This state represents the natural range of variability under pristine conditions. The plant communities of this site are dynamic in response to changes in disturbance regimes and weather patterns. Primary natural disturbance mechanisms affecting this ecological site are long-term drought and insect attack. Historically wildfire was infrequent and patchy and had a minimal impact due to low fuel loading. The extended fire return interval resulted in long-lived stable shadscale dominated plant communities. The state is sparsely vegetated and soil stability is primarily provided by microbiotic soil crust.
The Invaded State is characterized by the presence of non-native species in the understory. Ecological function has not changed at this time, however, the resiliency of the state has been reduced. A biotic threshold has been crossed with the introduction of non-native species that cannot be removed from the system and have the potential to alter disturbance regimes significantly from their historic range of variability.
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.
The Eroded State is characterized by reduced soil stabilization due to loss of vegetative cover and microbiotic soil crust. A biotic threshold has been crossed, with the loss of microbiotic soil crust leading to active soil erosion. This state is characterized by a new ecological equilibrium, one that includes reduced nutrient cycling and infiltration.
Introduction of non-natives due to anthropogenic impacts, including OHV use, dry land farming, grazing, linear corridors, mining, military training operations and settlements.
Repeated disturbance further decreases microbiotic soil crust and vegetative cover.
Model keys
Briefcase
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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.
) icon wherever it occurs. Drag and drop items to reorder. Cookies are used to store briefcase items between browsing sessions. Because of this, the number of items that can be added to your briefcase is limited, and briefcase items added on one device and browser cannot be accessed from another device or browser. Users who do not wish to place cookies on their devices should not use the briefcase tool. Briefcase cookies serve no other purpose than described here and are deleted whenever browsing history is cleared.
