Loamy - North
Scenario model
Current ecosystem state
Select a state
Management practices/drivers
Select a transition or restoration pathway
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Transition T1A
• Invasion and expansion of non-native cool-season grasses
More details
• Continuous season-long grazing
• Excessive haying
• Non-use
• No fire -
Transition T1B
•Encroachment by ponderosa pine
More details
•No fire -
Transition T2A
•No Fire
More details
•Encroachment by ponderosa pine -
Transition T2B
•Non-use/Light stocking
More details
•Continuous season-long grazing
•Seasonal grazing
•Excessive haying
•No Fire -
Restoration pathway R3A
•Prescribed burning
More details
•Brush management
•Forest stand improvement
•Fire -
Transition R3B
•Prescribed burning
More details
•Prescribed grazing
•Fire
•Forest stand improvement -
Transition T3A
• Low to medium-intensity wildfire
More details
• Prescribed burning
• Brush management
• Prescribed grazing -
Transition R4A
•Prescribed burn
More details
•Seeding
•Long-term prescribed grazing
•Herbaceous weed control -
Transition R4B
•Encroachment
More details
•No Fire -
Transition T4A
•Heavy continuous season-long grazing
More details
•Frequent severe defoliation
•Heavy disturbance
•Invasion by non-native species -
Restoration pathway R5A
•Removal of disturbance
More details
•Long-term prescribed grazing
•Herbaceous weed control -
No transition or restoration pathway between the selected states has been described
Target ecosystem state
Select a state
Description
The Reference State represents what is believed to show the natural range of variability that dominated the dynamics of the ecological site prior to European settlement. This site in the Reference State (1.0) is dominated by cool-season grasses, with warm-season grasses being subdominant. Shrubs and forbs may represent subdominant or minor parts of the plant community.
In pre-European times, the primary disturbance mechanisms for this site in the reference condition included occasional fire and grazing by large ungulates. Timing of fires and grazing coupled with weather events dictated the dynamics that occurred within the natural range of variability. Taller cool- and warm-season grasses would have declined and a corresponding increase in forbs and shrubs would have occurred.
Today, a similar state may be difficult to find without some invasion of non-native cool-season grasses, most commonly Kentucky bluegrass. Near reference conditions 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.
Characteristics and indicators
The Reference State (1.0) is dominated by cool-season bunchgrasses and subdominant warm-season mid-statured grasses. The Reference State is very susceptible to invasion of non-native cool-season grasses and the encroachment of ponderosa pine.
Resilience management
Management strategies to sustain the Reference State (1.0) include, setting proper stocking rates, monitoring utilization of key species, providing adequate time for plant recovery following grazing events or other disturbance events (e.g. fire, drought, hailstorms), and maintaining soil and site stability. The use of prescribed burning may be effective at limiting or minimizing the invasion and establishment of non-native cool-season grasses and will effectively treat encroachment of ponderosa pine.
Submodel
Description
The Native/Introduced State is dominated by native cool-season bunchgrasses, and up to 15 percent (total annual production) non-native cool-season grasses. Warm-season grasses will be subdominant. Forbs and shrubs may also be subdominant. This state can be found on areas that are properly managed with grazing and possibly periodic prescribed burning. This state represents what is most typically found on this ecological site.
This state is the result of long-term continuous season-long stocking at moderate to moderately heavy stocking levels, during the typical growing season (May through October); excessive haying; or extended periods of non-use, no fire, and the build-up litter. If the native cool-season grasses decline, a corresponding increase of non-native cool-season grasses can occur. Non-native cool-season grasses will include Kentucky bluegrass, smooth brome, timothy, orchardgrass, and annual brome.
Characteristics and indicators
Non-native cool-season grasses will make up to 15 percent of the total annual production in the Native/Invaded State (2.0).
Resilience management
Management strategies to sustain the Native/invaded State (2.0) include, setting proper stocking rates, monitoring utilization of key species, providing adequate time for plant recovery following grazing events or other disturbance events (e.g. fire, drought, hailstorms), and maintaining soil and site stability. The use of prescribed burning may be effective at limiting or minimizing the expansion of non-native cool-season grasses and ponderosa pine on the ecological site. Because of the adaptability and persistence of these non-native grass species, a recovery to the Reference State (1.0) is highly unlikely.
Submodel
Description
The Conifer State consists of areas where tree canopy increases to a level that impedes the reproductive capability of the major native perennial grass species. The increase in conifer canopy is a result of encroachment from forest sites, or from rangeland sites that have been invaded; and the disruption of the natural historic fire regime that kept the trees in an immature stage. This state is reached when mature conifer canopy reaches approximately 25 percent or more. The canopy typically is dominated by ponderosa pine, but bur oak may also be present in minor amounts.
