Physiographic features

This site occurs on mountain sides on secondary ridges. Slopes are north and east facing. Slopes range from 30 to 60 percent. The elevation ranges from 5500 to 8200 feet (1620 to 2485 meters).

Table 2. Representative physiographic features

Climatic features

The Big and Little Wood River Foot slopes and Plains, proposed as MLRA 10X, has a mean elevation of 5310 feet above sea level, and varies from 3600 to 9235 feet. In general, average annual precipitation is greatest on the western side, with the southeast area being the driest. However, the northern fringe receives upwards of 41 inches of precipitation. Monthly precipitation is generally greatest at the end of the year, diminishes steadily until a
low in July and August, then increases rapidly in the autumn.
Monthly temperatures can vary considerably. Highs of up to 102° and lows down to -52° Fahrenheit have been recorded. The average annual temperature is 42.9°. The frost-free period ranges from 60 to 85 days. The freeze-free period is a bit longer: 80 to 105 days.
Both morning and afternoon average relative humidity values peak in the winter, and reach their low in July and august. The average number of sunny, cloud-free days is above average for the summer months, but below average for the period from November through February.

Table 3. Representative climatic features

Influencing water features

This site is not influenced by adjacent streams or run on.

Wetland description

This site is not influenced by adjacent wetlands.

Soil features

The soils are very gravelly silt loams to an unfractured bedrock at less than 20 inches deep or clay loams that are moderately deep. The clay soils have a restrictive clay layer at 4 to 10 inches. This layer can prevent water and root penetration. The underlying material is metasedimentary sandstone, limestone, or conglomerate. The water intake and internal movement is moderate to slow. Permeability is very slow with the available water holding capacity (AWC) very low to low. Erosion hazard is moderate to high depending on the surface texture when plant cover is lacking.

Table 4. Representative soil features

Animal community

Wildlife Interpretations.
Animal Community – Wildlife Interpretations

This rangeland ecological site provides diverse habitat for many native wildlife species. The plant community exhibits a diverse mixture of forbs throughout the growing season offering excellent habitat for invertebrates. Wildlife use these areas on a seasonal basis due to the high elevation, short growing season and temperature regimes. Mule deer and elk are the large herbivores using the site. The rangeland habitat provides seasonal habitat for resident and migratory animals including western toad, sagebrush lizard, shrews, bats, ground squirrels, mice, coyote, red fox, badger, sage-grouse, Ferruginous hawk, prairie falcon, horned lark and western meadowlark. Sagebrush obligate avian and mammal species including sage-grouse, Brewer’s sparrow, sage thrasher and pika utilize these sites on a limited basis due to the low vertical structure of sagebrush, high elevation and associated cold temperatures throughout much of the year. Sage-grouse an area sensitive species, may utilize the low sagebrush plant community as winter, breeding, nesting and brood-rearing habitat. Encroachment of noxious and invasive plant species (cheatgrass and medusahead) in isolated areas can replace native plant species which provide critical feed, brood-rearing and nesting cover for a variety of native wildlife. Water features are sparse provided by seasonal streams, artificial water catchments and springs.

State 1 Phase 1.1 – Low Sagebrush/ Idaho Fescue/ Bluebunch Wheatgrass Reference Plant Community (RPC): This plant community provides a diversity of grasses, forbs and shrubs, used by native insect communities that assist in pollination. An extensive array of forbs is represented throughout the growing season leading to a diverse insect community. Many avian and mammal species utilize this habitat based on the availability of invertebrate prey species. The reptile and amphibian community is represented by leopard lizard, short horned lizard, sagebrush lizard, western skink, western rattlesnake, western toad, boreal chorus frog and northern leopard frog. Amphibians are associated with springs and isolated water bodies adjacent to this plant community. Development of spring sites that collect all available water would exclude amphibian use on these sites. Native shrub-steppe obligate avian species utilizing the habitat include the Brewer’s sparrow, sage sparrow, sage thrasher and sage-grouse. Area sensitive species include sage-grouse which utilize the low sagebrush for winter habitat. Sage-grouse may utilize this plant community for brood-rearing, breeding and nesting habitat. The plant community provides limited seasonal forage needs for large mammals including mule deer, antelope, and elk. A diverse small mammal population including golden-mantled ground squirrels, chipmunks and yellow-bellied marmots utilize this community. Pikas may utilize the site if adjacent to rocky open areas. Habitat for the pygmy rabbit would be marginal due to the low height and density of available sagebrush.

State 1 Phase 1.2- Bluebunch Wheatgrass/ Sandberg Bluegrass/ Bottlebrush Squirreltail Plant Community: This plant community is the result of fire. The plant community, dominated by herbaceous vegetation with little or no sagebrush provides less vertical structure for animals. Insect diversity would be reduced but a diverse native forb plant community would still support select pollinators. The reptiles, short horned lizard and sagebrush lizard would be limited or excluded due to the loss of sagebrush. Amphibian habitat would be tied to permanent spring sites in the area. Development of spring sites that collect all available water would exclude amphibian use on these sites. The dominance of herbaceous vegetation with little sagebrush canopy would prevent use of these areas as nesting habitat by Brewer’s sparrow, sage sparrow, sage thrasher, and sage-grouse. This plant community provides limited brood-rearing habitat for sage-grouse when adjacent sagebrush cover is provided. Use as winter cover and winter food by sage-grouse is eliminated. The dominant herbaceous vegetation improves habitat for grassland avian species (horned lark and western meadowlark). Large mammal (mule deer, antelope, and elk) use would be seasonal and offer little thermal cover and young of year cover. Small mammal diversity would be reduced and the plant community would not provide suitable habitat for pygmy rabbit.

