This state represents the natural range of variability under pristine conditions. Community phase changes are primarily driven by long-term drought and insect attack. Wildfire is infrequent and patchy in this ecological site due to low fuel loading and widely spaced shrubs
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. A combination of factors including surface disturbance, changes in the kinds of animals and their grazing patterns, drought, changes in fire history or any other type of vegetation removal can introduce non-native species to the system. The ability of non-native species to fill the interstitial spaces between shrubs provides a continuous fuel load which may increase fire frequency, contributing to the difficultly in returning this site to the reference state.
LATR and AMDU persist after invasion by non-native annuals, but the other shrubs and desirable grasses may be unsuccessful in competing with the non-natives. A biotic threshold has been crossed, with the introduction of non-native annuals that cannot be removed from the system due to their widespread naturalization. At this time ecological function has not changed, however the resiliency of the state has been reduced by the presence of non-native annual species. The non-natives have the potential to alter disturbance regimes significantly from their natural or historic range of disturbances.
An abiotic threshold has been crossed, triggered by a frequent and repeated wildfire. This alternative stable state is extremely persistent due to strong feedbacks, including fire regimes, energy capture and nutrient cycling.
Introduction of non-native species due to anthropogenic disturbances including OHV use, dry land farming, grazing, linear corridors, mining, military operations, and settlements.
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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.
