Subirrigated
Scenario model
Current ecosystem state
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Management practices/drivers
Select a transition or restoration pathway
- Transition T1A More details
- Transition T1B More details
- Transition T2A,B More details
- Transition T2C More details
- Restoration pathway T3A,B More details
- Transition T3C More details
- Restoration pathway T4A More details
- Restoration pathway T4B,C More details
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No transition or restoration pathway between the selected states has been described
Target ecosystem state
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Description
The Reference State represents the natural range of variability that dominates the dynamics of this ES. This state is typically dominated by warm-season grasses. Before European settlement of North America, the primary disturbance mechanisms for this site in the reference condition included periodic fire, grazing by large herding ungulates, fluctuations in the water table, and ponding frequency and duration. Frequent surface fires (every 3 to 5 years) and grazing, coupled with weather events, dictated the dynamics that occurred within the natural range of variability. Today, the primary disturbances are lack of fire, concentrated livestock grazing, and weather fluctuations. Species that are desirable for livestock and wildlife can decline and a corresponding increase in less desirable species will occur.
Submodel
Description
The Native/Invaded State represents the more common range of variability that exists with higher levels of grazing management, but in the absence of periodic fire due to fire suppression. This state is dominated by warm-season grasses. It can be found on areas that are properly managed with grazing and/or prescribed burning, and sometimes on areas receiving occasional short periods of rest. Taller warm-season species can decline and a corresponding increase in short statured grass will occur.
Submodel
Description
The Invaded State is a result of encroachment mainly by invasive introduced cool-season grasses. The ecological processes are not functioning, especially the biotic processes and the hydrologic functions. The introduced cool-season grasses cause reduced infiltration and increased runoff. Preliminary studies would tend to indicate this threshold may exist when Kentucky bluegrass exceeds 30 percent of the plant community and native grasses represent less than 40 percent of the plant community composition. The opportunity for high intensity spring burns is severely reduced by early green-up and increased moisture and humidity at the soil surface. Grazing pressure cannot cause a reduction in sod grass dominance. Production is limited to the sod forming species. Infiltration continues to decrease, runoff increases, and energy capture into the system is restricted to early season low producing species. Nutrient cycling is limited by root depth of the dominant species.
Once the state is well established, even drastic events such as high intensity fires driven by high fuel loads of litter and thatch will not result in more than a very short-term reduction of Kentucky bluegrass. These events may reduce the dominance of Kentucky bluegrass but due to the large amount of rhizomes in the soil there is no opportunity for the native species to establish before Kentucky bluegrass rebounds.
Submodel
Mechanism
Non-use and/or no surface fire for extended periods of time (typically for 10 or more years), causing litter levels to become high enough to reduce native grass vigor, diversity, and density, heavy, continuous grazing, or invasion of non-native plant species will likely lead this state over a threshold resulting in the Native/Invaded State (State 2).
Mechanism
Tillage will cause a shift over a threshold leading to the 4.1 Annual Crops Plant Community Phase within the Crop Production State (State 4).
Mechanism
Heavy, continuous grazing (stocking levels well above carrying capacity for extended portions of the growing season and at the same time of year each year) will cause a shift across a threshold leading to the 3.2 Kentucky Bluegrass/Baltic Rush/Forbs Plant Community Phase within the Invaded State (State 3).
Mechanism
Tillage will cause a shift over a threshold leading to the 4.1 Annual Crops Plant Community Phase within the Crop Production State (State 4).
Mechanism
Long-term prescribed grazing (moderate stocking levels coupled with adequate recovery periods, or other grazing systems such as high-density, low-frequency intended to treat specific species dominance, or periodic light to moderate stocking levels possibly including periodic rest) coupled with prescribed burning occurring at relatively frequent intervals (3 to 5 years), and a return to normal disturbance regime levels may lead this 3.1 Smooth Bromegrass-Kentucky Bluegrass Plant Community Phase within the Invaded State (State 3) over a threshold to the Native/Invaded State (State 2).
Seeding followed by Long-term prescribed grazing (moderate stocking levels coupled with adequate recovery periods, or other grazing systems such as high-density, low-frequency intended to treat specific species dominance, or periodic light to moderate stocking levels possibly including periodic rest) may lead this Invaded State (State 3) over a threshold to the Native/Invaded State (State 2).
Mechanism
Tillage will cause a shift over a threshold leading to the 4.1 Annual Crops Plant Community Phase within the Crop Production State (State 4).
Mechanism
Seeding may lead this Crop Production State (State 4) over a threshold to the Native/Invaded State (State 2).
Mechanism
Seeding may lead this Crop Production State (State 4) over a threshold to the Invaded State (State 3).
Cropping followed by abandonment may lead this plant community phase over a threshold to the 3.3 Annual Pioneer- Perennial Pioneer Plant Community Phase within the Invaded State (State 3).
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.