Shallow To Gravel
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 inadequate recovery periods.
More details -
Transition T1B
Woody encroachment and no fire or woody species management.
More details -
Transition T2A
Woody encroachment and no fire or woody species management.
More details -
Restoration pathway R3A
Prescribed burning, wildfire, timber harvest, brush management.
More details -
Restoration pathway R3B
Prescribed burning, wildfire, timber harvest, brush management.
More details -
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 Shallow to Gravel 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 plant 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 decisions that are unfavorable for a healthy Reference Community.
Submodel
Description
The Shortgrass Sod State (2) has transitioned from the Reference State (1) and much of the native, warm-season, tall- and midgrass components have been replaced by less desirable plants. 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 shortgrass sod communities. The Shortgrass Sod State includes the Shortgrass Sod 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, reduced 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 Shortgrass Sod State (2), 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
Mechanism
Long-term (more than 10 years) heavy grazing 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 Shortgrass Sod 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 biotic integrity are degraded to the point that recovery is unlikely. Once this occurs, a return to the Reference State is highly 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 transition to the Invaded Woody State (3).
Mechanism
Disruption of the natural fire regime and the encroachment of invasive exotic and native woody species can cause the Shortgrass Sod State (2) to transition to the Invaded Woody State (3).
Mechanism
Prescribed burning, wildfire, timber harvest, and brush management will move the Invaded Woody State (3) toward the Reference State (1). 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.
Land that transitioned to the Invaded Woody State from the Shortgrass Sod State (2) cannot be restored to the Reference State through removal of the woody species as the native plant community, soils, and hydrologic function have been too severely impacted for that restoration to occur.
Mechanism
Prescribed burning, wildfire, harvest, and brush management will move the Invaded Woody State (3) toward the Shortgrass Sod State (2). 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 Shortgrass Sod State by management practices. The amount of time required for this restoration to occur depends on the severity and duration of the encroachment.
Land that transitioned from the Shortgrass Sod State into the Invaded Woody State cannot return 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.
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.