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Draft. A draft ecological site description is either incomplete or has not undergone quality control and quality assurance review.
MLRA notes
Major Land Resource Area (MLRA): 025X–Owyhee High Plateau
MLRA 25 lies within the Intermontane Plateaus physiographic province. The southern half is in the Great Basin Section of the Basin and Range Province. This part of the MLRA is characterized by isolated, uplifted fault-block mountain ranges separated by narrow, aggraded desert plains. This geologically older terrain has been dissected by numerous streams draining to the Humboldt River. The northern half of the area lies within the Columbia Plateaus geologic province. This part of the MLRA forms the southern boundary of the extensive Columbia Plateau basalt flows. Deep, narrow canyons drain to the Snake River which incise the broad volcanic plain. The Humboldt River, route of a major western pioneer trail, crosses the southern half of this area. Reaches of the Owyhee River in this area have been designated as National Wild and Scenic Rivers.
Ecological site concept
This ecological site meets the NESH 2014 requirements for PROVISIONAL. A provisional ecological site is established after ecological site concepts are developed and an initial state-and-transition model is drafted. Following quality control and quality assurance reviews of the ecological site concepts, an identification number and name for the provisional ecological site are entered into ESIS. A provisional ecological site may include literature reviews, land use history information, some soils data, legacy data, ocular estimates for canopy and/or species composition by weight, and even some line-point intercept information. A provisional ecological site does not meet the NESH 2014 standards for an Approved ESD, but does provide the conceptual framework of soil-site correlation for the development of the ESD.
Associated sites
R025XY003ID LOAMY 12-16
R025XY004ID SHALLOW STONY 12-16
R025XY006ID SOUTH SLOPE STONY 10-13
R025XY008ID NORTH SLOPE STONY 12-16
R025XY010ID CLAYPAN 12-16
R025XY011ID LOAMY 13-16
R025XY023ID NORTH SLOPE LOAMY 16-22
R025XY028ID LOAMY BOTTOM 12-16
Similar sites
R025XY035ID CHURNING CLAY 12-16
Table 1. Dominant plant species
Tree Not specified
Shrub (1) Artemisia cana
Herbaceous (1) Elymus trachycaulus
Physiographic features
This site occurs on active floodplain terraces and in basins and on basalt table lands. Slopes are nearly level to undulating and range from 0 to 4 percent on all aspects. Elevations range from 5000 to 6000 feet (1524-1829 meters). This site is seasonally ponded from November to May.
Table 2. Representative physiographic features
Landforms (1) Flood plain
(2) Terrace
Flooding duration Brief (2 to 7 days) to long (7 to 30 days) Flooding frequency Occasional to frequent Ponding duration Brief (2 to 7 days) to long (7 to 30 days) Ponding frequency Frequent Elevation 5000 – 6000 ft Slope 0 – 4 % Ponding depth 0 – 4 in Water table depth 18 – 60 in Aspect N, E, S Climatic features
In MLRA 25 summers are hot, especially at lower elevations, and winters are cold and snowy. Precipitation is usually lighter at lower elevations throughout the year. At higher elevations precipitation is much greater, and snow accumulates to a considerable depth. The average total precipitation is 14.39 inches (based on 6 long term climate stations located throughout the MLRA).
The mean annual temperature is 45.9 degrees F. The average high is 59.7 and the average low temperature is 32.1 degrees. The prevailing wind is from the west. Average wind speed is greatest, at about 10 miles per hour, in March.
The frost-free period ranges from 79 to 103 days and the freeze free period ranges from 114 to 140 days.
Table 3 Representative climatic features
Frost-free period (average) 100 days Freeze-free period (average) 140 days Precipitation total (average) 20 in BarLineFigure 1. Monthly precipitation range
BarLineFigure 2. Monthly average minimum and maximum temperature
">Influencing water features
This site is influenced by ponding and run on.
