Loamy Steep 15-19" PZ Frigid Rocky Mountain Front Foothills
Scenario model
Current ecosystem state
Select a state
Management practices/drivers
Select a transition or restoration pathway
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Transition T1A
There are several other key factors signaling the approach of transition T1A: increases in physical soil crusting, decreases in cover of cryptogamic crusts, decreases in soil surface aggregate stability and/or evidence of erosion, including water flow patterns, development of plant pedestals, and litter movement. The trigger for this transition is improper grazing management and/or long-term drought, leading to a decrease in rough fescue composition, increased bare ground and a reduction in total plant canopy cover.
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Transition T1B
The drivers for this transition are improper grazing management, intense or repeated fires, and/or heavy human disturbance. The rapid transition to the Degraded state is generally realized where livestock are confined to small pastures for long periods, such as feeding areas, horse pastures, and bull lots.
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Transition T1C
The trigger for this transition is the presence of aggressive invasive species, with invasive species composition by dry weight approaching 10 percent.
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Transition T1D
Long-term stress conditions for native species (e.g., overgrazing, drought, and fire) accelerate this transition. If populations of invasive species reach critical levels, the site transitions to the Naturalized Herbaceous Invaded state. These naturalized plants are present in quantities greater than a trace amount by dry weight (approximately 10 pounds per acre) or greater than two percent canopy cover.
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Restoration pathway R2A
Grazing practices that promote rough fescue are primarily light to moderate grazing during the critical season (late June through July) or fall and dormant season of moderate use. Use of low-intensity prescribed fire, range reseeding to bolster midstatured bunchgrasses, and addition of soil amendments such as biochar may be necessary.
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Transition T2A
In this state, improper grazing management is defined as grazing events that exceed moderate grazing (40 to 50 percent grazing use), a grazing season that exceeds half of the growing season, and/or grazing events that consume plant regrowth in the same growing season.
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Transition T2B
The trigger is the presence of seeds and/or other viable material such as stolons and rhizomes of invasive species.
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Transition T2C
This transition is being driven by 10 pounds per acre or more than two percent canopy cover of herbaceous naturalized plants. The trigger is the presence of seeds and/or other viable material such as stolons or rhizomes of invasive species.
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Restoration pathway R3A
Rest rotation grazing combined with extensive soil rebuilding measures such as mulching or adding biochar as well as major reseeding events are needed to push the Degraded state to the Reference state. However, these practices may not effectively restore site stability and hydrology issues associated with removed soil organic matter and lost plant resources.
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Restoration pathway R3B
Rest rotation grazing combined with extensive soil rebuilding measures such as mulching or adding biochar as well as major reseeding events are needed to push the Degraded state to the Reference state. However, these practices may not effectively restore site stability and hydrology issues associated with removed soil organic matter and lost plant resources.
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Transition T3A
The trigger is the presence of seeds or viable material of invasive species. This state has sufficient bare ground that the transition could occur simply due to the presence or introduction of invasive seeds or viable material.
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Restoration pathway R4A
The drivers for the restoration pathway are the removal of invasive species, restoration of native bunchgrass species, persistent management of invasive species, and proper grazing management. Without continued control, invasive species are likely to return (probably rapidly) due to the presence of seeds and/or other viable material in the soil and management practices that increase soil disturbance.
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Restoration pathway R4B
Significant pest management, primarily the use of herbicides, is needed to remove viable biomass of invasive species combined with grazing management.
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Transition T4D
An Integrated Pest Management (IPM) Plan will be necessary to maintain and improve this state and any other state within this ecological site.
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Restoration pathway R5A
Restoration of the Naturalized Herbaceous Invaded state to the Reference state requires substantial energy input. The drivers for the restoration pathway are the removal of invasive species, restoration of native bunchgrass species, persistent management of invasive species, and proper grazing management. Without continued control, invasive species are likely to return (probably rapidly) due to the presence of seeds and/or other viable material such as stolons and rhizomes in the soil and management practices that increase soil disturbance.
