Land use 1
Rangeland

Rangeland is the dominant land use for this site and provides the most diverse ecosystem services. Rangeland is land on which the historic and introduced vegetation is predominantly grasses, grass-like plants, forbs or shrubs managed as a natural ecosystem. Range may include natural grasslands, savannas, shrublands, tundra, alpine communities, marshes and meadows.

Characteristics and indicators. This land use consists of diverse native plant communities dominated by big sagebrush and perennial cool season grasses that provide for site stability, hydrologic function, and biotic integrity of the site.

State 1.1
Reference

The Reference State consists of two plant communities: the Wyoming Big Sagebrush/Rhizomatous Wheatgrass Community (1.1), and the Rhizomatous Wheatgrass Community (1.2). Each community differs in percent composition of bunchgrasses, rhizomatous grasses and percent shrub cover. Forbs are a minor component on this site. The percentage of shrub cover is less than 30 percent. The dominant shrub species is Wyoming big sagebrush in the Reference State (1). Two important processes that occur result in plant community changes within the Reference State: sagebrush-killing disturbances (fire, browse, insects, drought, flood) and time without those disturbances, generally referred to as “natural succession.”

Characteristics and indicators. The shift from the Rhizomatous Wheatgrass Plant Community (1.2) to the Wyoming Big Sagebrush/Rhizomatous Wheatgrass Plant Community (1.1) is dependent upon an increase of shrub cover. Without sagebrush-killing disturbance, shrubs will increase on this ecological site even with proper grazing management. Improper grazing management may accelerate the rate of increase for shrub species. The shift from the Wyoming Big Sagebrush/Rhizomatous Wheatgrass to the Rhizomatous Wheatgrass Plant Community is dependent upon sagebrush-killing disturbances such as fire, drought, flood, browse, and insects. Management actions can and are often used to mimic these processes through mechanical and chemical treatments. Prescribed fire is not often used on this site due to current land management, lack of fine fuels, and inadequate burn windows (Clause and Randall 2014).

Resilience management. The Clayey BRV ecological site has moderate resilience due to its xeric soil moisture regime and frigid temperature regime. Precipitation is typically adequate and more effective with cooler temperatures, but timing of precipitation lowers resilience. Moisture is often not present when needed to support recovery efforts. The site can usually recover after disturbance, but is susceptible to delays in recovery during extreme climatic events such as drought. The site has moderately low resistance to invasion by annual grasses because of climate suitability. Winter precipitation patterns favor annual invasion while cooler temperatures provide some resistance. The site is susceptible to invasion during hotter climatic periods.

Community 1.1.1
Big Sagebrush/Rhizomatous Wheatgrass Plant Community

The Big Sagebrush/Rhizomatous Wheatgrass Plant Community is well adapted to Eastern Idaho Plateaus climatic conditions. The diversity in plant species allows for drought tolerance, and natural plant mortality is very low. These plants have strong, healthy root systems that allow production to increase significantly with favorable moisture conditions. Abundant plant litter is available for soil building and moisture retention. Plant litter is properly distributed with very little movement off-site. This plant community provides for soil stability and a properly functioning hydrologic cycle. The soils associated with this site are fertile and hold moderately large amounts of soil moisture, providing a very favorable soil-water-plant relationship. However, heavy soil surface textures result in slightly higher runoff, less infiltration, and hence lower productivity than the Loamy site. Chemical treatment of shrubs has replaced natural sagebrush killing events on many sites in the area. However, chemical treatments impact non-target species, particularly broad-leafed species (forbs and shrubs) differently than natural events such as drought or fire. Where fire tends to result in a short-term increase in forbs, some chemical treatments result in a short-term (or medium-term) reduction in forb density and diversity. The Big Sagebrush/Bunchgrass Community (1.1.1) can occur across the entire ecological site or can occur in a mosaic. This community can occur over time without these disturbances and accelerated with added herbaceous grazing pressure. Wyoming and basin big sagebrush are dominant with mountain big sagebrush at the upper end of the precipitation range for this site. Sagebrush canopy cover ranges from 10 to 20 percent. At this sagebrush canopy level in this precipitation zone, there is little competition between the shrub over-story and the herbaceous under-story (Winward, 2007). A Big Sagebrush/Bunchgrass Community with a degraded under-story is an “at-risk” community, particularly when occurring homogeneously across the landscape. In the Big Sagebrush/Bunchgrass Community (1.1.1), there are generally few canopy gaps, and most basal gaps are small (1-2 feet). Rock cover on the soil surface is essentially nonexistent. Many plant inter-spaces have canopy or litter cover. Production of grasses is much lower than in the Bunchgrass Community (1.1.3) and slightly lower than in the Bunchgrass/Big Sagebrush Community (1.1.2).

