Loamy
Scenario model
Current ecosystem state
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Management practices/drivers
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- Transition T1A More details
- Restoration pathway R2A 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 has a mix of grasses, forbs, and shrubs. Grasses provide the most annual production with shrubs secondary. The state has a diversity of cool and warm season species such as western wheatgrass, blue grama, sideoats grama, and squirreltail, with Wyoming big sagebrush scattered throughout.
Resilience management
The reference state is the most resilient to disturbance. A mix of grass and shrubs provides a diversity of root systems which maximizes ecological processes such as decomposition, mineralization, and soil aggregation. This in turn provides for greatest water infiltration and protection from erosion.
Submodel
Description
Big sagebrush dominates the plant community. Western wheatgrass and blue grama remain scattered and in low vigor. If blue grama is present, it frequently appears low in stature in shallow rooted patches. As the site continues to lose herbaceous species due to multiple feedbacks, bare ground increases and a surface soil crust develops. This soil surface condition retards water infiltration and grass establishment/recruitment and allows the site to persist in a big sagebrush state.
Production, species composition, and diversity are drastically reduced. Water cycle, nutrient cycle, and biotic integrity have been severely affected. As litter amounts decrease, bare areas increase. The semiarid environment coupled with loss of cover, magnifies soil surface crusting which impairs infiltration subsequently increasing overland flow. In advanced stages of non-activity, big sagebrush will show signs of decadence and mortality.
Resilience management
This state has limited resilience to disturbance. Erosion is active with new gullies evident. Long-duration drought may affect and kill the sagebrush as well.
Mechanism
The major long-term driver is repetitive, high utilization grazing of grass species while not allowing for regrowth and recovery for multiple years. This type of management eventually decreases health and vigor of grasses, fine fuel and the site's ability to carry fire. Big sagebrush gains a competitive advantage due to deep root systems and natural grazing defenses. Eventually the bare soil forms a crust due to low aggregate stability and a high percentage of bare ground. This makes it difficult for recruits to germinate.
Mechanism
Short-term sagebrush treatment, coupled with range seeding, and a period of grazing rest for stand establishment. Shrub removal should not be wholesale but in a mosaic of patchiness as sagebrush is an important species for the health of the site.
It is also best to implement long-term grazing management strategies where indicator plant species are seldom defoliated during the critical growth period and have an opportunity to colonize and restore ecosystem health.
Model keys
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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.