Subirrigated
Scenario model
Current ecosystem state
Select a state
Management practices/drivers
Select a transition or restoration pathway
-
Transition 1A
Long term, heavy grazing or haying with inadequate growing season recovery periods.
More details -
Transition 1B
Tillage to facilitate production agriculture.
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Transition 1C
No fire or woody species management.
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Transition 2A
Tillage to facilitate production agriculture.
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Transition 2B
No fire or woody species management.
More details -
Transition 3A
No fire or woody species management.
More details -
Restoration pathway 4A
Prescribed burning, timber harvest, and brush management.
More details -
Restoration pathway 4B
Prescribed burning, timber harvest, and brush management.
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Restoration pathway 4C
Prescribed burning, timber harvest, and brush management.
More details -
No transition or restoration pathway between the selected states has been described
Target ecosystem state
Select a state
State 1
Reference State
Description
This state describes the range of vegetative community phases that occur on the Subirrigated ecological site where the natural processes are mostly intact. The Reference Community (1.1) is a representation of the native plant community phase that occupies a site that has been minimally altered by management. The Degraded Native Grass (1.2), the At-Risk (1.3), and the Excessive Litter (1.4) Communities are the phases that result from management decisions that are unfavorable for a healthy Reference Community (1.1).
High perennial grass cover and production allows for increased soil moisture retention, vegetative production, and overall soil quality.
Submodel
Description
The Native/Invaded Grass State (2) occurs when an ecological threshold has been crossed and the majority of the native, warm-season tall and mid grasses of the Reference State (1) have been replaced by less desirable native grasses and non-native, invasive grasses. The plant community consists of the more grazing tolerant native species and a significant component of introduced, cool-season grasses such as reed canary grass, smooth brome, tall fescue, and Kentucky bluegrass. Forb diversity is limited to species with low palatability. Plant diversity is low. The Native/Invaded Grass State includes the Native/Invaded Grass Community (2.1) and the Invaded Cool-Season Grass Community (2.2).
The loss of warm-season, tall and mid grasses 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 tolerant plant communities. Impaired energy capture and altered hydrologic function are reflected in reduced vegetative productivity, shallower rooting depth and degraded soil quality. Continuous and heavy grazing pressure will maintain this plant community in a sod bound condition.
Grazing management practices that allow for adequate periods of recovery between grazing events and grazing timed early and late during the growing season will reduce the vigor of the non-native, cool-season grasses and may allow the warm-season, tall grasses to increase in abundance and productivity. Return to the Reference State (1) is unlikely due to the loss of plant diversity, overall soil disturbance, and alterations to hydrologic function.
Submodel
Description
The threshold to the Sodbusted State (3) is crossed as a result of mechanical disturbance to facilitate production agriculture. Extensive areas of this ecological site were plowed and converted to crop production by early European settlers and their subsequent generations. In addition to permanently altering the existing vegetative community, repeated tillage negatively impacted soil properties. Reductions in organic matter, mineral levels, soil structure, oxygen levels, and water-holding capacity along with increased runoff and erosion as well as shifts in the populations of soil-dwelling organisms were common on these sites. The extent of these changes depended upon the duration of cropping as well as crops grown and other management practices.
If farming operations are suspended, the site can be abandoned or seeded to permanent vegetation. Seedings are either a tame pasture forage mixture, the Seeded Pasture Community (3.2), or a mixture of native grasses and forbs, the Reseeded Native Grass Community (3.1). Abandonment results in the Natural Reclamation Community (3.3). Permanent alterations of the soil, plant community, and the hydrologic cycle make restoration to the Reference State (1) extremely difficult, if not impossible.
Submodel
Description
Once the woody canopy cover reaches 15 percent, the threshold is crossed to the Invaded Woody State (4). Woody species are encroaching due to heavy grazing with the lack of prescribed fire or other brush management practices. Typical ecological impacts are a loss of native warm-season grasses, degraded forage productivity, and reduced soil quality. This state consists of the Invaded Woody Community (4.1).
Submodel
Mechanism
Heavy grazing or haying with inadequate, growing season recovery periods will cause the Reference State (1) to lose a significant proportion of warm-season, tall and mid grass species and cross a threshold to the Native/Invaded 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 (1).
Mechanism
The Reference State (1) is significantly altered by mechanical tillage to facilitate production agriculture shifting site to the Sod-busted State (3). The disruption to the plant community, the soil, and the hydrology of the system make restoration to a true reference state 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 Native/Invaded Grass State (2) is significantly altered by mechanical tillage to facilitate production agriculture shifting site to the Sod-busted State (3). The disruption to the plant community, the soil, and the hydrology of the system make restoration unlikely.
Mechanism
Disruption of the natural fire regime and 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 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, timber harvest, and brush management will move the 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 through mechanical brush management treatments and prescribed fire. If resprouting brush such as honey locust or Siberian elm 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 this state.
If the Invaded Woody State transitioned from the Native/Invaded Grass State (2) or the Sod-busted State (3), the land cannot be restored back to the Reference State (1) as the native plant community, soils, and hydrologic function have been too severely impacted prior to the woody encroachment to allow restoration back to the Reference State (1).
Relevant conservation practices
| Practice | External resources |
|---|---|
|
Brush Management |
|
|
Prescribed Burning |
Mechanism
Prescribed burning, wildfire, timber harvest, and brush management will move the Invaded Woody State (4) toward the Native/Invaded Grass State (2). The forb component of a site with heavy tree density or canopy cover will initially increase following tree removal through mechanical brush management treatments and prescribed fire. If resprouting brush such as honey locust or Siberian elm 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 this state.
If the Invaded Woody State (4) transitioned from the Native/Invaded Grass State (2) or the Sod-busted State (3), the land cannot be restored back to the Reference State (1) as the native plant community, soils, and hydrologic function have been too severely impacted prior to the woody encroachment to allow restoration back to the Reference State (1).
Relevant conservation practices
| Practice | External resources |
|---|---|
|
Brush Management |
|
|
Prescribed Burning |
Mechanism
Prescribed burning, wildfire, timber harvest, and brush management will move the Invaded Woody State (4) toward the Sod-busted State (3). The forb component of a site with heavy tree density or canopy cover will initially increase following tree removal through mechanical brush management treatments and prescribed fire. If resprouting brush such as honey locust or Siberian elm 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 this state.
If the Invaded Woody State (4) transitioned from the Native/Invaded Grass State (2) or the Sod-busted State (3), the land cannot be restored back to the Reference State (1) as the native plant community, soils, and hydrologic function have been too severely impacted prior to the woody encroachment to allow restoration back to the Reference State (1).
Relevant conservation practices
| Practice | External resources |
|---|---|
|
Brush Management |
|
|
Prescribed Burning |
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.