Loamy Bottomland
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 and natural regeneration over time, coupled with excessive grazing pressure
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Transition T1B
Extensive soil disturbance followed by seeding with improved forage species
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Restoration pathway R2A
Reintroduction of historic disturbance return intervals
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Transition T2A
Extensive soil disturbance followed by seeding improved forage species
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Transition T3A
Absence of disturbance and natural regeneration over time, coupled with excessive grazing pressure
More details -
No transition or restoration pathway between the selected states has been described
Target ecosystem state
Select a state
Mechanism
Shrubs and trees make up a portion of the plant community in the Savannah State (1), hence woody propagules are present. Therefore, the Savannah State is always at risk for shrub dominance and the transition to the Woodland State in the absence of fire. The driver for Transition T1A is lack of fire and/or brush control. Most fires will burn only the understory. Even with proper grazing and favorable climate conditions, lack of fire for years will allow trees and shrubs to increase in canopy to reach the 50 percent threshold level. The introduction of aggressive woody invader species increases the risk and accelerates the rate at which this transition state is likely to occur. This transition can occur from any community within the Savannah State (1), it is not dependent on degradation of the herbaceous community, but on the lack of brush control. Improper grazing and prolonged drought will provide a competitive advantage to shrubs, which will accelerate this process. Tallgrasses will decrease to less than five percent species composition.
Mechanism
The transition to the Converted State from the Savannah State occurs when the site is cleared and plowed for planting to cropland or hayland. The threshold for this transition is the plowing of the prairie soil and removal of the woody plant community. The Converted State includes cropland, tame pasture, and go-back land. The site is considered go-back land during the period between cessation of active cropping, fertilization, and weed control and the return to the native states. Agronomic practices are used to convert rangeland to the Converted State and to make changes between the communities in the Converted State. The driver for these transitions is management’s decision to farm the site.
Mechanism
Restoration of the Woodland State to the Savannah State requires substantial energy input. The driver for this restoration pathway is removal of woody species, restoration of native herbaceous species, and ongoing management of invasive species. Without maintenance, woody and invasive species are likely to return (probably rapidly) due to presence of propagules in the soil.
Mechanism
The transition to the Converted State from the Woodland State (T2A) occurs when the site is cleared and plowed for planting to cropland or hayland. The size and density of brush in the Woodland State will require heavy equipment and energy-intensive practices (i.e. rootplowing, raking, rollerchopping, or heavy disking) to prepare a seedbed. The threshold for this transition is the plowing of the prairie soil and removal of the woody plant community. The Converted State includes cropland, tame pasture, and go-back land. The site is considered go-back land during the period between cessation of active cropping, fertilization, and weed control and the return to the native states. Agronomic practices are used to convert rangeland to the Converted State and to make changes between the communities in the Converted State. The driver for these transitions is management’s decision to farm the site.
Mechanism
Transition from the Converted State can occur in the short-term through cessation of agronomic practices. Cropland and tame pasture require repeated and continual inputs of fertilizer and weed control to maintain the Converted State. If the soil chemistry and structure have not been overly disturbed (which is likely to occur with tame pasture) the site can be restored to the Savannah State. The level of disturbance while in the Converted State determines whether the site restoration pathway is likely to be R3A (a return to the Savannah State) or T3A (a return to the Woodland State).
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.