Terrace
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 disturbance, coupled with natural regeneration over time
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Transition T1B
Merchantable timber is harvested by clearcut and site is planted to a monoculture of pine trees
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Transition T1C
Removal of native vegetation and introduction of improved forage species or annual crops
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Restoration pathway R2A
Reduction of overstory canopy using fire and selective thinning
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Transition T2A
Merchantable timber is harvested by clearcut and site is planted to a monoculture of pine trees
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Transition T2B
Merchantable timber harvested by clearcut, followed by planting of improved forage species or annual crops
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Restoration pathway R3A
Selective harvest combined with reintroduction of natural disturbances and native species
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Transition T3A
Lack of natural/anthropogenic disturbance and natural regeneration over time
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Transition T3B
Timber harvest by clearcut, followed by planting improved forage species or annual crops
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Transition T4A
Lack of natural/anthropogenic disturbance and natural regeneration over time
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Transition T4B
Site is planted to a monoculture of pine trees
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No transition or restoration pathway between the selected states has been described
Target ecosystem state
Select a state
Description
The Terrace ecological site is a Loblolly Pine/White Oak Woodland. The terrace position is a mixture of both adjacent upland and bottomland sites. The terrace position is not as dry as the uplands, nor as wet as the bottomlands. The soils adequately provide moisture to the plants and the soils provide a good growing medium. The overstory canopy is moderate, from 60 to 80 percent. Basal areas are similar, from 85 to 105 square feet per acre. A moderate fire interval exists between 5 to 10 years. The sites midstory and understory fluctuate in biomass at time since last fire. More grasses and forbs will dominate immediately afterwards and slowly progress into more shrubs until the next fire.
Submodel
Description
A long-term lack of fire and management has caused the community to cross a threshold, resulting in an Encroached State (2). The crossing of this threshold represents a closure in the overstory canopy, which limits the productivity of the ground layer. The limited ground layer does not provide enough fuel to harbor a burn with the intensity found in State 1. Fire-intolerant hardwoods have become part of the overstory. The overstory trees are overstocked and limit the growth of neighboring species. The overstocking reduces tree growth and causes stress, making them vulnerable to attacks from insects and/or diseases. The plant communities will stay in this constant state and continue to age without disturbance or intervention.
Submodel
Description
The Plantation State is a result of conversion activities. The landowner has maximized silviculture production by planting a monoculture of pine species, usually loblolly pine, but sometimes slash pine (Pinus ellioti) is planted.
Submodel
Mechanism
The transition from State 1 to the State 2 is a result of time and long periods (greater than 10 years) of no fire and/or forest management practices. Without fire to suppress tree seedlings, biomass and diversity is lost from the grass and forb layers of the system.
Mechanism
The transition is due to the land manager maximizing silviculture potential. Merchantable timber is harvested by clearcut. Then, the site is prepared and planted to a monoculture of pine trees.
Mechanism
The transition is due to the land manager maximizing agricultural production. Merchantable timber is harvested by clearcut. Then, the site is prepared and planted to either an improved grass or row crops.
Mechanism
Restoration of this community to the reference state begins with a selective timber harvest. Removing unwanted trees opens up the canopy, allowing sunlight penetration to the ground. Years of overstory growth have limited the fuel necessary to have an effective fire. Time will be needed to encourage understory growth. Once the herbaceous layer has established, more frequent than natural burns (1 to 2 years) may be required to suppress the woody vegetation.
Mechanism
The transition is due to the land manager maximizing silviculture potential. Merchantable timber is harvested by clearcut. Then, the site is prepared and planted to a monoculture of pine trees.
Mechanism
The transition is due to the land manager maximizing agricultural potential. Merchantable timber is harvested by clearcut. Then, the site is prepared and planted to either an improved grass or row crops.
Mechanism
When restoring a plantation, the land manager can either clearcut the timber, prepare the site, and plant trees. Otherwise, gap-phase regeneration is possible through selective timber harvests. This involves replanting the desired overstory species in small openings within the current structure of the woodland. The benefit is a slow progression of restoration instead of starting from primary succession.
Mechanism
This community transition is caused by neglecting the plantation understory. Without fire, mowing, or herbicides, unwanted understory saplings can begin to grow into the overstory.
Mechanism
The transition is due to the land manager maximizing agricultural production. Merchantable timber is harvested by clearcut. Then, the site is prepared and planted to either an improved grass or row crops.
Mechanism
This community transition is caused by neglecting crop or pasture. Without continuation of agricultural management first-successional herbaceous plants will occupy the ground layer, followed by shrubs, and eventually shade-loving, fire-intolerant overstory species.
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.