Shallow Clay 25-28" PZ
Scenario model
Current ecosystem state
Select a state
Management practices/drivers
Select a transition or restoration pathway
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Transition T1A
Absence of disturbance and natural regeneration over time, may be coupled with excessive grazing pressure
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Transition T1B
Extensive soil disturbance followed by seeding
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Restoration pathway R2A
Adequate rest from defoliation, followed by reintroduction of historic disturbance regimes
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Transition T2A
Absence of disturbance and natural regeneration over time, may be coupled with excessive grazing pressure
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Transition T2B
Extensive soil disturbance followed by seeding
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Restoration pathway R3A
Adequate rest from defoliation and removal of woody canopy
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Transition T3A
Extensive soil disturbance followed by seeding
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Restoration pathway R4A
Absence of disturbance and natural regeneration over time, may be coupled with excessive grazing pressure
More details -
No transition or restoration pathway between the selected states has been described
Target ecosystem state
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State 1
Midgrass/Shortgrass Prairie State
Description
The Midgrass/Shortgrass Prairie Community is the reference community for the Shallow Clay ecological site. In reference conditions, the site is dominated by sideoats grama with lesser amounts of other midgrasses. Little bluestem is found in areas where favorable moisture conditions exist or where inclusions of more advanced soil development have occurred. Buffalograss, curlymesquite, and hairy grama are sub-dominant shortgrasses. Blue grama is a minor, but significant, part of the reference shortgrass component on this site. Perennial forbs are scattered across the site. Shrubs are a minor component of the plant community.
In the Shortgrass/Midgrass Community, sideoats grama declines and shortgrasses such as buffalograss and curlymesquite, dominate the site along with other midgrasses. More annual grasses and forbs begin to appear on the site. Mesquite, lotebush, pricklypear, and tasajillo begin to invade from adjacent sites and the shrub canopy begins to gradually increase.
Submodel
State 2
Shortgrass/Forbs State
Description
The Shortgrass/Forb Community is composed of perennial shortgrasses, including buffalograss, curlymesquite, and threeawns which dominate the site along with annual forbs and grasses. Invading shrubs such as mesquite, lotebush, and pricklypear increase in density and canopy, but their growth habit is stunted because of shallow soils, limited rooting depth, and lack of available moisture. A few individual plants of sideoats grama and Arizona cottontop remain in isolated areas, but silver bluestem, dropseeds, and white tridens are the most common midgrasses.
Submodel
State 3
Annuals/Bare Ground State
Description
Annual forbs such as broomweed are abundant in the Annual Grass/Forb Community. Stunted mesquite, lotebush, and pricklypear are scattered across the site. In the lowest stages of degradation, there is a significant amount of bare ground, and scalded areas are obvious. Some of the scalds are the result of geologic erosion while others are the result of long-term abuse and mismanagement. This plant community is a terminal state that will not return to historic plant communities because of total degradation of the soil, and complete loss of most of the higher successional native plant species.
Submodel
Description
The soils of this site are poorly suited to cultivation or conversion to pastureland because of poor soil-moisture-plant relationship, shallow root zones, and moderate slopes that are susceptible to erosion. A small amount of this site has been cultivated in the past, but very few acres are still planted to annual crops. Those limited areas of cropland remaining are planted to wheat or forage sorghum, but yields are usually low. King Ranch bluestem has been seeded on some areas that were formerly cropland.
Submodel
Mechanism
Abusive grazing is the result of overstocking and continuous grazing for an extended period of time. The consequences of abusive grazing, the lack of fire, and failure to carry out maintenance brush management practices may be intensified by drought conditions. As a result of this level of mismanagement, there is no longer a viable population of late successional grasses. Little bluestem is eliminated and only scattered plants of sideoats grama, Arizona cottontop, vine mesquite still exist. The site is characterized by shortgrasses, encroachment of annual grasses and forbs, an increase in shrubs, and an increase in bare ground.
Mechanism
This is generally not a recommended alternative on this site because the site is poorly suited to use as cropland or conversion to pastureland. Some areas have been seeded to King Ranch bluestem. Seedbed preparation and planting to the desired crop, introduced grass, or native grass is required if this conversion is attempted. Most areas that were cultivated or seeded to introduced species in the past have been abandoned and are now open land dominated by bare ground, annual grasses and forbs, early successional perennial grasses and forbs, and stunted shrubs. The site is highly susceptible to water erosion. This is a terminal state because the soil has been altered and the historic plant species no longer exist on the site.
Mechanism
A prescribed grazing management strategy that emphasizes sustainable stocking rates, rotational grazing, and grazing deferment periods is required to enhance the recovery process in order to return to a midgrass plant community. Periodic prescribed burning is needed to keep woody species under control and encourage diversity in the grass and forb plant community. Brush management with mechanical and/or chemical treatments may be necessary in areas where unwanted woody species have become too dense. Individual plant treatment may be a viable option at this stage. Range planting is needed to re-introduce the desired midgrass and scattered tallgrass species back into the plant community.
Relevant conservation practices
| Practice | External resources |
|---|---|
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Brush Management |
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Prescribed Burning |
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Prescribed Grazing |
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Range Planting |
Mechanism
When abusive grazing continues for an extended period of time, fire is eliminated from the ecosystem, and no brush management is carried out, the site is characterized by bare ground, annual grasses and forbs, early successional perennial grasses and forbs, and stunted shrubs. The site is highly susceptible to water erosion.
Mechanism
This is generally not a recommended alternative on this site because the site is poorly suited to use as cropland or conversion to pastureland. Some areas have been seeded to King Ranch bluestem. Brush management, seedbed preparation and planting to the desired crop, introduced grass, or native grass is required if this conversion is attempted. Most areas that were cultivated or seeded to introduced species in the past have been abandoned and are now open land dominated by bare ground, annual grasses and forbs, low successional perennial grasses and forbs, and stunted shrubs. The site is highly susceptible to water erosion. This is a terminal state because the soil has been altered and the historic plant species no longer exist on the site.
Mechanism
In order to have any possibility of recovery from this state, a carefully planned and implemented prescribed grazing management strategy must be implemented, extensive brush management is required, and range planting is necessary to re-introduce perennial grasses and forbs to the plant community. Since the site is droughty and subject to erosion, this is a difficult, risky, and expensive consideration. If the reseeded areas become established, a prescribed burning management program is needed to maintain balance, diversity, and vigor in the plant community. This is usually not a practical alternative because of the risks and expense involved.
Relevant conservation practices
| Practice | External resources |
|---|---|
|
Brush Management |
|
|
Prescribed Burning |
|
|
Prescribed Grazing |
|
|
Range Planting |
Mechanism
This is generally not a recommended alternative on this site because the site is poorly suited to use as cropland or conversion to pastureland. Brush management, seedbed preparation and planting to the desired crop, introduced grass, or native grass is required if this conversion is attempted. Some areas have been seeded to King Ranch bluestem. Most areas that were cultivated or seeded to introduced species in the past have been abandoned and are now open land dominated by bare ground, annual grasses and forbs, low successional perennial grasses and forbs, and stunted shrubs. The site is highly susceptible to water erosion.
Mechanism
Abusive grazing, lack of fire, lack of brush management, and abandonment are factors that result in these previously treated areas reverting to areas that are dominated by bare ground, annual grasses and forbs, low successional perennial grasses and forbs, and stunted shrubs. The site is highly susceptible to water erosion. In this scenario, this is a terminal state because the soil has been altered and the reference plant species no longer exist on the site.
Model keys
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