Shallow Upland
Scenario model
Current ecosystem state
Select a state
Management practices/drivers
Select a transition or restoration pathway
-
Transition T1A
Woody species encroachment
More details -
Transition T1B
Tree removal
More details
Mechanical and chemical suppression of woody vegetation
Tillage
Introduction of annual or perennial forage species -
Restoration pathway R2A
Natural regeneration and disturbance regimes
More details -
Transition T2A
Tree removal
More details
Mechanical and chemical suppression of woody vegetation
Tillage
Introduction of annual or perennial forage species -
Transition T3B
Lack of management
More details
Abandonment -
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 influences.
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 vegetation growth; wildlife grazing or browsing reduces the amount of grass available. Reduced grass availability lessens fire intensity and causes wildlife migration.
Characteristics and indicators
The Reference State consists of a hardwood forest characterized by mixed hardwoods and sporadic gaps where other vegetation grows. Hardwood species include oak, beech, and hickory (Foti, 2004). Native grass species, such as big bluestem, switchgrass, little bluestem, and Indiangrass, grow in canopy openings and throughout the understory (Arkansas Geological Survey, 2005).
Submodel
Description
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 woody species. Woody species shade and outcompete herbaceous species. Fire intensity diminishes, and woody species take control of nutrient and water cycling.
Characteristics and indicators
The Encroached State consists of many woody species (especially eastern redcedar) and significant canopy closure. Time and fire intensity determine the community phases and species abundance and variation. As the woody canopy increases and the Encroached State develops, the hydrology of the ecological site alters. The denser canopy intercepts most precipitation and changes hydrological patterns to favor woody species over herbaceous species. Understory species, therefore, have less available water for growth and must compete with an extensive overstory root system (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 and chemicals to increase forage. Fertilizer inputs and brush management are essential for maintaining high productivity. Wildlife or livestock grazing or browsing reduces the amount of available forage.
Characteristics and indicators
The Pasture State consists of species grown for specific management goals, mainly livestock grazing. Common pasture species include buffalograss, western wheatgrass, little bluestem, sideoats grama, Bermudagrass, and bahiagrass. The quality and quantity of forbs, grasses, and legume species within this state depend on the level of management inputs (seeding, weed management, and land use). Both warm-season and cool-season grasses are suitable for this ecological site.
Submodel
Mechanism
The main trigger for this transition is the absence of wildfire, which allows woody species to grow and compete for nutrients, water, and sunlight.
The main slow variable for this transition is the 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
Restoration efforts for this pathway begin with mechanical and chemical treatment of undesirable woody vegetation and seeding 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 trigger for this transition is the 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, causing shading and increased competition for soil moisture, nutrients, and sunlight. Woody species dominance reduces the vigor and reproductive capacity of herbaceous species in the understory.
Model keys
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Major Land Resource Areas
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.