Provisional. A provisional ecological site description has undergone quality control and quality assurance review. It contains a working state and transition model and enough information to identify the ecological site.
MLRA notes
Major Land Resource Area (MLRA): 024X–Humboldt Basin and Range Area
Major land resource area (MLRA) 24, the Humboldt Area, covers an area of approximately 8,115,200 acres (12,680 sq. mi.). It is found in the Great Basin Section of the Basin and Range Province of the Intermontane Plateaus. Elevations range from 3,950 to 5,900 feet (1,205 to 1,800 meters) in most of the area, some mountain peaks are more than 8,850 feet (2,700 meters).
A series of widely spaced north-south trending mountain ranges are separated by broad valleys filled with alluvium washed in from adjacent mountain ranges. Most valleys are drained by tributaries to the Humboldt River. However, playas occur in lower elevation valleys with closed drainage systems. Isolated ranges are dissected, uplifted fault-block mountains. Geology is comprised of Mesozoic and Paleozoic volcanic rock and marine and continental sediments. Occasional young andesite and basalt flows (6 to 17 million years old) occur at the margins of the mountains. Dominant soil orders include Aridisols, Entisols, Inceptisols and Mollisols. Soils of the area are generally characterized by a mesic soil temperature regime, an aridic soil moisture regime and mixed geology. They are generally well drained, loamy and very deep.
Approximately 75 percent of MLRA 24 is federally owned, the remainder is primarily used for farming, ranching and mining. Irrigated land makes up about 3 percent of the area; the majority of irrigation water is from surface water sources, such as the Humboldt River and Rye Patch Reservoir. Annual precipitation ranges from 6 to 12 inches (15 to 30 cm) for most of the area, but can be as much as 40 inches (101 cm) in the mountain ranges. The majority of annual precipitation occurs as snow in the winter. Rainfall occurs as high-intensity, convective thunderstorms in the spring and fall.
Ecological site concept
This ecological site is on summits and side slopes of low mountains, hills and upper piedmont slopes. Soils associated with this site are well drained and formed in residuum derived from mixed parent material. The soil profile is characterized by an ochric epipedon and an abrupt boundary to layer of clay accumulation (argillic horizon) 30cm (11in) or less from the soil surface. Important abiotic factors contributing to the presence of this ecological site include wet non-satiated conditions in the spring, shallow depth to an abrupt boundary, and very dry soil conditions in the summer and fall. Dominant vegetation in the reference plant community is low sagebrush (ARAR8), Thurber's needlegrass (ACTH7) and bluebunch wheatgrass (PSSPS).
Idaho fescue (FEID)-Bluebunch wheat grass (PSSPS) codominant grasses; more productive site; soil with a dark surface horizon (mollic epipedon), site typically found on backslopes of mountains
Black sagebrush (ARNO4) dominant shrub; soils are shallow to moderately deep, with greater than 35 percent rock fragments and calcium carbonates throughout
Mountain Big sagebrush (ARTRV) dominant shrub; soils are moderately deep, formed in residuum/colluvium, and have a dark colored (mollic epipedon) surface horizon
Wyoming big sagebrush (ARTRW8) dominant shrub; soils are deep, have a light-colored surface (ochric epipedon), and lack an abrupt boundary to an argillic horizon
Mountain big sagebrush (ARTRV) dominant shrub; occurs on all but north aspects; soils are moderately deep, have a dark colored (mollic epipedon) surface horizon, greater than 35 percent rock fragments
Idaho fescue (FEID)- Bluebunch wheat grass (PSSPS) codominant grasses; more productive site; soil with a dark surface horizon (mollic epipedon), site typically found on backslopes of mountains
This ecological site is on summits and side slopes of low mountains, hills and upper piedmont slopes. Landform shape is linear-linear to linear-convex. Slopes range from 8 to 50 percent, but slope gradients less than 30 percent are typical. Elevations are from 5,500 to about 7,000 feet (1,676 to 2,133 meters). Runoff is high to very high.
Table 2. Representative physiographic features
Landforms
(1) Mountains > Hill (2) Mountain (3) Piedmont slope > Fan collar
Runoff class
High to very high
Elevation
5,500–7,000 ft
Slope
8–50%
Aspect
Aspect is not a significant factor
Climatic features
The climate associated with this site is semiarid and characterized by cool, moist winters and warm, dry summers. Average annual precipitation is 10 to 12 inches (25 to 30cm). Mean annual air temperature is 45 to 48 degrees F. The average growing season is about 80 to 110 days. Representative weather stations are not available for this site.
