Natural Resources
Conservation Service
Scenario model
Current ecosystem state
Select a state
Management practices/drivers
Select a transition or restoration pathway
- Transition A More details
- Transition A More details
- Transition B More details
- Transition A More details
-
No transition or restoration pathway between the selected states has been described
Target ecosystem state
Select a state
Description
The Reference State 1.0 represents the natural range of variability under pristine conditions. The Reference State has 3 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, but has an additional community phase. Ecological function has not changed in this state; however the resiliency of the state has been reduced by the presence of invasive weeds. Non-natives may increase in abundance but will not become dominant within this State. These non-natives can be highly flammable and can promote fire where historically fire had been infrequent. Negative feedbacks enhance ecosystem resilience and contribute to the stability of the state. These feedbacks 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.
Submodel
Description
This state has one community phase and is a product of many years of heavy grazing during time periods harmful to perennial bunchgrasses. Sites may also transition to a shrub state if the hydrology of the area is affected by lowering water tables. In both cases, mat muhly is significantly reduced and silver sagebrush becomes dominant. Rabbitbrush may be a significant component. Sandberg bluegrass, bottlebrush squirreltail, and creeping wildrye may be maintained as minor components. The shrub overstory and shallower rooted grasses 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 one community phase and is characterized by the dominance of weedy species such as povertyweed and cheatgrass. Russian thistle (Salsola tragus), whitetop (Cardaria draba), clasping pepperweed (Lepidium perfolatum) are non-native species that may be present in the annual state.
Submodel
Mechanism
Trigger: This transition is caused by the introduction of non-native annual plants, such as cheatgrass and mustards. Slow variables: Over time the annual non-native species 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: Long-term chronic drought, and/or inappropriate grazing management. Slow variables: Long-term reduction in mat muhly and other grasses. Threshold: Loss of the perennial grass component changes nutrient cycling, nutrient redistribution, and reduces soil organic matter.
Mechanism
Trigger: Long-term chronic drought, inappropriate grazing management coupled with severe trampling, off-site or on-site water diversion, repeated fire, or combinations of these disturbances. Slow variables: Increased production and cover of non-native annual species. Long-term lowering of the water table. Reduced organic matter inputs. Threshold: Hydrology has permanently changed. Loss of deep-rooted perennial bunchgrasses and shrubs truncates, spatially and temporally, nutrient capture and cycling within the community. Increased continuous fine fuels from annual non-native plants modify the fire regime by changing intensity, size, and spatial variability of fires.
Mechanism
Trigger: Long-term chronic drought, inappropriate grazing management coupled with severe trampling, off-site or on-site water diversion, repeated fire, or combinations of these disturbances. Slow variables: Long-term decline in deep-rooted perennial grass density and increase in shrub overstory. Production and cover of non-native annual species increases over time. Long-term lowering of the water table and reduced organic matter inputs. Threshold: Hydrology has permanently changed. Loss of deep-rooted perennial bunchgrasses and shrubs truncates, spatially and temporally, nutrient capture and cycling within the community. Increased continuous fine fuels from annual non-native plants modify the fire regime by changing intensity, size, and spatial variability of fires.
Model keys
Briefcase
Add { ecological sites } and { Major Land Resource Areas } to your briefcase by clicking on the briefcase
(
) icon wherever it occurs. Drag and drop items to reorder. Cookies are used to store briefcase items between browsing sessions. Because of this, the number of items that can be added to your briefcase is limited, and briefcase items added on one device and browser cannot be accessed from another device or browser. Users who do not wish to place cookies on their devices should not use the briefcase tool. Briefcase cookies serve no other purpose than described here and are deleted whenever browsing history is cleared.
Ecological sites
Major Land Resource Areas
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.
Accessibility statement