Soil features
The soils supporting this site are very deep but have a restrictive layer that makes the effective rooting depth shallow to moderately deep. The soils are somewhat poorly or well drained with slow permeability. Runoff is medium to high because of the position on the landscape. The erosion hazard is slight by water, and moderate by wind. The available water holding capacity (AWC) is low to moderate. These soils are usually >60 inches deep but have a restrictive layer at 18 to 40 inches. The surface texture is generally silt loam with no surface stones. The subsoil is usually moderately well to well developed with clay ranging from approximately 15 to 45 percent. These soils are characterized by a xeric soil moisture regime, a seasonal water table at about 3 feet, and shallow restrictive layers. Soil temperature regime is frigid.
Table 4. Representative soil features
Surface texture (1) Silt loam
(2) Silty clay loam
Drainage class Somewhat poorly drained to well drained Permeability class Slow Soil depth 18 – 40 in Surface fragment cover <=3" 0 – 6 % Surface fragment cover >3" 0 – 3 % Available water capacity
(0-40in)4.7 – 7.8 in Calcium carbonate equivalent
(0-40in)0 – 5 % Sodium adsorption ratio
(0-40in)0 – 12 Soil reaction (1:1 water)
(0-40in)6.1 – 7.3 Subsurface fragment volume <=3"
(Depth not specified)0 – 14 % Subsurface fragment volume >3"
(Depth not specified)0 – 55 % Ecological dynamics
The dominant visual aspect is silver sagebrush with slender wheatgrass and Nevada bluegrass co-dominant in the understory. Composition by weight of the potential plant community is about 40 percent grasses, 15 percent forbs and 45 percent shrubs.
During the last few thousand years, this site has evolved in an arid climate characterized by dry summers and cold, wet winters. This site has also evolved with seasonal ponding in the winter and into the spring. Herbivory has historically occurred on this site at low levels of utilization. Herbivores include pronghorn antelope and mule deer.
Fire has historically occurred on the site at intervals of 50-70 years. Fire frequency is usually associated with wildfires from adjacent ecological sites. Usually, this site occurs in association with mountain and basin big sagebrush sites.
The Historic Climax Plant Community (HCPC), the Reference State (State 1), moves through many phases depending on the natural and man-made forces that impact the community over time. State 1, described later, indicates some of these phases. The Reference Plant Community Phase is Phase 1.1. This plant community is dominated by silver sagebrush in the overstory with slender wheatgrass, Nevada bluegrass and sedges in the understory. There is a wide variety of forbs. The plant species composition of Phase 1.1 is listed later under “Reference Plant Community Phase Plant Species Composition”.
Total annual production is 850 pounds per acre (950 kilograms per hectare) in a normal year. Production in a favorable year is 1100 pounds per acre (1232 kilograms per hectare). Production in an unfavorable year is 600 pounds per acre (720 kilograms per hectare). Structurally, cool season deep rooted perennial bunchgrasses and shrubs are equal followed by perennial forbs.
FUNCTION:
This site is suited for livestock in summer and fall. Wet spring soils can limit livestock grazing. It is used by big game in late spring, summer, and fall. Waterfowl use the site when the site is ponded.
This site has limited value for recreation.
Due to the number of rhizomatous plant species on the site, including silver sagebrush, this site is not easily degraded by fire or grazing.
Ponded water on the site provides good infiltration of the precipitation and run-on. Infiltration can be good with a mixed stand of shrubs and perennial grasses. Runoff and erosion hazard is slight.
Impacts on the Plant Community.
Influence of fire:
In the absence of normal fire frequency, shrubs can gradually increase. Grasses and forbs decrease as shrubs increase. With the continued absence of fire, silver sagebrush can displace many of the primary understory species.
When fires become more frequent than historic levels (50-70 years), silver sagebrush will usually maintain itself in the plant community although very frequent fires will keep the overall vigor low. Slender wheatgrass, sedges, bottlebrush squirreltail and basin wildrye will usually persist in the plant community and may increase. With very frequent fires, foxtail barley may invade the site and become dominant.
