Discharge Closed Depression (CdD)
Scenario model
Current ecosystem state
Select a state
Management practices/drivers
Select a transition or restoration pathway
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Transition T1A
Introduction of non-native invasive species such as introduced gasses, forbs, or noxious weeds.
More details -
Transition T2C
Displacement of native species by invasive species (introduced grasses, noxious weeds, etc.)
More details -
Transition T2A
Tillage or herbicide application and seeding of annual crops
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Transition T2B
Artificial impoundment of water
More details -
Transition T2D
Artificial drainage, tillage or herbicide application, and seeding of annual crops
More details -
Transition T3A
Tillage or herbicide application and seeding of annual crops
More details -
Transition T3B
Artificial impoundment of water
More details -
Restoration pathway R4B
Cessation of annual cropping combined with reestablishment of native species
More details -
Transition T4A
Cessation of annual cropping combined with introduction of invasive species
More details -
Restoration pathway R5A
Restoration of natural hydrology and reestablishment of native species (labor intensive and costly)
More details -
Restoration pathway R6A
Restoration of natural hydrology and reestablishment of native species (labor intensive and costly)
More details -
No transition or restoration pathway between the selected states has been described
Target ecosystem state
Select a state
Description
The Historic Reference State (1) contained three community phases characterized by varying degrees of seasonal ponding. This state is considered extinct and is included here for historical reference purposes. Seasonal ponding was a key dynamic on this site and varied depending on annual precipitation patterns and catchment size. Vegetation was characterized concentric rings, or zones, within the depression that correspond to the hydroperiod of that particular zone. Some phases only exhibited one vegetation zone dominated by facultative upland species while other phases exhibited two or more zones with the most hydrophytic vegetation in the center of the depression and subsequent, drier plant communities toward the edges.
Submodel
Description
The Contemporary Reference State (2) contains three community phases. Seasonal ponding is a key dynamic on this site and varies depending on annual precipitation patterns and catchment size. Vegetation is characterized concentric rings, or zones, within the depression that correspond to the hydroperiod of that particular zone. The Ephemeral Phase (2.1) may only exhibit one vegetation zone dominated by facultative upland species. Other phases may exhibit two or more zones with the most hydrophytic vegetation in the center of the depression and subsequent, drier plant communities toward the edges.
Submodel
Description
The Invaded State (3) occurs when invasive plant species invade adjacent native grassland communities and displace the native species. Data suggest that native species diversity declines significantly when invasive species exceed 30 percent of the plant community. Non-native perennial grasses, such Kentucky bluegrass are the most widespread concerns. Kentucky bluegrass is widespread throughout the Northern Great Plains (Toledo et al., 2014) and mainly affects the ephemeral and temporarily ponded phases of this site. It is very competitive and displaces native species by forming dense root mats, altering nitrogen cycling, and having allelopathic effects on germination (DeKeyser et al., 2013). It may also alter soil surface hydrology and modify soil surface structure (Toledo et al., 2014). Plant communities dominated by Kentucky bluegrass have significantly less cover of native grass and forb species (Toledo et al., 2014; DeKeyser et al., 2009). Invasive grass species can invade relatively undisturbed sites, and it is not clear what triggers them to displace native species. In some cases, they have been found to substantially increase under long-term grazing exclusion (DeKeyser et al., 2009, 2013; Grant et al., 2009), but a consistent correlation to grazing management practices cannot be made at this time.
Noxious weeds such as leafy spurge and Canada thistle are not widespread in MLRA 53A, but they can be a concern in localized areas. These species are very aggressive perennials. They typically displace native species and dominate ecological function when they invade a site. In some cases, these species can be suppressed through intensive management (herbicide application, biological control, or intensive grazing management). Control efforts are unlikely to eliminate noxious weeds, but their density can be sufficiently suppressed so that species composition and structural complexity are similar to that of the Contemporary Reference State (2). However, cessation of control methods will most likely result in recolonization of the site by the noxious species.
Submodel
Description
The Undrained Cropland State (4) occurs when native vegetation is killed out, either by tillage or by herbicide application, and the site is seeded to annual crops. No other alterations are made to the natural hydrology or soils. This state typically only occurs in the Ephemeral Phase (2.1) and the Temporarily Ponded Phase (2.2). In this state the site is suitable for spring seeded crops such as spring wheat and barley, although seeding of crops may be delayed 2 to 3 weeks due to wet soil conditions. In wet years, this state may be too wet to farm and will transition to the Wet/Foxtail Barley Phase (4.2).
