Panspot (Pn)
Scenario model
Current ecosystem state
Select a state
Management practices/drivers
Select a transition or restoration pathway
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Transition T1A
Introduction of non-native grass species, particularly annual bromes such as field brome and cheatgrass.
More details -
Transition T2A
Prolonged drought, improper grazing management, or a combination of these factors
More details -
Transition T2B
Conversion to cropland
More details -
Restoration pathway R3A
Range seeding, grazing land mechanical treatment, timely moisture, proper grazing management (management intensive and costly)
More details -
Transition T3B
Conversion to cropland
More details -
Transition T4A
Cessation of annual cropping
More details -
Transition T5A
Conversion to cropland
More details -
No transition or restoration pathway between the selected states has been described
Target ecosystem state
Select a state
Description
The Historic Reference State (1) contains one community phase characterized by shortgrasses and rhizomatous wheatgrasses. This state is considered extinct and is included here for historical reference purposes. It evolved under the combined influences of climate, grazing, and fire, with climatic variation having the greatest influence on cover and production. In general, this state was resilient to grazing; however, localized areas likely received heavy grazing, which may have resulted in shifts in the species composition. Fire dynamics are not well understood, but fire was most likely a minor influence on this site due to the sparse vegetation.
Submodel
Description
The Contemporary Reference State (2) contains two community phases characterized by shortgrasses and rhizomatous wheatgrasses. It evolved under the combined influences of climate, grazing, and fire, with climatic variation having the greatest influence on cover and production. This state differs from the historical reference state in that it is influenced by introduced plant species and has altered fire and grazing regimes. In general, this state is resilient to grazing although grazing can influence species composition in localized areas. Fire dynamics are not well understood, but fire is most likely a minor influence on this site due to the sparse vegetation.
Submodel
Description
The Altered State (3) consists of one community phase. The dynamics of this state are driven by long-term drought, improper grazing management, or a combination of these factors. Perennial grasses decrease with long-term improper grazing and bare ground increases. It is hypothesized that this results in increased heating of the soil by solar radiation, which exacerbates the already dry site conditions and creates a self-perpetuating condition of extreme drought. Under these conditions, it is very difficult for perennial species to persist or establish. This hypothesis has not been tested and requires further investigation. Non-native annual bromes may also persist in this state, but it is not known if they the site properties sufficiently to transition it to an Invaded State.
Submodel
Description
The Cropland State (4) occurs when land is put into cultivation. Major crops in MLRA 53A are small grains such as wheat.
Submodel
Description
The Post-Cropland State (5) occurs when cultivated cropland is abandoned and allowed to either revegetate naturally or is seeded back to perennial species for grazing or wildlife use. This state can transition back to the Cropland State (4) if the site is put back into cultivation.
Submodel
Mechanism
Introduction of non-native grass species occurred in the early 20th century. The naturalization of these species in relatively undisturbed grasslands, coupled with changes in fire and grazing regimes, transitions the Reference State (1) to the Contemporary Reference State (2).
Mechanism
Prolonged drought, improper grazing practices, or a combination of these factors weaken the resilience of the Contemporary Reference State (2) and drive its transition to the Altered State (3). The Contemporary Reference State (2) transitions to the Altered State (3) when perennial grasses become rare and contribute little to production. Cactus and annual forbs dominate the plant community.
Mechanism
Tillage or application of herbicide followed by seeding of cultivated crops, such as winter wheat, spring wheat, and barley, transitions the Contemporary Reference State (2) to the Cropland State (4).
Mechanism
It is hypothesized that solar heating creates a self-perpetuating condition of extreme drought that suppresses establishment of perennial species, therefore a reduction in livestock grazing pressure alone may not be sufficient to restore the Altered State (3) to the Contemporary Reference State (2). Intensive management treatments may be necessary (Hart et al., 1985), but it is not known how well this site responds to practices such as mechanical treatment of grazing land and range seeding. Therefore, returning the Altered State (3) to the Contemporary Reference State (2) will likely require considerable energy and cost and may not be feasible within a reasonable amount of time.
Relevant conservation practices
| Practice | External resources |
|---|---|
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Prescribed Grazing |
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Grazing Land Mechanical Treatment |
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Range Planting |
Mechanism
Tillage or application of herbicide followed by seeding of cultivated crops, such as winter wheat, spring wheat, and barley, transitions the Altered State (3) to the Cropland State (4).
Mechanism
The transition from the Cropland State (4) to the Post-Cropland State (5) occurs with the cessation of cultivation. The site may also be seeded to perennial forage species. Such seedings may be comprised of introduced grasses and legumes or a mix of native species.
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.