Land use 1
Rangeland

Site is native rangeland that has not been been modified by mechanical manipulations.

State 1.1
Bunchgrass State

The Bunchgrass State is considered the Reference State of this ecological site. The state consists of two known potential plant communities, the Bluebunch Community and the Mixed Bluebunch Community. These are described below but are generally characterized by a mid-statured, cool-season grass community with limited shrub production. Community 1.1 is dominated by bluebunch wheatgrass and is considered the reference, while Community 1.2 has a codominance of bluebunch and needle and thread with an increase in green rabbitbrush and Wyoming big sagebrush. These communities may meld into each other due to the varying conditions that occur in Southwest Montana, particularly during dry cycles where the needle and thread growth cycle takes better advantage of the limited moisture.

State 1.2
Altered State

This state is characterized by having less than 15 percent bluebunch wheatgrass by dry weight. It is represented by two (2) communities that differ in the percent composition of needle and thread, production, and soil degradation. Production in this state can be similar to that in the Bunchgrass State (1). Some native plants tend to increase under prolonged drought and heavy grazing practices. A few of these species may include needle and thread, Sandberg bluegrass, scarlet globemallow, hairy goldenaster, and fringed sagewort.

Characteristics and indicators. Less than 15% bluebunch wheatgrass Increase in short stature grasses Increase in bare ground (near 35%)

Resilience management. Conservative grazing management, Integrated Pest Management, time

State 1.3
Degraded State

Degraded State lacks midstatured bunchgrasses. Sandberg bluegrass and prairie Junegrass dominant grasses, increaser shrubs nearly replace larger shrub species. Larger shrub species that remain are heavily hedged. This state is likely a terminal one (e.g., restoration will likely be impossible, unsuccessful, or require major energy inputs).

Characteristics and indicators. 25-50% bare ground annual grasses common complete removal of bluebunch wheatgrass and replaced with sandberg bluegrass, western wheatgrass, and blue grama sagebrush nearly gone and replaced with rabbitbrush and broom snakeweed

Resilience management. Prescribed grazing, Range seeding, Brush Management, Integrated Pest Management

State 1.4
Invaded State

The Invaded State is identified as being in the exponential growth phase of invader abundance where control is a priority. Dominance (or relative dominance) of noxious or invasive species reduces species diversity, forage production, wildlife habitat, and site protection. A level of 20 percent invasive species composition by dry weight indicates that a substantial energy input will be required to create a shift to the grassland state (herbicide, mechanical treatment), even with a return to proper grazing management or favorable growing conditions. Prescriptive grazing 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.

Characteristics and indicators. High amounts of invading species (both native and introduced).

Resilience management. Integrated Pest Management Prescribed Grazing Brush Management Prescribed Fire Range Seeding

Transition T1A
State 1.1 to 1.2

The Bunchgrass State (1) transitions to the Altered Bunchgrass State (2) if bluebunch wheatgrass, by dry weight, decreases to below 10% or if bare ground cover is increased beyond 20%. The driver for this transition is 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 Bunchgrass State. There are several other key factors signaling the approach of transition T1A: increases in soil physical 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 bluebunch wheatgrass composition to <15% and reduction in total plant canopy cover.

Transition T1C
State 1.1 to 1.3

The Bunchgrass State (1) transitions to the Degraded Shrub/Shortgrass State (3) when Bluebunch wheatgrass is removed from the plant community and Needle-and-thread is subdominant to short statured bunchgrasses such as Sandberg bluegrass. The trigger for this transition is loss of taller bunchgrasses, which creates open spaces with bare soil. Soil erosion results in decreased soil fertility, driving transitions to the Degraded Shrub/Shortgrass State. There are several other key factors signaling the approach of transition T1C: increases in soil physical 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 driver for this transition is improper grazing management, intense or repeated fires, and/or heavy human disturbance. Rapid transition is generally realized where livestock are confined to small pastures for long periods of time.

