Sandy 22-25 P.Z.
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 grazing, or haying, with inadequate growing season recovery periods.
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Transition T1B
Tillage to facilitate production agriculture.
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Transition T1C
Woody encroachment with no fire or brush management.
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Transition T2A
Tillage to facilitate production agriculture.
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Transition T2B
Woody encroachment with no fire or brush management.
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Transition T3A
Woody encroachment with no fire or brush management.
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Restoration pathway R4A
Prescribed burning, wildfire, mechanical harvest, brush management.
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Restoration pathway R4B
Prescribed burning, wildfire, mechanical harvest, brush management.
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Restoration pathway R4C
Prescribed burning, wildfire, mechanical harvest, brush management.
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No transition or restoration pathway between the selected states has been described
Target ecosystem state
Select a state
Description
The Reference State describes the range of vegetative community phases that occur on the Sandy 22-25 PZ ecological site where the natural processes are 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 the Reference Community (1.1), the Degraded Native Grass Community (1.2), the At-Risk Community (1.3), and the Excessive Litter Community (1.4). 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 Degraded Native Grass and the At-Risk Grass Communities are the phases that result from management decisions that are unfavorable for a healthy Reference Community. The Excessive Litter Community results when herbivory and fire are removed from the land. In the absence of fire, all community phases are susceptible to eastern redcedar invasion and subject to crossing a threshold into the Invaded Woody State (4).
Submodel
Description
The Native/Invaded Grass State (2) has transitioned from the Reference State (1) and much of the native warm-season tall- and midgrass community has been replaced by warm-season shortgrasses or non-native cool-season grasses. This State develops with continuous season-long grazing or heavy rotational grazing with inadequate growing season recovery periods. It can also develop with extended periods (more than ten years) of non-use with no fire.
The loss of warm-season tall- and midgrasses has negatively impacted energy flow and nutrient cycling. Water infiltration is reduced due to the shallow root system and rapid runoff characteristics of the grazing-evasive plant communities. The Native/Invaded Grass State includes the Shortgrass Sod/Invasive Grass (2.1) Community.
Submodel
Description
This threshold is crossed as a result of mechanical disturbance to facilitate production agriculture. If farming operations are suspended, the site can be abandoned, which will result in the Naturally Reclaimed Community (3.3), be re-seeded to a tame pasture forage mixture, the Seeded Pasture Community (3.2), or to a mixture of native grasses and forbs, the Reseeded Native Grass Community (3.1).
Permanent alterations of the soil community and the hydrologic cycle make restoration to the original native Reference Community extremely difficult, if not impossible. Formation of a compacted plow pan in the soil profile is likely.
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, reduced diversity of functional and structural groups, reduced Forage production, and reduced soil quality.
Prescribed burning, wildfire, timber harvest, and brush management will move this state toward a grass dominated state. If the Invaded Woody State transitioned from the Native/Invaded Grass State (2) or the Sodbusted State (3), the land cannot transition 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 return to the Reference State. The Invaded Woody State includes one community, the Invaded Woody Community (4.1).
Submodel
Mechanism
Heavy continuous, season-long grazing, heavy rotational grazing with inadequate growing season recovery periods, or haying without adequate recovery periods will cause the Reference State (1) to lose a significant proportion of warm-season, tall- and midgrass species and cross a threshold to the Native/Invaded Grass State (2).
Water infiltration and other hydrologic functions will be reduced due to the root-matting presence of sod-forming grasses. With the decline and loss of deeper-penetrating root systems, soil structure and biological integrity are catastrophically degraded to the point that recovery is unlikely. Once this occurs, it is highly unlikely that grazing management alone will return the community to the Reference State.
Mechanism
The Sodbusted State (3) is significantly altered by tillage to facilitate production agriculture. The disruption to the plant community, the soil, and the hydrology of the system make restoration to a true Reference State (1) unlikely.
Mechanism
Disruption of the natural fire regime and the encroachment of invasive exotic and native woody species can cause the Reference State (1) to shift to the Invaded Woody State (4).
Mechanism
The Sodbusted State (3) is significantly altered by tillage to facilitate production agriculture. The disruption to the plant community, the soil, and the hydrology of the system make restoration to the Native/Invaded Grass State (2) unlikely.
Mechanism
Disruption of the natural fire regime and the encroachment of invasive exotic and native woody species can cause the Native/Invaded Grass State (2) to shift to the Invaded Woody State (4).
Mechanism
Disruption of the natural fire regime and the encroachment of invasive exotic and native woody species can cause the Sodbusted State (3) to shift to the Invaded Woody State (4).
Mechanism
Prescribed burning, wildfire, mechanical harvest, and brush management will move Invaded Woody State (4) toward the Reference State (1). The forb component of a site with heavy tree density or canopy cover will initially increase following tree removal. If re-sprouting brush is present, stumps must be chemically treated immediately after mechanical 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.
Land that transitioned to the Invaded Woody State from the Native/Invaded Grass State (2) or the Sodbusted State (3) cannot be restored to the Reference State (1) through removal of woody species.
Mechanism
Prescribed burning, wildfire, mechanical harvest, and brush management will move Invaded Woody State (4) toward one of the herbaceous plant-dominated states. The forb component of a site with heavy tree density or canopy cover will initially increase following tree removal. If re-sprouting brush is present, stumps must be chemically treated immediately after mechanical 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.
Land that transitioned to the Invaded Woody State from the Native/Invaded Grass State (2) or the Sodbusted State (3) cannot be restored to the Reference State (1) through removal of woody species.
Mechanism
Prescribed burning, wildfire, mechanical harvest, and brush management will move Invaded Woody State (4) toward one of the herbaceous plant-dominated states. The forb component of a site with heavy tree density or canopy cover will initially increase following tree removal. If re-sprouting brush is present, stumps must be chemically treated immediately after mechanical 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.
Land that transitioned to the Invaded Woody State from the Native/Invaded Grass State (2) or the Sodbusted State (3) cannot be restored to the Reference State (1) through removal of woody species.
Model keys
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