Upland Shallow Loam (pinyon-Utah juniper)
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
- Transition T3A More details
- Restoration pathway R4A 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
This state is very similar to the reference state, except that non-native grasses and/or forbs are now present in all phases. The current potential state may include naturalized or invasive nonnative species. The primary disturbance mechanisms for this state include natural and human caused disturbances. Drought, insects, and occasional fire still influence the community shifts; however, domestic livestock grazing, recreational activities, and other man caused disturbances now present. Plant communities within the current potential state are more likely managed and used for various purposes by man, with out significant alteration in plant community composition or production. In time, continuous surface disturbances (i.e. improper grazing, off highway vehicles (OHV) use, recreational activities, etc.) will likely stress the native perennial grasses and allow for non-natives species to increase. This shift in species composition could affect nutrient cycling, hydrology and soil stability. At this time there is no known way to effectively remove the non-native plants from the site once they have become established. Therefore, this site is often irreversibly altered from the reference state
Characteristics and indicators
Current Potential State: Community phases maintained by drought, insects, infrequent crown fires, domestic livestock grazing, and vegetation manipulation.
Indicators: A developed understory co-existing with a canopy of older Pinyon and juniper.
Feedbacks: Infrequent, but regular droughts to reduce tree cover, and allow for the establishment of grasses and forbs in the understory. Long fire intervals that result in an increase in tree establishment and loss of the herbaceous understory.
At-risk Community Phase: Communities 2.1 and 2.2 are at risk of moving into State 3 when remaining native understory plants are stressed and introduced species are dominant.
Trigger: Canopy closure and or presence of invasive species have increased to the point where they influence the nutrient cycling and disturbance regime. Seeding of naturalized species after significant amounts of vegetation management or natural disturbance.
Submodel
Description
This state occurs when natural or management actions have allowed trees to become very mature and have effectively closed out the understory. The primary disturbance mechanisms for this state include increased erosion, improper grazing, and other surface disturbances, such as recreational activities. This state has the lowest resiliency and resistance of any state in this description.
Characteristics and indicators
Eroded state: Community phases maintained by time, drought, and erosion.
Indicators: A lack of understory with a canopy of older Pinyon and Juniper, where plant interspaces very large and connected.
Feedbacks: Increased tree establishment, drought, surface disturbances, heavy rainfall, erosion, and loss of biological crusts that facilitate the continued erosion of this site. Infrequent, but regular droughts to reduce tree cover, coupled with adequate moisture to support and increase the herbaceous understory and biological crusts.
At-risk Community Phase: Community 3.1 is most at risk when the biological crusts are severely disturbed. However one this state is reached there may be no feasible way back to the Current Potential State, due to the large amounts of monetary and energy inputs that would be needed.
Trigger: Seeding of naturalized species after significant amounts of vegetation management or catastrophic natural disturbance.
Submodel
Description
This state is a result of a large amount of management actions. The trees were removed and adapted grasses established. This state reflects the desired management goals. If grazing tolerant species were established these communities can better withstand grazing and other disturbances. Due to the shallow soils and unpredictable precipitations patterns, it is difficult to establish grasses from seed, so this state may be hard to achieve.
Characteristics and indicators
Seeded state: Community phases maintained by time without disturbances and vegetation manipulation,
Indicators: A developed perennial herbaceous understory of seeded species, typically non-natives, co-existing with some Pinyon and Utah juniper.
Feedbacks: Moist cycles that maintain perennial bunch grasses. Loss of the herbaceous understory and an increase in tree establishment.
At-risk Community Phase: All communities are at risk if they are allowed to transition into state 3.
Restoration Pathway: Reestablishment of native and introduced species through time and proper management.
Submodel
Mechanism
This transition is from a state that has resistance and resilience to withstand some disturbances to a state that has lost much of the natural resistance and resilience. At this point natural and/or management actions have decreased the understory to a point where erosion increases. Reduced influence from fire, insects, and drought could cause the tree canopy to close, effectively reducing the herbaceous understory thus facilitating the transition.
Improper grazing combined with periods of drought and increased surface disturbance can facilitate this transition because soil stability is lost and susceptibility to soil loss increases. Of particular concern during this transition is
the reduction of biological crusts due to surface disturbance and or soil compaction. The soil compaction can reduce the ability for biological crusts to survive thus affecting the nutrient cycling and the soil stability (Belnap 1995).
Mechanism
This transition is a result of a reduction in the tree canopy and reestablishment of grasses and other herbaceous species. Because of the shallow soils and the unpredictable precipitation, this pathway should be used cautiously. However, if the community is approaching state 3, due to a loss of understory combined with surface disturbance, this pathway could be preferable. This pathway may facilitate the recovery of the soils and the biological crust community. An unlikely but possible fire could also be cause for the use of this pathway. Reseeding after a fire may be the only way to successfully restore the ecological dynamics to a site. Either way this pathway involves large energy and monetary inputs by man.
Mechanism
This transition may not be possible. Because of the shallow soils and the unpredictable precipitation, this pathway should be used cautiously. This pathway may facilitate the recovery of the soils and the biological crust community. This pathway involves large energy and monetary inputs by man.
Mechanism
This pathway occurs as a result of long periods without disturbance and the community is allowed to develop ecosystem functions. This could be through prescribed grazing with domestic livestock to favor the development of native grasses over the introduced species.
Model keys
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