Subirrigated
Scenario model
Current ecosystem state
Select a state
Management practices/drivers
Select a transition or restoration pathway
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Transition T1A
Heavy continuous grazing, non-use, no-fire, invasion
More details - Transition T1c More details
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Transition T1B
Tillage
More details -
Transition T2A & T2B
Non-use, no fire, heavy continuous grazing
More details -
Transition T2C
Tillage
More details -
Restoration pathway T3A & T3B
Prescribed burning, long term prescribed grazing, seeding
More details -
Transition T3C
Tillage
More details -
Restoration pathway T4A
Seeding
More details -
Restoration pathway T4B & T4C
Seeding, cropped and abandoned
More details -
No transition or restoration pathway between the selected states has been described
Target ecosystem state
Select a state
Description
The Reference State represents the natural range of variability of the dynamics of this ES. This state is typically dominated by warm-season grass and grass-like species. Before Europeans settled in North America, the primary disturbance mechanisms for this site in the Reference condition included periodic fire, grazing by large herding ungulates, and fluctuations in the water table. Frequent surface fires ( occurring every 3 to 5 years) and grazing, coupled with weather events dictated the natural range of variability. Today, the primary disturbance is from a lack of fire, concentrated livestock grazing, and weather fluctuations. In some locations, this site likely received relatively heavy grazing pressure. Tall warm-season grasses would have declined and shorter statured grass and grass-likes would have increased. Today, a similar state, the Native/Invaded State (State 2) 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.
Submodel
Description
This state represents the more common range of variability that exists with higher levels of grazing management in the absence of periodic fire. The Native/Invaded 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
This 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 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 sodgrass dominance. Production is limited to the sod-forming species. As infiltration decreases and runoff increases, the amount of energy captured 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 it's dominance, but due to the large amount of rhizomes in the soil, there is no opportunity for the native species to re-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, and/or 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
Encroachment of non-native invasive/noxious species, abandonment of cropping, or seeding of introduced and/or native improved varieties of forage species may lead this plant community phase over a threshold to the Invaded State (State 3) and more specifically to the 3.3 Annual/Pioneer, Non-native Perennial Plant Community Phase. In the case of a seeding, refer to the corresponding Forage Suitability Group (FSG) description for adapted species and expected production (production estimates in the FSG description may be unrealistically high due to the degraded condition of the site at this phase).
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
T2A – 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, will likely lead this state over a threshold leading to the 3.1 Smooth Bromegrass-Kentucky Bluegrass-Little Bluestem Plant Community Phase within the Invaded State (State 3).
T2B – Heavy continuous grazing (stocking levels well above carrying capacity for extended portions of the growing season and often at the same time of year each year), will likely lead this state over a threshold leading to the 3.2 Kentucky Bluegrass-Baltic Rush-Forbs Plant Community Phase within the Invaded State (State 3). Grazing repeatedly in the early growing season can expedite this shift by causing mechanical disturbance due to trampling.
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
T3A – 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).
T3B – 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
T4B – Seeding may lead this Crop Production State (State 4) over a threshold to the Invaded State (State 3).
T4C – 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.