Southern Sandy Loam Upland
Scenario model
Current ecosystem state
Select a state
Management practices/drivers
Select a transition or restoration pathway
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Transition T1A
Fire suppression, no management
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Transition T1B
Clearcut, site preparation, tree planting
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Transition T1C
Clearcut, grass/crop planting
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Restoration pathway R2A
Selective timber harvest, prescribed burns
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Transition T2A
Fire suppression, no management
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Transition T2B
Clearcut, site preparation, tree planting
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Transition T2C
Clearcut, grass/crop planting
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Restoration pathway R3A
Selective timber harvest, mid-story shrub control, prescribed burns
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Transition T3A
Clearcut, site preparation, tree planting
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Transition T3B
Clearcut, grass/crop planting
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Restoration pathway R4A
Gap-phase regeneration or clearcut with tree planting
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Transition T4A
Fire suppression, no management
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Transition T4B
Clearcut, grass/crop planting
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Restoration pathway R5A
Tree planting, mid-story shrub control, prescribed burns
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Transition T5A
Clearcut, site preparation, tree planting
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No transition or restoration pathway between the selected states has been described
Target ecosystem state
Select a state
Description
There are two communities in the Woodland State: Longleaf Pine Woodland Community (1.1) and the Fire-primed Understory Community (1.2). The reference state has a moderate overstory cover (40 to 70 percent) of longleaf pine with an occasional upland oak mixed in (blackjack oak and post oak are most common). The understory is diverse, dominated by grasses and forbs. Significant portions of the forest floor are dominated by little bluestem, sometimes up to 75 percent of the site. Saplings and some shrubs are in the area, but make up a small percentage of the mid-story canopy. The forest composition is uneven-aged with members of the pine community probably over 200 years old.
Natural disturbances of fires, lightning strikes, hurricanes (wind throw), ice events (rare), and beetle infestations maintain the uneven-age structure. The natural canopy spacing is kept intact by periodic fires ranging from 1 to 3 years. Representative basal areas range from 40 to 70 square feet per acre. The basal area and canopy cover generally increase at a parallel rate. Growth competition can be seen in the outer rings on trees in locations where the basal area exceeds 90 square feet per acre.
Submodel
Description
The understory dominance state has crossed a threshold in which normal environmental events cannot transition the community back to the reference state (State 1). The mid-story canopy has become so thick, it has begun to limit the productivity of the grass/forb-ground layer. The limited ground layer does not provide enough fuel to harbor a burn with the intensity found in State 1.
Submodel
Description
A long-term lack of fire and management has caused the plant community to cross two major thresholds resulting in a closed canopy community. Fire intolerant hardwoods have become part of the overstory. The overstory trees are overstocked and limit the growth of neighboring species. The overstocking reduces the overall value of the timber stand. The value is decreased because of reduction in longleaf pine numbers and an increase less valueable hardwoods.
Submodel
Description
The Plantation State is a result of conversion activities. The landowner has maximized silviculture production by planting a monoculture of tree species.
Submodel
Mechanism
The transition from a Woodland (State 1) to the Mixed Mid-story (State 2) is a result of time and long periods (greater than 10 years) of no fire. Without fire to suppress shrubs and tree seedlings, biomass and diversity is lost from the grass and forb layers of the system. The transition is also characterized by tree sapling’s bud zones escaping the height at which fire is effective at suppression.
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 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
The driver for restoration is fire. Enough fuel is still left in this community to carry a fire through the site. More frequent burns (1 to 2 years) may be required, initially, to suppress the woody vegetation. Some tree species may have escaped the effective fire height and will have to be selectively cut down to return to the reference state.
Mechanism
The transition from a Mixed Mid-story (State 2) to the Mixed Forest (State 3) is a result of time and long periods (greater than 20 years) of no fire. Without fire to suppress fire intolerant trees, they become part of the overstory canopy. The overstory is so saturated that the understory herbaceous layer is almost non-existent. As the overstory canopy closes, the mid-story becomes well established with shade tolerant species.
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 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
Among all restoration pathways, the R3A path is the most energy intensive. Restoration of this community to the State 1 begins with a selective timber harvest. Removing unwanted trees (shade and fire intolerant) 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 an understory and, if possible, mowing the understory may help. Once the herbaceous layer has established, frequent 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, prepared, and planted to a monoculture of 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
This restoration pathway can be accomplished in different ways depending on goals. One option is to create canopy openings by reducing the number of overstory trees. Then, restore the resulting canopy gaps with species from the State 1's understory. Restoring the understory may include replanting longleaf pine. This method keeps the woodland structure intact and slowly changes the species composition.
Another restoration method is to selectively harvest and remove brush (via mechanical or chemical means) followed by re-planting longleaf pine and oak species (using reduced planting rates.) The herbaceous understory will take time to develop, but this process can be expedited if adapted plant material is available. Fire is the best option to maintain desired canopy cover for enhancement of the understory, and reduce undesirable woody species. Fire frequencies of 1 to 2 years during both growing and cool seasons may be desired in order to maintain an open canopy and reduce undesirable plant competition. If fire is not a viable option, management of woody encroachment could be controlled by mowing or the use of herbicides.
Mechanism
This community transition is caused by neglecting the plantation understory. Without mowing or herbicides, the brush canopy becomes a dense thicket.
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 restoration path can be accomplished by planting a mix of longleaf pine and oak species to their natural frequencies (see State 1 Overstory Composition table); trying to attain a 40 to 70 percent mature overstory canopy. Management will be required to control unwanted species by burning, mowing, and/or herbicides. Controlling introduced pasture grasses is difficult, with complete control likely not attainable. The herbaceous understory will take time to develop, but this process can be expedited if adapted plant material seed is available.
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.