With continued long-term fire suppression and no brush management or forest stand improvement, the conifer canopy can eventually become closed with much of the herbaceous understory lost. This loss is partly driven by the interception of precipitation. Ponderosa pine canopies can significantly reduce precipitation reaching the ground due to canopy interception. In areas with intermediate and dense canopy’s, the expected reduction can reach 30 percent (Wrage, 1994).
Characteristics and indicators
Ponderosa pine will be the dominant species in the Conifer State (4.0), with a canopy cover of 30 percent or greater.
Resilience management
Continued lack of fire and expansion of ponderosa pine will maintain the Conifer State (4.0).
Submodel
Description
The Invaded State (4.0) is the result long-term no use, and no fire, or continuous early-season stocking and/or excessive haying, which has allowed Kentucky bluegrass and other non-native cool-season grasses to dominate the site. No use and no fire will cause an excessive thatch layer to develop. Plant litter accumulation tends to favor the more shade-tolerant introduced grass species. Hydrological function can be reduced as the dense root mats created by Kentucky bluegrass reduces water infiltration. The nutrient cycle can also be impaired, resulting in a higher level of nitrogen which also favors the introduced species. Kentucky bluegrass is very resistant to overgrazing and will expand under heavy continuous grazing and out-compete other native species that are not as adapted to overgrazing.
Characteristics and indicators
Non-native cool-season grasses will make up 30 percent or more of the total annual production in the Invaded State (4.0).
Resilience management
Management strategies to sustain this plant community include setting proper stocking rates, monitoring utilization of key species, providing adequate time for plant recovery following grazing events or other disturbance events. If adequate native propagules remain in the plant community, long-term prescribed grazing, and prescribed burning, may reduce the amount of Kentucky bluegrass and other non-native cool-season grasses to facilitate a transition to the Native/Invaded State (2.0).
Another potential option to facilitate a transition to the Native/Invaded State (2.0) would include mechanical and/or chemical herbaceous weed control to reduce the non-native cool-season grasses, seeding of a native grass and forb species, followed by the implementation of long-term prescribed grazing. This option may not be ecologically nor economically feasible.
Submodel
Description
This state occurs as a result of extreme disturbance that typically removes most of the native species normally present on this site. Disturbance in the form of long-term severe grazing, heavy grazing in combination with occupation by black-tailed prairie dogs, or high-intensity fire may result in this transition. The dominant species present is highly variable, but the common characteristics include high amounts of bare ground, reduced soil aggregate stability, increased runoff and increased erosion (including increased sediment loads in the runoff). Invasive forbs, often noxious weeds, and Kentucky bluegrass are commonly present and dominant. Restoration of the ecological processes will be very difficult.
In many cases, this phase is dominated by annual and/or pioneer perennial species. Highly competitive weedy species such as Canada thistle, ox eye daisy, hound’s tongue, leafy spurge, knapweeds, and a variety of other invasive broadleaf forbs can invade this state. Bare ground is also typically much higher than on any other plant community phase.
Characteristics and indicators
Pioneer perennials and annual grasses and forb species will dominate this state. Bare ground is also typically much higher than on any other plant community phase.
Resilience management
Potential option to facilitate a restoration of the Early Successional State (5.0) would include mechanical and/or chemical herbaceous weed control to reduce invasive grasses and forbs, followed by seeding native grass and forb species, followed by implementation of long-term prescribed grazing. This restoration may not be ecologically and/or economically feasible.
Submodel
Mechanism
•Invasion of non-native cool-season grasses.
•Continuous season-long grazing: long-term grazing at moderate to moderately heavy stocking levels during the typical growing season (May through October), without change in season of use or adequate recovery periods following grazing events.
•Excessive haying includes annual mechanical harvesting of rangeland plant communities without adequate time for plant recovery. Leaving inadequate post-harvest stubble height for retention of photosynthetic leaf area, nor providing adequate insulation cover from extreme heat or cold will result in a decline in plant health and vigor and increased plant mortality. Desirable grasses and forbs for forage and wildlife cover will decrease, and other less desirable grasses and forbs species will increase.
•Extended periods of no use and no fire results in heavy litter buildup which favors non-native cool-season grasses such as Kentucky bluegrass, smooth brome, and other non-native species, and the reduction of native warm-season grasses.
Constraints to recovery
Disturbance regime results in the transition from plant communities dominated by native mid and tall-height cool-season and warm-season grass to plant communities with up to 15 percent non-native cool-season grasses. Because of the adaptability and persistence of these non-native grass species, a recovery to the Reference State (1.0) is highly unlikely.
Mechanism
•Encroachment and establishment of ponderosa pine.
•Extended periods of no fire will result in establishment and expansion of ponderosa pine.
•Non-use and no fire can also contribute to this transition. Excessive litter buildup can create micro-sites with higher soil moisture that extends into the warmer summer season. The extra soil moisture can be optimal for pine germination and establishment.
