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Draft. A draft ecological site description is either incomplete or has not undergone quality control and quality assurance review.
Classification relationships
Holland, R.F. 1986. Preliminary descriptions of the terrestrial natural communities of California. Unpublished report. State of California, The Resources Agency, Department of Fish and Game, Natural Heritage Division, Sacramento, CA. (Updated September 2003). Element Code: Big Sagebrush-Antelope Bitterbrush 35.110.07.
Sawyer, J.O. and T. Keeler-Wolf. 1995. A Manual of California Vegetation. California Native Plant Society, Sacramento, CA. Big Sagebrush Series.
Associated sites
R021XE205CA South Slope 16-30 P.Z.
R021XE209CA Ashy Claypan 16-30 P.Z.
R021XE210CA Mahogany Savanna
Similar sites
R021XE205CA South Slope 16-30 P.Z.
PSSPS-ACHNA dominant grasses.
R021XE204CA Eroded Slope 16-30 P.Z.
Less productive site; PSSPS-ACHNA dominant grasses.
R021XE224CA South Slope 30+ P.Z.
More productive site; PSSPS-ACHNA dominant grasses.
R021XE222CA Loamy Slope 30+ P.Z.
More productive site; PUTR2 minor shrub. BRMA4-ACHNA dominant grasses.
Table 1. Dominant plant species
Tree Not specified
Shrub (1) Artemisia tridentata ssp. vaseyana
(2) Purshia tridentataHerbaceous (1) Festuca idahoensis
(2) Pseudoroegneria spicata ssp. spicataPhysiographic features
This site occurs on mountain sideslopes. Slopes range from 4 to 50 percent, but slopes from 15 to 50 percent are most typical. Elevation ranges from 4400 to 6714 feet.
Table 2. Representative physiographic features
Landforms (1) Mountain slope
Elevation 4400 – 6714 ft Slope 4 – 50 % Aspect Aspect is not a significant factor Climatic features
The climate of this site is subhumid, characterized by cool, moist winters and warm, dry summers. The area's precipitation comes mostly from winter Pacific cyclonic storms, with a very slight summer monsoonal season that is erratic but can be locally significant. Most storms have strong winds from the southwest or west, which blow substantial amounts of snow off south and west facing slopes (particularly steep slopes or slopes with short vegetation), and increase snow accumulations on adjacent north and/or east facing slopes, and/or in nearby concave depressions. Average annual precipitation ranges from 16 to 30 inches with most occurring during the winter months. Approximately half the precipitation falls as snow; half as rain. The mean annual air temperature is 43 to 45 degrees F. The average growing season is about 60 to 80 days.
Table 3 Representative climatic features
Frost-free period (average) 80 days Freeze-free period (average) 0 days Precipitation total (average) 30 in BarLineFigure 1. Monthly precipitation range
BarLineFigure 2. Monthly average minimum and maximum temperature
">Influencing water features
There are no influencing water features associated with this site.
Soil features
The soils of this site are moderately deep and well drained. The soils formed in volcanic ash and colluvium over residuum derived from andesite or tuff. The soil surface is partly covered by 20 percent gravel, 5 percent cobbles and 5 percent stones. The soil profiles are modified with high amounts of rock fragments. There are also high amounts of vitric volcanic ash and glass throughout the soil profile which enhances the water holding capacity of these soils. These soils are usually moist in winter, spring, and early summer, and dry later in summer and fall. They have a xeric soil moisture regime and a frigid temperature regime. Soil series associated with this site includes Warnermount.