Table 3. Representative climatic features
Frost-free period (characteristic range)
90-120 days
Freeze-free period (characteristic range)
80-110 days
Precipitation total (characteristic range)
10-12 in
Frost-free period (actual range)
Freeze-free period (actual range)
Precipitation total (actual range)
8-14 in
Frost-free period (average)
100 days
Freeze-free period (average)
90 days
Precipitation total (average)
10 in
Influencing water features
Influencing water features are not associated with this site.
Wetland description
N/A
Soil features
The soils associated with this site are moderately deep, well drained and formed in residuum derived from igneous and mixed rocks. The soil profile is characterized by an light colored surface (ochric epipedon), a layer of clay accumulation (argillic horizon) within 30cm, greater than 35 percent clay in the particle size control section, and greater than 40 percent rock fragments by volume. The swelling of the subsoil with wetting results in poor aeration during the early spring, creating wet non-satiated conditions. These subsoils interfere with deep root development, but some strong tap roots are able to penetrate the subsoil along vertical cleavage planes.
Soil series associated with this site include: Devada, Millerlux, Robson, and Zoesta.
Table 4. Representative soil features
Parent material
(1) Colluvium–igneous rock (2) Residuum–igneous and sedimentary rock
Surface texture
(1) Cobbly loam
(2) Very gravelly loam
(3) Gravelly loam
Family particle size
(1) Loamy
Drainage class
Well drained
Permeability class
Slow to moderate
Soil depth
12–20 in
Surface fragment cover <=3"
9–34%
Surface fragment cover >3"
6–21%
Available water capacity (0-40in)
1–2.4 in
Soil reaction (1:1 water) (0-40in)
6.6–7.8
Subsurface fragment volume <=3" (1-19in)
14–25%
Subsurface fragment volume >3" (5-26in)
6–26%
Ecological dynamics
An ecological site is the product of all the environmental factors responsible for its development and it has a set of key characteristics that influence a site’s resilience to disturbance and resistance to invasive species. Key characteristics include 1) climate (precipitation, temperature), 2) topography (aspect, slope, elevation, and landform), 3) hydrology (infiltration, runoff), 4) soils (depth, texture, structure, organic matter), 5) plant communities (functional groups, productivity), and 6) natural disturbance regime (fire, herbivory, etc.) (Caudle 2013). Biotic factors that influence resilience include site productivity, species composition and structure, and population regulation and regeneration (Chambers et al. 2013).
This ecological site is dominated by deep-rooted cool season, perennial bunchgrasses and long-lived shrubs (50+ years) with high root to shoot ratios. The dominant shrubs usually root to the full depth of the winter-spring soil moisture recharge, which ranges from 1.0 to over 3.0 m (Dobrowolski et al. 1990). However, community types with low sagebrush as the dominant shrub were found to have soil depths and thus available rooting depths of 71 to 81 cm in a study in northeast Nevada (Jensen 1990). These shrubs have a flexible generalized root system with development of both deep taproots and laterals near the surface (Comstock and Ehleringer 1992).
Great Basin sagebrush communities have high spatial and temporal variability in precipitation both among years and within growing seasons. Periodic drought regularly influences sagebrush ecosystems and drought duration and severity has increased throughout the 20th century in much of the Intermountain West. Major shifts away from historical precipitation patterns have the greatest potential to alter ecosystem function and productivity. Species composition and productivity can be altered by the timing of precipitation and water availability with the soil profile (Bates et al. 2006). Low sagebrush is fairly drought tolerant but also tolerates periodic wetness during some portion of the growing season. Low sagebrush is also susceptible to the sagebrush defoliator, Aroga moth. Aroga moth can partially or entirely kill individual plants or entire stands of big sagebrush (Furniss and Barr 1975), but the research is inconclusive of the damage sustained by low sagebrush populations.
The perennial bunchgrasses that are dominant on this site include Idaho fescue and bluebunch wheatgrass. These species generally have somewhat shallower root systems than the shrubs, but root densities are often as high as or higher than those of shrubs in the upper 0.5 m but taper off more rapidly than shrubs. Differences in root depth distributions between grasses and shrubs result in resource partitioning in these shrub/grass systems.
The invasibility of plant communities is often linked to resource availability. Disturbance can decrease resource uptake due to damage or mortality of the native species and depressed competition or can increase resource pools by the decomposition of dead plant material following disturbance. The invasion of sagebrush communities by cheatgrass (Bromus tectorum) has been linked to disturbances (fire, abusive grazing) that have resulted in fluctuations in resources (Chambers et al. 2007). The introduction of annual weedy species, like cheatgrass, may cause an increase in fire frequency and eventually lead to an annual state. Conversely, as fire frequency decreases, sagebrush will increase and with inappropriate grazing management the perennial bunchgrasses and forbs may be reduced.