Constraints to recovery
With continued long-term fire suppression and no brush management, the ponderosa pine canopy can eventually become closed with much of the herbaceous understory lost. This loss is partly driven interception of precipitation. Ponderosa pine canopy can significantly reduce precipitation reaching the ground due to canopy interception. In areas with intermediate and dense canopies, the expected reduction can reach 30 percent (Wrage, 1994).
Mechanism
•Encroachment and establishment of ponderosa pine.
•Extended periods of no fire will result in establishment and expansion of ponderosa pine.
•Non-use and no fire can also contribute to this transition. Excessive litter build up can create micro-sites with higher soil moisture that extends into the warmer summer season. The extra soil moisture can be optimal for pine germination and establishment.
Constraints to recovery
With continued long-term fire suppression and no brush management, the ponderosa pine canopy can eventually become closed with much of the herbaceous understory lost. This loss is partly driven by the interception of precipitation. Ponderosa pine canopy can significantly reduce precipitation reaching the ground due to canopy interception. In areas with intermediate and dense canopies, the expected reduction can reach 30 percent (Wrage, 1994).
Mechanism
•Long-term no use resulting in heavy litter buildup which favors non-native cool-season grasses such as Kentucky bluegrass, smooth brome, and other non-native species, and the reduction of native warm-season grasses.
•Long-term no fire resulting in heavy litter buildup which favors non-native cool-season grasses such as Kentucky bluegrass, smooth brome, and other non-native species, and the reduction of native warm-season grasses.
•Continuous season-long grazing including, repeated light to moderate stocking levels, during the spring, early cool-season growing season (April through early June), without change in season of use or adequate recovery periods following grazing events.
•Excessive haying which includes annual mechanical harvesting of rangeland plant communities without adequate time for plant recovery. Leaving inadequate post-harvest stubble height for retention of photosynthetic leaf area, nor providing adequate insulation cover from extreme heat or cold will result in a decline in plant health and vigor and increased plant mortality. Desirable grasses and forbs for forage and wildlife cover will decrease, and other less desirable plants will increase.
Constraints to recovery
Disturbance regime results in the transition from plant communities dominated by native tall and mid-statured warm- and cool-season grass, and non-native cool-season grasses that make up 15 percent of the plant community, to plant communities dominated by non-native cool-season grasses with native grasses being sub-dominant. Because of the persistence of non-native cool-season grasses, a recovery to the Native/Introduced State (2.0) is uncertain and may not be feasible.
Context dependence
Preliminary studies indicate a threshold may exist when Kentucky bluegrass exceeds 30 percent of the plant community, and native grasses represent less than 40 percent of the plant community composition. Plant communities dominated by Kentucky bluegrass have significantly less cover and diversity of native grasses and forb species. (Toledo, D. et al., 2014).
Mechanism
•Wildfire of low to medium intensity that removes much of the pine canopy, including seedlings and poles, but does not adversely impact soil and site stability.
•Prescribed burning of low to medium intensity, that removes much of the pine canopy, including seedlings and poles, but does not adversely impact soil and site stability.
•Mechanical brush management or forest stand improvement to remove much or all the pine canopy.
•Prescribed grazing including proper stocking rates, change in season of use, and adequate time for plant recovery following grazing events.
•These mechanisms, in combination, may shift the Conifer State (3.0) to the Reference State (1.0) if adequate native propagules and seed bank are still present.
Context dependence
Constraints to recovery: Variables or processes that preclude recovery of the former state.
Adequate native grass and forb propagules and seed bank need to be present in order for a relative rapid recovery of the plant community following fire event. Revegetation will be critical to maintain the soil and site stability.
Relevant conservation practices
| Practice | External resources |
|---|---|
|
Brush Management |
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Prescribed Burning |
Mechanism
•Wildfire of low to medium intensity that removes much of the pine canopy, including seedlings and poles, but does not adversely impact soil and site stability.
•Prescribed burning of low to medium intensity that removes much of the pine canopy, including seedlings and poles, but does not adversely impact soil and site stability.
•Mechanical brush management or forest stand improvement to remove much or all the pine canopy.
•Prescribed grazing including proper stocking rates, change in season of use, and adequate time for plant recovery following grazing events.
•These mechanisms, in combination, may shift the Conifer State (3.0) to the Native/Introduced State (2.0) if adequate native propagules and seed bank are still present.
Constraints to recovery
Adequate native grass recovery and forb propagules and seed bank need to be present in order for a relative rapid recovery of the plant community following fire events. Revegetation will be critical to maintain the soil and site stability.
Relevant conservation practices
| Practice | External resources |
|---|---|
|
Brush Management |
|
|
Prescribed Burning |
|
|
Prescribed Grazing |
Mechanism
•Wildfire of low to medium intensity that removes much of the pine canopy, including seedlings and poles, but does not adversely impact soil and site stability.
