Choppy Sands
Scenario model
Current ecosystem state
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Management practices/drivers
Select a transition or restoration pathway
- Transition T1 More details
- Transition T2 More details
- Transition T3 More details
- Restoration pathway R1 More details
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No transition or restoration pathway between the selected states has been described
Target ecosystem state
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Description
Transition from Reference State (State 1)
T1 to Native/Invaded State (State 2)
This state represents the natural range of variability that dominated the dynamics of this ecological site. This state was dominated by warm-season grasses with minor amounts of cool-season grasses and forbs. The primary disturbance mechanisms for this site in the reference condition included frequent fire and grazing by large herding ungulates. Timing of fires and grazing coupled with weather events dictated the dynamics that occurred within the natural range of variability. Mid and tall statured grass species would have declined with a corresponding increase in short statured warm-season grasses and cool-season grass-like species. Due to their fire tolerance, scattered, single stem oak trees would have been present on the site in all plant community phases. However, oak regeneration would have been reduced in the active blowout phase. Blowouts would have occurred as a result of prolonged drought and/or adjacent to areas of high animal impact, such as near perennial water sources.
Slight shifts would have occurred in the timing of energy capture, hydrologic function and nutrient cycling between plant community phases 1.1 and 1.2 within State 1. Hydrologic function, energy capture and nutrient cycling would have been reduced in community phase 1.3 but would not have departed beyond the point of recovery.
Submodel
Description
This state is similar to the reference state in appearance and function. The invasion of introduced cool-season sodgrasses has altered the natural range of variability for this ecological site. This state still has a strong component of warm and cool season grass species, but invasive introduced cool-season sodgrasses are now present in all community phases of this state. The primary disturbance mechanisms for this state include periods of above and below normal precipitation, grazing by domestic livestock, and rare to infrequent fire. Periods of above normal precipitation facilitate the invasion and expansion of the introduced species.
Due to the reduction in fire frequency, the oak mottes increase in canopy cover, allowing the establishment of more shade tolerant shrub and trees species.
Submodel
Description
The appearance of this state is characterized by a shift in dominance from herbaceous to shrub and tree species with lesser amounts of grass and forbs. Smooth sumac or poison ivy become the dominant shrubs within the herbaceous portion of the site. Remnant warm- and cool-season grasses and forbs are still found within these shrubs but in reduced amounts due to increased shading. Kentucky bluegrass is present but may or may not be the dominant herbaceous species. Chokecherry and Juneberry thickets become more common near the edges of the oak mottes as do young trees such as green ash and hackberry.
Submodel
Description
This state is characterized by an almost total dominance of introduced grass and forb species. Remnant native species may still be found on the site but in only minor amounts. Once established, this is a very stable state.
Submodel
Mechanism
This is the transition from the native grass dominated reference state to a state that has been invaded by introduced cool-season grass and/or forb species. When propagules of Kentucky bluegrass are present, this transition occurs as natural and/or management actions favor a decline in the composition of warm season rhizomatous grasses and cool season bunch grasses and an increase in cool-season sodgrasses. This transition is compounded by a change in the historic grazing and fire regime where native herbivores would follow periodic fires with grazing. Following settlement, this historic grazing/fire sequence was largely replaced with season-long grazing by domestic livestock. Complete rest from grazing and suppression of fire can also lead to this transition. The threshold between states is crossed when Kentucky bluegrass, smooth brome, and other introduced species become established on the site. These species typically are part of functional/structural groups that were not present in the Reference State.
Mechanism
Transition from Native/Invaded State (State 2)
T2 to Tree and Shrub Dominant State (State 3)
Complete rest from grazing and elimination of fire are the two major contributors to this transition. Removal of these two disturbances shifts the competitive advantage within the herbaceous portion of the plant community to non-native species such as Kentucky bluegrass and leafy spurge. The lack of repeated fire events permits the shrubs such as smooth sumac to expand from the edges of the oak mottes into the adjacent herbaceous communities. Once established, this facilitates further expansion of the tree and shrub components. As shrub and tree canopy cover increases the potential for disturbance by fire decreases due to lack of fine fuels and reduction in fire behavior.
Mechanism
Transition from Native/Invaded State (State 2)
T3 to Invaded State (State 4)
The invasion of leafy spurge onto this site initiates this pathway. As leafy spurge becomes established on the site, it limits use by livestock and changes the micro climate at the soil surface facilitating a shift from the native herbaceous species to a community dominated by introduced grass and forb species. It is speculated the application of certain herbicides in an effort to control leafy spurge may facilitate the increase in Kentucky bluegrass.
Mechanism
Initial use of herbicides and/or mechanical brush control to reduce smooth sumac and other shrubs will permit adequate fine fuel loads to establish permitting the application of prescribed fire to further control sprouting shrubs species. Depending upon level of remnant native grasses and forbs, range seeding may be necessary to re-establish the herbaceous plant community.
Relevant conservation practices
| Practice | External resources |
|---|---|
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Brush Management |
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Prescribed Grazing |
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Invasive Plant Species Control |
Model keys
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