State and transition model
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The Reference State is a representative of the natural range of variability under pristine conditions. State dynamics are maintained by interactions between climatic patterns and disturbance regimes. Negative feedbacks enhance ecosystem resilience and contribute to the stability of the state. These include the presence of all structural and functional groups, low fine fuel loads, and retention of organic matter and nutrients. Plant community phase changes are primarily driven by fire, periodic drought and/or insect or disease attack. Due to the nature and extent of disturbance in this site, multiple community phases would likely occur in a mosaic across the landscape.
Characteristics and indicators. Low sagebrush is killed by fire and does not sprout (Young 1983). Establishment after fire is from seed, generally blown in and not from the seed bank (Bradley et al. 1992). Fire risk is greatest following a wet, productive year when there is greater production of fine fuels (Beardall and Sylvester 1976). Fire return intervals have been estimated at 100-200 years in black sagebrush (Artemisia nova) dominated sites (Kitchen and McArthur 2007) and likely is similar in the low sagebrush ecosystem; however, historically fires were probably patchy due to the low productivity of these sites.
The reference plant community is dominated by Thurber's needlegrass, bluebunch wheatgrass and low sagebrush. Webber's ricegrass, Cusick's and Sandberg's bluegrass are important grasses associated with this site. Potential vegetative composition is about 55% grasses, 10% forbs and 35% shrubs. Approximate ground cover (basal and crown) is 15 to 30 percent.
Figure 1. Annual production by plant type (representative values) or group (midpoint values)
Table 5. Annual production by plant type
Plant type
Low (lb/acre)
Representative value (lb/acre)
High (lb/acre)
Grass/Grasslike
165
275
385
Shrub/Vine
105
175
245
Forb
30
50
70
Total
300
500
700
Community 1.2 Community phase
This community phase is characteristic of a post-disturbance, early/mid-seral community. Bluebunch wheatgrass, Thurber’s needlegrass and perennial forbs dominate. Depending on fire severity, patches of intact sagebrush may remain. Rabbitbrush and other fire tolerant shrubs sprout and may increase post fire. Perennial forbs may be a significant component for a number of years following fire.
Resilience management. Low sagebrush is killed by fire and does not sprout (Young 1983). Establishment after fire is from seed, generally blown in and not from the seed bank (Bradley et al. 1992). Fire risk is greatest following a wet, productive year when there is greater production of fine fuels (Beardall and Sylvester 1976). Fire return intervals have been estimated at 100-200 years in black sagebrush (Artemisia nova) dominated sites (Kitchen and McArthur 2007) and likely is similar in the low sagebrush ecosystem; however, historically fires were probably patchy due to the low productivity of these sites.
Community 1.3 Community phase
This community phase is characteristics of a late-seral plant community. Decadent sagebrush dominates the overstory and the deep-rooted perennial bunchgrasses in the understory are reduced either from competition with shrubs and/or from herbivory. Sandberg bluegrass may increase in the understory and become the dominant grass on the site.
Pathway 1.1A Community 1.1 to 1.2
Low severity fire creates grass/sagebrush mosaic; high severity fire significantly reduces sagebrush cover and leads to early/mid seral community, dominated by grass and forbs.
Context dependence. Fire reduces the shrub overstory and allows for perennial bunchgrasses to dominate the site. Fires are typically low severity resulting in a mosaic pattern due to low fuel loads. A fire following an unusually wet spring facilitating an increase in fine fuels may be more severe and reduce sagebrush cover to trace amounts.
Pathway 1.1B Community 1.1 to 1.3
Time and lack of disturbance such as fire allows for sagebrush to increase and become decadent. Chronic drought, herbivory, or combinations of these will generally cause a decline in perennial bunchgrasses and fine fuels leading to a reduced fire frequency and allowing sagebrush to dominate the site.
Pathway 1.2A Community 1.2 to 1.1
Time, absence of disturbance and natural regeneration over time allows sagebrush to recover. Recovery of sagebrush depends on the availability of a local seed source (patches of mature shrubs) as well as precipitation patterns favorable for germination and seedling recruitment. Sagebrush seedlings are susceptible to less than favorable conditions for several years.
Context dependence. Recovery time of low sagebrush following fire is variable (Young 1983). After fire, if regeneration conditions are favorable, low sagebrush recovers in 2 to 5 years, however on harsh sites where cover is low to begin with and/or erosion occurs after fire, recovery may require more than 10 years (Young 1983). Slow regeneration may subsequently worsen erosion (Blaisdell 1982).