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Restoration pathway R5B
Restoration of the Naturalized Herbaceous Invaded state to the Altered state requires substantial energy input. The drivers for the restoration pathway are the removal of invasive species, persistent management of invasive species, and proper grazing management. Without continued control, invasive species are likely to return due to the presence of seeds or other viable material such as rhizomes in the soil and management practices that increase soil disturbance.
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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 of this ecological site consists of two potential plant communities: the Rough Fescue community and the Mixed Bunchgrass community. These are described below but are generally characterized by a tall to midstatured cool-season grass community with limited shrub production. Community 1.1 is dominated by rough fescue and is considered the reference, while Community 1.2 has a codominance of bunchgrasses and shortgrasses. These communities may meld into each other due to the varying conditions and may often exist together in a relatively small area.
Submodel
Description
This state is distinguished by having less than 15 percent midstatured bunchgrasses by weight. Some native plants tend to increase in quantity under prolonged drought and/or heavy grazing practices. A few of these species may include Idaho fescue, Sandberg bluegrass, Cusick's bluegrass (Poa cusickii), scarlet globemallow, hairy false goldenaster, and prairie sagewort. Poisonous plants such as larkspur (Delphinium spp.), lupine (Lupinus spp.), and deathcamas (Zigadenus spp.) may also increase under these conditions.
This state is a result of extended heavy grazing, which is often combined with extended drought. Heavy grazing is defined as grazing that exceeds 50 percent utilization in a grazing season and/or multiple grazing events during critical spring growth without plant recovery time between grazing events.
Submodel
Description
Degraded state lacks midstatured bunchgrasses. Sandberg bluegrass and prairie Junegrass are the dominant grasses, increaser shrubs nearly replace larger shrub species. Larger shrub species that remain are heavily hedged. This state is likely terminal and restoration will likely be impossible, unsuccessful, or require major energy inputs.
Submodel
Description
The Invaded state is identified as being in the exponential growth phase of invader abundance, where control is a priority. The dominance (or relative dominance) of noxious and other hard-to-control invasive species reduces species diversity, forage production, wildlife habitat, and site protection. Even with proper grazing management or favorable growing conditions, a level of 10 percent by weight of invasive species composition by dry weight indicates that significant energy input, such as herbicide or mechanical removal, will be required to create a shift to the grassland state. Prescriptive grazing that specifically focuses on the grazing of invasive plants can be used to manage invasive species. In some instances, carefully targeted grazing (sometimes in combination with other treatments) can reduce or maintain the species composition of invasive species.
This state differs from the Naturalized Herbaceous Invaded state in the severity of the ecological impact of the species. The species in the Invaded state are often considered noxious or to be those that, once present, are difficult to control and almost impossible to eradicate, such as cheatgrass (Bromus tectorum) or North Africa grass (Ventenata dubia).
Submodel
Description
This state has been invaded by plants that are not generally considered to have the same extreme impact on this ecological site as those in the Invaded state, though they can pose a negative impact on this ecological site, particularly on the hydrologic functions. This list of species is often introduced by encroachment from neighboring cultivated pastures such as Kentucky bluegrass (Poa pratensis), Timothy (Phleum pratense), smooth brome (Bromus inermis), and crested wheatgrass (Agropyron cristatum). It is not uncommon for introduced forbs to invade via wind-blown seeds such as dandelion, sweetclover (Melilotus officinalis), and yellow salsify.
This state may resemble the Reference state in structure or could be completely invaded. These naturalized plants have a dry weight of more than 10 pounds per acre or a canopy cover of more than two percent.
Submodel
Mechanism
The Reference state transitions to the Altered state if rough fescue and bluebunch wheatgrass decrease to less than 15 percent by dry weight, or if bare ground cover increases beyond 10 percent. The driver for this transition is the loss of taller bunchgrasses, which creates open areas in the plant canopy with bare soil. Soil erosion results in decreased soil fertility, driving transitions to the Altered state.
There are several other key factors signaling the approach of transition T1A: increases in physical soil crusting, decreases in cover of biological crusts, decreases in soil surface aggregate stability, or evidence of erosion, including water flow patterns, development of plant pedestals, and litter movement. The trigger for this transition is improper grazing management, or long-term drought, leading to a decrease in rough fescue composition, increased bare ground and a reduction in total plant canopy cover.