Influence of improper grazing management.
Season-long grazing and/or excessive utilization can be detrimental to this site. This type of management leads to reduced vigor of slender wheatgrass, sedges, bluegrasses and basin wildrye. With reduced vigor, recruitment of these species declines. As these species decline, the plant community becomes susceptible to an increase in silver sagebrush and an invasion of annuals and invasive species.
Continued improper grazing management influences fire frequency by increasing fine fuels. If foxtail barley and other annuals increase due to improper grazing management, fires become more frequent.
The site can also be damaged by hoof trampling from grazing on wet soils in the spring. Trampling can cause mortality of understory species and increase sprouting of silver sagebrush.
Proper grazing management that addresses frequency, duration and intensity of grazing can maintain the integrity of the plant community.
Weather influences:
General fluctuations of precipitation normally do not affect the production or composition of the plant community because the site is dependent on run-on water which creates ponding on the site.
Below normal temperatures in the spring can have an adverse impact on total production, regardless of the precipitation. An early, hard freeze can occasionally kill some plants. This site evolved with cold air drainage temperatures due to the topographic position.
Prolonged drought adversely affects this plant community in several ways. Prolonged drought reduces run-on from adjacent sites thus reducing ponding. Vigor, recruitment and production are usually reduced. Mortality can occur. Prolonged drought can lead to reduction in fire frequency.
Influence of Insects and disease:
Outbreaks can affect vegetation health. An outbreak of a particular insect is usually influenced by weather. There is no specific data for this site.
Influence of noxious and invasive plants:
Many of these species add to the fine-fuel component and lead to increased fire frequency. Invasive annual species compete with desirable plants for moisture and nutrients. The result is reduced production and change in composition of the understory.
Influence of wildlife:
Big game, primarily pronghorn antelope, use this site in the spring, summer and fall. Their numbers are seldom high enough to adversely affect the plant community.
Watershed:
This site is dependent on run-on water from adjacent sites. If associated sites degrade, run-on may increase on this site. Increased ponding of water may increase duration of ponding leading to mortality of many species including silver sagebrush. Increased run-on may also deposit more sediments onto the site and bury some species. Prolonged reduced run-on could reduce the stand of silver sagebrush and cause some mortality to associated species.
Plant Community and Sequence:
Transition pathways between common vegetation states and phases:
State 1.
Phase 1.1 to 1.2. Develops in the absence of fire and improper grazing management.
Phase 1.1 to 1.3. Develops with fire.
Phase 1.2 to 1.1. Develops with prescribed grazing and no fire.
Phase 1.3 to 1.1. Develops with prescribed grazing and no fire.
State 1 to unknown site. Increased run-on has cut a channel through the site, ponding has been reduced significantly and the water table has been lowered. Significant soil loss has occurred. Excessive soil loss and changes in the hydrologic cycle has caused State 1 to retrogress to a new site with reduced potential. It has crossed the threshold. It is economically impractical to move this site back towards the HCPC with accelerated practices.
Practice Limitations:
There are few limitations for accelerating or facilitating practices except for wet soils in the winter and spring.State and transition model
Custom diagramStandard diagram
Figure 3. 25x-32
More interactive model formats are also available. View Interactive Models
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 2 submodel, plant communities
State 1
Reference StateCommunity 1.1
Reference Plant CommunityThis plant community has silver sagebrush in the overstory with slender wheatgrass, bluegrasses, sedges and bottlebrush squirreltail in the understory. Some basin wildrye may be present. A wide variety of forbs occur but in small amounts. Natural fire frequency is 50-70 years and is mostly related to wildfires that burn onto the site from adjacent sites.
Figure 4. 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)Shrub/Vine 270 380 500 Grass/Grasslike 240 340 440 Forb 90 130 160 Total 600 850 1100 Figure 5. Plant community growth curve (percent production by month). ID0918 , ARCA13. State 1.
