Natural Resources
Conservation Service
CHURNING CLAY 12-16
Scenario model
Current ecosystem state
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Management practices/drivers
Select a transition or restoration pathway
- Transition T1 More details
- Transition T2 More details
- Transition T4 More details
- Transition T3 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 represents the natural range of variability under pre-Euro settlement conditions. 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.
Characteristics and indicators
This state is characterized by silver sagebrush overstory with Nevada bluegrass in the understory. Bottlebrush squirreltail, big bluegrass and slender wheatgrass and a variety of forbs species are sub-dominant. Natural fire frequency is estimated to be 50-70 years. Significant year-to-year variation in ponding and depth to water table are primary drivers for above ground biomass production. Prolonged drought or prolonged flooding decreases resilience and increases the probability of annual or perennial weed invasion.
Dominant plant species
silver sagebrush (Artemisia cana), shrub
bluegrass (Poa), grass
Submodel
Description
This state is similar to the Reference State 1.0. Ecological function has not changed, 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.
Dominant plant species
silver sagebrush (Artemisia cana), shrub
bluegrass (Poa), grass
Submodel
Description
The shrub state is the product of long-term reduction in perennial bunchgrasses. Sites may experience 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 and seasonal ponding is reduced or eliminated. In both cases, Nevada bluegrass is significantly reduced and silver sagebrush becomes dominant. The shrub overstory and shallow-rooted grasses dominate site resources such that soil water, nutrient capture, nutrient cycling and soil organic matter are temporally and spatially redistributed.
Characteristics and indicators
This state is characterized by the dominance of silver sagebrush, reduced perennial bunchgrasses and forbs, and stable or increasing non-natives. Bare ground is extensive. Rabbitbrush may be a significant component. Bottlebrush squirreltail and creeping wildrye may be maintained as minor components. Medusahead and foxtail barley are common.
Dominant plant species
silver sagebrush (Artemisia cana), shrub
Submodel
Description
Increased run-on has cut a channel through the site, ponding has been reduced significantly and soil loss has occurred. Changes in site hydrology and repeated wildfire affect vigor, recruitment, and production of native perennials. This state is dominated by non-native annuals and shallow-rooted, disturbance tolerant, perennials.
Characteristics and indicators
Bare ground is extensive. Soil erosion is actively occurring. Rabbitbrush or remnants of silver sagebrush may be present. Annual non-natives, like medusahead, and shallow-rooted perennials, like foxtail barley, are dominant.
Dominant plant species
cheatgrass (Bromus tectorum), grass
Submodel
Mechanism
Trigger: introduction of non-native annual and perennial plants, such as cheatgrass and medusahead. Slow variables: Over time the non-native species will increase within the community. Organic matter inputs are reduced. Disturbance tolerant native species like foxtail barley may also increase. Threshold: Any amount of introduced non-native species causes an immediate decrease in the resilience of the site. 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: Hydrologic altering of the site (i.e. gulling of associated channel upstream followed by severe soil erosion). Maybe also be coupled with repeated, inappropriate, growing season grazing and long term chronic drought. Slow variables: Long term decrease in deep-rooted perennial grass density, vigor, and reproduction. Threshold: Loss of deep-rooted perennial bunchgrasses changes nutrient cycling, nutrient redistribution, and organic matter inputs. Alteration in the hydrology of the site caused by soil erosion and gullying reduces soil moisture by increasing runoff and reducing or eliminating ponding.
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.
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 variable: 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.
Model keys
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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.
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