Constraints to recovery
The lack of deep-rooted bunchgrasses will prevent recovery to the Reference state without inputs such as seeding and mulching. Favorable growing conditions are necessary to facilitate restoration to the Reference state.
Context dependence
The transition to the Altered state is primarily driven by negative grazing events, however, prolonged drought may expedite this transition. If present, intense fire may also create conditions where the midstatured bunchgrasses are removed. Intense fire is often paired with hot, dry summer conditions which damage the caudex of these bunchgrasses.
Mechanism
The Reference state transitions to the Degraded state when rough fescue is completely removed from the plant community. Idaho fescue is subdominant, and often absent, to needle and thread and short-statured bunchgrasses such as Sandberg and Cusick's bluegrass. The trigger for this transition is the loss of most midstatured bunchgrasses, which creates open spaces with bare soil. Soil erosion as a result of increased bare ground and shallow roots decreases soil fertility, driving transitions to the Degraded state.
There are several other key factors signaling the approach of transition T1B including increases in soil physical crusting, decreases in cover of cryptogamic crusts, decreases in soil surface aggregate stability, and/or evidence of erosion, including rills, water flow patterns, development of plant pedestals, and litter movement. The drivers for this transition are improper grazing management, intense or repeated fires, and heavy human disturbance. The rapid transition to the Degraded state is generally realized where livestock are confined to small pastures for long periods, such as feeding areas, horse pastures, and bull lots.
Degradation may be so extreme that traditional restoration methods may not be successful and require extensive mechanical and financial inputs.
Constraints to recovery
The lack of deep-rooted bunchgrasses will prevent recovery to the Reference state without inputs such as seeding and mulching.
Context dependence
The transition to the Degraded state is primarily driven by negative grazing events, however prolonged drought may expedite this transition. If present, intense fire may also create conditions where the midstatured bunchgrasses are removed. Intense fire is often paired with hot, dry summer conditions which damage the caudex of these bunchgrasses.
Mechanism
Healthy plant communities are the most resistant to invasion. However, sometimes, regardless of grazing management, without some form of active weed management (chemical, mechanical, or biological control), the Reference state can transition to the Invaded state in the presence of aggressive invasive species such as spotted knapweed, leafy spurge, and cheatgrass. The Rocky Mountain Front Foothills LRU tends to resist invasion, though drought, repeated heavy grazing, and intense human activities can open the interspaces of the Reference state and allow for encroachment. Long-term stress conditions for native species (e.g., overgrazing, drought, and fire) accelerate this transition. If populations of invasive species reach critical levels, the site transitions to an Invaded state. The trigger for this transition is the presence of aggressive invasive species, with invasive species composition by dry weight approaching 10 percent.
Constraints to recovery
The removal of invasive species requires significant inputs of time, weed management, and capital. Many invasive species such as cheatgrass, spotted knapweed, and leafy spurge are challenging to control and may always be present on a site, once established. The level of invasion needs to be minimal or the species must be easy to control to return to the Reference State
Context dependence
Invasive species vary in aggressiveness and ease of control. Some species such as yellow salsify may have minimal impact on an ecological site while an aggressive species such as cheatgrass may begin to affect the site at a very low composition. Drought, fire return interval, and grazing patterns may influence the speed at which a site will be invaded.
Mechanism
Healthy plant communities are most resistant to invasion, but sometimes the Reference state can transition to the Naturalized Herbaceous Invaded state in the presence of herbaceous invasive species. Nonnative plants take advantage of small gaps in the plant community and prolific seed producers. The list of species includes but is not limited to, Kentucky bluegrass, Timothy, smooth brome, dandelion, yellow salsify, and sweetclover. Rough fescue communities tend to resist invasion, though dry climate cycles, heavy grazing, or intense human activities can open the interspaces of the Reference state and allow for encroachment. Long-term stress conditions for native species (e.g., overgrazing, drought, and fire) accelerate this transition. If populations of invasive species reach critical levels, the site transitions to the Naturalized Herbaceous Invaded state. These naturalized plants are present in quantities greater than a trace amount by dry weight or greater than two percent canopy cover.
