The reference state is representative of the natural range of variability under pristine conditions. Plant community phase changes are driven by drought, infrequent wildfire, disease, insect attack and occasional flooding in response to heavy rainfall events. Fire is rare in this system. This ecological site experiences seasonal flooding and is important for redistributing moisture and nutrients throughout the landscape. Plant community dynamics are controlled by interactions between weather patterns and disturbance regimes.
The Invaded State is characterized by the presence of non-native species in the understory. Non-native annuals will persist once introduced into the plant community, due to their annual growth form, abundant seed production and long term seed viability. Non-native annuals such as red brome, redstem filaree, and Mediterranean grass are potential invaders on this ecological site. Saltcedar is also a potential invader. A biotic threshold is crossed with the introduction of non-natives that are difficult to remove from the system and have the potential to alter disturbance regimes significantly from their historic range of variation. Non-native annuals are highly flammable and promote wildfire where fires historically have been infrequent.
The eroded state is characterized by increased erosion, channel entrenchment, sediment transport and the loss of perennial vegetation. Natural ecosystem processes are disrupted and sediment and nutrients are increasingly redistributed downstream. Feedbacks contributing to the stability of this state include soil erosion, nutrient loss, increased runoff and decreased infiltration. These feedbacks prevent the establishment of native vegetation and lead to further ecological damage. This state is considered to be hydrologically impaired. Non-natives persist in the plant community due to their annual growth form, persistent seed bank and competitive ability.
Introduction of non-native species due to a combination of factors including: 1) surface disturbance, 2) changes in the kinds of animals and their grazing patterns, 3) drought and/or 4) changes in fire history.
Restoration pathway. Ecological processes can be restored to the site, but non-natives remain. Possible restoration techniques include stabilizing the site by reestablishing native perennials and the use of erosion control structures to dissipate energy and reestablish the flood plain.
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.