Transition T1B
State 1.1 to 1.4

Healthy plant communities are most resistant to invasion however, regardless of grazing management, without some form of active weed management (chemical, mechanical, or biological control) and without prevention the Bunchgrass State (1) can transition to the Invaded State (4) in the presence of aggressive invasive species such as spotted knapweed, leafy spurge, and cheatgrass. The Central Rocky Mountain Valleys tend to resists invasion of cheatgrass however repeated heavy grazing or intense human activities can open the interspaces of the bunchgrass community 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 Invaded State. The trigger for this transition is the presence of aggressive invasive species. Species composition by dry weight of invasive species approaches 10%.

Restoration pathway R2A
State 1.2 to 1.1

The Altered Bunchgrass State (2) has lost soil or vegetation attributes to the point that recovery to the Bunchgrass State (1) will 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. Low intensity prescribed fires to reduce competitive increaser plants such as needle-and-thread and Sandberg bluegrass. A low intensity fire will also reduce Wyoming big sagebrush densities. In areas with potential of annual grass infestation, fire should be carefully planned or avoided. The drivers for this restoration pathway are reclamation efforts along with proper grazing management.

Transition T2A
State 1.2 to 1.3

As improper grazing management continues vigor of bunch grasses will decrease, and the shorter grasses and shrubs will increase towards the Degraded Shortgrass State (3). Prolonged drought will provide a competitive advantage to shrubs allowing them to become co-dominant with grasses. Shrub canopy will increase. Key transition factors: increase of native shrub canopy cover; reduction in bunchgrass production; decrease in total plant canopy cover and production; increases in mean bare patch size; increases in soil crusting; decreases in cover of cryptobiotic crusts; decreases in soil aggregate stability; and/or evidence of erosion including water flow patterns and litter movement.

Transition T2B
State 1.2 to 1.4

Invasive species can occupy the Altered State (2) and drive it to the Invaded State (4). The Altered State is at risk if invasive seeds and/or other viable material are present. The driver for this transition is more than 20% dry weight of invasive species. The trigger is the presence of seeds and/or other viable material of invasive species.

Restoration pathway R3B
State 1.3 to 1.1

The Degraded Shortgrass State (3) has lost soil or vegetation attributes to the point that recovery to the Bunchgrass State (1) will require reclamation efforts, such as soil rebuilding, intensive mechanical treatments, and/or revegetation. Studies suggest (Whitford et al 1989) a mulch with high carbon to nitrogen ratio such as wood chips or bark in low moisture scenarios can be beneficial for slow mobilization of plant available nitrogen. 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 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 presence of seeds and/or other viable material in the soil and management related increases soil disturbance.

Restoration pathway R3A
State 1.3 to 1.2

Since the bunchgrass plant community has been significantly reduced, restoration to the Altered State (2) is unlikely unless a seed source is available. If a sufficient amount of grass remains on the site, chemical application and/or biological control in conjunction with proper grazing management, can reduce the amount of shrubs and invasive species and restore the site to the Shortgrass Community (2.2). Low intensity fire can be utilized to reduce Wyoming big sagebrush 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. Broom snakeweed and fringed sagewort may or may not re-sprout depending on conditions (USDA Forest Service 2011).

Transition T3A
State 1.3 to 1.4

Invasive species can occupy the Degraded Shortgrass State (3) and drive it to the Invaded State (4). The Degraded Shortgrass State is at risk of this transition occurring if invasive seeds or viable material are present. The driver for this transition is 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 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), long-term lack of fire, or extensive drought.

Restoration pathway R4C
State 1.4 to 1.1

Restoration of the Invaded State (4) to the Bunchgrass State (1) 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-related practices that increase soil disturbance. If invaded by conifer encroachment, treatment depends on the condition of the rangeland. See Plant community 4.1 for alternative measures of restoration. Sites that have transitioned from the Degraded State (3) to the Invaded State (4) 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.

Restoration pathway R4B
State 1.4 to 1.2

If invasive species are removed before remnant populations of bunchgrasses have been drastically reduced the Invaded State (4) can return to the Altered State. The driver for the reclamation pathway is weed management without 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.

Restoration pathway R4A
State 1.4 to 1.3

If invasive species are removed the site could return to the Degraded Shortgrass State (3). Without sufficient remnant populations of preferred plants the Invaded State (4) 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. The invading species cause a significant increased soil loss due to lack of ground cover (Lacey et al. 1989).