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec J F M A M J J A S O N D 0 0 0 10 30 30 15 10 0 5 0 0 Community 1.2
Silver Sagebrush with Reduced Vigor BunchgrassesThis plant community is dominated by silver sagebrush in the overstory. There are reduced amounts of sedges, bluegrasses and basin wildrye and these species may be in reduced vigor. Slender wheatgrass, meadow barley, and bottlebrush squirreltail may have increased. This state has developed due to improper grazing management and lack of fire.
Figure 6. Plant community growth curve (percent production by month). ID0918 , ARCA13. State 1.
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec J F M A M J J A S O N D 0 0 0 10 30 30 15 10 0 5 0 0 Community 1.3
Grass DominatedThis plant community is dominated by slender wheatgrass, sedges and bluegrasses. Basin wildrye is still present. Bottlebrush squirreltail and meadow barley may have increased. There is still a wide variety of forbs present and in small amounts. Foxtail barley may have invaded the site. There is large amount of re-sprouting silver sagebrush with low stature. This plant community will rapidly return to Phase 1.1. This plant community is the result of a recent wildfire.
Figure 7. Plant community growth curve (percent production by month). ID0918 , ARCA13. State 1.
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec J F M A M J J A S O N D 0 0 0 10 30 30 15 10 0 5 0 0 State 2
Unknown new siteCommunity 2.1
Unknown new siteIncreased run-on has cut a channel through the site, ponding has been reduced significantly and the water table has been lowered. Significant soil loss has occurred. Excessive soil loss and changes in the hydrologic cycle has caused State 1 to retrogress to a new site with reduced potential. This site could be dominated with annuals and invasive species. Some rabbitbrush, greasewood or remnants of silver sagebrush can be present. This site has crossed the threshold. It is uneconomical to return it to Sate 1 with accelerated practices.
Additional community tables
Table 6. Community 1.1 plant community composition
Group Common name Symbol Scientific name Annual production () Foliar cover (%) Grass/Grasslike1 Grass/Grasslike 240–440 slender wheatgrass ELTR7 Elymus trachycaulus 90–165 – sedge CAREX Carex 45–80 – meadow barley HOBR2 Hordeum brachyantherum 25–45 – basin wildrye LECI4 Leymus cinereus 25–45 – squirreltail ELEL5 Elymus elymoides 15–30 – mat muhly MURI Muhlenbergia richardsonis 0–5 – Forb2 Forb 90–160 lupine LUPIN Lupinus 25–45 – ragwort SENEC Senecio 15–30 – cinquefoil POTEN Potentilla 10–15 – common yarrow ACMI2 Achillea millefolium 10–15 – pale agoseris AGGL Agoseris glauca 10–15 – textile onion ALTE Allium textile 1–10 – owl's-clover ORTHO Orthocarpus 1–10 – longleaf phlox PHLO2 Phlox longifolia 1–10 – tall annual willowherb EPBR3 Epilobium brachycarpum 1–10 – fernleaf biscuitroot LODI Lomatium dissectum 1–10 – aster ASTER Aster 0–5 – Shrub/Vine3 Shrubs 270–500 silver sagebrush ARCA13 Artemisia cana 200–385 – rubber rabbitbrush ERNA10 Ericameria nauseosa 25–45 – yellow rabbitbrush CHVI8 Chrysothamnus viscidiflorus 1–15 – greasewood SAVE4 Sarcobatus vermiculatus 0–10 – Table 7. Community 1.2 plant community composition
Group Common name Symbol Scientific name Annual production () Foliar cover (%) Table 8. Community 1.3 plant community composition
Group Common name Symbol Scientific name Annual production () Foliar cover (%) Table 9. Community 2.1 plant community composition
Group Common name Symbol Scientific name Annual production () Foliar cover (%) Interpretations
Animal community
Animal Community – Wildlife Interpretations
The ecological site provides diverse habitat value for wetland and upland wildlife species. The seasonal hydrology results in abundant forage attracting invertebrate and vertebrate animals to this ecological site. Habitat is provided for resident and migratory animals including western toad, western rattlesnake, shrews, jackrabbits, ground squirrels, mice, coyote, red fox, badger, sage-grouse, Ferruginous hawk, prairie falcon, grasshopper sparrow, waterfowl and shorbirds. Large herbivore use of the ecological site includes mule deer and pronghorn antelope. Native reptile and amphibians are reliant on these sites on a seasonal basis during the year. Species of concern that may frequent the site includes common sagebrush lizard and greater sage-grouse. Loss of site hydrology significantly reduces habitat value of this site and also adjacent ecological sites. Open water is seasonal, only being provided by seasonal runoff, ponding, flooding, seasonal high water table and natural springs.
