Terrace
Scenario model
Current ecosystem state
Select a state
Management practices/drivers
Select a transition or restoration pathway
-
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.
More details -
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.
More details -
Transition T3B
Lack of management or abandonment.
More details -
Transition T3A
Forage species suppression, brush management, plantation tree establishment and management.
More details -
Transition T4A
Lack of management or abandonment.
More details -
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 is representative of the natural range of variability without major anthropogenic influences.
Drivers: Fire frequency between 3 and 25 years, climate (decadal scale), insect and disease presence or establishment, and wildlife grazing or browsing.
Feedbacks: Fire-tolerant species dominate the ecological site. Wildlife grazing or browsing decreases the amount of grass available, decreasing fire intensity and causing wildlife migration to a new grazing location.
Characteristics and indicators
The reference state consists of a bottomland hardwood forest. The common trees species for this state are oaks, hickories, loblolly pine, and sweet gum.
Submodel
Description
The encroached state is dominated by woody species.
Driver: Absence of wildfire, seed dispersal by wildlife, climate (decadal scale), and canopy density.
Feedbacks: Woody species dominate the ecological site, shading herbaceous species. As herbaceous species are outcompeted for resources, fire frequency decreases. Nutrient and water cycling are controlled by woody species.
Characteristics and indicators
The Encroached State consists of many woody species, especially eastern redcedar, where there is significant canopy closure. Time and fire frequency determine the community phases and species abundance and variation. As the woody canopy increases the hydrology of the site is altered. The increased canopy intercepts most of the precipitation. Understory species have less available water for growth and must compete with an extensive overstory root system.
Submodel
Description
The Pasture State is characterized by the dominance of improved forage species. The quality and quantity of forb, grass, and legume species within this state will depend on the level of management inputs including seeding, weed management, and land uses. Species of both warm-season and cool-season grasses are feasible for these sites.
Drivers: Mechanical soil disturbance and seed planting, climate (decadal scale), seed dispersal, and wildlife or livestock grazing or browsing.
Feedbacks: Land managers use mechanical and chemical equipment to increase forage. Inputs of fertilizer and brush management are required to maintain high productivity. Wildlife and livestock grazing and browsing decrease the amount of available forage.
Characteristics and indicators
The Pasture State consists of species that are grown for specific management goals, mainly livestock grazing. Common pasture species include buffalograss, western wheatgrass, little bluestem, sideoats grama, Bermudagrass, and bahiagrass. Quality and quantity of forb, grass, and legume species within this state depend on the level of management inputs (seeding, weed management, and land uses). Species of both warm-season and cool-season grasses are feasible for these sites.
Submodel
Description
The plantation state is characterized by the planting of merchantable trees species. The most common species for a plantation is loblolly pine. Community phases differ by tree type (softwood or hardwood) and the harvesting process.
Drivers: Prescribed fires, pest management, vegetation management, canopy density.
Feedbacks: Timber harvesting. Planted tree species dominate this ecological site, shading out other vegetation. Anthropogenic management decreases competition with other species and assists in growth.
Characteristics and indicators
A plantation state consists of tree species that are planted and managed to maximize the production of merchantable timber. The most common plantation species is loblolly pine, followed by hardwood trees. Community phases differ by tree type (softwood or hardwood), timber harvest method, management, and reforesting practices.
Submodel
Mechanism
Trigger: The absence of wildfire allows woody species to increase and outcompete herbaceous species for nutrients, water, and sunlight.
Slow variables: Increased competition for sunlight, nutrients, and moisture resources. Increased overstory competition results in decreased vigor and reproductive capacity of herbaceous understory species.
Thresholds: Nutrient cycles shift from grass-and-leaf dominance to leaf-and-needle dominance. Increased woody canopy cover alters hydrologic cycles, potentially increasing runoff, decreasing infiltration, and increasing precipitation interception to woody species.
Mechanism
Trigger: Mechanical and chemical woody vegetation suppression, tillage, and annual forage species introduction.
Slow Variables: Increase production and management of forage species.
Thresholds: Changes in soil properties, such as structure, organic matter, and nutrient cycling, as well as changes in type and frequency of disturbance.
Relevant conservation practices
| Practice | External resources |
|---|---|
|
Brush Management |
|
|
Prescribed Burning |
|
|
Land Clearing |
|
|
Prescribed Grazing |
Mechanism
Trigger: Native tree removal, mechanical and chemical woody vegetation suppression, introduce plantation tree species.
Slow Variables: Increased production and management of plantation species.
Thresholds: Changes in soil properties such as structure, organic matter, and nutrient cycling as well as changes in type and frequency of disturbance.
Mechanism
Restoration efforts should begin through the mechanical and chemical treatment of undesirable woody vegetation and by seeding native species. Following the initial treatment of the ecological site, restoration must be accompanied by grazing management and the reintroduction of historic disturbance regimes. Returning to a historic fire interval through prescribed burning assists in woody vegetation suppression and invasive species management.
Relevant conservation practices
| Practice | External resources |
|---|---|
|
Brush Management |
|
|
Prescribed Burning |
Mechanism
Trigger: Mechanical and chemical woody vegetation treatment, tillage, and forage species introduction.
Slow Variables: Increase production and management of forage species.
Thresholds: Changes in soil properties, such as structure, organic matter, and nutrient cycling, as well as changes in type and frequency of disturbance.
Relevant conservation practices
| Practice | External resources |
|---|---|
|
Brush Management |
|
|
Prescribed Burning |
|
|
Land Clearing |
|
|
Prescribed Grazing |
Mechanism
Trigger: Native tree removal, mechanical and chemical woody vegetation suppression, introduce plantation tree species.
Slow Variables: Increased production and management of plantation species.
Thresholds: Changes in soil properties such as structure, organic matter, and nutrient cycling as well as changes in type and frequency of disturbance.
Mechanism
Triggers: Lack of management or abandonment.
Slow Variables: Increase in the establishment and size of woody species.
Thresholds: Woody species dominate ecological processes. This reduces vigor and reproduction of understory species due to shading and increased competition for soil moisture, nutrients, and sunlight.
Mechanism
Trigger: Forage species removal and suppression, mechanical and chemical woody vegetation suppression, introduce and manage plantation tree species.
Slow Variables: Increased production and management of plantation species.
Thresholds: Changes in soil properties such as structure, organic matter, and nutrient cycling as well as changes in kind and frequency of disturbance.
Mechanism
Triggers: Lack of management or abandonment.
Slow Variables: Increase in the establishment and size of woody species.
Thresholds: Woody species dominant ecological processes resulting in reduced vigor and reproduction of herbaceous species in the understory due to shading and increased competition for soil moisture, nutrients, and sunlight.
Mechanism
Trigger: Tree removal, mechanical and chemical woody vegetation suppression, tillage, introduce annual or perennial forage species.
Slow Variables: Increase production and management of forage species.
Thresholds: Changes in soil properties such as structure, organic matter, and nutrient cycling as well as changes in type and frequency of disturbance.
Model keys
Briefcase
Add ecological sites and Major Land Resource Areas to your briefcase by clicking on the briefcase (
) icon wherever it occurs. Drag and drop items to reorder. Cookies are used to store briefcase items between browsing sessions. Because of this, the number of items that can be added to your briefcase is limited, and briefcase items added on one device and browser cannot be accessed from another device or browser. Users who do not wish to place cookies on their devices should not use the briefcase tool. Briefcase cookies serve no other purpose than described here and are deleted whenever browsing history is cleared.
Ecological sites
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.