The reference state is representative of the natural range of variability under pristine conditions. Plant community phase changes are primarily driven by long-term drought, wildfire, disease and insect attack. Plant communities of the reference state are stable and long lived, both creosotebush and white bursage persist in the plant community even though their relative percentages may change over time. Plant communities are dynamic in response to changes in disturbance regimes and weather patterns.
The invaded state is characterized by the presence of non-native species. Introduced annuals such as red brome and redstem filaree have invaded the reference plant community and have become a dominant component of the herbaceous cover. A biotic threshold is crossed, with the introduction of non-native annuals that are difficult to remove from the system and will alter disturbance regimes significantly from their natural or historic range of disturbances. These non-native annuals are highly flammable and promote wildfires where fires historically have been infrequent.
Introduction of non-native species due 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.
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.