Pathway 1.3A Community 1.3 to 1.1
A low severity fire, or late fall/winter herbivory causing mechanical damage to sagebrush or combinations will reduce the sagebrush overstory and create a sagebrush/grass mosaic.
Context dependence. Low severity fire or late fall/winter herbivory causes mechanical damage to sagebrush would reduce sagebrush overstory.
Pathway 1.3b Community 1.3 to 1.2
High severity fire significantly reduces sagebrush cover leading to early mid-seral community.
Context dependence. Fire will decrease or eliminate the overstory of sagebrush and allow for the perennial bunchgrasses to dominate the site. Fires will typically be high intensity due to the dominance of sagebrush in this community phase.
State 2 Current Potential State
This state is similar to the Reference State 1.0. Ecological function has not changed, however the resiliency of the site has been reduced by the presence of invasive weeds. This state has the same three general community phases. These non-native species can be highly flammable, and promote fire where historically fire had been infrequent. Negative feedbacks enhance ecosystem resilience and contribute to the stability of the state. These feedbacks include the presence of all structural and functional groups, low fine fuel loads, and retention of organic matter and nutrients. Positive feedbacks decrease ecosystem resilience and stability of the state. These include the non-natives’ high seed output, persistent seed bank, rapid growth rate, ability to cross pollinate, and adaptations for seed dispersal.
Characteristics and indicators. The invasion of sagebrush communities by cheatgrass (Bromus tectorum) has been linked to disturbances (fire, abusive grazing) that have resulted in fluctuations in resources (Chambers et al. 2007). The introduction of annual weedy species, like cheatgrass, may cause an increase in fire frequency and eventually lead to an annual state. Conversely, as fire frequency decreases, sagebrush will increase and with inappropriate grazing management the perennial bunchgrasses and forbs may be reduced.
This community phase is compositionally similar to the Reference State Community Phase 1.1 with the presence non-native species in trace amounts. This community is codominated by Thurber's needlegrass and bluebunch wheatgrass with a significant component of low sagebrush. Bluegrass and and Webber's needlegrass are common within the community. Other shrubs and perennial forbs make up a smaller component of this site.
Community 2.2 Community phase
This community phase is characteristic of a post-disturbance, early to mid-seral community where annual non-native species are present. Perennial bunchgrasses and forbs dominate the site. Depending on fire severity patches of intact sagebrush may remain. Rabbitbrush may be sprouting or dominant in the community. Perennial forbs may be a significant component for a number of years following fire. Annual non-native species are stable or increasing within the community.
Resilience management. Low sagebrush is killed by fire and does not sprout (Young 1983). Establishment after fire is from seed, generally blown in and not from the seed bank (Bradley et al. 1992). Fire risk is greatest following a wet, productive year when there is greater production of fine fuels (Beardall and Sylvester 1976). Recovery time of low sagebrush following fire is variable (Young 1983). After fire, if regeneration conditions are favorable, low sagebrush recovers in 2 to 5 years, however on harsh sites where cover is low to begin with and/or erosion occurs after fire, recovery may require more than 10 years (Young 1983). Slow regeneration may subsequently worsen erosion (Blaisdell 1982).
Community 2.3 Community phase
This community is at risk of crossing a threshold to another state. Sagebrush dominates the overstory and perennial bunchgrasses in the understory are reduced, either from competition with shrubs or from inappropriate grazing management, or from both. Rabbitbrush may be a significant component. Sandberg bluegrass may increase and become co-dominate with deep rooted bunchgrasses. Annual non-natives species are stable or increasing due to lack of competition with perennial bunchgrasses. This site is susceptible to further degradation from inappropriate grazing management, drought, and fire.
Pathway 2.1a Community 2.1 to 2.2
Fire reduces the shrub overstory and allows for perennial bunchgrasses to dominate the site. Fires are typically low severity resulting in a mosaic pattern due to low fuel loads. Annual non-native species are likely to increase after fire.
Context dependence. Low severity fire creates grass/sagebrush mosaic; high severity fire significantly reduces sagebrush cover and leads to early mid-seral community dominated by grasses and forbs; non-native annual species present.
Pathway 2.1b Community 2.1 to 2.3
Time and lack of disturbance allows for sagebrush to increase and become decadent. Chronic drought reduces fine fuels and leads to a reduced fire frequency, allowing low sagebrush to dominate the site. Inappropriate grazing management reduces the perennial bunchgrass understory; conversely Sandberg bluegrass may increase in the understory depending on grazing management.
Pathway 2.2a Community 2.2 to 2.1
Time and lack of disturbance and/or grazing management that favors the establishment and growth of sagebrush allows the shrub component to recover.
