Subirrigated
Scenario model
Current ecosystem state
Select a state
Management practices/drivers
Select a transition or restoration pathway
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Transition T1A
Long-term annual haying in mid-summer. Continuous, seasonal grazing in summer.
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Transition T1B
Seeding of introduced grass species.
More details -
Restoration pathway R2A
Long-term early haying or long-term, early grazing with adequate growing season recovery periods. This restoration will take an extended amount of time and may not be feasible.
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Transition T2A
Encroachment facilitated by long-term, annual, mid-summer haying. Seeding.
More details -
No transition or restoration pathway between the selected states has been described
Target ecosystem state
Select a state
Description
The Reference State (1) describes the range of vegetative communities that occur on the Subirrigated ecological site where the range of natural variability under historic conditions and disturbance regimes 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 two community phases which are the Reference Community (1.1) and the At-Risk Community (1.2). The Reference Community serves as a description of the native plant community that occurs on the site when the natural disturbance regimes are intact or closely mimicked by management practices. The At-Risk Community results from management actions that are unfavorable for a healthy Reference Community.
Submodel
Description
The Native/Non-Native Grass State (2) transitioned from the Reference State (1) and a significant portion of the native grasses has been replaced by non-native cool-season grasses. The management that resulted in the Native/Invaded Grass State is typically long-term annual haying in mid-summer. Under this management strategy, introduced grasses encroach from adjacent seeded areas. In the past, many Sandhills meadows were interseeded with non-native introduced grasses in an attempt to improve forage production. This interseeding often produced to a mixture of native and non-native grasses.
The loss of warm-season tall- and midgrasses negatively impacts energy flow and nutrient cycling and alters hydrologic function. The Native/Invaded Grass State is very resistant to change; Return to the Reference State will take a significant amount of time. If inadequate amounts of warm-season tall- and midgrasses are present, restoration to the Reference State will not be feasible.
The Native/Non-Native Grass State includes one community, the Native/Invaded Grass Community (2.1).
Submodel
Description
The Invaded Grass State (3) transitioned from the Native/Invaded Grass State (2) and most of the native grasses, both warm- and cool-season, have been replaced by non-native cool-season grasses through encroachment from other areas. The management that causes this transition is typically long-term, repetitive haying during the same time during the growing season or a combination of heavy grazing and repetitive haying.
The Invaded Grass State will also result when non-native, forage grasses such as reed canarygrass and creeping meadow foxtail are interseeded to improve forage production. In the past, many Sandhills meadows were interseeded with non-native grasses for this purpose.
Due to the aggressive nature of these non-native grasses, restoration to either the Reference State or the Native/Invaded Grass State is unlikely. The Invaded Grass State includes one plant community, the Non-Native Dominant Community (3.1).
Submodel
Mechanism
The Reference State (1) most often transitions to the Native/Non-Native state with long-term annual haying during mid-summer. This transition can also occur with long-term, seasonal grazing during the summer months. This process is accelerated when mid-summer haying or grazing is accompanied by heavy grazing in the fall.
Mechanism
Seeding non-native forage species will convert the Reference State (1) to the Invaded Grass State (3). Encroachment of non-native forage species from other areas will also cause this transition.
Mechanism
Long-term haying or grazing prior to the onset of the rapid growth period of warm-season tallgrasses will improve the health and vigor of the warm-season grasses restoring the Native/Invaded Grass State (2) to the Reference State (1). Early haying or grazing reduces cool-season grass competition and provides high quality hay. Grazing after a killing frost in the fall will also help reduce cool-season grass abundance. Care must be used on areas where Subirrigated, Wet Subirrigated, and Wet Land sites are interspersed as concentrated grazing in the spring when water tables are highest can damage the wetter sites. This restoration will take a considerable amount of time and is only feasible if adequate warm-season tallgrasses remain in the plant community.
Mechanism
When warm-season grasses are low in vigor due to long-term repeated haying at the same time each year, non-native grasses will encroach if a viable seed source is available transitioning the Native/Invaded Grass State (2) to the Non-Native State (3). This transition will also occur when the Native/Invaded Grass State is further stress by heavy grazing. The Non-Native State also occurs when reed canarygrass and/or creeping meadow foxtail have been seeded after deterioration of native grass production.
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.