Natural Resources
Conservation Service
SHALLOW GRANITIC HILL 5-7 P.Z.
Scenario model
Current ecosystem state
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Management practices/drivers
Select a transition or restoration pathway
- Transition 1 More details
- Transition 2a More details
- Transition 2b More details
- Transition 3 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
This state represents the natural range of variability under pristine conditions. The reference state is dominated by long-lived evergreen shrub communities with an understory of cool and warm season perennial bunchgrasses. Plant community phase changes are primarily driven by fire, long-term drought and insect attack. Historically, fire is rare in this system, but does impact long-term plant community dynamics.
Submodel
Description
Introduced annuals such as red brome, schismus and redstem stork's bill have invaded the reference plant community and have become a dominant component of the herbaceous cover. This invasion of non-natives is attributed to a combination of factors including: 1) surface disturbances, 2) changes in the kinds of animals and their grazing patterns, 3) drought, and 4) changes in fire history. These non-natives annuals are highly flammable and promote wildfires where fires historically have been infrequent.
A biotic threshold has been crossed, with the introduction of no-natives that cannot be removed from the system. The presence of non-natives has reduced the ecological resilience of the site. Following a disturbance this state relies on the availability of an offsite seed source. These non-natives have the potential to significantly alter disturbance regimes from their historic range.
Submodel
Description
This state is characterized by the inability of blackbrush to return to the site. An abiotic and/or biotic threshold has been crossed, due to insufficient climatic conditions and/or lack of an available seed source, respectively. In the absence of ideal conditions blackbrush will not return to the site. Shrubs with high growth rates and high reproductive capacities will persist after invasion by non-native annuals. However, other shrubs, such as blackbrush, are unsuccessful competitors in the disturbance regime created by the non-natives and can be removed from the system.
Submodel
Description
This state is characterized by a fire return interval too frequent for native woody perennials to reestablish and the dominance of non-native annual grasses. A biotic threshold has been crossed removing important structural and functional groups. Ecological functions including nutrient cycling and infiltration have been severely reduced.
Submodel
Mechanism
Introduction of non-natives due to anthropogenic disturbances, including OHV use, dry land farming, grazing, linear corridors, mining, military training operations, and settlements.
Mechanism
Large scale high intensity fire in combination with insufficient climatic conditions for germination and establishment of blackbrush.
Mechanism
Large scale repeated fire excludes native perennials and creates non-native annual grassland.
Model keys
Briefcase
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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.
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