Sandy 22-25" PZ
Scenario model
Current ecosystem state
Select a state
Management practices/drivers
Select a transition or restoration pathway
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Transition T1A
Long-term (> 10 years), heavy defoliation through grazing or haying.
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Transition T1B
Long-term (> 10 years), heavy, grazing during summer months or prolonged (>10 years) absence of grazing and fire.
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Transition T1C
Woody encroachment with no fire or brush management.
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Transition T1D
Tillage to facilitate production agriculture.
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Restoration pathway R2A
Long-term (>15 years) prescribed grazing. This restoration may not be feasible.
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Transition T2A
Long-term (> 10 years), heavy, grazing during summer months.
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Transition T2B
Woody encroachment with no fire or brush management.
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Transition T2C
Tillage to facilitate production agriculture.
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Restoration pathway R3A
Long-term (>15 years) prescribed grazing. This restoration may not be feasible.
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Restoration pathway R3B
Long-term (>15 years) prescribed grazing. This restoration may not be feasible.
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Transition T3A
Woody encroachment with no fire or brush management.
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Transition T3B
Tillage to facilitate production agriculture.
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Restoration pathway R4A
Prescribed burning, timber harvest, brush management.
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Restoration pathway R4B
Prescribed burning, timber harvest, brush management.
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Restoration pathway R4C
Prescribed burning, timber harvest, brush management.
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Restoration pathway R4D
Prescribed burning, timber harvest, brush management.
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Transition T5A
Woody encroachment with no fire or brush management.
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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 (1) describes the range of vegetative communities that occur on the Sandy 22-25" PZ ecological site where the range of natural variability under historic conditions and disturbance regimes is mostly intact. The Reference State developed under the combined influences of climatic conditions, periodic fire activity, grazing by large herbivores, and impacts from small mammals and insects. High perennial grass cover and production allows for increased soil moisture retention, vegetative production and overall soil quality.
The Reference State includes three community phases which are the Reference Community (1.1) and the At-Risk Community (1.2). The Reference Community serves as a description of the native plant community that naturally occurs on the site when the natural disturbance regimes are intact or closely mimicked by management practices. The At-Risk Community results from management actions that are unfavorable for a healthy Reference Community.
Submodel
Description
The Degraded Native Grass State (2) transitioned from the Reference State (1) and much of the native warm-season tall- and midgrass components have been replaced by warm-season shortgrasses, cool-season grasses, and upland sedges. This State is the result of long-term grazing management that did not provide adequate recovery time for warm-season tall- and midgrasses and cool-season bunchgrasses. The management that results in the Degraded Native Grass State is typically heavy continuous season long grazing but heavy rotational grazing with inadequate growing season recovery periods can also cause this transition. Over time, repeated annual haying during the rapid growth period of warm-season tallgrasses with inadequate growing recovery periods will also cause this transition.
The loss of warm-season tall- and midgrasses negatively impacts energy flow, nutrient cycling, and hydrologic function. Runoff is higher and infiltration is lower than the Reference State. This state is very resistant to change. The Degraded Native Grass State includes the Warm-Season Shortgrass/Cool-Season Grass Community (2.1).
Submodel
Description
The Invaded Grass State (3) transitioned from the either the Reference State (1) or the Degraded Native Grass State (2) and much of the native grass components have been replaced by non-native, cool-season grasses. The management that results in the Invaded Grass State is typically heavy continuous seasonal grazing during the summer months but heavy rotational grazing with inadequate growing season recovery periods during the summer months can also cause this transition. Over time, repeated annual haying during the rapid growth period of warm-season tallgrasses with inadequate growing recovery periods will also cause this transition. Prolonged absence of grazing and fire may also result in a community dominated by non-native, cool-season grasses.
The loss of warm-season tall- and midgrasses negatively impacts energy flow, nutrient cycling, and hydrologic function. Runoff is higher and infiltration is lower than the Reference State. This state is very resistant to change. Once this State is reached, restoration to the previous state will require an extended amount of time and will only be feasible if adequate remnant native grasses persist the plant community. The Invaded Grass State includes the Non-Native Grass Community (3.1).