Table 4. Representative soil features
Parent material (1) Andesitic volcanic ash – andesite
Surface texture (1) Ashy loam
Family particle size (1) Loamy
Drainage class Well drained Permeability class Moderate Soil depth 20 – 40 in Surface fragment cover <=3" 15 – 20 % Surface fragment cover >3" 5 – 10 % Available water capacity
(0-40in)4.2 – 4.4 in Calcium carbonate equivalent
(0-40in)Not specified Electrical conductivity
(0-40in)Not specified Sodium adsorption ratio
(0-40in)Not specified Soil reaction (1:1 water)
(0-40in)6.1 – 7.3 Subsurface fragment volume <=3"
(Depth not specified)35 – 40 % Subsurface fragment volume >3"
(Depth not specified)25 – 30 % Ecological dynamics
Fire Ecology:
Prior to settlement in the mid to late 1800's, the primary disturbance in the sagebrush steppe was fire. Presettlement fire return intervals in mountain big sagebrush communities varied from 15 to 25 years. At this interval, the bunchgrass dominated community will be maintained. Following a fire, mountain big sagebrush will often reestablish within 10 to 15 years. Within 15 to 25 years, the brush community may return to preburn density and cover. When sagebrush canopy cover reaches about 15%, the perennial grasses and forbs start to decline.
Fire plays a major role in recycling organic matter in these communities. Without fire, nutrients are tied up in dead woody vegetation. Fire return intervals of 25 to 50 years will maintain a shrub-dominated site. Juniper commonly increases on this site when fire return intervals exceed 50 years.
Mountain big sagebrush communities are considered low risk for cheatgrass displacement due to lower winter temperatures and more moisture availability for perennial grasses to reestablish after fire. Although, fire on this site in fair to poor condition can result in cheatgrass-Douglas' rabbitbrush dominant communities.
Fire Effects:
First order effects are the immediate actions of fire and include plant mortality, consumption of organic material, creation of smoke and changes to the physical-chemical environment. Second order effects include the following:
1. Change in microclimate
2. Increase in range of soil temperatures
3. Change in soil nutrients and microbial activity
4. Regeneration of vegetation
5. Successsion and new vegetation patterns
6. Change in plant growth rates and competitive interactions
7. Altered wildlife habitat and activity of invertebrates and vertebrates
8. Changed water storage capacity and pattern of runoff.
Mountain big sagebrush is highly susceptible to injury from fire. Plants are readily killed in all seasons, even light severity fires. Mountain big sagebrush plants top-killed by fire will not resprout. Healthy sagebrush produces large amounts of seed during most years, but the seed is short-lived. Seed banks are small, and if present are largely destroyed by the fire. Sagebrush seed disperses only a few feet from mother plants.
Antelope bitterbrush is very susceptible to fire kill. It is considered a weak sprouter and is often killed by summer or fall fire. Antelope bitterbrush in some areas may sprout after a light-severity spring fire. Season of burning and environmental conditions impact antelope bitterbrush ability to survive fire and sprout. High fuel consumptions increase antelope bitterbrush mortality and therefore favors seedling establishment.
Perennial grasses generally produce small to moderate amounts of seed per plant during wet years, and little or no seed during dry years. Most of the seed does not survive for more than one year, thus seedbanks are small or absent. The initial response from grasses is largely from existing plants that survived the fire. Existing plants provide seed, which if the amount and timing of precipitation is adequate, can result in many new grass plants. Perennial grasses increase less rapidly than forbs, but quicker than sagebrush and most other shrubs than reestablish from seed.
Burning bluebunch wheatgrass may remove most of the aboveground biomass but does not usually result in plant mortality. Bluebunch wheatgrass is generally favored by burning. Burning stimulates flowering and seed production. However, season of burning affects mortality.
Idaho fescue grows in a dense, fine-leaved tuft. Fires tend to burn within the accumulated fine leaves at the base of the plant and may produce temperatures sufficient to kill some of the root crown. Mature Idaho fescue plants are commonly reported to be severely damaged by fire in all seasons.
Forbs often establish in mass after a fire due to abundant viable seeds that have a hard coat which allows for better survival during fires.
State and transition model
More interactive model formats are also available. View Interactive Models
Click on state and transition labels to scroll to the respective textEcosystem states
State 1 submodel, plant communities
State 1
Reference StateCommunity 1.1
Reference Plant CommunityThe reference plant community is characterized by an open canopy of soft-woody shrubs 0.5 to 2 meters tall and a dense understory of perennial grasses and forbs. During wetter years, the perennial forbs will remain green well into the summer and fall. The representative plant community is dominated by mountain big sagebrush, antelope bitterbrush, Idaho fescue and bluebunch wheatgrass. Potential vegetative composition is about 55% grasses, 20% forbs and 25% shrubs and trees. Approximate ground cover (basal and crown) ranges from 30 to 45 percent. Litter cover ranges from 25 to 30%.
