Physiographic features

This site occurs in alluvial bottomlands. Slopes vary from 1 to 15 percent and elevation ranges from 4700 to 6800 feet (1433-2072 meters).

Table 2. Representative physiographic features

Climatic features

MLRA 12 is dominated by dramatic changes in elevation which, in turn, influence local weather patterns. The intermontane valleys have elevations as low as 3800 feet, while the adjacent mountains may reach more than 12,600 feet. The average annual precipitation for the entire MLRA, based on 10 long term climate stations located throughout the MLRA, is approximately 9.38 inches. However, the dry valleys may have averages as low as 6 inches, while the upper peaks may have averages that exceed 46 inches per year.
Temperatures vary considerably over the year. The average annual temperature is 42.25 degrees F. The average low is 27.4 degrees while the average high temperature is 57 degrees.
In the summer the sun shines 78% of the time, but drops to 40% in the winter. The prevailing wind is location-dependent, and generally flows parallel to the orientation of the dominant valleys. In the summer localized afternoon upslope winds and evening downslope winds are common. The average windspeed is greatest in the spring and early summer.
The frost free period ranges from 102 to 107 days while the freeze free period ranges from 134 to 139 days across the MLRA.

Table 3. Representative climatic features

Influencing water features

This site is influenced by run on from adjacent sites.

Soil features

The soils of this site are mildly to moderately alkaline silt loams, loams and very gravelly and gravelly loams and fine sandy loams. They are very deep with poorly to somewhat excessively drainage. Some of the soils have a strongly contrasting textural stratification between 10 and 60 inches. Coarse fragments can exceed 35 percent by volume in the soil profile, especially in the subsoil. These are run-in areas and therefore are subject more to channel and gully erosion over sheet and rill erosion. The soils usually have a seasonal water table. Extensive channel or gully erosion may lower the water table and thus lower the productive potential of the soils. The available water capacity (AWC) is very low to moderate. Permeability ranges from slow to moderately rapid. These soils have a xeric soil moisture regime. The soil temperature regime ranges from frigid to cryic.

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. Large herbivore use of this ecological site is dominated by mule deer and to a lesser degree, pronghorn antelope. Important seasonal habitat is provided by the tall dense vegetation for resident and migratory animals including western toad, sagebrush lizard, western rattlesnake, shrews, bats, jackrabbits, ground squirrels, mice, coyote, red fox, badger, sage-grouse, Ferruginous hawk, prairie falcon, horned lark, and western meadowlark. Area sensitive species may include burrowing owl, pygmy rabbit, Great Basin ground squirrel, Idaho pocket gopher, and Merriam’s shrew. Changes in the plant community composition can reduce the number and diversity of wildlife species in the area. With reduced shrub cover, shrub-steppe obligate avian and mammal species become rare including sage-grouse, brewer’s sparrow, sage thrasher, sage sparrow, and pygmy rabbits. Encroachment of noxious and invasive plant species (cheatgrass and bulbous bluegrass) can replace native plant species which provide critical feed, brood-rearing, and nesting cover for a variety of native wildlife. Water is provided by seasonal runoff, artificial water catchments, adjacent streams, and spring sites.

State 1 Phase 1.1 - Basin Big Sagebrush/ Basin Wildrye/ Thickspike Wheatgrass Reference Plant Community (RPC): The RPC provides a diversity of grasses, forbs, and shrubs used by native insect communities that assist in the pollination process for the plant community. The reptile and amphibian community is represented by leopard lizard, short horned lizard, sagebrush lizard, western skink, western rattlesnake, western toad, and northern leopard frog. Amphibians are associated with springs, streams, and isolated water bodies adjacent to this plant community. Spring developments that capture all available water would preclude the use of these sites by amphibians. The plant community supports a variety of migratory and resident avian species that utilize the grasses, forbs, shrubs, and water for food, brood-rearing, and nesting cover. When streams are adjacent to this site, significant use of the tall and dense vegetation by waterfowl and shorebirds may occur. Shrub-steppe obligate bird species include the Brewer’s sparrow, sage sparrow, sage thrasher, and sage-grouse. Habitat (i.e. lek sites, brood-rearing, winter cover and food) for sage-grouse is provided by this diverse plant community. The plant community supports seasonal (late spring, summer, and winter) habitat needs for mule deer providing food, thermal cover, and young of year cover. Antelope may utilize the site for thermal and young of year cover. A diverse small mammal population including golden-mantled ground squirrels, chipmunks, jackrabbits, deer mice, Great Basin kangaroo rats, and pygmy rabbits would utilize the site.