Community 1.1.2
Rhizomatous Wheatgrass Plant Community

Rhizomatous wheatgrasses dominate in the Rhizomatous Wheatgrass Plant Community (1.2) and sagebrush is sub-dominant with foliar cover ranging from one to 10 percent. At this sagebrush canopy level in this precipitation zone, there is no competition between the shrub over-story and the herbaceous under-story. In fact, there is evidence to suggest that the under-story receives more benefit from the sage over-story than negative effects (Winward 2007). There are generally fewer canopy gaps, and basal gaps are generally less than one to two feet. Rock cover on the soil surface is low. Many plant inter-spaces have canopy or litter cover. Production of perennial grasses is higher than in the Wyoming Big Sagebrush/Rhizomatous Wheatgrass Plant Community (1.1), and shrub production is lower with more diversity, including sprouting shrubs.

Pathway 1.1A
Community 1.1.1 to 1.1.2

Sagebrush killing event such as moderate intensity fire or climatic events such as severe drought, prolonged soil saturation, freeze-kill, snow mold, and herbivory force the community change. Anthropogenic sagebrush thinning events such as chemical (Tebuthiruon) or mosaic mechanical (mowing, aerator, etc.) can result in a similar pathway in the absence of annual invasives.

Context dependence. Killing events are often episodic with climatic events and can occur suddenly with a particular event (fire, precipitation, temperature, insect irruption, etc.). A successful pathway is contingent upon a grazing regime that allows for periodic critical growth period rest (May-June). An integrated pest management plan is needed to prevent, avoid, manage, and suppress invasive species.

Pathway 1.2A
Community 1.1.2 to 1.1.1

Natural succession (time without sagebrush killing event).

Context dependence. Time period for pathway is dependent upon weather events such as drought and above normal precipitation years. Drought results in slower pathway while favorable precipitation can result in a faster pathway. A grazing regime that mimics the historic regime (light intensity, episodic grazing events) will not alter the pathway, but a continuous grazing regime at moderate to heavy intensity can accelerate the pathway.

State 1.2
Disturbed

The Disturbed State is a result of soil-disturbing activities outside of the normal disturbance regime expected for this site. Examples are high intensity hoof action, anthropogenic activity, rodent activity, or frequent flooding, which includes occasional irrigation. It may also occur after brush management preceded or followed by improper grazing techniques that include high-intensity grazing use without appropriate recovery periods. Brush management treatment methods include mechanical (heavy equipment/construction or a mowing/chaining/harrow type sage treatment), chemical (2,4-D or Tebuthiron), or biological (browse or insects). Fire could be a factor in maintaining this plant community by stimulating sprouting shrubs (rabbitbrush) and killing sagebrush. Removal of shrubs without proper grazing management can lead to an increase in bare ground and erosion of the upper soil horizon. Consequences of this are decreased soil organic matter and soil erosion, soil crusting, and a decrease in soil surface aggregate stability.

Characteristics and indicators. There is a shift toward sprouting shrub dominance or co-dominance with big sagebrush depending on how long it has been since the disturbance(s). Both green (aka yellow in USDA PLANTS) and rubber rabbitbrush may be present. Along with a shift in shrub species, the herbaceous under-story also shifts toward more disturbance tolerant species such as western wheatgrass. Annual weeds such as bur buttercup, flixweed, and lambsquarter, and invasive annual grasses such as cheatgrass are often present in small amounts (less than 5 percent composition by dry weight).

Resilience management. Site resilience is lower than the Reference State, but slightly higher than the Invaded State. Site hydrology has been modified resulting in greater runoff during spring melt and rainfall events. Therefore, the site is drier and unable to recover as quickly after a disturbance. However, sprouting shrubs and remnant perennial vegetation provide some amount of resiliency. Site resistance to invasion by annual grasses is lost due to niches in the under-story for establishment as well as site water availability during the time suited for winter annuals such as cheatgrass (Bromus tectorum). Episodic and limited moisture is more suited to annual life forms.

