Droughty Upland
Scenario model
Current ecosystem state
Select a state
Management practices/drivers
Select a transition or restoration pathway
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Transition T1A
Absence of fire or alternative brush management, woody species encroachment.
More details -
Transition T1B
Tree removal, mechanical and chemical woody vegetation suppression, tillage, introduce annual or perennial forage species.
More details -
Transition T1C
Tree removal, brush management, plantation tree establishment and management.
More details -
Restoration pathway R2A
Tree thinning, brush management, prescribed fire, and grazing.
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Transition T2A
Tree removal, mechanical and chemical woody vegetation suppression, tillage, introduce annual or perennial forage species.
More details -
Transition T2B
Woody species removal, plantation tree planting, prescribed fire.
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Transition T3B
Lack of management or abandonment.
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Transition T3A
Forage species suppression, brush management, plantation tree establishment and management.
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Transition T4A
Lack of management or abandonment.
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Transition T4B
Woody species removal, prescribed fire, seeding, and grazing.
More details -
No transition or restoration pathway between the selected states has been described
Target ecosystem state
Select a state
Description
The Reference State represents the natural range of variability for the ecological site without major human influence.
The main drivers for community pathways within the Reference State are fire frequency intervals between 3 and 25 years (Guyette and Spetich, 2003; Hallgren et al., 2012), climate effects (decadal scale), insect or disease presence or establishment, and wildlife grazing or browsing.
Fire is the main feedback mechanism within this state, and fire-tolerant species dominate the ecological site. Fire intervals suppress herbaceous vegetation growth; wildlife grazing or browsing reduces the amount of herbaceous vegetation available. Reduced grass availability lessens fire intensity and causes wildlife migration.
Characteristics and indicators
The Reference State consists of a hardwood forest characterized by a mixed hardwood overstory and an herbaceous forest floor. Hardwood species include oak and hickory (Eldredge, 1937). Softwood species, such as loblolly pine and shortleaf pine, are also on similar upland sites. Native grass species, such as big bluestem, switchgrass, little bluestem, and Indiangrass, are common (Arkansas Geological Survey, 2005).
Submodel
Description
Tree species and a closed canopy dominate the Encroached State.
The main drivers for community pathways within the Encroached State are the absence of wildfire, seed dispersal by wildlife, climate effects (decadal scale), and canopy density.
The main feedback mechanism for community pathways in this state is the dominance of tree species. Tree species shade and outcompete herbaceous species and shorter woody species. Less ground cover reduces fire risk. Tree species take control of nutrient and water cycling.
Characteristics and indicators
The Encroached State consists of many tree species (oak, eastern redcedar, hickory, beech) and significant canopy closure. Time, fire, and tree density determine community phases and species abundance or variation. The woody canopy cover increases, and the Encroached State develops. The denser canopy intercepts most of the precipitation and changes the hydrology of the site. Understory species likely have less available water for growth and must compete with extensive woody plant root systems (Zou et al., 2018).
Submodel
Description
The Pasture State consists of introduced herbaceous species planted to maximize livestock forage production.
The main drivers for community pathways within the Pasture State are the mechanical disturbance of the soil and seed planting, climate effects (decadal scale), seed dispersal, and wildlife and livestock grazing or browsing.
The main feedback mechanism for community pathways in this state is the use of mechanical equipment or chemicals to manipulate the site. Wildlife and livestock grazing or browsing reduces the amount of available forage. Fertilizer inputs and brush management are essential for maintaining high productivity.
Characteristics and indicators
The Pasture State consists of species grown for specific management goals, mainly livestock grazing. Common pasture species include clover, tall fescue, ryegrass, small grains, vetches, peas, lespedeza, alfalfa, Bermudagrass, bahiagrass, dallisgrass, Johnsongrass, crabgrass, millet, big bluestem, little bluestem, Indiangrass, eastern gamagrass, and switchgrass (UAES, 2022). The quality and quantity of forbs, grasses, and legume species within this state depend on the level of management inputs (seeding, weed management, nutrient inputs, and land use). Both warm-season and cool-season grasses grow in the Pasture State.
Submodel
Description
The Plantation State consists of merchantable trees planted to maximize timber production and wood volume. Common species in timber plantations include loblolly pine and oak.
Community phases differ by timber type (softwood or hardwood) and harvest method.
The main drivers for community pathways in the Plantation State are prescribed fire, pest management, vegetation management, and canopy density.
The main feedback mechanism for community pathways in this state is timber harvesting. Cultivated tree species dominate this ecological site and shade other vegetation. Timber management reduces competition with other species and assists the growth of desirable timber species.