Figure 3. 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 495 660 825 Shrub/Vine 207 276 345 Forb 180 240 300 Tree 18 24 30 Total 900 1200 1500 Table 6. Soil surface cover
Tree basal cover 0-0% Shrub/vine/liana basal cover 10-20% Grass/grasslike basal cover 10-20% Forb basal cover 10-10% Non-vascular plants 0-10% Biological crusts 0-10% Litter 30-30% Surface fragments >0.25" and <=3" 20-20% Surface fragments >3" 10-10% Bedrock 0% Water 0% Bare ground 20-30% Additional community tables
Table 7. Community 1.1 plant community composition
Group Common name Symbol Scientific name Annual production () Foliar cover (%) Grass/Grasslike1 Primary Perennial Grasses 444–660 Idaho fescue FEID Festuca idahoensis 240–360 – bluebunch wheatgrass PSSPS Pseudoroegneria spicata ssp. spicata 180–240 – Sandberg bluegrass POSE Poa secunda 24–60 – 2 Secondary Perennial Grasses 24–144 Thurber's needlegrass ACTH7 Achnatherum thurberianum 6–36 – mountain brome BRMA4 Bromus marginatus 6–36 – squirreltail ELEL5 Elymus elymoides 6–36 – prairie Junegrass KOMA Koeleria macrantha 6–36 – Forb3 Perennial Forbs 60–360 common yarrow ACMI2 Achillea millefolium 6–36 – sagebrush mariposa lily CAMAM9 Calochortus macrocarpus var. macrocarpus 6–36 – Indian paintbrush CASTI2 Castilleja 6–36 – tapertip hawksbeard CRAC2 Crepis acuminata 6–36 – prickly hawkweed HIHO Hieracium horridum 6–36 – Lewis flax LILE3 Linum lewisii 6–36 – lupine LUPIN Lupinus 6–36 – cold-desert phlox PHST11 Phlox stansburyi 6–36 – brightwhite PREX Prenanthella exigua 6–36 – woolly mule-ears WYMO Wyethia mollis 6–36 – 4 Annual Forbs 1–3 grand collomia COGR4 Collomia grandiflora 1–3 – Shrub/Vine5 Primary Shrubs 180–300 mountain big sagebrush ARTRV Artemisia tridentata ssp. vaseyana 120–180 – antelope bitterbrush PUTR2 Purshia tridentata 60–120 – 6 Secondary Shrubs 60–120 Utah serviceberry AMUT Amelanchier utahensis 12–24 – curl-leaf mountain mahogany CELE3 Cercocarpus ledifolius 12–24 – yellow rabbitbrush CHVI8 Chrysothamnus viscidiflorus 12–24 – roundleaf snowberry SYRO Symphoricarpos rotundifolius 12–24 – Tree7 Evergreen 12–36 western juniper JUOC Juniperus occidentalis 12–36 – Interpretations
Animal community
Livestock Interpretations:
This site is suitable for cattle and sheep grazing during the spring, summer and fall. Grazing should be keyed to needlegrasses and bluebunch wheatgrass. Mountain big sagebrush is eaten by domestic livestock but has long been consided to be of low palatability, and a competitor to more desirable species. Needlegrasses and bluebunch wheatgrass are both important forage species for all classes of grazing livestock. Where management results in abusive grazing use by livestock palatable perennial grass and forb species will decrease while shrub species increase. Excessive cattle use in late summer and fall will adversely affect bitterbrush production and seedling survival.
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:
This site provides habitat for many types of wildlife. Mountain big sagebrush is highly preferred and nutritious winter forage for mule deer and elk. Sagebrush/perennial grasslands provide critical breeding and nesting habitats for sage grouse. Sage grouse depend on sagebrush exclusively during the winter. Bluebunch wheatgrass and needlegrasses are also valuable forage species for many types of wildlife.
Hydrological functions
Runoff is high to very high. Perennial herbaceous plants, especially deep-rooted bunchgrasses, slow runoff and increase infiltration. Shrub canopy and associated litter lessen raindrop impact and provide an opportunity for snow catch and accumulation on the site. Water flow patterns are not common, but can be expected on steeper slopes. Rills and gullies are not expected on this site.
