Loamy
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 exotic cool-season grasses
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Transition T2A
Extended periods of non-use or very light grazing, no fire
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Transition T2B
Extended periods of non-use or very light grazing, no fire
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Restoration pathway R3A
Long term prescribed grazing with prescribed burning
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Transition T3A
Extended periods of non-use or very light grazing, no fire
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Restoration pathway R4A
Successful range planting with prescribed grazing and prescribed fire
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Restoration pathway R4B
Failed range planting
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Transition T4A
Long term non-use and no disturbances
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Restoration pathway R5A
Prescribed burning and/or chemical/mechanical brush management followed by successful range planting
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Restoration pathway R5B
Prescribed burning and/or chemical/mechanical brush management followed by failed range planting
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Transition T6A
Cessation of annual cropping
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No transition or restoration pathway between the selected states has been described
Target ecosystem state
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Description
This state represents the natural range of variability that dominated the dynamics of this ecological site. This state was dominated by cool-season grasses. The primary disturbance mechanisms for this site in the reference condition include frequent fire and grazing by large herding ungulates. Timing of fires and grazing, coupled with weather events, dictate the dynamics that occur within the natural range of variability. Cool season species can decline and a corresponding increase in warm season grasses will occur.
Characteristics and indicators
Because of changes in disturbances and other environmental factors (particularly the widespread occurrence of exotic species), the Reference State is considered to no longer exist.
Resilience management
If intact, the reference state should probably be managed with current disturbance regimes which has permitted the site to remain in reference condition, as well as maintaining the quality and integrity of associated ecological sites. Maintenance of the reference condition is contingent upon a monitoring protocol to guide management.
Submodel
Description
This state is similar to State 1: Reference State but has been colonized by exotic cool-season grasses (commonly Kentucky bluegrass, smooth brome, and/or quackgrass). Although the state is still dominated by native grasses, an increase in these exotic cool-season grasses can be expected. These exotic cool-season grasses have been particularly and consistently invasive under long-term no-use and no fire. To slow or limit the invasion of these exotic cool-season grasses, it is imperative that managerial techniques (e.g., prescribed grazing, prescribed burning) be carefully constructed, monitored, and evaluated with respect to that objective. If management does not include measures to control or reduce these exotic cool-season grasses, the transition to State 3: Invaded State should be expected.
Annual production of this state can be quite variable, in large part due to the amount of exotic cool-season grasses. However, annual production may range from 1700-3000 pounds per acre with the contribution from exotic cool-season grasses varying from 4% to 39% of total production.
Characteristics and indicators
The presence of trace amounts of exotic cool-season grasses indicates a transition from State 1 to State 2. The presence of exotic biennial or perennial leguminous forbs (i.e., sweet clover, black medic) may not, on their own, indicate a transition from State 1 to State 2 but may facilitate that transition.
Resilience management
To slow or limit the invasion of these exotic grasses, it is imperative that managerial techniques (e.g., prescribed grazing, prescribed burning) be carefully constructed, monitored, and evaluated with respect to that objective. Grazing management should be applied that enhances the competitive advantage of native grass and forb species. This may include: (1) early spring grazing when exotic cool-season grasses are actively growing and native cool-season grasses are dormant; (2) applying proper deferment periods allowing native grasses to recover and maintain or improve vigor; (3) adjusting overall grazing intensity to reduce excessive plant litter (above that needed for rangeland health indicator #14 – see Rangeland Health Reference Worksheet); (4) incorporating early heavy spring utilization which focuses grazing pressure on exotic cool-season grasses and reduces plant litter, provided that livestock are moved when grazing selection shifts from exotic cool-season grasses to native grasses.
Prescribed burning should be applied in a manner that maintains or enhances the competitive advantage of native grass and forb species. Prescribed burns should be applied as needed to adequately reduce/remove excessive plant litter and maintain the competitive advantage for native species. Timing of prescribed burns (spring vs. summer vs. fall) should be adjusted to account for differences in annual growing conditions and applied during windows of opportunity to best shift the competitive advantage to the native species.