Submodel
Description
The Invaded Woody State (4) is the result of woody encroachment. Once the tree canopy cover reaches 15 percent with an average tree height exceeding five feet, the threshold to the Invaded Woody State has been crossed. Woody species are increasing due to the lack of prescribed fire, brush management, or other woody tree removal. Typical ecological impacts are a loss of native grasses, reduce diversity of functional and structural groups, reduced forage production, and reduced soil quality. Prescribed burning, wildfire, timber harvest and brush management will move the Invaded Woody State toward a grass dominated state. If the Invaded Woody State transitioned from Native/Invaded Grass State (2) or the Sodbusted State (3), the land cannot return to the Reference State (1) as the native plant community, soils, and hydrologic function had been too severely impacted prior to the woody encroachment to allow the return to the Reference State through woody species removal alone. The Invaded Woody State includes one community, the Invaded Woody Community (4.1).
Submodel
Description
The threshold to the Sodbusted State (5) is crossed as a result of mechanical disturbance to facilitate production agriculture. If farming operations are suspended, the site can be seeded to native grasses resulting in the Reseeded Native Grass Community (5.1), be seeded to a tame pasture forage mixture resulting in the Seeded Pasture Community (5.2) or be abandoned with no seeding which will result in the Natural Reclamation Community (5.3). Permanent alterations of the soil, plant community, and hydrologic cycle make restoration to the Reference State (1) extremely difficult, if not impossible.
Submodel
Mechanism
The Reference State (1) transitions to the Degraded Native Grass State (2) in response to long-term (greater than ten years), heavy, repeated defoliation of the key forage species by grazing or haying. This change typically occurs with long-term heavy, continuous season long grazing but heavy rotational grazing without adequate recovery periods may also cause this transition.
The Reference State loses a significant proportion of warm-season, tall- and midgrasses and crosses a threshold to the Degraded Native Grass State. Deep rooted plants are replaced by shallow rooted, sod- forming grasses which tend to form root mats and water infiltration is reduced. Forage production and plant species diversity has declined. Initially, the plant community will be a mosaic, with shortgrass and tallgrass communities intermingled but as the management continues the plant community becomes dominated by warm-season shortgrasses and rhizomatous cool-season grasses.
Mechanism
The Reference State (1) transitions to the Invaded Grass State (3) in response to long-term (greater than ten years), heavy, repeated defoliation (grazing) of the key forage species during the summer months. This change typically occurs with long-term heavy, continuous seasonal grazing during the summer but heavy rotational grazing without adequate recovery periods may also cause this transition. Removal of livestock grazing for an extended period of time (more than 10 years) with no fire will also cause the plant community to transition to one dominated by non-native, cool-season grasses.
The Reference State loses a significant proportion of warm-season grasses and crosses a threshold to the Invaded Grass State. Deep rooted plants are replaced by shallow rooted, non-native, sod-forming grasses which tend to form root mats and water infiltration is reduced. Forage production and plant species diversity has declined. Initially, the plant community will be a mosaic, native and non-native species intermingled but as the management continues, the plant community becomes dominated by non-native grasses.
Mechanism
Long-term (more than ten years) disruption of the natural fire regime and the encroachment of invasive exotic and native woody species with no woody species management can cause the Reference State (1) to transition to the Invaded Woody State (4).
Mechanism
The Reference State (1) has been significantly altered by tillage to facilitate production agriculture. When the land is no longer cropped, the resulting state is the Sodbusted State (5). The disruption to the plant community, the soil, and the hydrology of the system prevent restoration to a true Reference State.
Mechanism
Long-term (more than 15 years) prescribed grazing with adequate growing season recovery periods will move the Degraded Native Grass State (2) toward the Reference State (1). The amount of time required for and feasibility of this restoration depends upon the abundance of warm-season tall- and midgrasses and cool-season bunch grasses remaining in the plant community and the amount of degradation to the soils and hydrologic function. This restoration may not be feasible.
Mechanism
The Degraded Native Grass State (2) transitions to the Invaded Grass State (3) in response to long-term (greater than ten years), heavy, repeated defoliation of the key forage species by grazing or haying. This change typically occurs with long-term heavy, continuous grazing during the summer months but heavy rotational grazing without adequate recovery periods may also cause this transition.
As the Degraded Native Grass State loses a significant proportion of native grasses which are replaced by non-native grasses shallow rooted, sod- forming grasses begin to form root mats and water infiltration is reduced. Forage production and plant species diversity are substantially reduced. Initially, the plant community will be a mosaic, with native and non-native species intermingled but as the management continues the plant community becomes dominated by non-native grasses.
Mechanism
Long-term (more than ten years) disruption of the natural fire regime and the encroachment of invasive exotic and native woody species with no woody species management can cause the Degraded Native Grass State (2) to transition to the Invaded Woody State (4).
