Sandy Lowland
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) continuous, season long or heavy, rotational grazing with inadequate growing season recovery time. Annual haying.
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Transition T1B
Woody encroachment with no fire or brush management.
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Transition T1C
Tillage to facilitate production agriculture.
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Restoration pathway R2A
Long-term (>15 years) prescribed grazing or biennial haying. This restoration may not be feasible.
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Transition T2A
Woody encroachment with no fire or brush management.
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Transition T2B
Tillage to facilitate production agriculture.
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Restoration pathway R3A
Prescribed burning, timber harvest, brush management.
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Restoration pathway R3B
Prescribed burning, timber harvest, brush management.
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Restoration pathway R3C
Prescribed burning, timber harvest, brush management.
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Transition T4A
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
Select a state
Description
The Reference State (1) describes the range of vegetative communities that occur on the Sands Lowland 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 two community phases which are the Reference Community (1.1) and the At-Risk Community. The Reference Community serves as a description of the native plant community that 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. In the absence of fire and brush management, this state is susceptible to encroachment by eastern redcedar.
Submodel
Description
The Native/Invaded 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 and cool-season grasses. The Native/Invaded Grass State develops with long term grazing management that did not provide adequate recovery time for warm-season tall- and midgrasses. Non-native cool-season grasses are often present in the plant community and may become subdominant. The management that results in the Native/Invaded Grass State is typically heavy continuous season long grazing but heavy rotational grazing with inadequate growing season recovery periods can also cause this transition. Repeated annual haying during the rapid growth period of warm-season tallgrasses with inadequate growing recovery periods will also cause this transition over time.
The loss of warm-season tall- and midgrasses negatively impacts energy flow and nutrient cycling and alters hydrologic function. Plant litter is decreased. Infiltration is lower than in the Reference State. Return to the Reference State will take a significant amount of time and if adequate amounts of warm-season tall- and midgrasses are not present, restoration to the Reference State will not be feasible. The Native/Invaded Grass State is very resistant to change; however, eastern redcedar encroachment can quickly convert this state to the Invaded Woody State (3). The Native/Invaded Grass State includes the Warm-Season Shortgrass/Cool-Season Grass Community (2.1).
Submodel
Description
The Invaded Woody State (3) 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 (3.1).
Submodel
Description
The threshold to the Sodbusted State (4) 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 and forms resulting in the Reseeded Native Grass Community (4.1), be seeded to a tame pasture forage mixture resulting in the Seeded Pasture Community (4.2) or be abandoned with no seeding which will result in the Natural Reclamation Community (4.3). 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 Native/Invaded 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. Annual haying at the same time each year will also facilitate this change. Once the Reference State loses a significant proportion of warm-season, tall- and midgrasses it crosses a threshold to the Native/Invaded Grass State.
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 (3).
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 (4). The disruption to the plant community, the soil, and the hydrology of the system prevent restoration to the Reference State.
Mechanism
Long-term (more than 15 years) prescribed grazing with adequate growing season recovery periods will move the Native/Invaded Grass State (2) toward the Reference State (1). When the land is used for hay production, biennial haying may facilitate this restoration. The amount of time required for restoration, and feasibility of this restoration depends upon the abundance of warm-season tall- and midgrasses remaining in the plant community. This restoration may not be feasible.
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 Native/Invaded Grass State (2) to transition to the Invaded Woody State (3).
Mechanism
The Native/Invaded 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 (4). The disruption to the plant community, the soil, and the hydrology of the system prevent restoration to the Native/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 Reference State by management practices. The amount of time required for this restoration to occur depends on the severity and duration of the encroachment. To maintain the site as grassland, maintenance burns will need to be conducted periodically to mimic the historical fire frequency of Sandhills grasslands.
Land that transitioned to the Invaded Woody State from the Native/Invaded Grass State (2) or the Sodbusted State (4) 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 woody species removal alone.
Mechanism
The Invaded Woody State (4) can be restored to the Native/Invaded 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. To maintain the site as grassland, maintenance burns will need to be conducted periodically to mimic the historical fire frequency of Sandhills grasslands.
Land that transitioned to the Invaded Woody State from the Native/Invaded Grass State or the Sodbusted State (4) cannot be restored to the Reference State (1) 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 woody species removal alone.
Mechanism
The Invaded Woody State (4) can be restored to the Sodbusted State (4) 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 Sodbusted State by management practices. To maintain the site as grassland, maintenance burns will need to be conducted periodically to mimic the historical fire frequency of Sandhills grasslands.
Land that transitioned to the Invaded Woody State from the Native/Invaded Grass State (2) or the Sodbusted State cannot be restored to the Reference State (1) 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 woody species removal alone.
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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.