Context dependence. Recovery time of low sagebrush following fire is variable (Young 1983). After fire, if regeneration conditions are favorable, low sagebrush recovers in 2 to 5 years, however on harsh sites where cover is low to begin with and/or erosion occurs after fire, recovery may require more than 10 years (Young 1983). Slow regeneration may subsequently worsen erosion (Blaisdell 1982).
Pathway 2.3a Community 2.3 to 2.1
A low severity fire would decrease the overstory of sagebrush and allow for the understory perennial grasses to increase. Brush management with minimal soil disturbance; late fall winter grazing causing mechanical damage to sagebrush
Pathway 2.3b Community 2.3 to 2.2
High severity of fire significantly reduces sagebrush cover leading to early/mid-seral community.
Context dependence. Fires will decrease or eliminate the overstory of sagebrush and allows for perennial grasses to increase. Low sagebrush is killed by fire and does not sprout (Young 1983). Annual non-native species respond well to fire and may increase post-burn.
State 3 Annual State
Annual non-natives dominated site productivity and site resources. The dominance of non-natives controls the spatial and temporal distribution of soil moisture, soil nutrients, and energy resources. Remaining patches of sagebrush and/or perennial bunchgrass suffer from increase competition and narrowed fire returned intervals.
Characteristics and indicators. This state experiences frequent fire due to increased cover and continuity of fine fuels. Fire is frequent enough to prevent the recovery of long-lived native perennials like Lahontan sagebrush. Disturbance tolerant shrubs may be present or increasing depending on time since disturbance.
Cheatgrass, mustards, and bur buttercup dominate. Sandberg bluegrass and perennial forbs may be present in trace amounts. Erosion may be significant.
State 4 Sagebrush State
Sagebrush cover exceeds site concept and may be decadent, reflecting stand maturity and lack of seedling establishment due to competition with mature plants. The shrub overstory and Sandberg bluegrass understory dominate site resources such that soil water, nutrient capture, nutrient cycling and soil organic matter are temporally and spatially redistributed. Bare ground and soil redistribution may be increasing. Non-natives are stable to increasing.
Decadent sagebrush dominates the overstory. Rabbitbrush may be a significant component. Deep-rooted perennial bunchgrasses may be present in trace amounts or absent from the community. Sandberg bluegrass and annual non-native species increase. Bare ground is significant. Mule’s ear, balsamroot and other perennial forbs may make up a significant component of the understory. Some excessive pedestalling of grasses may be seen. Bare ground may be increasing.
Community 4.2 Community phase
Bluegrass dominates the site; annual non-native species may be present but are not dominant. Rabbitbrush may be sprouting. Mule’s ear, balsamroot and other perennial forbs may make up a significant component of the understory. Trace amounts of sagebrush may be present.
Pathway 4.1a Community 4.1 to 4.2
Removal of shrub canopy. Fire, brush management with minimal soil disturbance, and/or inappropriate sheep grazing.
Pathway 4.2a Community 4.2 to 4.1
Natural regeneration over time, lack of disturbance and presence of a sagebrush seed source. Completion of this community phase pathway is unlikely.
Context dependence. Natural regeneration over time, lack of disturbance and/or grazing management that favors the establishment and growth of sagebrush allows for the shrub component to recover. Establishment after fire is from seed, generally blown in and not from the seed bank (Bradley et al. 1992). Recovery time of low sagebrush following fire is variable (Young 1983). After fire, if regeneration conditions are favorable, low sagebrush recovers in 2 to 5 years, however on harsh sites where cover is low to begin with and/or erosion occurs after fire, recovery may require more than 10 years (Young 1983). Slow regeneration may subsequently worsen erosion (Blaisdell 1982).
State 5 Eroded State
An abiotic threshold has been crossed and state dynamics are driven by fire and time. This state is characterized by the dominance of non-native annuals and active soil redistribution and erosion. Ecological process including hydrology, energy capture and nutrient cycling are spatially and temporally truncated. Shorter fire return intervals, increase in invasive species and poor reproductive potential of remaining natives are feedbacks contributing to the stability of this site.
Characteristics and indicators. The invasion of sagebrush communities by cheatgrass (Bromus tectorum) has been linked to disturbances (fire, abusive grazing) that have resulted in fluctuations in resources (Chambers et al. 2007). The introduction of annual weedy species, like cheatgrass, may cause an increase in fire frequency and eventually lead to an annual state.
Sagebrush and Rabbitbrush dominate overstory. Sandberg bluegrass or annual species dominate understory. Soils are actively eroding with bare ground cover increasing and excessive frost-heaving/ pedestalling.