Recreational uses
Recreation uses include hiking, camping, birdwatching and hunting.
Other products
Native peoples used big sagebrush leaves and branches for medicinal teas, and the leaves as a fumigant. Bark was woven into mats, bags and clothing.
Other information
Mountain big sagebrush has potential for range restoration and soil stabilization.
Antelope bitterbrush is extensively used in land reclamation. Antelope bitterbrush enhances succession by retaining soil and depositing organic material, and, in some habitats and with some ecotypes, by fixing nitrogen.
Supporting information
Type locality
Location 1: Modoc County, CA Township/Range/Section T47N R16E S31 Latitude 41° 53′ 51″ Longitude 120° 10′ 15″ General legal description On the Modoc National Forest in the Warner Mountains, Modoc County, California. Other references
Brown, J. K. 2000. Ecological principles, shifting fire regimes and management considerations. In: Wildland fire in ecosystems: effects of fire on flora. Gen. Tech. Rep. RMRS-GTR-42-vol. 2. Ogden, UT: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station. 257 p.
Modoc Elk Working Group. 2000. The Greater Modoc Area-A Strategic Plan for Elk Management. Modoc County, CA
Fire Effects Information System [Online]. http://www.fs.fed.us/feis
Miles, S.R. and C.B. Goudey. 1997. Ecological Subregions of California Section and Subsection Descriptions. United States Department of Agriculture Forest Service, Pacific Southwest Region R5-EM-TP-005. Subsection M261Gf-Warner Mountains.
Wisdom, M.J., M.M. Rowland, and L.H. Suring (eds). 2005. Habitat threats in the sagebrush ecosystem: methods of regional assessment and applications in the Great Basin. Alliance Communications Group, Lawrence, KS.
Contributors
P.NOVAK-ECHENIQUE
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) P.Novak-Echenique Contact for lead author State Rangeland Management Specialist Date 02/08/2007 Approved by Approval date Composition (Indicators 10 and 12) based on Annual Production Indicators
-
Number and extent of rills:
None -
Presence of water flow patterns:
Water flow patterns are typically non-existent but can rarely occur on steep slopes in areas recently subjected to intense summer convection storms or rapid snowmelt. -
Number and height of erosional pedestals or terracettes:
Pedestals are non-existent. Frost heaving of shallow rooted plants should not be considered a "normal" condition. -
Bare ground from Ecological Site Description or other studies (rock, litter, lichen, moss, plant canopy are not bare ground):
Bare ground 20-30%. Surface rock fragments 30 to 40%; shrub canopy 10 to 15%. Litter 25-30%. -
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 and 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 catastrophic 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 moderate fine granular. Soil surface colors are dark and soils are typified by a mollic epipedon. Organic carbon of the surface 2 to 4 inches is typically 2 to 4 percent. 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 (Idaho fescue, bluebunch wheatgrass) 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 not typical. Subsoil argillic horizons are not be interpreted as compacted soil layers. -
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):
Dominant:
Deep-rooted, cool-season, perennial bunchgrasses >> tall shrubs (mountain big sagebrush & antelope bitterbrush) > deep rooted, cool-season perennial forbsSub-dominant:
fibrous, shallow-rooted, cool-season perennial and annual forbs > shallow-rooted cool-season, perennial grassesOther:
Additional:
-
Amount of plant mortality and decadence (include which functional groups are expected to show mortality or decadence):
Dead branches within individual shrubs not uncommon and standing dead shrub canopy material may be as much as 15% of total woody canopy, some of the mature bunchgrasses (<10%) have dead centers. -
Average percent litter cover (%) and depth ( in):
Between plant interspaces. -
Expected annual annual-production (this is TOTAL above-ground annual-production, not just forage annual-production):
For normal or average growing season (through July) ~ 1300 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:
Western juniper and yellow rabbitbrush are increasers on this site. Cheatgrass and non-native annual forbs are invaders on this site. -
Perennial plant reproductive capability:
All functional groups should reproduce in normal and above normal growing seasons.
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