FRACTURED STONY LOAM 14+ P.Z.
Scenario model
Current ecosystem state
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Management practices/drivers
Select a transition or restoration pathway
- Transition A More details
- Transition A More details
- Transition B More details
- Restoration pathway A More details
- Transition A More details
- Restoration pathway A More details
- Transition A 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
The Reference State 1.0 is a representative of the natural range of variability under pristine conditions. The reference state has three general community phases; a shrub-grass dominant phase, a perennial grass dominant phase and a shrub dominant phase. State dynamics are maintained by interactions between climatic patterns and disturbance regimes. Negative feedbacks enhance ecosystem resilience and contribute to the stability of the state. These include the presence of all structural and functional groups, low fine fuel loads, and retention of organic matter and nutrients. Plant community phase changes are primarily driven by fire, periodic drought and/or insect or disease attack.
Submodel
Description
This state is similar to the Reference State 1.0. with similar community phases plus the 2.4 at-risk community phase. Ecological function has not changed, however the resiliency of the state has been reduced by the presence of invasive weeds. Negative feedbacks enhance ecosystem resilience and contribute to the stability of the state. These include the presence of all structural and functional groups, low fine fuel loads and retention of organic matter and nutrients. Positive feedbacks decrease ecosystem resilience and stability of the state. These include the non-natives high seed output, persistent seed bank, rapid growth rate, ability to cross pollinate and adaptations for seed dispersal. Additionally, the presence of highly flammable, non-native species reduces state resilience because these species can promote fire where historically fire has been infrequent leading to positive feedbacks that further the degradation of the system.
Submodel
Description
This state has one community phase and is the product of many years of heavy grazing during time periods harmful to deep-rooted perennial bunchgrasses. With a reduction in deep-rooted perennial bunchgrass competition, bluegrasses and squirreltail will increase and become the dominant grass. Sagebrush dominates the overstory. Bitterbrush and/or rabbitbrush may be significant components. Sagebrush cover exceeds site concept and may be decadent, reflecting stand maturity and lack of seedling establishment due to competition with mature plants. Bare ground is also increasing. The shrub overstory and bluegrass understory dominate site resources such that soil water, nutrient capture, nutrient cycling and soil organic matter are temporally and spatially redistributed.
Submodel
Description
This state has two community phases. One phase is characterized by the dominance of annual non-native species such as cheatgrass and tansy mustard. The second phase has either mountain big sagebrush and/or rabbitbrush dominating the overstory with an understory of annual non-natives.
Submodel
Description
This state has three community phases a grass-dominated phase; a grass-shrub phase and a shrub dominated phase. The state is characterized by the dominance of seeded species such as smooth brome and crested wheatgrass. Other seeded species include forage kochia, Wyoming big sagebrush, and native and non-native perennial forbs.
Submodel
Mechanism
Trigger: This transition is caused by the introduction of non-native annual weeds, such as cheatgrass.
Slow variables: Over time the annual non-native plants will increase within the community.
Threshold: Any amount of introduced non-native species causes an immediate decrease in the resilience of the site. Annual non-native species cannot be easily removed from the system and have the potential to significantly alter disturbance regimes from their historic range of variation.
Mechanism
Trigger: Inappropriate, long-term grazing of perennial bunchgrasses during growing season would favor shrubs and initiate transition to Community Phase 3.1.
Slow variables: Long term decrease in deep-rooted perennial grass density.
Threshold: Loss of deep-rooted perennial bunchgrasses changes spatial and temporal nutrient cycling and nutrient redistribution, and reduces soil organic matter.
Mechanism
Trigger: Fire and/or multiple fires lead to plant community phase 4.1, inappropriate grazing management that favors shrubs in the presence of non-native annual species leads to community phase 4.2.
Slow variables: Increased production and cover of non-native annual species.
Threshold: Cheatgrass or other non-native annuals dominate understory
Mechanism
Sagebrush removal by mechanical or chemical treatments such as brush beating and/or herbicide usually coupled with seeding of perennial bunchgrass species. This restoration leads to Community Phase 2.4.
Relevant conservation practices
| Practice | External resources |
|---|---|
|
Brush Management |
|
|
Range Planting |
Mechanism
Trigger: To Community Phase 4.1: Severe fire. To Community Phase 4.2: Inappropriate grazing management in the presence of annual non-native species.
Slow variables: Increased production and cover of non-native annual species.
Threshold: Increased continuous fine fuels modify the fire regime by changing intensity, size, and spatial variability of fires. Changes in plant community composition and spatial variability of vegetation due to the loss of perennial bunchgrasses and sagebrush truncate energy capture spatially and temporally thus impacting nutrient cycling and distribution.
Mechanism
Seeding of deep-rooted bunchgrasses, coupled herbicide. Brush treatments may be applied if needed. Probability of success is extremely low.
Relevant conservation practices
| Practice | External resources |
|---|---|
|
Brush Management |
|
|
Range Planting |
Mechanism
Trigger: Catastrophic fire.
Slow variables: Increased production and cover of non-native annual species.
Threshold: Increased continuous fine fuels modify the fire regime by changing intensity, size, and spatial variability of fires. Changes in plant community composition and spatial variability of vegetation due to the loss of perennial bunchgrasses and sagebrush truncate energy capture spatially and temporally, thus impacting nutrient cycling and distribution.
Model keys
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Ecological sites
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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.