Community 1.2.1
Big Sagebrush/Rabbitbrush Plant Community

This plant community is a result of recovery after a past soil-disturbing activity. It is co-dominated by sprouting shrubs, mainly green rabbitbrush (aka yellow rabbitbrush in USDA PLANTS) and Wyoming big sagebrush. The understory typically consists of a combination of perennial rhizomatous grasses, mainly western wheatgrass, and annual grasses and forbs. Total annual production ranges from 400 to 800 pounds per acre (lbs/ac) with a RV of 600 lbs/ac. The soil is typically adequately protected, but erosion can occur during high runoff events. The biotic integrity is reduced due to low vegetative production, relative dominance and unexpected structural/functional groups, and potentially invasive species if present. The watershed is functioning-at-risk.

Community 1.2.2
Rabbitbrush/Rhizomatous Wheatgrass Plant Community

This plant community is the result of a recent soil-disturbing activity. Western wheatgrass is the dominant perennial grass, and annual grasses and forbs are often present. With sagebrush removed, green rabbitbrush (aka yellow rabbitbrush in USDA PLANTS) is the dominant shrub, often exceeding 10 percent of the annual production. Subdominant under-story species include bottlebrush squirreltail, Sandberg bluegrass, and unpalatable annual and perennial forbs. In the absence of annuals, there can be a substantial amount of bare ground. Total annual production ranges from 400 to 800 lbs/ac with a RV of 600 lbs/ac. The soil is not adequately protected, and erosion is expected without management to allow for adequate litter and residual. The biotic integrity is reduced due to low vegetative production, relative dominance and unexpected structural/functional groups, and potentially invasive species if present. The watershed is functioning-at-risk.

Pathway 2.1A
Community 1.2.1 to 1.2.2

Sagebrush killing event, typically high intensity fire or consecutive anthropogenic sagebrush treatments such as chemical (Tebuthiruon) or mechanical (mowing, aerator, etc.).

Context dependence. Killing events are often episodic with climatic events and can occur suddenly with a particular event (fire, precipitation, temperature, insect irruption, etc.). If extreme conditions/disturbances such as hot temperatures, drought, or high intensity grazing occur, there is risk of a transition to the Invaded State depending upon severity and cumulative disturbance.

Pathway 2.2A
Community 1.2.2 to 1.2.1

Natural succession (time without sagebrush killing event).

Context dependence. Time period for pathway is dependent upon weather events such as drought and above normal precipitation years. Drought results in slower pathway while favorable precipitation can result in a faster pathway. A grazing regime that mimics the historic regime (light intensity, episodic grazing events) will not alter the pathway, but a continuous grazing regime at moderate to heavy intensity can accelerate the pathway.

State 1.3
Invaded

The Invaded State occurs once perennial grasses are reduced and the site is invaded by annual grasses and forbs. It often occurs in conjunction with severe grazing intensity and drought conditions.

Characteristics and indicators. In the Invaded State, sagebrush canopy varies, but the under-story is dominated by annual invasive and weedy species. There will be indicators of reduced soil and site stability as well as reduced hydrologic function, mainly water flow patterns and pedestals, but rills and gullies are likely. Compaction is likely, as well as soil surface loss and degradation. Biotic integrity is affected by functional/structural groups not expected for the site, invasive plants, and the loss of perennial species and functional/structural groups. The site is more prone to drought with large fluctuations in annual production in response to weather events. The site is less diverse with lower quality habitat for wildlife and pollinators, and the risk of wildfire is increased from fine fuel production.

Resilience management. Site resilience is lower than all other states because the site hydrology has been modified resulting in greater runoff during spring melt and rainfall events. Therefore, the site is drier and unable to recover as quickly after a disturbance. Site resistance to invasion by annual grasses is lost due to niches in the under-story for establishment as well as site water availability during the time suited for winter annuals such as cheatgrass (Bromus tectorum). Episodic and limited moisture is more suited to annual life forms.

