Salt Meadow
Scenario model
Current ecosystem state
Select a state
Management practices/drivers
Select a transition or restoration pathway
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Transition T1A
Overgrazing, compaction, soil surface sealing, and increased salinity
More details -
Restoration pathway R2A
Flooding, seeding, soil disturbance (plowing, harrowing, aeration), and herbicide control with prescribed grazing
More details -
Transition T2A
Disturbance, altered hydrology
More details -
Restoration pathway R3A
Herbicide, or herbicide in conjunction with mechanical control or prescribed fire, seeding and prescribed grazing
More details -
Restoration pathway R3B
Herbicide, or herbicide in conjunction with mechanical control or prescribed fire, seeding and prescribed grazing
More details -
No transition or restoration pathway between the selected states has been described
Target ecosystem state
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Description
The Reference State is characterized a grassland with salt tolerant species such as inland saltgrass and alkali sacaton. Saltgrass is typically the dominant grass on fine textured soils with a high salt content, and a shallow water table. Alkali sacaton may dominate on soils with lower salt concentrations or where the water table occurs at a greater depth. Fourwing saltbush, the dominant shrub, comprises <5% of the vegetation. Forbs such as seepweed and iodinebush are present in small amounts. When the plant community deteriorates, inland saltgrass, seepweed, iodinebush, and tamarisk (saltcedar) dominate amidst large bare–ground interspaces.
Overgrazing, soil sealing, soil compaction, or increases in salinity initiate the transition to the Inland Saltgrass-dominated State. Overgrazing reduces the competitive influence of the more palatable grasses, promotes soil sealing by reducing plant cover and organic matter, and increasing the amount of bare ground. Inland saltgrass possesses the ability to break through compacted soils and survive under conditions of extreme salinity. On areas with high salt concentrations, flooding may help flush salts from the system, provided the site has adequate drainage. Seeding may be necessary to reestablish the more palatable grasses.
Submodel
Description
Inland Saltgrass-dominated State are characterized by dense sod-like areas of inland saltgrass with frequent interspaces of salt-crusted bare ground. Iodinebush or four-wing saltbush are scattered between patches of saltgrass. In areas of heavier salt concentrations, iodinebush may be more prevalent.
The dominance of Inland saltgrass and sparsity or absence of Alkali sacaton and western wheatgrass are indicators of the transition. Physical and chemical crusts are common.
Submodel
Description
Tamarisk-invaded State is characterized by the presence of tamarisk. Where the water table is shallow (less than 4 feet), tamarisk typically occurs as scattered multi-stemmed trees (Tesky, 1992), with an understory dominated by alkali sacaton or inland saltgrass. On areas where the water table is deeper (5 to 20 feet), tamarisk may eventually dominate forming a dense monoculture (Horton et al, 1960, Tesky, 1992) with little or no herbaceous vegetation beneath the tree canopy. Disturbance such as fire, heavy grazing, and drought may encourage tamarisk establishment by reducing the competitive influence of native vegetation. Changes in timing, intensity, and frequency of flooding favors tamarisk establishment.
Tamarisk control is costly and may require a combination of control methods and the return of natural flooding regimes. Recovery from the tamarisk-dominated state requires combined, multiyear treatments--herbicide, root plow, fire, seeding, and follow-up control of resprouts. These communities have a zonal or target appearance corresponding with water depth and salt concentrations, progressing from Community Phase 1.1 (CP 1.1) to CP 3.1 as distance to water table increases.
The presence of Tamarisk indicates a transition to this state. Grass cover is variable, ranging from patchy to very sparse. Soil sealing and crusts are present in most bare interspaces.
Submodel
Mechanism
Drivers of the transition to Inland Saltgrass-dominated State (T1A) is overgrazing, compaction, soil surface sealing, and increased salinity. Heavy grazing causes a decrease in palatable grasses, providing a competitive advantage for inland saltgrass. The loss of grass also increases the size and frequency of bare interspaces that seal over with chemical or physical crusts. Soil crusts can limit seedling establishment and increase salinity at the soil surface by decreasing infiltration, preventing water from flushing salts out of the rooting zone. Excessive trampling or vehicle traffic can cause the formation of a compaction layer, restricting root growth. Inland saltgrass is equipped with a dense network of sharp pointed underground rhizomes enabling it to spread even in heavy compacted soils (Hansen et al, 1976). Presumably, these rhizomes possess the ability to pierce soil crusts. Salinity may increase due to changes in water table depth, drainage, or the amount of water the site receives. Saltgrass can survive under conditions of extreme salinity, in part due to its ability to take up salty water and extrude the salt through specialized glands on the leaves.
Key indicators of approach to transition:
--Decrease in alkali sacaton and western wheatgrass
--Increase in size and frequency of bare interspaces
--Increased salinity
Mechanism
Restoration Pathway to the Reference State (R2A) requires flooding to decrease salt concentrations allowing reestablishment of alkali sacaton and western wheatgrass, where salinity is the limiting factor. Compacted soil layers, argillic horizons, or poor drainage limit this alternative. Seeding, in conjunction with breaking up compaction layers or heavy soil crusts allows the reestablishment of grasses. Herbicide control of dense inland saltgrass patches prior to seeding facilitates the establishment of more palatable grasses. Prescribed grazing following grass establishment ensures successful establishment and reducing compaction.
Mechanism
Transition to Tamarisk-invaded State (T2A) is initiated by disturbance. Disturbance such as fire, grazing, or drought may encourage the establishment of tamarisk by decreasing the vigor of native vegetation and providing competition-free areas. Changes in seasonal timing, rate, and volume of run-on water may facilitate the establishment of tamarisk (Everitt, 1980). Dams have reduced river volume and caused shifts in the timing of peak flow from spring to summer. The reduced flows in the spring and consistent water discharge in the summer lowers the water table and provides moisture during tamarisk seed production, creating ideal conditions for tamarisk establishment. Increases in salinity due to irrigation return water also promotes tamarisk dominance.
Key indicators of approach to transition:
--Increase in size and frequency of bare interspaces
--Changes in timing and volume of peak discharge
--Increased depth of water table
--Increased soil salinity
Mechanism
Restoration Pathway to the Reference State (R3A): Tamarisk control is costly and often labor intensive. Control programs utilizing herbicide, or herbicide in conjunction with mechanical control or prescribed fire, have proven effective in some instances (Duncan, 1994, Neill, 1990). Seeding may be necessary if adequate seed sources are not present. Deferment followed by prescribed grazing, will help to ensure grass establishment and proper forage use. Without restoring historical flow regimes, extensive follow-up management may be necessary to maintain the Reference State (Smith and Devitt, 1996). Repairs to headcuts and gullies may be necessary for this pathway.
Mechanism
Restoration Pathway to the Inland Saltgrass-dominated State (R3B): Tamarisk control is costly and often labor intensive. Control programs utilizing herbicide, or herbicide in conjunction with mechanical control or prescribed fire, have proven effective in some instances (Duncan, 1994, Neill, 1990). Seeding may be necessary if adequate seed sources are not present. Deferment followed by prescribed grazing, will help to ensure grass establishment and proper forage use. Without restoring historical flow regimes, extensive follow-up management may be necessary to maintain the Inland Saltgrass-dominated State (Smith and Devitt, 1996).
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