Shallow Clay (SwC)
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 species, such as Kentucky bluegrass and sweetclover.
More details -
Transition T2A
Prolonged drought, improper grazing management, or a combination of these factors
More details -
Transition T2B
Displacement of native species by non-native invasive species (Kentucky bluegrass, noxious weeds, etc.)
More details -
Restoration pathway R3A
Range seeding, grazing land mechanical treatment, timely moisture, proper grazing management (management intensive, costly, and may be unfeasible in some cases)
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) contains one community phase characterized rhizomatous wheatgrasses and mid-statured bunchgrasses. This state is considered extinct and is included here for historical reference purposes. It evolved under the combined influences of climate, grazing, and fire, with climatic variation having the greatest influence on cover and production. In general, this state was resilient to grazing; however, localized areas likely received heavy grazing, which resulted in the species composition shifting to short-statured species. Fire most likely resulted in a short-term shift in species composition to more warm-season grasses such as blue grama and fewer cool-season bunchgrasses.
Submodel
Description
The Contemporary Reference State (2) contains two community phases characterized by mid-statured bunchgrasses and sedges such as threadleaf sedge. It evolved under the combined influences of climate, grazing, and fire, with climatic variation having the greatest influence on cover and production. This state differs from the historical reference state in that it is influenced by introduced plant species and has altered fire and grazing regimes. In general, this state is resilient to grazing and fire, although these factors can influence species composition in localized areas
Submodel
Description
The Shortgrass State (3) consists of one community phase. The dynamics of this state are driven by long-term drought, improper grazing management, or a combination of these factors. Shortgrasses increase with long-term improper grazing at the expense of cool-season midgrasses (Coupland, 1961; Biondini and Manske, 1996). In particular, communities dominated by blue grama can alter soil properties, creating conditions that resist establishment of other grass species (Dormaar and Willms, 1990; Dormaar et al., 1994). Reductions in stocking rates can reduce shortgrass cover and increase the cover of cool-season midgrasses, although this recovery may take decades (Dormaar and Willms, 1990; Dormaar et al., 1994).
Submodel
Description
The Invaded State (4) occurs when invasive plant species invade adjacent native grassland communities and displace the native species. Data suggest that the diversity of native species declines significantly when invasive species exceed 30 percent of the plant community. Non-native perennial grasses, such as Kentucky bluegrass, are the most widespread concerns. Kentucky bluegrass is widespread throughout the Northern Great Plains (Toledo et al., 2014) and is very competitive. It 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 grasslands, 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
Mechanism
Introduction of non-native 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
Prolonged drought, improper grazing management, or a combination of these factors weakens the resilience of the Contemporary Reference State (2) and drives its transition to the Shortgrass State (3). The Contemporary Reference State (2) transitions to the Shortgrass State (3) when mid-statured grasses become rare and contribute little to production. Subshrubs and shortgrasses such as blue grama and prairie Junegrass dominate the plant community.
Mechanism
The Contemporary Reference State (2) transitions to the Invaded State (4) 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
A reduction in livestock grazing pressure alone may not be sufficient to reduce the cover of shortgrasses in the Shortgrass State (3) (Dormaar and Willms, 1990). Blue grama, in particular, can resist displacement by other species (Dormaar and Willms, 1990; Laycock, 1991; Dormaar et al., 1994; Lacey et al., 1995). Intensive management, such as reseeding and mechanical treatment, may be necessary (Hart et al., 1985), but these practices are labor intensive, costly, and may not be possible on this site due to topography. Therefore, returning the Shortgrass State (3) to the Contemporary Reference State (2) may require considerable energy and cost, and may not be feasible within a reasonable amount of time.
Relevant conservation practices
| Practice | External resources |
|---|---|
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Prescribed Grazing |
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Grazing Land Mechanical Treatment |
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Range Planting |
Model keys
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