Submodel
Description
The Impounded State (5) occurs when water is artificially impounded on the site by damming or excavation. Water may be impounded for livestock water or for wildlife. Impoundment of water typically transitions the site to a semi-permanent wetland with open water, deep marsh, and drawdown vegetation zones. In many cases impoundment creates a larger wetland with high quality habitat for wildlife. In other cases, such as when an excavated pond is constructed in the center of the depression, a small semi-permanent wetland is created in the center while the remainder of the depression is drained, thus reducing total wetland area. In either case the natural hydrology of the site is significantly altered, resulting in a new state with different plant communities and ecological dynamics.
Submodel
Description
The Drained Cropland State (6) occurs when the site is drained, tilled or sprayed, and seeded to annual crops. Surface water is typically drained by means of surface ditches, diversions, or both. Following drainage, remaining native vegetation is killed out either by tillage or herbicide application, then the site is seeded to annual crops. The hydrology of the site is significantly altered and no longer functions in its natural condition.
Submodel
Mechanism
Introduction of non-native grass and forb species occurred in the early 20th century. The naturalization of these species in relatively undisturbed grasslands, coupled with changes in fire and grazing regimes, transitions the Reference State (1) to the Contemporary Reference State (2).
Mechanism
The Contemporary Reference State (2) transitions to the Invaded State (3) when aggressive perennial grasses or noxious weeds displace native species. The most common concerns are introduced bluegrasses, which are widespread invasive species in the Northern Great Plains (Henderson and Naeth, 2005; Toledo et al., 2014). The precise triggers of this transition are not clear, but data suggest that exclusion of grazing and fire may be a contributing factor in some cases (DeKeyser et al., 2013). In addition, other rangeland health attributes, such as reproductive capacity of native grasses and soil quality, have been substantially altered.
Mechanism
Tillage or application of herbicide and seeding of cultivated crops such as wheat, barley, or introduced hay transitions the Contemporary Reference State (2) to the Undrained Cropland State (4). This transition occurs primarily in the Ephemeral Phase (2.1) or the Temporarily Ponded Phase (2.2).
Mechanism
Artificial impoundment of water by damming or excavation transitions the Contemporary Reference State (2) to the Impounded State (4).
Mechanism
The combination of artificial drainage, tillage or herbicide application, and seeding of annual crops transitions the Contemporary Reference State (2) to the Drained Cropland State (4). This transition occurs primarily in the Seasonally Ponded Phase (2.3).
Mechanism
Tillage or application of herbicide and seeding of cultivated crops such as wheat, barley, or introduced hay transitions the Invaded State (3) to the Undrained Cropland State (4).
Mechanism
Artificial impoundment of water by damming or excavation transitions the Invaded State (3) to the Impounded State (5).
Mechanism
Cessation of annual cropping combined with reestablishment of native species transitions the site from the Undrained Cropland State (4) to the Contemporary Reference State (2). Specialized seeding techniques may be necessary, depending on site conditions, as well as intensive weed control to prevent invasion of non-native grasses and noxious weeds. These restoration methods are labor intensive, costly, and may be not be practical in all situations.
Relevant conservation practices
| Practice | External resources |
|---|---|
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Brush Management |
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Wetland Restoration |
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Herbaceous Weed Control |
Mechanism
Cessation of annual cropping combined with the introduction of invasive species transitions the site from the Undrained Cropland State (4) to the Invaded State (3).
Mechanism
Restoration of natural hydrology and reestablishment of native species transitions the site from the Impounded State (5) to the Contemporary Reference State (2). Specialized seeding techniques may be necessary, depending on site conditions, as well as intensive weed control to prevent invasion of non-native grasses and noxious weeds. Restoration of natural hydrology may require removal of dams or refilling of excavated pits. These restoration methods are labor intensive, very costly, and may be impractical, perhaps even detrimental, in some situations.
Relevant conservation practices
| Practice | External resources |
|---|---|
|
Brush Management |
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Wetland Restoration |
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|
Herbaceous Weed Control |
Mechanism
Cessation of annual cropping combined with restoration of natural hydrology and reestablishment of native species transitions the site from the Drained Cropland State (6) to the Contemporary Reference State (2). Specialized seeding techniques may be necessary, depending on site conditions, as well as intensive weed control to prevent invasion of non-native grasses and noxious weeds. Restoration of natural hydrology may require removal of diversions, plugging drainage ditches, or both. These restoration methods are labor intensive, very costly, and may be impractical in some situations.
Relevant conservation practices
| Practice | External resources |
|---|---|
|
Brush Management |
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Wetland Restoration |
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Herbaceous Weed Control |
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.