Community 1.3.1
Big Sagebrush/Annual Plant Community

This plant community is the result of improper grazing. Improper grazing is defined as either high- or low-intensity grazing without the appropriate recovery period. Wyoming big sagebrush dominates with annual production often exceeding 40 percent. The under-story is dominated by annual grasses and forbs while perennial grass and forbs are sparse and bunchgrasses are limited to the protected areas under shrubs. The predominant perennial grasses include Sandberg bluegrass and rhizomatous wheatgrass (western wheatgrass). Total annual production ranges from 300 to 700 lbs/ac with a RV of 500 lbs/ac. Soil erosion is accelerated because of the lack of deep-rooted perennials. The biotic community has been compromised. The watershed is degraded. Water flow patterns and pedestals are obvious. Infiltration is reduced, and runoff is increased.

Community 1.3.2
Annual Plant Community

This plant community results from a severe sagebrush killing disturbance once a site has been invaded by annuals. Repeated disturbances, such as fire, can maintain this plant community, but that is a rare occurrence for this site. Otherwise, sagebrush will typically re-establish on this site fairly quickly, within 5 to 10 years. However, to achieve pre-disturbance sagebrush canopy levels will take much longer. This site has low potential for recovery once dominated by annuals. Seeding is recommended to restore herbaceous perennial functional structural groups. Productivity in this plant community phase is highly variable based on current year's weather. Total annual production ranges from 300 to 700 lbs/ac with a RV of 500 lbs/ac.

Pathway 3.1A
Community 1.3.1 to 1.3.2

Sagebrush killing event, typically catastrophic fire or mechanical sagebrush treatments (mowing, aerator, disking, etc.)

Context dependence. Killing events are often episodic with climatic events and can occur suddenly with a particular event (fire, precipitation, temperature, insect irruption, etc.). Consecutive disturbances and extreme conditions such as hot temperatures, drought, or high intensity grazing will exacerbate this pathway to an annual dominated system.

Pathway 3.2A
Community 1.3.2 to 1.3.1

Natural succession (time without sagebrush killing event).

Context dependence. Time period for pathway is dependent upon weather events such as drought and above normal precipitation years. Drought results in slower pathway while favorable precipitation can result in a faster pathway. A grazing regime that mimics the historic regime (light intensity, episodic grazing events) will not alter the pathway, but a continuous grazing regime at moderate to heavy intensity can accelerate the pathway.

Transition T1A
State 1.1 to 1.2

Soil-disturbance outside of the normal disturbance regime expected for this site is the main mechanism for transition. Examples include fire, high intensity hoof action, anthropogenic activity (e.g. mechanical or chemical treatments), rodent activity, or frequent flooding, which includes occasional irrigation.

Constraints to recovery. Recovery is inhibited by consecutive disturbances over a relatively short time period and drought conditions. Annual grasses are likely in small amounts, increasing with each additional disturbance.

Context dependence. Drought and annual invasion are most likely variables to prevent restoration.

Transition T1B
State 1.1 to 1.3

Extreme disturbance, including catastrophic fire, drought, or other soil removal disturbance, resulting in removal of perennial vegetation followed by annual invasion, typically associated with post-drought conditions, results in the Annual Plant Community.

Constraints to recovery. Recovery is inhibited by fire risk and annual invasion.

Context dependence. Drought and annual invasion are variables that prevent restoration.

Transition T2A
State 1.2 to 1.3

The driver is extreme herbivory resulting in removal of perennial herbaceous vegetation followed by annual invasion, typically associated with post-drought conditions. It is common for this to occur without a sagebrush killing event, resulting in the shrub/annual plant community.

Constraints to recovery. Recovery is inhibited by fire risk and annual invasion.

Context dependence. Drought and annual invasion are variables that prevent restoration.

Land use 2
Pastureland

This is a moderately deep to deep site with very few limitations for agriculture production, and therefore is often converted to irrigated pasture due to high water holding capacity, low slopes, and landscape position that lends itself to tillage and irrigation practices. The site is also converted to dryland pasture to a lesser extent. Pastureland is land composed of introduced or domesticated native forage species that is used primarily for the production of livestock. Pastures receive periodic renovation and cultural treatments, such as tillage, fertilization, mowing, weed control, and may be irrigated. Pastures are not in rotation with crops.

