Sandy Foothill Palmer Divide
Scenario model
Current ecosystem state
Select a state
Management practices/drivers
Select a transition or restoration pathway
- Transition T1A More details
- Transition T1B More details
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Restoration pathway R2A
Prescribed Grazing. Prescribed Burning.
More details - Transition T2A More details
-
No transition or restoration pathway between the selected states has been described
Target ecosystem state
Select a state
Description
The Reference state of the Sandy Foothill Palmer Divide ecological site is characterized by three distinct plant communities. These communities represent the natural range of variability and fluctuate within the parameters that define the state. Precipitation patterns and management strategies regarding herbivory and fire frequency are the primary drivers that determine the distribution of these communities throughout this state (Anderson et al, 1982).
Characteristics and indicators
This state has not been sod-busted or overly eroded and has slight to moderate vegetative deviation from the historical mixed-grass prairie community.
Resilience management
The Reference state can be maintained by managing herbivory with appropriate stocking rates, and the timing and duration of grazing periods. Maintaining a natural fire regime with appropriately timed prescribed burning also contributes to this resilience.
Submodel
Description
The Altered state is characterized by the Blue Grama plant community. An ecological threshold has been crossed relative to the Reference state resulting in loss of resilience. This state is relatively resistant to disturbances due to this sod forming growth form of blue grama.
Characteristics and indicators
This state has a lack of diversity due to the dominance of blue grama and a corresponding reduction in the amount of warm-season tallgrasses. The structure of the plant community has changed from tallgrasses to shortgrass.
Resilience management
Light to moderate herbivory maintains this state.
Submodel
Description
The Blue Grama, Sleepygrass, Yucca, and Broom Snakeweed community characterizes this state. A further ecological threshold has been crossed as shown by a loss of resilience and resistance to disturbance.
Characteristics and indicators
An increase in the amount of bare ground is readily distinguishable. Plant community structure appears as patchy areas of blue grama and sleepygrass (Achnatherum robustum) with scattered shrubs such as soapweed yucca (Yucca glauca), broom snakeweed (Gutierrezia sarothrae), and plains pricklypear.
Resilience management
Light herbivory maintains this state.
Submodel
Description
The Invaded state is characterized by the Cheatgrass, Russian Thistle, and Broom Snakeweed community. An ecological threshold has been crossed as shown by a significant degradation of biologic integrity, and impaired hydrologic function.
Characteristics and indicators
The distinguishing characteristic is the dominance of invasive species.
Resilience management
This state is unstable.
Submodel
Mechanism
Excessive herbivory without adequate recovery periods and disruption of the natural fire regime.
Constraints to recovery
Impaired hydrologic function, reduced nutrient cycle, and altered energy flow due to the shallow root-pan that developed under the sod-bound blue grama.
Context dependence
Drought accelerates this transition.
Mechanism
Excessive herbivory without adequate recovery periods and disruption of the natural fire regime. Tillage or disturbance and fragmentation associated with residential construction also causes this transition.
Constraints to recovery
Interruption of the hydrologic cycle and the complete loss of the historical structural functional groups make recovery to the Reference state highly unlikely.
Context dependence
Local precipitation patterns greatly influence the response of the vegetative community.
Mechanism
Prescribed grazing management that allows adequate recovery and proper stocking facilitate recovery to the Reference state. Appropriately timed prescribed burning accelerates this process.
Context dependence
Local precipitation patterns influence the rate of recovery.
Relevant conservation practices
| Practice | External resources |
|---|---|
|
Prescribed Burning |
|
|
Prescribed Grazing |
Mechanism
Excessive herbivory without adequate recovery periods causes this transition. Interruption of the natural fire regime accelerates this process.
Constraints to recovery
Loss of a natural revegetation source, presence of a compaction layer in the soil due to lack of deep-rooted native grasses, reduced water infiltration, and increased surface runoff are all constraints to recovery once this threshold has been crossed.
Context dependence
Local precipitation patterns influence the development of the vegetative community.
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.