invasive grass species such as Kentucky bluegrass and smooth bromegrass.
Relevant conservation practices
| Practice | External resources |
|---|---|
|
Prescribed Grazing |
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 4.2 Annual/Pioneer Perennial Sod Plant Community Phase and the Invaded State (State 4).
Mechanism
Prescribed burning in conjunction with long-term prescribed grazing may lead this plant community across a threshold back to the Reference State (State 1). This would have to take place before the trees reach maturity and are still susceptible to fire and reproductive propagules of the perennial grasses are still present.
Relevant conservation practices
| Practice | External resources |
|---|---|
|
Prescribed Grazing |
Mechanism
Wildfire that is intense enough to crown and kill mature trees will cause this plant community to cross a threshold and lead to the Invaded State (State 4) and specifically to the Annual/Pioneer Perennial Plant Community Phase (4.2).
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 phase over a threshold to the Reference State (State 1). 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 |
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 phase over a threshold to the Reference State (State 1). 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 |
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.