Characteristics and indicators. Pasture on this site can be either dryland or irrigated. Irrigated pasture was often historically tilled and irrigation infrastructure installed. Perennial forage species such as Kentucky bluegrass, smooth brome, and white or alsike clover were often seeded historically. In more recent times, creeping meadow foxtail was introduced to the Bear River Valley, and has taken over many flood irrigated pastures. Irrigated pasture is maintained through irrigation, dragging, grazing and occasional haying practices. Hay production with aftermath grazing is common, but pastures on this site can also managed for grazing throughout the growing season with some dormant season grazing as well. Dryland pasture was often historically tilled and planted to crested wheatgrass and has maintained itself over time with minimal inputs such as mowing, disking, dragging, or harrowing. Occasional haying on dryland pasture typically occurs only in the wettest years.

State 2.1
Irrigated Pasture

See Clayey Forage Suitability Group (FSG) for MLRA 34A LRU F (10-14" ppt, 70-90 day growing season) for more information at Wyoming's electronic Field Office Technical Guide, Section II, Forage Suitability Groups https://efotg.sc.egov.usda.gov/references/public/WY/mlra34A_fsg_clayey_lru_F_.pdf This FSG covers moderately deep to deep soils with clay loam or heavier soil textures and greater than 6 inches available water-holding capacity (AWC) in the top 60 inches of the soil profile. Production expected to range from 2,000 to 4,000 lbs./ac. with representative value (RV) of 3,000 lbs./ac. Adapted species for use as irrigated pasture include native species such as Idaho fescue, prairie junegrass, Canby's bluegrass, blue wildrye, slender wheatgrass, western wheatgrass, and tufted hairgrass; introduced species including meadow brome, timothy, orchardgrass, beardless wildrye, Altai wildrye, red fescue, sheep fescue, and tall fescue, creeping meadow foxtail, Canada bluegrass, and Kentucky bluegrass; forb and shrub species such as cicer milkvetch, birdsfoot trefoil, small burnett, white clover, alsike clover, red clover, and strawberry clover. Selection of species should be based on production goals and intended use (goals and objectives). More information regarding preferred varieties for irrigated pasture can be found at http://animalrange.montana.edu/documents/extension/mteb99.pdf AND https://www.nrcs.usda.gov/Internet/FSE_PLANTMATERIALS/publications/mtpmctn10704.pdf

Characteristics and indicators. Irrigated pasture on this site varies from a very diverse mix of native wetland plants to a monoculture of creeping meadow foxtail. Flood irrigation water management often results in hydric soil and hydrophytic vegetation.

Resilience management. Resilience on this site when in irrigated pasture is much higher than reference state. Resistance to annual invasion is typically much higher than the reference state. However, improper grazing or irrigation water management techniques could result in noxious weed invasion by perennials such as perennial pepperweed, musk thistle, Canada thistle, or scentless chamomile.

State 2.2
Dryland Pasture

See Clayey Forage Suitability Group (FSG) for MLRA 34A LRU F (10-14" ppt, 70-90 day growing season) for more information at Wyoming's electronic Field Office Technical Guide, Section II, Forage Suitability Groups https://efotg.sc.egov.usda.gov/references/public/WY/mlra34A_fsg_clayey_lru_F_.pdf This FSG covers moderately deep to deep soils with clay loam or heavier soil textures and greater than 6 inches available water-holding capacity (AWC) in the top 60 inches of the soil profile. Production expected to range from 600 to 1,000 lbs./ac. with representative value (RV) of 800 lbs./ac. Adapted species for use as dryland pasture include native species such as Indian ricegrass, big bluegrass, basin wildrye, slender wheatgrass, and western wheatgrass; introduced species including crested wheatgrass, Russian wildrye, sheep fescue, and intermediate or pubescent wheatgrass; and forb and shrub species such as dryland alfalfa, sweetclover, forage kochia, winterfat, and four-wing saltbush. Selection of species should be based on production goals and intended use (goals and objectives). More information regarding adapted species for dryland can be found at https://www.nrcs.usda.gov/Internet/FSE_PLANTMATERIALS/publications/mtpmspu1138.pdf

Characteristics and indicators. Dryland pasture on this site is typically dominated by a mono-culture of crested wheatgrass. It is common for sagebrush to re-colonize the site over time without periodic renovation or cultural practices such as mowing or tillage.