State 1 Phase 1.3 – Low Sagebrush/ Sandberg Bluegrass Plant Community:
This plant community is the result of improper grazing management and no fire. An increase in canopy cover of sagebrush contributes to a sparse herbaceous understory. Native insects assist in pollination but the reduced herbaceous understory results in less diversity and numbers of insects. The reduction of grasses and forbs in the plant community would reduce the available prey species and cover for the resident reptile species. Amphibian habitat would be tied to permanent spring sites in the area. Development of spring sites that collect all available water would exclude amphibian use on these sites. This plant community supports a less diverse variety of migratory and resident avian species with the reduced understory vegetation. Fewer prey species and less understory cover results in less food, brood rearing and nesting habitat. Key shrub-steppe avian obligates include Brewer’s sparrow, sage sparrow, sage thrasher and sage- grouse. Critical habitat (winter cover and winter food) for sage-grouse is available. The plant community supports a shorter duration of seasonal food habitat for mule deer, antelope, and elk. A small mammal population including golden-mantled ground squirrels, chipmunks and yellow-bellied marmots utilize these areas. Pikas may be present in areas with adjacent open rocky habitat.

State 2 - Sandberg Bluegrass / Cheatgrass / Medusahead Plant Community:
This plant community is the result of continued improper grazing management and/or frequent fire. The plant community does not support a diverse insect community. The reduced forb and shrub component in the plant community would support a very limited population of pollinators. Most reptilian species are not supported with food, water or cover. This plant community does not support the habitat requirements for sage-grouse, sage thrasher, Brewer’s sparrow or sage sparrow. Diversity of grassland avian species is reduced due to poor cover and available food. Birds of prey including hawks and falcons may range throughout these areas looking for prey species. Large mammals may utilize the herbaceous vegetation in the early part of the year when the invasive annuals (cheatgrass) are more palatable. At other times of the year large mammals would not regularly utilize these areas due to poor food and cover conditions. The diversity and populations of small mammals would be dominated by open grassland species like the Columbian ground squirrel.

State 3 - Low Sagebrush/ Sandberg Bluegrass / Cheatgrass / Medusahead Plant Community: This plant community is the result of improper grazing management and no fire. An increase in canopy cover of sagebrush comes at the expense of a sparse herbaceous understory dominated by invasive plant species. Native insect populations and diversity are severely reduced. The reptile population is reduced and represented by leopard lizard, short horned lizard and sagebrush lizard. The reduction of native grasses and forbs in the plant community would reduce the available prey species and cover for these resident reptile species. Key shrub-steppe avian obligates include Brewer’s sparrow, sage sparrow, sage thrasher and sage- grouse. Their use of these areas will be reduced. Critical habitat (winter cover and winter food) for sage grouse is available. The plant community supports a short duration seasonal food habitat for large mammals including mule deer, antelope, and elk. A small mammal population including golden-mantled ground squirrels, chipmunks and yellow-bellied marmots utilize these areas. Pikas may be present in areas with adjacent open rocky habitat


Grazing Interpretations.

This site is suited for grazing by livestock in spring, early summer, and fall. Early spring grazing should be avoided due to prolonged wetness in the soil.
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 C and D.

Recreational uses

Colorful spring and early summer blooming forbs provide excellent opportunities for photography and nature study. Hunting opportunities for pronghorn antelope and sage grouse exist.

Wood products

None

Other products

None

Other information

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, Rangeland Management Specialist, IASCD
Joe May, State Rangeland Management Specialist, NRCS, Idaho
Lee Brooks, Range Management Specialist, IASCD

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, Rangeland Management Specialist, IASCD
Brendan Brazee, State Rangeland Management Specialist, NRCS, Idaho
Lee Brooks, Range Management Specialist, IASCD

References

• . 2004. Restoring Western Ranges and Wildlands. General Technical Report RMRS-GTR-136 Vols 1-3. USDA Forest Service, Rocky Mountain Research Station.

Other references

Hironaka, M., M.A. Fosberg, A. H. Winward. 1983. Sagebrush- Grass Habitat Types of Southern Idaho. University of Idaho. Moscow, Idaho. Bulletin Number 35

USDA, NRCS.2001. The PLANTS Database, Version 3.1 (http://plants.usda.gov.). National Plant Data Center, Baton Rouge, LA 70874-4490 USA

USDA, Forest Service, Fire Effects Information Database. 2004. www.fs.fed.us/database/feis

USDI Bureau of Land Management, US Geological Survey; USDA Natural Resources Conservation Service, Agricultural Research Service; Interpreting Indicators of Rangeland Health. Technical Reference 1734-6; version 4-2005.

Contributors

Dave Franzen And Jacy Gibbs
DLF

Approval

Kirt Walstad, 12/13/2023