State 1 Phase 1.1 – Silver Sagebrush/ Slender Wheatgrass/ Nevada Bluegrass Reference Plant Community (RPC): The RPC provides a diversity of grasses, forbs and shrubs used by native insect communities who assist in pollination of the plant community. The insects are food for the many predator species utilizing the site. The reptile and amphibian community is represented by common sagebrush lizard, western rattlesnake, western toad and northern leopard frog. Ponding occurs in late fall through early spring. The length of time ponding occurs on the site determines the amount of habitat provided for amphibians. Loss of hydrology will limit or exclude amphibians from this ecological site. Sage-grouse may utilize the site as brood-rearing, nesting and winter habitat. Year-round forage for pronghorn antelope and mule deer is available. Silver sagebrush is desirable forage for mule deer and pronghorn. Limited thermal cover and young of year cover for large herbivores is provided by woody vegetation and basin wildrye. A small mammal population including deer mouse, meadow vole and yellow-bellied marmots may utilize the habitat on a seasonal basis.
State 1 Phase 1.2 - Silver Sagebrush/ Slender Wheatgrass/ Meadow Barley/ Bottlebrush Squirreltail Plant Community: This phase has developed due to improper grazing management and lack of fire. Insect diversity would be similar to State 1 Phase 1.1 insect community. The increase in sagebrush reduces understory vegetation and cover for ground nesting animals. Quality of nesting and brood-rearing habitat for sage-grouse is reduced due to a reduction in vigor and production of understory vegetation. Silver sagebrush is desirable forage for large herbivores. Continued improper grazing management of the herbaceous vegetation would reduce the summer and fall grazing season for mule deer and pronghorn. Small mammal populations and diversity would be similar to State 1 Phase 1.1 small mammal community.
State 1 Phase 1.3 –Slender Wheatgrass/ Sedges/ Bluegrasses/ Meadow Barley Plant Community: This state developed due to a recent wildfire. Pollinators would be supported by an increase in forbs. The loss of sagebrush has reduced the vertical habitat available to animals. Reptile and amphibian community would be similar to Sate 1 Phase 1.1 community. Habitat quality for grassland bird species may increase if grazing of the plant community is managed properly. If the plant community is not managed properly nesting for grassland bird species would be minimal. The open landscape, when ponded, may provide additional nesting, feeding and brood-rearing habitat for waterfowl and shorebirds. Mallards, teal, long-billed curlew and sandhill crane may visit the site during the growing season. Birds of prey (northern harrier and Ferruginous hawk) may range throughout these areas looking for prey species. Mule deer and pronghorn will utilize the herbaceous vegetation in spring and fall although grazing season will be shortened due to improper management. Small mammal populations and diversity would be reduced due to reduced vertical structure and increased vulnerability from predators. Large tracts of this State and Phase would fragment the historic plant community and reduce quality of habitat for sage-steppe obligate animal species.
Grazing Interpretations.
This site is suited for livestock grazing in the late spring, summer and fall. Avoid livestock use in the spring when the soils are wet, as trampling damage can occur.
Estimated initial stocking rate will be determined with the landowner or decision-maker. They will be based on the inventory which includes species, composition, similarity index, production, past use history, season of use and seasonal preference.
