Subirrigated
Scenario model
Current ecosystem state
Select a state
Management practices/drivers
Select a transition or restoration pathway
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Transition T1A
Annual mid-summer haying or grazing with encroachment of non-native cool-season grass
More details -
Transition T1B
Seeding of non-native cool-season grass.
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Restoration pathway R2A
Long-term (> 10 years) grazing or haying timed to promote warm-season grass vigor.
More details -
Transition 2A
Continued annual mid-summer haying or grazing. Seeding non-native cool-season grass.
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 four plant community phases which are the Reference Community (1.1), the At-Risk Community (1.2), and the Excessive Litter 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 result from management decisions that are unfavorable for a healthy Reference Community. The Excessive Litter Community results when herbivory and fire are eliminated from the landscape.
Submodel
Description
The Invaded Grass State (2) has been degraded from the Reference State (1) and much of the native warm-season grass community has been replaced by native and non-native cool-season grasses. Non-native grasses make up 15 to 30 percent of the annual production. The reduction of the warm-season tall- and midgrasses has negatively impacted energy flow and nutrient cycling. This state occurs as a result of grazing or haying during the mid-summer year after year with the invasion of non-native, cool-season grasses. The Native/Invaded Grass State includes the Native/Non-Native Cool-Season Grass Community (2.1).
Submodel
Description
In the Invaded Grass State (3) much of the native warm-season grass community has been replaced by native and non-native cool-season grasses with non-native grasses producing 30 percent or more of the annual production. Native, warm-season grasses are present at minor or trace levels or are missing from the plant community. This state may occur either as a result of continued non-native grass invasion or interseeding of non-native grasses. The Invaded Grass State includes the Invaded Cool-Season Grass Community (3.1).
Submodel
Mechanism
The Reference State (1) transitions to the Native/Invaded Grass State (2) with the replacement of native, warm-season, tallgrasses by native cool-season grasses and the encroachment of non-native cool-season grasses such as Kentucky bluegrass, smooth brome, creeping bentgrass, creeping meadow foxtail, quackgrass, non-native cultivars of reed canarygrass and other cool-season grasses. Restoration to the Reference State will only be feasible when adequate remnants of warm-season tallgrasses are present and when the hydrology of the site has only been minimally impacted by the change in the plant community.
Mechanism
The transition from the Reference State (1) to the Invaded Grass State (3) occurs when non-native cool-season grasses such as creeping meadow foxtail, non-native cultivars of reed canarygrass, or other non-native grasses are seeded into native hay meadows.
Mechanism
Long-term (more than ten years) timely haying or rotational grazing can return the Native/Invaded Grass State (2) to the Reference State (1). Haying or grazing prior to the onset of active warm-season grass growth or alternating haying with timely grazing will improve warm-season grass vigor. Early haying also reduces cool-season grass competition and provides quality hay. Grazing this plant community in mid-May to early June will suppress cool-season grasses as will grazing in the fall after a killing frost. Caution must be used on areas where Subirrigated and Wet Land complexes exist ,as concentrated spring grazing can compaction on wetter sites. The amount of time needed for this restoration will depend upon the level of non-native grass encroachment. If the replacement of native, warm-season tallgrasses by non-native, cool-season grasses is extensive this restoration may not be feasible.
Mechanism
Th Native/Invaded Grass State (2) transitions to the Invaded Grass State (3) with continued annual mid-summer haying or continued summer grazing which causes the further increase of non-native cool-season grasses including Kentucky bluegrass, smooth brome, creeping bentgrass, creeping meadow foxtail, quackgrass, non-native cultivars of reed canarygrass and other cool-season grasses. This transition also occurs when reed canarygrass, creeping meadow foxtail, or other non-native cool-season grasses are seeded into the site. Alterations to the plant community and to hydrology make restoration 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.