Mechanism
The Degraded Native Grass State (2) has been significantly altered by tillage to facilitate production agriculture. When the land is no longer cropped, the resulting state is the Sodbusted State (5). The disruption to the plant community, degradation of the soil, and the negative impact to the hydrology of the system prevent a true restoration.
Mechanism
Long-term (more than 15 years) prescribed grazing with adequate growing season recovery periods may move the Invaded Grass State (3) toward the Reference State (1). The amount of time required for and feasibility of this restoration depends upon the abundance of warm-season tall- and midgrasses and cool-season bunch grasses remaining in the plant community and the amount of degradation to the soils and hydrologic function. This restoration may not be feasible.
Mechanism
Long-term (more than 15 years) prescribed grazing with adequate growing season recovery periods may move the Invaded Grass State (3) toward the Degraded Native Grass State (2). This restoration may not be feasible. The feasibility of this restoration depends upon the abundance of native grasses remaining in the plant community and the amount of degradation to the soils and hydrologic function.
Mechanism
Long-term (more than ten years) disruption of the natural fire regime and the encroachment of invasive exotic and native woody species with no woody species management can cause the Invaded Grass State (3) to transition to the Invaded Woody State (4).
Mechanism
The Invaded Grass State (3) has been significantly altered by tillage to facilitate production agriculture. When the land is no longer cropped, the resulting state is the Sodbusted State (5). The disruption to the plant community, the soil, and the hydrology of the system prevent restoration to the Invaded Grass State.
Mechanism
The Invaded Woody State (4) can be restored to the Reference State (1) through prescribed burning, wildfire, timber harvest, or brush management. The forb component may initially increase following tree removal. Ongoing brush management such as hand cutting, chemical spot treatments, or periodic prescribed burning is required to prevent a return to the Invaded Woody State. The heavier the existing canopy cover, the greater the energy input required to return to the Native/Invaded Grass State. The amount of time required for the herbaceous vegetation of the Reference State to return depends upon the severity and duration of the encroachment.
Land that transitioned to the Invaded Woody State from the Degraded Native Grass State (2), the Invaded Grass State (3), or the Sodbusted State (5) cannot be restored to the Reference State through the removal of woody species as the native plant community, soils, and hydrologic function have been too severely impacted for that restoration to occur with brush management alone.
Mechanism
The Invaded Woody State (4) can be restored to the Degraded Native Grass State (2) through prescribed burning, wildfire, timber harvest, or brush management. The forb component may initially increase following tree removal. Ongoing brush management such as hand cutting, chemical spot treatments, or periodic prescribed burning is required to prevent a return to the Invaded Woody State. The heavier the existing canopy cover, the greater the energy input required to return to the Native/Invaded Grass State. The amount of time required for the herbaceous vegetation of the Degraded Native State to return depends upon the severity and duration of the encroachment.
Land that transitioned to the Invaded Woody State from the Degraded Native Grass State cannot be restored to the Reference State (1) through the removal of woody species as the native plant community, soils and hydrology have been too severely impacted for tat restoration to occur with the remove of brush alone.
Mechanism
The Invaded Woody State (4) can be restored to the Invaded Grass State (3) through prescribed burning, wildfire, timber harvest, or brush management. The forb component may initially increase following tree removal. Ongoing brush management such as hand cutting, chemical spot treatments, or periodic prescribed burning is required to prevent a return to the Invaded Woody State. The heavier the existing canopy cover, the greater the energy input required to return to the Invaded Grass State. The amount of time required for this restoration to occur depends on the severity and duration of the encroachment.
Land that transitioned to the Invaded Woody State from the Invaded Grass State cannot be restored to the Reference State (1) or the Degraded Native Grass State (2) through the removal of woody species as the native plant community, soils, and hydrologic function have been too severely impacted for that restoration to occur with removal of brush alone.
Mechanism
The Invaded Woody State (4) can be restored to the Sodbusted State (5) through prescribed burning, wildfire, timber harvest, or brush management. The forb component may initially increase following tree removal. Ongoing brush management such as hand cutting, chemical spot treatments, or periodic prescribed burning is required to prevent a return to the Invaded Woody State. The heavier the existing canopy cover, the greater the energy input required to return to the Native/Invaded Grass State.
Land that transitioned to the Invaded Woody State from the Sodbusted State cannot be restored to the Reference State (1) or the Degraded Native Grass State (2) through the removal of woody species as the native plant community, soils, and hydrologic function have been too severely impacted for that restoration to occur.
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.