Submodel
Description
This state is the result of invasion and dominance of the exotic cool-season grasses (commonly Kentucky bluegrass, smooth brome, and/or quackgrass). Once the state is well established, prescribed burning and grazing techniques have been largely ineffective in suppressing or eliminating these species, even though some short-term reductions may appear successful. These exotic cool-season species often form monotypic stands; as a result, plant diversity is often markedly reduced and peak production is restricted to late spring/early summer due to the monotypic nature of these stands.
Characteristics and indicators
This site is characterized by exotic cool-season grasses constituting greater than 30 percent of the annual production and native grasses constituting less than 40 percent of the annual production.
Resilience management
Light or moderately stocked continuous, season-long grazing or a prescribed grazing system which incorporates adequate deferment periods between grazing events and proper stocking rate levels will maintain this State. Application of herbaceous weed treatment, occasional prescribed burning, and/or brush management may be needed to manage noxious weeds and increasing shrub (e.g., western snowberry) populations.
Submodel
Description
This state typically results from the abandonment of cropland, hayland, or residences/farmsteads. Vegetation is typically dominated by Kentucky bluegrass, smooth brome, and/or quackgrass. Common forb and shrub associates include northern bedstraw, common dandelion, Canada goldenrod, common yarrow, Canada thistle, western snowberry, and wild rose. If the site is adjacent to woodlands, sprouts and seeds from the woodland species may begin to encroach and colonize the site.
Characteristics and indicators
Tillage has destroyed the native plant community, altered soil structure and biology, reduced soil organic matter, and resulted in the formation of a tillage induced compacted layer which is restrictive to root growth. Removal of perennial grasses and forbs results in decreased infiltration and increased runoff.
Resilience management
Continued tillage will maintain the state. Control of noxious weeds will be required.
Submodel
Description
A Wooded State may develop on this site when it is in close proximity to wooded areas where the woodland vegetation may encroach upon the site and/or serve as a seed source for these species to colonize the site. Scattered shrub patches forming almost continuous woody dominated plant communities may also develop on the site due to elimination of fire as a disturbance and alteration of the historic grazing regimes. Over time, the site may be characterized as consisting of bur oak, green ash, and quaking aspen with an understory of smaller trees and shrubs. An herbaceous component of smooth brome, wildrye, and/or Kentucky bluegrass is often present, particularly when the canopy is more open. Under more closed canopies, the herbaceous understory is predominantly shade-tolerant sedges (e.g., Pennsylvania sedge, Sprengel’s sedge).
Characteristics and indicators
The dominance of woody species (by cover and production) distinguishes this state from other herbaceously dominated states.
Resilience management
This state is resistant to change in the long-term absence of fire. Restoration efforts would require the use of prescribed fire, mechanical treatment, and prescribed grazing. Considerable time and effort will be required to restore to other States.
Submodel
Mechanism
This is the transition from the State 1: Reference State to State 2: Native/Invaded State due to the colonization of exotic cool-season grasses (e.g., Kentucky bluegrass, smooth brome, quackgrass). This transition was facilitated by long-term season-long grazing, as well as long-term non-use and no fire events. The threshold between the states was crossed when exotic cool-season grasses became established on the site.
Constraints to recovery
Current knowledge and technology will not facilitate a successful restoration to Reference State.
Mechanism
This Transition from State 2: Native/Invaded State to State 3: Invaded State results from long-term non-use or very light grazing, with no fire, but can also occur under other management. Complete rest from grazing and elimination of fire are the more common contributors to this transition.
Preliminary studies indicate this threshold exists when both exotic cool-season grasses exceed 30% of the plant community and native grasses represent less than 40% of the plant community composition. Curbing the invasion by Kentucky bluegrass, smooth brome, or quackgrass through prescribed spring burns is limited by early green-up. Efficacy of prescribed grazing techniques have also been largely limited. The peak production period of this state is restricted due to the monotypic nature of the stands.
Constraints to recovery
Variations in growing conditions (e.g., cool, wet spring) will influence effects of various management activities on exotic cool-season grass populations.
Mechanism
This transition from the State 2: Native/Invaded to State 5: Wooded State generally occurs with long-term non- use or very light grazing, and no fire. Removal of all disturbance from sites located adjacent to wooded areas that can serve as a seed source for woody species to expand onto this site. This has become more frequent following European settlement when the historic fire regime was markedly reduced.
