The Reference State (1) describes the range of vegetative communities that occur on the Wet Subirrigated ecological site where the range of natural variability under historic conditions and disturbance regime is mostly intact. The Reference State developed under the combined influences of climatic conditions, periodic fire activity, grazing by large herbivores, and impacts from small mammals and insects. High perennial grass cover and production allows for increased soil moisture retention, vegetative production, and overall soil quality.
The Reference State includes three community phases which are the Reference Community (1.1), the Degraded Native Grass Community (1.2) and the At-Risk Community (1.3), The Reference Community serves as a description of the native plant community that naturally occurs on the site when the natural disturbance regimes are intact or closely mimicked by management practices. The Degraded Native Grass and At-Risk Communities results from management actions that are unfavorable for a healthy Reference Community.
The Invaded Grass State (2) transitioned from the Reference State (1) and a large portion of the native, warm-season tallgrass and native cool-season grass components have been replaced by non-native cool-season grasses. Encroachment by non-native, cool-season grasses is typically caused by heavy, continuous or heavy, continued seasonal grazing, repetitive haying, or a combination of heavy grazing and repetitive haying. Prolonged absence of grazing and fire may also produce a plant community dominated by non-native, cool-season grasses. While the non-native grasses may enter the plant community through encroachment from adjacent introduced grass plantings, this State most often develops when meadows are interseeded with non-native species. In the past, interseeding with non-native species was a common practice. This attempt to improve forage production profoundly impacted the nature of the Wet Subirrigated site. Due to the aggressive nature of the typical non-native grasses found in this State, return to the Reference State is highly unlikely.
Historically, the Reference State (1) transitioned to the Invaded Grass State (2) with heavy grazing or with long term repeated haying. This transition also occurs when non-native grasses are interseeded into the plant community. Once non-native grasses have established, the plant community is very difficult to alter due to the aggressive nature of the non-native grasses and restoration to the Reference State is highly unlikely.
Model keys
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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.