•Prescribed burning of low to medium intensity that removes much of the pine canopy, including seedlings and poles, but does not adversely impact soil and site stability.
•Mechanical brush management or forest stand improvement to remove much or all the pine canopy.
•These mechanisms, in combination, may shift the Conifer State (3.0) to the Invaded State (4.0).
Constraints to recovery
Variables or processes that preclude recovery of the former state. Adequate grass and forb propagules and seed bank need to be present in order for a relative rapid recovery of the plant community following fire event. Revegetation will be critical to maintain the soil and site stability.
In the case of high-intensity fire, and heavy disturbance, the Conifer State (3.0) has the potential to transition to the Early Successional State (4.0).
Relevant conservation practices
| Practice | External resources |
|---|---|
|
Brush Management |
|
|
Prescribed Burning |
Mechanism
•Early-season prescribed burning.
•Long-term prescribed grazing including proper stocking rates, change in season of use, and adequate time for plant recovery following grazing events.
•Seeding of desired herbaceous species.
•Chemical and/or mechanical herbaceous weed control treatment followed by seeding of native grass and forb species, and long-term prescribed grazing may be an option. This could accelerate the reestablishment of structural functional groups similar to those in State 2.0, however, the resulting plant community may not achieve management objectives.
•Those mechanisms, in combination, may shift the Invaded State (4.0) to the Native/Introduced State (2.0).
Constraints to recovery
Plant communities dominated by non-native cool-season grasses can be very resilient, and difficult to restore to a native-dominated plant community. Preliminary studies indicate this threshold occurs when Kentucky bluegrass exceeds 30 percent of the plant community, and native grasses represent less than 40 percent of the plant community (Toledo, D. et al., 2014). Because of the persistence of these species, a transition to the Native/Introduced State may not be ecologically or economically feasible.
Relevant conservation practices
| Practice | External resources |
|---|---|
|
Brush Management |
|
|
Prescribed Grazing |
|
|
Native Plant Community Restoration and Management |
Mechanism
•Encroachment and establishment of ponderosa pine.
•Extended periods of no fire will result in the establishment and expansion of ponderosa pine.
•Non-use and no fire can also contribute to this transition. Excessive litter build up can create micro-sites with higher soil moisture that extends into the warmer summer season. The extra soil moisture can be optimal for ponderosa pine germination and establishment.
•These mechanisms in combination will shift the Invaded State (4.0) to the Conifer State (3.0).
Context dependence
With continued long-term fire suppression and no brush management, the ponderosa pine canopy can eventually become closed with much of the herbaceous understory lost. This loss is partly driven by the interception of precipitation. Ponderosa pine canopy can significantly reduce precipitation reaching the ground due to canopy interception. In areas with intermediate and dene canopies, the expected reduction can reach 30 percent (Wrage, 1994).
Relevant conservation practices
| Practice | External resources |
|---|---|
|
Prescribed Grazing |
Mechanism
•Heavy, continuous season-long grazing: long-term grazing at moderately heavy to heavy stocking levels during the typical growing season (May through October), without changing season of use or adequate recovery periods followed by grazing events.
•Frequent and severe defoliation by livestock or wildlife: Continuous year-long heavy grazing, or heavy, concentrated disturbance such as intense rodent activity, or livestock concentration areas.
•Heavy disturbance: Soil and site stability is compromised from one, or a combination of, excessive grazing or defoliation, heavy livestock or vehicle traffic, wildfire, or drought.
•Invasion and expansion of ruderal and invasive species.
Constraints to recovery
The disturbance regime resulting in the transition from plant communities dominated by non-native cool-season grasses to plant communities dominated by pioneer perennial plants and invasive non-native forbs will need to be altered to reverse this transition. A return to the Invaded State (4.0) is possible with economic and management inputs.
Mechanism
•Chemical and/or mechanical herbaceous weed control treatment followed by seeding of native or introduced grass and forb species.
•Long-term prescribed grazing including proper stocking rates, change in season of use, and adequate time for plant recovery following grazing events.
•Reducing or removing disturbances.
•These management activities could accelerate the reestablishment of structural functional groups similar to those in state 4.0, however, the resulting plant community may not achieve management or economic objectives.
Context dependence
The ecological processes are difficult to restore because of the loss of plant diversity and overall soil disturbance. Soil erosion is potentially very high because of the bare ground and shallow rooted herbaceous plant community. Water runoff will increase, and infiltration will decrease due to low plant diversity and vigor. This plant community will require financial inputs and time to move toward another plant community. This is due to the loss of diversity (including the loss of seedbank) , within the existing plant community, and the plant communities on adjacent sites.
Relevant conservation practices
| Practice | External resources |
|---|---|
|
Forage and Biomass Planting |
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Prescribed Grazing |
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Range Planting |
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Invasive Plant Species 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.