Constraints to recovery
Naturalized grasses are increasingly hard to control and may always be present in a low amount once established.
Context dependence
This site often exists land that has been planted to hay or pasture. Small gaps between native plants offer an opportunity for these competitive species to establish.
Mechanism
The Altered state has lost soil or vegetation attributes to the point that recovery to the Reference state can require reclamation efforts such as soil rebuilding, intensive mechanical and cultural treatments, and/or revegetation. Examples of mechanical treatment may be brush control, while cultural treatments may include prescribed grazing, targeted brush browsing, or prescribed burning. Grazing practices that promote rough fescue are primarily light to moderate grazing during the critical season (late June through July) or fall and dormant season of moderate use. Heavy utilization may not have negative impacts, though grazing should match the species composition of the site before exceeding moderate utilization (Dormaar and Willms, 1998).
Low-intensity prescribed fires to reduce competitive increaser plants such as Idaho fescue, needle and thread, and Sandberg bluegrass. A low-intensity fire will also reduce shrubby cinquefoil populations, if present. In areas with the potential for annual grass infestation, fire should be carefully planned or avoided. The drivers for this restoration pathway are reclamation efforts along with grazing management.
Context dependence
If midstatured bunchgrasses exist, a grazing management using light-intensity grazing along with time for recovery combined with favorable growing conditions may facilitate the restoration back to the Reference state.
Mechanism
As improper grazing continues, the vigor of bunchgrasses will decrease. The shorter grasses and shrubs will increase towards the Degraded state. In this state, improper grazing management is defined as grazing events that exceed moderate grazing (40 to 50 percent grazing use), a grazing season that exceeds half of the growing season, and/or grazing events that consume plant regrowth in the same growing season. Highly managed grazing events that exceed moderate grazing levels for short timeframes are generally not included in this definition due to increased rest periods between these grazing events.
Additionally, prolonged drought will provide a competitive advantage to shrubs, allowing them to become co-dominant with grasses. Shrub canopies may increase, though they will express low-growth forms as a result of browsing by livestock. Mat-forming forbs and lesser spikemoss will also increase.
Key transition factors include an increase in native shrub canopy cover, a decrease in bunchgrass production, a decrease in total plant canopy cover and production, an increase in mean bare patch size, an increase in soil crusting, a decrease in cryptobiotic crust cover, a decrease in soil aggregate stability, and/or evidence of erosion, such as water flow patterns and litter movement.
Constraints to recovery
Removal of all midstatured grasses will require reseeding and soil rebuilding efforts to restore to the Altered state
Context dependence
Exceptionally dry conditions may expedite the transition from the Altered state. The loss of soil organic matter may increase the odds of invasion by annual grasses.
Mechanism
Invasive species can occupy the Altered state and drive it to the Invaded state. The Altered state is at risk if invasive seeds or other viable material are present. More than 10 percent of the dry weight of invasive species is the driving force behind this transition.
Constraints to recovery
The addition of aggressive non-native plants could completely prevent restoration to the Altered state. Significant capital and time will be necessary.
Context dependence
The condition of the Invaded state must resemble that of the Altered state to be restored to the Altered state. The kind and amount of invasive species may also affect the ability of the site to be restored.
Mechanism
Invasive species can occupy the Altered state and drive it to the Naturalized Herbaceous Invaded state. The Altered state is at risk of invasion due to increased bare ground and basal gaps, which allow for ease of establishment. This transition is being driven by a trace (10 pounds per acre), dry weight, or more than two percent canopy cover of herbaceous naturalized plants. The trigger is the presence of seeds and/or other viable material of invasive species.
Constraints to recovery
Naturalized grasses are increasingly hard to control and may always be present in a low amount once established.
Context dependence
This site often exists land that has been planted to hay or pasture. Small gaps between native plants offer an opportunity for these competitive species to establish.
