Loamy Till Swamp
Scenario model
Current ecosystem state
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Management practices/drivers
Select a transition or restoration pathway
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Transition T1A
Cedar seedbank exhausted, hardwood dominance and persistance
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Transition T1B
Variable increase in soil wetness (natural or anthropogenic)
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Transition T1C
Anthropogenic drainage, land clearing, cultivation of pasture grasses and / or legumes
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Transition T2A
Selective harvest of hardwoods, cedar regeneration promotion
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Transition T2B
Variable increase in soil wetness (natural or anthropogenic)
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Transition T3A
Decrease in soil wetness (natural or anthropogenic)
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Transition T3B
Intense increase in soil wetness (natural or anthropogenic)
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Transition T4A
Long-term agricultural abandonment
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Transition T5A
Decrease in soil wetness (natural or anthropogenic)
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No transition or restoration pathway between the selected states has been described
Target ecosystem state
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Description
These are softwood dominated forests most often comprised of mature northern white cedar (Thuja occidentalis) found on shallow organic over dense till soils. The canopy is often a pure stand of cedar (up to 95 percent abundance) and can be somewhat open but is more often closed. Minor inclusions of hardwoods may be present. Tall shrubs are generally absent, low shrubs and forbs are often sparse to locally abundant (greater than 30 percent cover). Bryophytes are the dominant groundcover, covering both hummocks and hollows. Changes in light availability and soil wetness are the dominant drivers for these communities, with logging being the main factor attributable to this.
Submodel
Description
These are hardwood dominated seepage swamps most often comprised of red maple (Acer rubrum), black, white, or green ash (Fraxinus nigra, F. americana, F. pennsylvania, respectfully), and yellow birch (Betula alleghenies) are found on shallow to absent organic soil over dense till. The canopy will be mostly hardwoods with softwoods, often northern white cedar (Thuja occidentalis), hemlock (Tsuga canadensis), or red spruce (Picea rubra); present but making up less than 25 percent of the canopy. The canopy will often be closed (greater than 60 percent canopy cover) with both the tall and shrub layer being generally sparse. Sapling regeneration can be common. The herbaceous layer is generally complex due to the variable canopy but consists of forbs and primarily herbaceous litter.
Submodel
Description
These are graminoid and shrub dominated wetlands that are typical successional communities after an alteration to the surrounding landscape increases the local hydroperiods. This is most often the result of beaver damming but can be the result of anthropogenic influences such as building of roads and man-made dams as well. This state may persist indefinitely or may be seen as a transitional community and will depend on the surrounding hydrologic regime. It can be identified by the presence of the root restrictive layer and shallow organic soils compared to other sites which may have deeper organic soils. Standing dead snags may or may not be present depending on time since hydrological change.
Submodel
Description
This state represents a once forested area now cleared for pasture. This will typically only occur on gentler slopes (<15 percent) due to potential for water erosion. Pasture vegetation can consist of grasses, legumes, other forbs, shrubs or a mixture. Many of these forages are introduced, having originally come from areas in other states or continents. Overgrazed pastures can lead to soil compaction and numerous bare spots, which may then become focal points of accelerated erosion and colonization sites of undesirable plants or weeds. In these systems, water control structures may be used to prevent excess water in the fields and historical drainage and cultivation of this site may lead to the loss of the mucky organic surface texture.
Submodel
Description
These are wetlands of emergent vegetation and areas of open water, often reflecting slightly higher seasonal high-water tables or increased long-term hydroperiods. Hydrologic regimes are often the longest in this state, with long-term or permanent inundation influencing the development of freshwater emergent species. Organic soils are often deepest in these states but may often include shallow organics or high organic content mineral soils. These communities will often form near monocultures and be so dense that germination of other species is limited.
Submodel
Mechanism
This transition may occur through extensive selective harvesting of cedar, in which the seedbank supply is exhausted, and the conditions are unfit for regeneration. This may also occur through extensive winter browse by deer on regenerating cedar in early successional forests due to its high forage value. In any case, hardwood species will persist and outcompete northern white cedar, transitioning a community from evergreen to hardwood dominance.
Mechanism
This transition may occur through variable increases in soil wetness, often because of natural or anthropogenic influence such as beaver or man-made dams. This may also be intensified by extensive harvesting, which reduces canopy cover and water use by trees, promoting graminoids and shrubs to become dominant. In dammed areas, existing trees may be killed and standing dead snags will be remnant in the overstory.
Mechanism
The reference state transitions to the managed grassland state with the clearing of woody vegetation and the establishment of pasture grasses and legumes. Water control structures may have been used in historically transitioned sites to drain excess water from the site and make it more suitable for pasture species. Current transition from the reference state to a converted cultural state may not be suitable following local, state, and federal laws.
Mechanism
This transition may occur through selective harvesting of hardwood species and forest management to promote cedar regeneration. This may require planting of seedlings if the seedbank is exhausted and active management to ensure seedling survival. If hydrologic changes were the dominant transitional driver, restoration to the natural hydrology of the site may be needed.
Mechanism
This transition may occur through variable increases in soil wetness, often because of natural or anthropogenic influence such as beaver or man-made dams. This may also be intensified by extensive harvesting, which reduces canopy cover and water use by trees, promoting graminoids and shrubs to become dominant. In dammed areas, existing trees may be killed and standing dead snags will be remnant in the overstory.
Mechanism
This transition may occur through decreases in soil wetness, often due to the removal of beaver or man-made dams. Lower seasonal high-water tables and seasonal fluctuation can allow for regeneration and sapling establishment.
Mechanism
This transition may occur through intense increase in soil wetness, often because of natural or anthropogenic influence such as beaver or man-made dams. In dammed areas, existing trees may be killed and standing dead snags will be remnant in the overstory. Depending on the average depth of standing water, freshwater emergent vegetation may become dominant.
Mechanism
This transition may occur following long-term agricultural abandonment. Northern white cedar, white pine, gray birch, aspen, red spruce, pin cherry, and balsam fir may be post-agricultural successional species that will invade a fallow pastureland depending on the available seedbank and the duration and intensity of the 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.