Constraints to recovery
The extended fire interval may make recovery doubtful due to the abundance of exotic cool-season grasses and lack of native grasses. Fire intensity along with consumption of available fuels may cause incomplete or patchy burns. Continued recruitment of tree seeds from adjacent sites will hamper site restoration.
Reticence to undertake tree removal and the perception that trees may be a desirable vegetation component for wildlife habitat, carbon sequestration, aesthetics, etc. are some of the constraints to recovery. Managers wanting to manage the site for deer, livestock, or grassland nesting birds will need to consider the intensive management required to restore and maintain the site in State 2. The disturbance regime necessary to restore this site to State 2: Native/Invaded State is very labor intensive and costly; therefore, addressing woody removal earlier in the encroachment phase is the most cost-effective treatment for woody control.
Mechanism
This restoration pathway from the State 3: Invaded State 2: Native/Invaded State may be initiated with the implementation of long-term prescribed burning followed by intensive prescribed grazing management. The success of this restoration pathway depends on the presence of remnant populations of native grasses in Community Phase 3.1. These remnant populations may not be readily apparent without close inspection. The application of prescribed burning may be needed at relatively short intervals in the early phases of this restoration process. Some efforts have shown promise with early season prescribed burning; however, fall burning may also be effective. Both prescribed grazing and prescribed burning are necessary to successfully initiate this restoration pathway.
It may be possible using selected plant materials and agronomic practices to approach something very near the functioning of State 2: Native/Invaded State. Application of chemical herbicides and the use of mechanical seeding methods using adapted varieties of the dominant native grasses are possible and can be successful. After establishment of the native plant species, management objectives must include the maintenance of those species, the associated reference state functions, and continued treatment of exotic grasses.
Context dependence
Grazing management should be applied in a manner that enhances/maximizes the competitive advantage of native grass and forb species over the exotic species. This may include the use of prescribed grazing to reduce excessive plant litter accumulations above that needed for rangeland health indicator #14 (see Rangeland Health Reference Worksheet). Increasing livestock densities may facilitate the reduction in plant litter provided length and timing of grazing periods are adjusted to favor native species.
Grazing prescriptions designed to address exotic grass invasion and favor native species may involve earlier, short, intense grazing periods with proper deferment to improve native species health and vigor. Fall (e.g., September, October) prescribed burning followed by an intensive, early spring graze period with adequate deferment for native grass recovery may shift the competitive advantage to the native species, facilitating the restoration to State 2: Native/Invaded.
Prescribed burning should be applied in a manner that enhances the competitive advantage of native grass and forb species over the exotic species. Prescribed burns should be applied at a frequency which mimics the natural disturbance regime, or more frequently as is ecologically (e.g., available fuel load) and economically feasible. Burn prescriptions may need adjustment to: (1) account for change in fine fuel orientation (e.g., “flopped” Kentucky bluegrass); (2) fire intensity and duration by adjusting ignition pattern (e.g., backing fires vs head fires); (3) account for plant phenological stages to maximize stress on exotic species while favoring native species (both cool- and warm-season grasses).
Mechanism
This transition pathway from State 3: Invaded State to State 5: Wooded State may be initiated by long-term non-use or very light grazing, and no fire. This primarily occurs near wooded areas that can serve as seed sources for the woody species to expand onto the site. This has become more frequent following European settlement when the historic fire regime was altered.
Constraints to recovery
The extended fire interval may make recovery doubtful due to the abundance of exotic cool-season grasses and lack of native grasses. Fire intensity along with consumption of available fuels may cause incomplete or patchy burns. Continued recruitment of tree seeds from adjacent sites will hamper site restoration.
Constraints to recovery include the reticence to undertake tree removal and the perception that trees may be a desirable vegetation component for wildlife habitat, carbon sequestration, aesthetics, etc. Managers wanting to manage the site for deer, livestock, or grassland nesting birds will need to consider the intensive management required to restore and maintain the site in State 2. The disturbance regime necessary to restore this site to State 2: Native/Invaded State is very labor intensive and costly; therefore, addressing woody removal earlier in the encroachment phase is the most cost-effective treatment for woody control.