Mechanism
The Degraded state has lost soil or vegetation attributes to the point that recovery to the Reference state will require reclamation efforts such as soil rebuilding, intensive mechanical treatments, and/or revegetation. Studies suggest that mulch with a high carbon-to-nitrogen ratio, such as wood chips or bark in low moisture scenarios, can be beneficial for the slow mobilization of plant available nitrogen (Whitford et al., 1989). Biochar may also be added to the system to improve soil organic carbon (SOC), which should improve cation exchange capacity (CEC), microbial activity, and hydrologic conductivity (Stavi, 2012). The drivers for the restoration pathway are the removal of increaser species, restoration of native bunchgrass species, persistent management of invasives and shrubs, and proper grazing management. Without continued control, invasive and shrub species are likely to return (probably rapidly) due to the presence of seeds and/or other viable material in the soil and management-related increased soil disturbance.
Context dependence
The Degraded state lacks the midstatured bunchgrass of the Reference state and may be affected by soil loss. Restoration methods will vary based on soil conditions but will require significant inputs to add soil organic matter as well as seeding the site. This site may have lost so much soil that it will never return to the Reference state.
Mechanism
Since the deep-rooted bunchgrass plant community has been removed, restoration to the Altered state is unlikely unless a seed source is available. If a sufficient amount of bunchgrass remains on the site, chemical application and/or biological control, in conjunction with proper grazing management, can reduce the number of shrubs and invasive species and restore the site. Grazing management strategies that follow light grazing and allow for long periods of rest will allow for limited recovery of remaining bunchgrasses. However, grazing management alone may not directly result in restoration. Restoration methods such as reseeding may be necessary.
Low-intensity fire can be utilized to reduce shrub competition and allow the reestablishment of grass species. Caution must be used when considering fire as a management tool on sites with fire-tolerant shrubs such as rubber rabbitbrush, as these shrubs will re-sprout after a burn. Some shrubs, like broom snakeweed and prairie sagewort, may or may not re-sprout depending on conditions (Tirmenstein, 1999).
Context dependence
The Degraded state is lacking the midstatured bunchgrass of the Altered state and may be affected by soil loss. Restoration to the Altered state may require soil rebuilding practices as well as seeding of native species.
Mechanism
The Degraded state is particularly susceptible to invasion by weeds, which drives it to the Invaded state. The Degraded state is at risk of this transition occurring if invasive seeds or viable material are present. The driver for this transition is the presence of critical population levels of invasive species. The trigger is the presence of seeds or viable material of invasive species. This state has sufficient bare ground that the transition could occur simply due to the presence or introduction of invasive seeds or viable material. This is particularly true of aggressive invasive species such as spotted knapweed and cheatgrass. This transition could be assisted by overgrazing (failure to adjust stocking rate to declining forage production), a long-term lack of fire, or extensive drought.
Constraints to recovery
The Degraded state has shallow-rooted plants which affect its ability to utilize precipitation and often has reduced litter cover which also affects soil moisture. Reduced soil nutrients from erosion may affect the site's ability to recruit native plants.
Context dependence
Favorable moisture is necessary to facilitate restoration. The Degraded state has reduced soil organic matter as well as shallow-rooted plants which affects the site's infiltration rates and ability to store moisture. The reestablishment of native species is greatly reduced by these soil conditions.
Mechanism
Restoring the Invaded state to the Reference state requires a significant energy input. The drivers for the restoration pathway are the removal of invasive species, restoration of native bunchgrass species, persistent management of invasive species, and proper grazing management. Without continued control, invasive species are likely to return (probably rapidly) due to the presence of seeds and/or other viable material in the soil and management practices that increase soil disturbance.
Sites that have transitioned from the Degraded state to the Invaded state may be severely lacking in soil and vegetative properties that will allow for restoration to the Reference state. Hydrologic function damage may be irreversible, especially with accelerated gully erosion.
Context dependence
The Invaded state must have a plant community similar to one of those in the Reference state. Without midstatured bunchgrasses present, significant inputs such as reseeding will be necessary to facilitate this restoration.