Resilience management. Resilience on this site when in dryland pasture is similar to the Reference State. However, it may be lower if dominated by a mono-culture that lacks diversity, resulting in a plant community that is vulnerable to drastic changes following disturbance. Resistance to annual invasion is similar to reference, but could be slightly higher if planted to highly competitive species such as crested wheatgrass or Russian wildrye. However, new research from the Great Basin indicates that native seedings can be as competitive as introduced species (Ott et.al. 2019).

Transition T1A
State 2.1 to 2.2

Irrigation abandonment results in transition from irrigated pasture to dryland pasture.

Land use 3
Cropland

This is a moderately deep to deep site with very few limitations for agriculture production, and therefore is often converted to irrigated crop due to high water holding capacity, low slopes, and landscape position that lends itself to tillage and irrigation practices. Cropland is land used primarily for the production and harvest of annual or perennial field, forage, food, fiber, horticultural, orchard, vineyard, or energy crops.

Characteristics and indicators. Cropland on this site is typically irrigated. Irrigated crop is typically perennial and consists of a mixture of legume (alfalfa or clover) and a variety of cool-season perennial forage grasses in rotation with short-season annual cereal grains such as barley. The annual portion of the crop rotation is often grown as a forage (not cash) crop.

State 3.1
Irrigated Cropland

See Clayey Forage Suitability Group (FSG) for MLRA 34A LRU F (10-14" ppt, 70-90 day growing season) for more information at Wyoming's electronic Field Office Technical Guide, Section II, Forage Suitability Groups https://efotg.sc.egov.usda.gov/references/public/WY/mlra34A_fsg_clayey_lru_F_.pdf This FSG covers moderately deep to deep soils with clay loam or heavier soil textures and greater than 6 inches available water-holding capacity (AWC) in the top 60 inches of the soil profile. Production expected to range from 2,000 to 4,000 lbs./ac. with representative value (RV) of 3,000 lbs./ac. The most common crop rotation on this site is one to three years of annual grains with 7 to 9 years of perennial forage/hay crop. Adapted species for use as annual irrigated crop include short-season grains such as barley grown for forage or cash grain crop. Adapted species for use as perennial irrigated crop (hayland) include legumes such as alfalfa, clovers, sainfoin, cicer milkvetch, and birds foot trefoil; introduced species including meadow brome, timothy, and orchardgrass.

Characteristics and indicators. Irrigated crop on this site is varies from annual to perennial forage. Center pivot or side roll sprinklers are the most common form of irrigation, however improved flood irrigation such as graded borders also occurs.

Resilience management. Resilience on this site when in irrigated crop is typically high due to added irrigation water. Resistance to annual invasion is typically high as well. However, severe ground disturbance, improper aftermath grazing or irrigation water management techniques could result in noxious weed invasion by perennials such as perennial pepperweed, musk thistle, Canada thistle, or scentless chamomile.

Conversion C1A
Land use 1 to 2

Most range conversion to pasture occurred at the end of the 19th century and was done using horse-pulled implements and hand tools. Flood irrigation infrastructure was installed and introduced species seeded such as Kentucky bluegrass and clover. Wild flood irrigation is the most common with little control and sometimes water is checked at the bottom of fields to backup water and promote extended flooded condtions that result in more hydrophytic vegetation and hydric soil development.

Conversion C1B
Land use 1 to 3

Most range conversion to crop occurred at the end of the 19th century and was done using horse-pulled implements and hand tools. Flood irrigation infrastructure such as graded borders were installed and introduced species seeded such as smooth brome and alfalfa in rotation with annual cereal grains such as oats and barley. The water source is surface water from the Bear River. In recent times there have been some range conversion to crop using sprinkler irrigation to improve water efficiency and control plus reduce labor. Higher value forage grasses such as meadow brome and non-bloat legumes such as sainfoin and cicer milkvetch have also been introduced into the crop rotation.

Conversion C2A
Land use 2 to 3

In more recent times, wild flood irrigation is being converted to crop under sprinkler irrigation, resulting in the ability to grow higher value forages and legumes in rotation with annual cereal grains such as oats and barley.