Closed Depression
Scenario model
Current ecosystem state
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Management practices/drivers
Select a transition or restoration pathway
- Transition T1A More details
- Transition T5A More details
- Transition T2A - T2B More details
- Transition T5A More details
- Restoration pathway R3A More details
- Transition T5A 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 ecological site. This State is dominated by cool- season grasses, grass-likes, and forbs. In pre-European times, the primary disturbance mechanisms for this site in the Reference condition included periods of below-average and above-average precipitation (resulting in alternating periods of ponding and drying) and grazing by large herding ungulates. Timing of grazing coupled with weather events dictated the dynamics that occurred within the natural range of variability. Today, this State 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. Wheatgrass species can decline and a corresponding increase in foxtail barley, warm-season shortgrasses, and forbs will occur. Under extended periods of disturbance, the main change is a reduction in vigor and production and an increase in bare ground and forb composition. The Reference State (1.0) has one plant community (1.1) with two distinct sub-phases as a result of the alternating periods of ponding and drying.
Submodel
Description
The Native/Invaded State is dominated by native and non-native cool-season grasses. The non-native cool-season grasses, primarily Kentucky bluegrass, make up less than 15 percent of the total annual production. This State is the result of heavy, continuous grazing and/or excessive haying, or heavy disturbance which can create soil compaction. The Native/Invaded State is very resilient and resistant to change. This State, like the Reference State (1.0), will have one plant community (2.1) with two distinct sub-phases as a result of the alternating periods of ponding and drying.
Submodel
Description
The Invaded State is the result of heavy, continuous grazing and/or excessive haying, or heavy disturbance that creates soil compaction. It is dominated by native and non-native cool-season grasses. The non-native cool-season grasses make up more than 30 percent of the total annual production. Preliminary studies tend to indicate a threshold may be crossed when Kentucky bluegrass exceeds 30 percent of the plant community and native grasses represent less than 40 percent of the plant community. Plant communities dominated by Kentucky bluegrass will have significantly less cover and diversity of native grasses and forb species (Toledo, D. et al., 2014). This State is very resilient and resistant to change.
Submodel
Description
This State developed through mechanical manipulation of the watershed causing the loss of hydrologic function, biotic integrity, and soil site stability. On existing rangeland, hydrologic function is disrupted through terracing, contour furrowing, or pitting in the area surrounding the closed depression. Other causes include installation of dugouts, severe mechanical disturbance through tillage, and the conversion to cropland or pastureland.
Submodel
Mechanism
Invasion of non-native herbaceous species; heavy, continuous grazing (grazing at full to heavy levels for extended portions of the growing season without adequate recovery periods); and/or excessive haying, or heavy disturbance may cause a shift to the Native/Invaded State (2.0). During the wet cycles prior to soils drying, the Reference Plant Community (1.1) is highly susceptible to compaction if heavy grazing occurs when the soil is saturated. This type of disturbance can cause a rapid decline in the native vegetation and a subsequent influx of non-native forb species to occur.
Mechanism
Heavy disturbance, installation of water control structures (terraces or dugouts), or land use conversion to crop or pasture will transition any plant community in this ecological site to the Degraded State (4.0).
Mechanism
T2A) Heavy, continuous grazing (grazing at full to heavy levels for extended portions of the growing season without adequate recovery periods) and/or excessive haying, or heavy disturbance causing soil compaction will likely lead to the Foxtail Barley-Bluegrass (greater than 30 percent) Plant Community Phase (3.1) within the Invaded State. This transition is most likely to originate from the drier sub-phase of the Native/Invaded State to the drier 3.1 Plant Community.
T2B) Soil compaction due to heavy disturbance when the soils are saturated coupled with heavy, continuous grazing and/or excessive haying, and invasion of non-native species may cause a shift to the Introduced Forbs/Foxtail Barley Plant Community (3.2). This combination of disturbances can cause a rapid decline in the native vegetation and a subsequent influx of non-native grasses and forb species to occur. This transition is most likely to originate from the wetter sub-phase of the Native/Invaded State to the wetter 3.2 Plant Community.
Mechanism
Heavy disturbance, installation of water control structures (terraces or dugouts), or land use conversion to crop or pasture will transition any plant community in this ecological site to the Degraded State (4.0).
Mechanism
Removal of heavy disturbance combined with long-term prescribed grazing that includes alternating season of use and allowing adequate recovery periods between grazing events, and possibly the use of prescribed burning, may eventually lead this plant community back to the Native/Invaded State (2.0). Due to soil compaction and the high percentage of non-native cool-season grasses, this transition may not be feasible or meet management goals.
Relevant conservation practices
| Practice | External resources |
|---|---|
|
Prescribed Burning |
|
|
Prescribed Grazing |
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.