Mechanism
If invasive species are removed before remnant populations of bunchgrasses have been drastically reduced, the Invaded state can return to the Altered state. The driver for the reclamation pathway is weed management with possible reseeding. Continued Integrated Pest Management (IPM) will be required as many of the invasive species that can occupy the Invaded State have extended dormant seed life. The trigger is invasive species control.
Context dependence
The Invaded state must have a plant community similar to one of those in the Altered state. Without those species present, significant inputs such as reseeding will be necessary to facilitate this restoration.
Mechanism
If noxious and aggressive invasive species are removed, the site could return to the Naturalized Herbaceous Invaded state. Without sufficient remnant populations of preferred plants, the Invaded state is not likely to return to any of the other states. The driver for the reclamation pathway is weed management without reseeding. The trigger is invasive species control. Invading species cause a significant increase in soil loss due to a lack of ground cover (Lacey et al., 1989).
An Integrated Pest Management (IPM) Plan will be necessary to maintain and improve this state and any other state within this ecological site.
Context dependence
The Invaded state must have a plant community similar to one of those in the Naturalized Herbaceous Invasive state. Without those species present, significant inputs such as reseeding will be necessary to facilitate this restoration. Continued pest management such as herbicide application or targeted grazing will be necessary to maintain or remove invasive weeds.
Mechanism
The conditional return to the Reference state requires that the plant population must resemble that of the Reference state with only the addition of these trace amounts of naturalized plants. If the plant community closely resembles that of the Altered state or Degraded state, then other restoration pathways will be necessary to return to the Reference state.
Restoration of the Naturalized Herbaceous Invaded state to the Reference state requires substantial energy input. The drivers for the restoration pathway are the removal of invasive species, restoration of native bunchgrass species, persistent management of invasive species, and proper grazing management. Without continued control, invasive species are likely to return (probably rapidly) due to the presence of seeds and/or other viable material in the soil and management practices that increase soil disturbance.
The forb species present in this state tend to be susceptible to readily available conventional herbicide treatments. Application methods must be controlled so as not to affect the native forbs that are common in this state. Mowing herbaceous forbs such as sweetclover or sainfoin is a successful method of control. Caution should be taken to ensure this occurs before seed is set to reduce the risk of dispersing seed.
Naturalized grasses in this state can be hard to eradicate especially once established (Vaness and Wilson, 2007). They are often palatable to livestock and reproduce by rhizome. Repeated spring fires, specifically in May, have proven to be an effective control method in conjunction with rest from grazing animals (Abrams and Hulbert, 1987).
Context dependence
The conditional return to the Reference state requires that the plant population must resemble that of the Reference state with only the addition of these trace amounts of naturalized plants.
Mechanism
The conditional return to the Altered state is that the plant population must resemble that of the Altered state with only the addition of these trace amounts of naturalized plants. If the plant community closely resembles that of the other states within this ecological site, then other restoration pathways will be necessary to return to the Altered state. If restoration of this site to the Reference state is desired, additional restoration methods will be necessary, such as the implementation of grazing management as well as the possibility of requiring reseeding of native plants.
Restoration of the Naturalized Herbaceous Invaded state to the Altered state requires substantial energy input. The drivers for the restoration pathway are the removal of invasive species, persistent management of invasive species, and proper grazing management. Without continued control, invasive species are likely to return (probably rapidly) due to the presence of seeds and/or other viable material in the soil and management practices that increase soil disturbance.
The forb species present in this state tend to be susceptible to readily available, conventional herbicide treatments. Application methods must be controlled so as to not affect the native forbs that are common in this state. Mowing of herbaceous forbs such as yellow sweet clover or sainfoin is a successful method of control. Caution should be taken to ensure this occurs before seed is set to reduce the risk of dispersing seed.
Naturalized grasses in this state can be hard to eradicate. They are often palatable to livestock and reproduce by rhizome. Repeated spring fires, specifically in May, have proven to be an effective control method in conjunction with rest from grazing animals (Abrams and Hulbert, 1987).
Context dependence
The conditional return to the Altered state is that the plant population must resemble that of the Altered state with only the addition of these trace amounts of naturalized plants.
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