State 2
Cropland

Native rangeland is converted to a Cultivated system dominated by introduced species for forage or grain production. This system often receives multiple inputs including fertilizer, herbicides, and irrigation.

Characteristics and indicators. Site is sodbusted and converted to forage or grain production

State 2.1
Cultivated Forage Community

The Cultivated Forage Community is the most common within the Cultivated State. It consists primarily of long-term grass or forb crop planted for grazing or hay. If irrigation water is available, species will be highly variable based on the goals and objectives of the land manager; however. alfalfa is likely included. Production of an irrigated site in this community is typically high

If irrigation is not available, the dry climate limits species options and will likely include Crested wheatgrass or Russian wildrye. Alfalfa is rarely a lone species under dryland conditions.

State 2.2
Abandoned Cultivated Field

The Abandoned Cultivated Field Community is a relatively rare occurrence due to the productive nature of this ecological site. However, as traditional land use transitions from agriculture to recreation, abandonment of cultivation may occur.

If the site was in the Actively Cultivated State at the time of abandonment, the resulting plant community will likely transition into an herbaceous annual weed community. Over time, the weeds will typically yield to a naturalized community of perennial grasses and forbs sourced from the surrounding plant community. Needle and thread, blue grama, Sandberg bluegrass, rabbitbrush, and fringed sagewort are the common native species that can be considered colonizing species. Active Cultivated States are rarely abandoned without some attempt of being planted to a Cultivated Forage Community first.

If the site was managed as a Cultivated Forage Community at the time of abandonment, the plant community tends to transition into a community that resembles a Degraded State over time. With enough time, native colonizing species will slowly fill the interspaces between the forage crops.

Once the Abandoned Cultivated Field Community has reached maturity, it will have similar ecological processes as the Degraded State (3.1)

State 2.3
Active Cultivated Community

Active Cultivated Community is common on this ecological site as the soil pH, water holding capacity and inherent soil organic matter tend to be favorable to annual cropping. If irrigation is available this community is capable of producing a wide variety of crops including corn silage, seed potatoes, pumpkins, sunflower, and other specialty crops. The relatively short growing season tends to be the restriction if irrigated.

Long-term annual cropping can destroy soil aggregation, create soil erosion (both wind and water), deplete organic matter, and alter pH so a conservative crop management system will need to be applied to prevent degradation of the site.

Transition T1A
State 2.1 to 2.2

Cultivated Forage Community is abandoned. This pathway rarely occurs in present time however has occurred frequently in the past which is how Community 5.2 may be observed. In this process, a reason for abandonment occurs and the field sits idle from management. Over time the surrounding native vegetation fills the interspaces between plants.

Transition T1B
State 2.1 to 2.3

Cultivated Forage Community is converted from permanent cover to an annually cropped system. Change takes place when cultivation or plowing occurs. This community pathway is a frequent occurrence on this ecological site particularly when the Cultivated Forage Community’s production begins to drop. This is often on a 10-20year cycle in this MLRA.

Transition T2A
State 2.2 to 2.1

Abandoned Cultivated Field is planted to a forage or hay crop of the manager’s preference. Often this pathway will require tillage or herbicide to terminate the existing plant community and seeding to initiate change.

Transition T2B
State 2.2 to 2.3

An abandoned cultivated field is converted to an annually cropped system. Change takes place when cultivation or plowing occurs. This community pathway is often necessary to convert a lower producing or undesirable community into an annually cropped system.

Transition T3A
State 2.3 to 2.1

Active Cultivation Community is planted to a forage or hay crop of the manager’s preference. This is a common pathway in this MLRA.

Transition T3B
State 2.3 to 2.2

Active Community is abandoned. This pathway rarely occurs in present time however has occurred frequently in the past which is how Community 5.2 may be observed. In this process, a reason for abandonment occurs and the field sits idle from management. Over time the surrounding native vegetation fills the interspaces between weedy, herbaceous plants

Conversion C1
Land use 1 to 2

Native rangeland is converted via tillage for production of forage crop or grains.