Mechanism
The restoration pathway from State 4: Go-Back State to State 2: Native/Invaded State may result from a successful range planting with prescribed grazing and prescribed burning. Following seeding, prescribed grazing, prescribed burning, haying, or use of herbicides will generally be necessary to achieve the desired result and control any noxious weeds.
Context dependence
A successful range planting will include proper seedbed preparation, weed control (both prior to and after the planting), selection of adapted native species representing functional/structural groups inherent to the State 1, and proper seeding technique. Management (e.g., prescribed grazing, prescribed burning) during and after establishment must be applied in a manner that maintains the competitive advantage for the seeded native species. Adding non-native species can impact the above and below ground biota. Elevated soil nitrogen levels have been shown to benefit smooth brome and Kentucky bluegrass more than some native grasses. As a result, fertilization, exotic legumes in the seeding mix, and other techniques that increase soil nitrogen may promote smooth brome and Kentucky bluegrass invasion.
The method or methods of herbaceous weed treatment will be site specific to each situation; but generally, the goal would be to apply the pesticide, mechanical control, or biological control (either singularly or in combination) in a manner that shifts the competitive advantage from the targeted species to the native grasses and forbs. The control method(s) should be as specific to the targeted species as possible to minimize impacts to non-target species.
Mechanism
This restoration pathway from State 4: Go-Back State to State 3: Invaded State results from a failed range planting and/or secondary succession.
Context dependence
Failed range plantings can result from many causes (both singularly and in combination) including drought, poor seedbed preparation, improper seeding methods, seeded species not adapted to the site, insufficient weed control, herbicide carryover, poor seed quality (purity & germination), and/or improper management.
Mechanism
The transition from State 4: Go-Back State to State 5: Wooded State may occur with long term non-use and no disturbances, particularly when the site is adjacent to wooded areas. Sprouts and seeds from the wooded area may begin to encroach and colonize the site.
Constraints to recovery
The extended fire interval may make recovery doubtful due to the abundance of exotic cool-season grasses and lack of native grasses. Fire intensity along with consumption of available fuels may cause incomplete or patchy burns. Continued recruitment of tree seeds from adjacent sites will hamper site restoration.
Constraints to recovery include reticence to undertake tree removal and the perception that trees may be a desirable vegetation component for wildlife habitat, carbon sequestration, aesthetics, etc. Managers wanting to manage the site for deer, livestock, or grassland nesting birds will need to consider the intensive management required to restore and maintain the site in State 2. The disturbance regime necessary to restore this site to State 2: Native/Invaded State is very labor intensive and costly; therefore, addressing woody removal earlier in the encroachment phase is the most cost-effective treatment for woody control.
Mechanism
Restoration Pathway from State 5: Wooded State to State 2: Native/Invaded State occurs with the implementation of prescribed burning and/or chemical/mechanical brush management followed by successful range planting.
Context dependence
Fire intensity, along with consumption of available fuels, may cause incomplete or patchy burns. Continued recruitment of shrub tree seeds from adjacent sites and resprouting of existing shrubs will hamper site restoration. Intensive management is required to restore and maintain the site in State 2: Native/Invaded State.
Mechanism
Restoration Pathway from State 5: Wooded State to State 3: Invaded State occurs with the implementation of prescribed burning and/or chemical/mechanical brush management followed by a failed range planting.
Context dependence
Fire intensity along with consumption of available fuels may cause incomplete or patchy burns. Continued recruitment of shrub tree seeds from adjacent sites and resprouting of existing shrubs will hamper site restoration. Intensive management is required to restore and maintain the site in State 3: Invaded State.
Mechanism
This transition from any plant community to State 4: Go-Back State. It is commonly associated with the cessation of cropping without the benefit of range planting, resulting in a “go-back” situation. Soil conditions can be quite variable on the site, in part due to variations in the management/cropping history (e.g., development of a tillage induced compacted layer (plow pan), erosion, fertility, and/or herbicide/pesticide carryover). Thus, soil conditions should be assessed when considering restoration techniques.
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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.