Deep Sand
Scenario model
Current ecosystem state
Select a state
Management practices/drivers
Select a transition or restoration pathway
-
Transition T1 to 2
Excessive grazing.
More details
Lack of fire. -
Restoration pathway R2 to 1
Prescribed grazing.
More details
Prescribed fire.
Brush management. -
Transition T2 to 3
Excessive grazing.
More details -
No transition or restoration pathway between the selected states has been described
Target ecosystem state
Select a state
Description
The Reference State is defined by three native plant communities that are a result of periodic fire (or lack of fire), drought, herbivory, and ungulate grazers (or non-use). These events are part of the natural disturbance regime and climatic processes that contribute to the development of the site. The reference plant community (1.1) consists of tall, mid, short, warm, and cool-season grasses, forbs and shrubs. This plant community is dominated by warm-season tallgrasses. The 1.2 community is dominated by blue grama and sand sagebrush and is at risk of exceeding the resilience limits of the Reference State and transitioning to the Shrub State. The 1.3 community resembles the reference plant community with lower plant density and excessive amounts of litter.
A loss of plant cover and an increase in bare ground creates the probability of wind erosion. Drought-induced wind scouring coupled with disturbance (wildfire, continuous grazing, rodents, and vehicle traffic) can lead to blowouts and possibly an active sand dune. Extreme care and management should be taken when managing these areas.
Submodel
Description
The Reference State has been driven beyond the limits of ecosystem resilience and has crossed a threshold to the Shrub State. The designation of the Shrub State denotes changes in plant species composition. Litter distribution, nutrient cycling, and carbon sequestration are not uniform. Litter levels are high and nutrients are cycling primarily under sagebrush. The water cycle is impaired. Dense shrub canopy and increased bare ground reduce effective precipitation and infiltration through evaporation and interception. Energy flow is impaired. Warm-season grasses, forbs, and shrubs have largely been replaced by a dominance of sand sagebrush. Wind scour can occur and enlarge to form blowouts. Water flow becomes connected and runoff is possible during intense storms. Desertification is advanced. Species diversity has substantially decreased. Production varies with the density and vigor of sand sagebrush. Cheatgrass can significantly invade this plant community. This change in plant species affects the hydrology, erosion potential, forage production, and wildlife habitat. Understory plants may be negatively affected by shrubs reducing the availability of light, soil moisture, and soil nutrients. As the size and density of shrubs increase, the cover and productivity of understory plants decrease.
As establishment of shrubs increase, fine-fuel loads decrease. Prescribed fire can become an ineffective tool.
Submodel
Description
The Eroded State is characterized by two plant community phases. An ecological threshold has been crossed as a result of this transition.
The designation of the Eroded State denotes changes in infiltration, runoff, aggregate stability, and species composition. The changes in water movement and the plant community affect changes in hydrologic functionality, biotic integrity, and soil and site stability. Infiltration, runoff, and soil erosion vary depending on the vegetation present.
Submodel
Mechanism
The trigger for this transition is long-term excessive grazing and lack of fire. Due to the increased canopy cover of sand sagebrush there is less infiltration and an increase in interception of rainfall events.
Mechanism
Appropriately timed prescribed grazing, brush management, and prescribed fire are the tools required to return this state to the Reference State.
Relevant conservation practices
| Practice | External resources |
|---|---|
|
Brush Management |
|
|
Prescribed Burning |
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|
Prescribed Grazing |
Mechanism
Long-term heavy, continuous grazing without adequate recovery periods results in a shift from the Shrub State to the Eroded State. Ecological function has been compromised. The effects of this ecological threshold being crossed include changes in aggregate stability, nutrient availability, plant cover, and hydrologic function. Accelerated wind erosion can cause the formation of blowouts.
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.