Hydrological functions
The soils in this site are in hydrologic group D.
Recreational uses
This site offers good opportunities for wildlife photography and some value for game bird and varmit hunting.
Wood products
None
Other products
None
Other information
Field Offices
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Supporting information
Inventory data references
Information presented here has been derived from NRCS clipping and other inventory data. Also, field knowledge of range-trained personnel was used. Those involved in developing this site description include: Dave Franzen, co-owner, Intermountain Rangeland Consultants, LLC Jacy Gibbs, co-owner, Intermountain Rangeland Consultants, LLC Jim Cornwell, State Rangeland Management Specialist, NRCS, Idaho Joe May, State Rangeland Management Specialist, NRCS, Idaho Leah Juarros, Resource Soil Scientist, NRCS, Idaho Lee Brooks, Assistant State Conservationist, NRCS, Idaho (Retired)
Type locality
Location 1: Owyhee County, ID Township/Range/Section T15S R2E S13 Contributors
Dave Franzen And Jacy Gibbs
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) Contact for lead author USDA, Natural Resources Conservation Service Idaho State Office 9173 W. Barnes Drive, Suite C Boise, ID 83709 (208) 378-5722 Date 06/11/2007 Approved by Approval date Composition (Indicators 10 and 12) based on Annual Production Indicators
-
Number and extent of rills:
Rarely occur on this site. -
Presence of water flow patterns:
Rarely occur on this site. Water is ponded seasonally on the site in the winter and early spring. -
Number and height of erosional pedestals or terracettes:
These rare on this site. -
Bare ground from Ecological Site Description or other studies (rock, litter, lichen, moss, plant canopy are not bare ground):
On sites in mid-seral status, bare ground may range from 10-20 percent. -
Number of gullies and erosion associated with gullies:
None. -
Extent of wind scoured, blowouts and/or depositional areas:
Not present. Immediately following wildfire, some soil movement may occur on lighter textured soils. -
Amount of litter movement (describe size and distance expected to travel):
Fine litter in the interspaces may move up to 2 feet following the drying or movement of ponded water. Coarse litter generally moves very little during ponding. -
Soil surface (top few mm) resistance to erosion (stability values are averages - most sites will show a range of values):
Values should range from 4-6. -
Soil surface structure and SOM content (include type of structure and A-horizon color and thickness):
The A or A1 horizon is typically 2 to 7 inches thick. Structure ranges from weak thick platy to weak very fine granular. Soil organic matter (SOM) ranges from 1 to 4 percent. -
Effect of community phase composition (relative proportion of different functional groups) and spatial distribution on infiltration and runoff:
This is good even with somewhat-poorly drained to poorly drained soils due to the ponding of water. Shrubs can catch snow in the interspaces. -
Presence and thickness of compaction layer (usually none; describe soil profile features which may be mistaken for compaction on this site):
Not present, but can easily form with continued livestock grazing when the soils are wet. -
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:
Cool season deep-rooted perennial bunchgrasses = shrubsSub-dominant:
Perennial forbsOther:
Additional:
-
Amount of plant mortality and decadence (include which functional groups are expected to show mortality or decadence):
Slver sagebrush usually does not become decadent. Grass and forb mortality will occur as shrubs increase. -
Average percent litter cover (%) and depth ( in):
Additional litter cover data is needed but is expected to be 40-60 percent to a depth of 0.2 inches. -
Expected annual annual-production (this is TOTAL above-ground annual-production, not just forage annual-production):
850 pounds per acre (950 kilograms per hectare)in a year with normal temperatures and precipitation. Perennial grasses produce 40 percent of the total production, forbs 10-20 percent and shrubs 45 percent. -
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:
Includes cheatgrass, annual mustards, povertyweed, Brewer’s navarretia, foxtail barley. -
Perennial plant reproductive capability:
All functional groups have the potential to reproduce in most years.
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