Loamy Bottom (Great Basin Wildrye)
Scenario model
Current ecosystem state
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Management practices/drivers
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- Transition T1a More details
- Transition T2a More details
- Transition T2b More details
- Restoration pathway R3a 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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Submodel
Description
Plant communities in this state can include native, acclimatized, naturalized and invasive non-native species. This state is irreversibly changed from the reference state because these non native species will now remain a permanent part of the community.
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Mechanism
Improper grazing (i.e. season long, overstocking, wrong season, etc.) and/or drought that remove fine fuels from the site lessening the potential for fire to occur. This allows both sprouting and non-sprouting shrubs such as Basin big sagebrush, Rubber rabbitbrush and Black greasewood to increase in the community. Shrubs may become decadent due to age. Great basin wildrye and other native bunchgrasses lose vigor and decrease in the community due to shrub competition and grazing pressure; Western wheatgrass may increase. Utah juniper seedlings and saplings may begin to invade the community if a seed source is available.
The threshold is crossed when there is an introduction of non native species, primarily cheatgrass and various annual mustards, that become established on the site.
Prior to crossing the threshold, if this site is properly grazed over an extended period of time native perennial vegetation may recover. Fire frequency can return to within the normal range for the site. These events could set the site back into the normal range of variability.
Mechanism
Long-term improper grazing (including, season long, overstocking, wrong season, etc.); and/or prolonged drought; lengthened fire return interval resulting in a dense non-sprouting tree and/or shrub overstory, reduction of native perennial understory vegetation and increasing invading annuals. Utah junipers may increase to occupy a significant portion of the overstory, if a seed source is present. Basin big sagebrush dominates the shrub layer and may be decadent due to age. Rubber rabbitbrush and Greasewood may also be present. Great basin wildrye and other native bunchgrasses are significantly reduced due to increased shrub competition and heavy grazing pressure; Western wheatgrass may increase. The threshold is crossed when invasive annuals including cheatgrass, annual mustards, redstem storksbill, etc. dominate the understory. The occurrence of fire extends well beyond the normal period for the site.
Mechanism
Disturbance: Sustained, long-term improper grazing (including, season long, overstocking, wrong season, etc.) and/or prolonged drought; shortened fire frequency allows site to be dominated by sprouting shrubs including Yellow rabbitbrush, Black greasewood and Smooth horsebrush; significant reduction of perennial bunchgrass species. There is an invasion of annual grasses and weedy forb species primarily cheatgrass and various annual mustards.
Model keys
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