This state represents the natural range of variability under pristine conditions. This state is dominated by perennial bunchgrasses and primary natural disturbance mechanisms affecting this ecological site are wildfire, long-term drought and insect attack. Timing for disturbance in combination with weather events determines plant community dynamics. This site may experience light to moderate grazing by wildlife. Additional run-in moisture aids in maintaining the community phases of this state, by favoring a greater dominance by grasses with a lesser component of shrubs. This site is distinguished by higher ecological resistance and resilience due to the increased annual production, additional moisture, and higher amounts of organic matter when compared to the surrounding sites.
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.
AMDU and TIPA persist after invasion by non-native annuals. A biotic threshold has been crossed by the introduction of non-native annuals that cannot be removed from the system and will alter disturbance regimes significantly from their natural or historic range of disturbances. Ecological function has not changed, however the resiliency of the state has been reduced by the presence of non-native annual species.
Introduction of non-native species due to anthropogenic disturbance including OHV use, dry land farming, grazing, linear corridors, mining, military training operations, and settlements.
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.