Community 5.2 Community 5.2
Soil erosion is significant with extreme gulling, rills, and waterflow paths.
Pathway 5.1a Community 5.1 to 5.2
Excessive grazing, vehicle usage, and other ground disturbing activity lead to increased bare ground and soil erosion.
Transition T1 State 1 to 2
Trigger: This transition is caused by the introduction of non-native annual plants, such as cheatgrass and mustards.
Slow variables: Over time the annual non-native species will increase within the community.
Threshold: Any amount of introduced non-native species causes an immediate decrease in the resilience of the site. Annual non-native species cannot be easily removed from the system and have the potential to significantly alter disturbance regimes from their historic range of variation.
Transition T3 State 2 to 3
Trigger: Repeated, widespread and sever fire. Slow Variables: Increase production and cover of non-native annual species over time. Threshold: Loss of deep-rooted perennials bunchgrasses and shrubs truncates, spatially and temporally, nutrient capture and cycling with the community.
Transition T4 State 2 to 4
Trigger: Prolonged drought coupled with inappropriate grazing grazing management will decrease or eliminate deep-rooted perennial bunchgrasses. Favoring growth and establishment of Sandberg bluegrass and shrubs. Soil disturbing treatments will reduce sagebrush and favor an increase in Sandberg bluegrass.
Slow variables: Long term decrease in deep-rooted perennial grass seed production, reproduction, and density allows for an increase in Sandberg bluegrass and favor shrub growth and establishment.
Threshold: Loss of deep-rooted perennial bunchgrasses changes nutrient cycling, nutrient redistribution, and reduces soil organic matter and infiltration.
Constraints to recovery. Fire or brush treatment may be coupled with inappropriate grazing management.
Restoration pathway R2 State 3 to 2
Seeding with native species followed by prescribe grazing. Minimize soil disturbance and maximize non-native annual plant biomass removal during early spring. Combine prescribe grazing with seeding of native species. Continue to protect site from wildfire. Probability for success extremely low.
Transition T7 State 3 to 5
Trigger: Inappropriate grazing, wildfire, prolonged droughts, and soil disturbing treatments. Controlling Variables: Excessive grazing will eliminate ground cover that holds soil. Soil disturbing treatment will create soil instability and could create compaction. Wind and precipitation will begin to create rills and gullies along unstable and compacted soils. Threshold: When the soil is disturbed, climatic influences such as precipitation and wind can begin forming gullies and rills.
Transition T5 State 4 to 3
trigger: Wildfire or shrub eliminating treatments. Controlling Treatments: Wildfire eliminates shrubs and perennial grasses, providing sufficient resources for annuals to dominate the landscape. Threshold: Decreasing shrubs and perennial annuals create opportunities of annuals to populate the landscape. With time, more annuals will be present causing frequent severe wildfires. These conditions will favor annual species due to availability of nutrients, soils, sunlight, and moisture.
Transition T6 State 4 to 5
Trigger: Inappropriate grazing management following fire, multiple fires, prolonged drought or any combination of these would increase soil erosion. Soil disturbing treatments such as a failed drill seeding could also increase erosion.
Slow variable: Bare ground interspaces large and connected; water flow paths long and continuous, understory is sparse.
Threshold: Soil redistribution and erosion is significant and linked to vegetation mortality evidenced by pedestalling and burying of herbaceous species and / or lack of recruitment in the interspaces.
Additional community tables
Table 6. Community 1.1 plant community composition
Livestock Interpretations:
This site has value for livestock grazing. Grazing management should be keyed to dominant grasses and palatable shrubs production. Domestic sheep and to a much lesser degree cattle consume low sagebrush, particularly during the spring, fall and winter. Thurber’s needlegrass species begin growth early in the year and remain green throughout a relatively long growing season. This pattern of development enables animals to use Thurber’s needlegrass when many other grasses are unavailable. Cattle prefer Thurber’s needlegrass in early spring before fruits have developed as it becomes less palatable when mature. Thurber’s needlegrasses are grazed in the fall only if the fruits are softened by rain. Bluebunch wheatgrass is considered one of the most important forage grass species on western rangelands for livestock. Although bluebunch wheatgrass can be a crucial source of forage, it is not necessarily the most highly preferred species. Sandberg bluegrass is a palatable species, but its production is closely tied to weather conditions. It produces little forage in drought years, making it a less dependable food source than other perennial bunchgrasses.
Stocking rates vary over time depending upon season of use, climate variations, site, and previous and current management goals. A safe starting stocking rate is an estimated stocking rate that is fine tuned by the client by adaptive management through the year and from year to year.