Characteristics and indicators
The Plantation State consists of trees planted and managed to maximize merchantable timber production. Loblolly pine is the most common species for planting, but hardwood trees are also prevalent. Community phases differ by tree type (softwood or hardwood), timber harvest method, and reforesting practices.
Submodel
Mechanism
The main triggers for this transition are the absence of fire and excessive grazing pressure, both of which allow woody seedlings to grow and outcompete herbaceous vegetation.
The main slow variable for this transition is increased competition for sunlight, nutrients, and moisture resources. Increased overstory competition reduces the vigor and reproductive capacity of the herbaceous understory.
The main threshold for this transition is a shift in nutrient cycling (from grass and leaf dominance to leaf and needle dominance). Increased woody canopy cover alters hydrologic cycles, potentially reducing runoff and infiltration and increasing precipitation interception by woody species.
Mechanism
The main triggers for this transition are tree removal, mechanical and chemical suppression of woody vegetation, tillage, and the introduction of annual or perennial forage species.
The main slow variables for this transition are increased production and management of forage species.
The main thresholds for this transition are changes in soil properties, such as structure, organic matter, and nutrient cycling, and changes in type and frequency of disturbance.
Relevant conservation practices
| Practice | External resources |
|---|---|
|
Brush Management |
|
|
Prescribed Burning |
|
|
Land Clearing |
|
|
Prescribed Grazing |
Mechanism
The main triggers for this transition are the removal of native trees, mechanical and chemical suppression of woody vegetation, and the introduction of plantation tree species.
The main slow variables for this transition are increased production and management of introduced species.
The main thresholds for this transition are changes in soil properties, such as structure, organic matter, and nutrient cycling, and changes in type and frequency of disturbance.
Mechanism
Restoration efforts for this pathway begin with the mechanical and chemical treatment of undesirable woody vegetation and seeding of native species. A grazing management plan and the reintroduction of historical disturbance regimes must accompany these initial treatments. Returning to a historical fire interval through prescribed burning helps to suppress woody vegetation and manage invasive species.
Relevant conservation practices
| Practice | External resources |
|---|---|
|
Brush Management |
|
|
Prescribed Burning |
Mechanism
The main triggers for this transition are tree removal, mechanical and chemical suppression of woody vegetation, tillage, and the introduction of annual or perennial forage species.
The main slow variables for this transition are increased production and management of forage species.
The main thresholds for this transition are changes in soil properties, such as structure, organic matter, and nutrient cycling, and changes in type and frequency of disturbance.
Relevant conservation practices
| Practice | External resources |
|---|---|
|
Brush Management |
|
|
Prescribed Burning |
|
|
Land Clearing |
|
|
Prescribed Grazing |
Mechanism
The main triggers for this transition are the removal of native trees, mechanical and chemical suppression of woody vegetation, and the introduction of plantation tree species.
The main slow variables for this transition are increased production and management of introduced species.
The main thresholds for this transition are changes in soil properties, such as structure, organic matter, and nutrient cycling, and changes in type and frequency of disturbance.
Mechanism
The main trigger for this transition is a lack of management or abandonment.
The main slow variables for this transition are increased establishment and increased size of woody species.
The main threshold for this transition is woody species dominance. Woody species dominate ecological processes by shading other species and increasing competition for soil moisture, nutrients, and sunlight. Woody species dominance reduces the vigor and reproductive capacity of herbaceous species in the understory.
Mechanism
The main triggers for this transition are the removal and suppression of forage species, mechanical and chemical suppression of woody vegetation, and the introduction and management of plantation tree species.
The main slow variables for this transition are the increased production and management of plantation species.
The main thresholds for this transition are changes in soil properties, such as structure, organic matter, and nutrient cycling, and changes in kind and frequency of disturbance.
Mechanism
The main trigger for this transition is a lack of management or abandonment.
The main slow variables for this transition are the increased establishment and increased size of woody species.
The main threshold for this transition is woody species dominance. Woody species dominate ecological processes by shading other species and increasing competition for soil moisture, nutrients, and sunlight. Woody species dominance reduces the vigor and reproductive capacity of herbaceous species in the understory.
Mechanism
The main triggers for this transition are tree removal, mechanical and chemical suppression of woody vegetation, tillage, and the introduction of annual or perennial forage species.
The main slow variables for this transition are increased production and management of forage species.
The main thresholds for this transition are changes in soil properties, such as structure, organic matter, and nutrient cycling, and changes in type and frequency of disturbance.
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.