Wildlife Interpretations:
Low sagebrush is considered a valuable browse plant during the spring, fall and winter months. In some areas it is of little value in winter due to heavy snow. Mule deer utilize and sometimes prefer low sagebrush, particularly in winter and early spring. Thurber needlegrass is valuable forage for wildlife. Bluebunch wheatgrass is considered one of the most important forage grass species on western rangelands for wildlife. Bluebunch wheatgrass does not generally provide sufficient cover for ungulates, however, mule deer are frequently found in bluebunch-dominated grasslands. Sagebrush-grassland communities provide critical sage-grouse breeding and nesting habitats. Sagebrush is a crucial component of their diet year-round, and sage-grouse select sagebrush almost exclusively for cover.
Hydrological functions
Runoff is very high. Permeability is very slow to slow. Hydrologic soil group is D. Rills are none. Rock fragments armor the surface. Water flow patterns are none to rare. Pedestals are none to rare. Occurrence is usually limited to areas of water flow patterns. Frost heaving of shallow rooted plants should not be considered an indicator of soil erosion. Gullies are none. Perennial herbaceous plants (especially deep-rooted bunchgrasses) slow runoff and increase infiltration. Shrub canopy and associated litter break raindrop impact and provide opportunity for snow catch and accumulation on site.
Recreational uses
Aesthetic value is derived from the diverse floral and faunal composition and the colorful flowering of wild flowers and shrubs during the spring and early summer. This site offers rewarding opportunities to photographers and for nature study. This site is has potential for upland bird and big game hunting.
Other information
Low sagebrush (ARAR8) can be successfully transplanted or seeded in restoration. Black sagebrush (ARNO4) is an excellent species to establish on sites where management objectives include restoration or improvement of domestic sheep, pronghorn, or mule deer winter range.
Supporting information
Inventory data references
Old SS Manuscripts, Range Site Descriptions, etc.
Type locality
Location 1: Lander County, NV
Township/Range/Section
T21N R44E S1
Latitude
39° 43′ 11″
Longitude
116° 58′ 16″
General legal description
NE¼ About 16 miles north of Austin, west-facing slopes off Mount Callahan, Toiyabe Range, Lander County, Nevada. This site also occurs in Eureka, Humboldt and Pershing Counties, Nevada.
Other references
Bates, J. D., T. Svejcar, R. F. Miller, and R. A. Angell. 2006. The effects of precipitation timing on sagebrush steppe vegetation. Journal of Arid Environments 64: 670-697.
Beardall, L. E. and V. E. Sylvester. 1976. Spring burning for removal of sagebrush competition in Nevada. In: Tall Timbers Fire Ecology Conference and Proceedings. Tall Timbers Research Station. 14: 539-547.
Blaisdell, J. P., R. B. Murray, and E. D. McArthur. 1982. Managing intermountain rangelands - sagebrush-grass ranges. Gen. Tech.Rep. INT-134. U.S. Department of Agriculture, Forest Service, Intermountain Forest and Range Experiment Station, Ogden, UT. p. 41.
Bradley, A. F., N. V. Noste, and W. C. Fischer. 1992. Fire ecology of forests and woodlands in Utah. Gen. Tech. Rep. INT-287. U.S. Department of Agriculture, Forest Service, Intermountain Research Station. P. 128.
Chambers, J., B. Bradley, C. Brown, C. D’Antonio, M. Germino, J. Grace, S. Hardegree, R. Miller, and D. Pyke. 2013. Resilience to Stress and Disturbance, and Resistance to Bromus tectorum L. Invasion in Cold Desert Shrublands of Western North America. Ecosystems:1-16.
Comstock, J. P. and J. R. Ehleringer. 1992. Plant adaptation in the Great Basin and Colorado Plateau. Western North American Naturalist 52:195-215.
Conrad, C. E. and C. E. Poulton. 1966. Effect of a wildfire on Idaho fescue and bluebunch wheatgrass. Journal of Range Management:138-141.
Daubenmire, R. 1975. Plant succession on abandoned fields, and fire influences in a steppe area in southeastern Washington.
Dobrowolski J.P., Caldwell M.M., Richards J.H. (1990) Basin Hydrology and Plant Root Systems. In: Plant Biology of the Basin and Range. Ecological Studies (Analysis and Synthesis), vol 80. Springer, Berlin, Heidelberg. https://doi.org/10.1007/978-3-642-74799-1_7
Furniss, M. M. and W. F. Barr. 1975. Insects affecting important native shrubs of the northwestern United States. General Technical Report INT-19. Intermountain Forest and Range Experiment Station, U.S. Department of Agriculture, Forest Service. Ogden, UT. p. 68.
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Contributors
CP/GKB
Approval
Kendra Moseley, 3/07/2025
Rangeland health reference sheet
Interpreting Indicators of Rangeland Health is a qualitative assessment protocol used to
determine ecosystem condition based on benchmark characteristics described in the Reference Sheet. A suite of 17 (or
more) indicators are typically considered in an assessment. The ecological site(s) representative of an assessment
location must be known prior to applying the protocol and must be verified based on soils and climate. Current plant
community cannot be used to identify the ecological site.
Author(s)/participant(s)
Patti Novak-Echenique
Contact for lead author
State Rangeland Management Specialist
Date
02/05/2010
Approved by
Kendra Moseley
Approval date
Composition (Indicators 10 and 12) based on
Annual Production
Indicators
Number and extent of rills:
Rills are none. Rock fragments armor the surface.
Presence of water flow patterns:
Water flow patterns are none to rare. A few, short (< 1m) may occur on steeper slopes after summer convection storms or rapid snowmelt. These will be meandering and disconnected and will begin to heal during the first growing season.
Number and height of erosional pedestals or terracettes:
Pedestals are none to rare. Occurrence is usually limited to areas of water flow patterns. Frost heaving of shallow rooted plants should not be considered an indicator of soil erosion.
Bare ground from Ecological Site Description or other studies (rock, litter, lichen, moss, plant canopy are
not bare ground):
Bare Ground ± 5-10% depending on amount of surface rock fragments
Number of gullies and erosion associated with gullies:
None
Extent of wind scoured, blowouts and/or depositional areas:
None
Amount of litter movement (describe size and distance expected to travel):
Fine litter (foliage from grasses and annual & perennial forbs) expected to move distance of slope length during intense summer convection storms or rapid snowmelt events. Persistent litter (large woody material) will remain in place except during large rainfall events.
Soil surface (top few mm) resistance to erosion (stability values are averages - most sites will show a range
of values):
Soil stability values should be 3 to 6 on most soil textures found on this site. (To be field tested.)
Soil surface structure and SOM content (include type of structure and A-horizon color and thickness):
Surface structure is typically platy. Soil surface colors are browns and soils have a mollic epipedon. Organic matter of the surface 2 to 4 inches is typically 0.7 to 2.0 percent dropping off quickly below. Organic matter content can be more or less depending on micro-topography.
Effect of community phase composition (relative proportion of different functional groups) and spatial
distribution on infiltration and runoff:
Perennial herbaceous plants (especially deep-rooted bunchgrasses) slow runoff and increase infiltration. Shrub canopy and associated litter break raindrop impact and provide opportunity for snow catch and accumulation on site.
Presence and thickness of compaction layer (usually none; describe soil profile features which may be
mistaken for compaction on this site):
Compacted layers are none. Subangular blocky or platy structure or subsoil argillic horizons are not to be interpreted as compacted.
Functional/Structural Groups (list in order of descending dominance by above-ground annual-production or live foliar
cover using symbols: >>, >, = to indicate much greater than, greater than, and equal to):
Although fire is rare on this site, with an extended fire return interval, the shrub component will increase at the expense of the herbaceous component.
Amount of plant mortality and decadence (include which functional groups are expected to show mortality or
decadence):
Dead branches within individual shrubs common and standing dead shrub canopy material may be as much as 20% of total woody canopy; some of the mature bunchgrasses (<10%) have dead centers.
Average percent litter cover (%) and depth ( in):
Between plant interspaces (±20-30%) and litter depth is ±¼ inch.
Expected annual annual-production (this is TOTAL above-ground annual-production, not just forage annual-production):
For normal or average growing season (through June) ± 500 lbs/ac; Spring moisture significantly affects total production. Favorable years ± 700 lbs/ac and unfavorable years ± 300 lbs/ac.
Potential invasive (including noxious) species (native and non-native). List species which BOTH characterize
degraded states and have the potential to become a dominant or co-dominant species on the ecological site if
their future establishment and growth is not actively controlled by management interventions. Species that become
dominant for only one to several years (e.g., short-term response to drought or wildfire) are not invasive
plants. Note that unlike other indicators, we are describing what is NOT expected in the reference state for the
ecological site:
Potential invaders include cheatgrass, annual mustards, halogeton, Utah juniper, and singleleaf pinyon. After wildfire, cheatgrass and annual mustards are most likely to invade.
Perennial plant reproductive capability:
All functional groups should reproduce in average (or normal) and above average growing season years. Reduced growth and reproduction occur during extreme or extended drought periods.
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.
Click on box and path labels to scroll to the respective text.