State 1 Phase 1.2 - Thickspike Wheatgrass/ Western Wheatgrass/ Basin Wildrye/ Sandberg Bluegrass/ Bottlebrush Squirreltail Plant Community: This plant community is the result of fire. Large areas of Phase 1.2 would fragment the reference plant community and would reduce the quality of habitat for shrub-steppe obligate animal species. The plant community, dominated by herbaceous vegetation with little or no basin big sagebrush provides less vertical structure, limiting use by sagebrush obligate animals. An increase in tall green rabbitbrush would provide some replacement vertical structure and late summer and fall pollinator habitat. Insect diversity may be reduced but a native forb plant community similar to State 1 Phase 1.1 would still support select pollinators. Reptile use, including short horned lizard, sagebrush lizard, and western rattlesnakes, would be limited due to the absence of sagebrush. The dominance of herbaceous vegetation with little sagebrush canopy cover would prevent use of these areas for nesting by Brewer’s sparrow, sage sparrow, sage thrasher, and sage-grouse. This plant community provides brood-rearing habitat for sage grouse when sagebrush cover is nearby. The dominance of herbaceous vegetation improves habitat for grassland avian species (horned lark, savannah sparrow, vesper sparrow, and western meadowlark). Mule deer and antelope habitat including forage, thermal cover, and young of year cover would still be provided by an increase in basin wildrye. Small mammal diversity would be reduced and the site would not provide suitable habitat for pygmy rabbits.

State 1 Phase 1.3 - Basin Big Sagebrush/ Thickspike Wheatgrass/ Sandberg Bluegrass Plant Community: This plant community is the result of improper grazing management and a lack of fire. An increase in canopy cover of sagebrush contributes to a sparse herbaceous understory. The reduced herbaceous understory results in a reduced diversity of insects. You can expect a decrease in populations and diversity of reptiles due to the reduced diversity and canopy cover of herbaceous vegetation. Shrub-steppe obligate bird species include Brewer’s sparrow, sage sparrow, sage thrasher, and sage-grouse. Reduced herbaceous understory is a key factor in reducing the quality of habitat (food and cover) for avian species. Habitat (lek sites, brood-rearing, winter cover and food) for sage-grouse is limited due to the reduced diversity and canopy cover of herbaceous vegetation. The loss of basin wildrye reduces the quality of thermal cover and young of year cover for mule deer and antelope. The reduced understory will result in a shorter forage season for large mammals. A small mammal population including golden-mantled ground squirrels, chipmunks, jackrabbits, deer mice, Great Basin kangaroo rats, and pygmy rabbits would utilize this plant community.

State 1 Phase 1.4 - Basin Big Sagebrush/ Thickspike Wheatgrass/ Utah Juniper Plant Community: This plant community is the result of a lack of recent fire. An increase in canopy cover of sagebrush and juniper contributes to a sparse herbaceous understory. A reduced herbaceous understory results in lower diversity and numbers of insects. The reptile community will be similar to State 1 Phase 1.1 community represented by leopard lizard, short horned lizard, sagebrush lizard, western rattlesnake, and western skink. The reduced diversity of insects and understory cover may reduce the quality of food and cover for reptile populations. As juniper increases, habitat cover for Brewer’s sparrow, sage thrasher, and sage sparrow may increase. Remaining sagebrush provides brood-rearing, winter cover, and winter food for sage-grouse but as juniper encroaches the quality of this habitat is severely reduced or eliminated. The plant community supports limited forage habitat, during spring and fall for mule deer. As juniper encroachment occurs, the site will provide additional thermal cover for large mammals. A small mammal population including golden-mantled ground squirrels, jackrabbits, deer mice, and kangaroo rats may utilize this site.

State 2 – Annuals/ Cheatgrass/ Rabbitbrushes Plant Community: This state has developed due to fire and improper grazing management. Large areas of State 2 would fragment the reference plant community and would reduce the quality of habitat for shrub-steppe obligate animal species. This plant community would not support as diverse an insect community as in State 1 Phase 1.1 due to the loss of the native forb community. The rabbitbrushes would provide late summer and fall pollinator habitat. Food and cover for reptile species would be reduced due to the loss of the sagebrush community. As rabbitbrush establishes it would provide vertical structure for animals. The plant community would not support the habitat requirements for sage-grouse, sage thrasher, Brewer’s sparrow, or sage sparrow. Birds of prey including hawks and falcons may range throughout these areas looking for prey species. Mule deer may utilize the invasive herbaceous vegetation in the early part of the year and rabbitbrush in the winter when the plants would be more palatable. The rabbitbrush may provide limited young of year cover for mule deer and antelope. Pygmy rabbits would not utilize this site due to the loss of sagebrush.

State 3 – Utah Juniper/ Annuals Plant Community: This site has developed due to improper grazing management and the lack of fire. The loss of native forbs and understory vegetation will reduce insect diversity on the site. The lack of flowering plants limits use of the habitat by pollinators like butterflies and moths. Quality of habitat for reptilian species identified in State 1 Phase 1.1 is limited. This plant community does not support the habitat requirements for sage-grouse. Birds using this site as resident or migratory habitat include Juniper titmouse, western bluebird, and Virginia’s warbler. The Juniper titmouse relies heavily on juniper seeds for winter food. Hunting success by raptors may decrease due to the heavy overstory of juniper. The plant community supports limited seasonal habitat (food and cover) for mule deer in the spring and fall. As juniper encroachment occurs, the site will provide additional thermal cover for large mammals.

State 4 - Range Seeding Plant Community: The proposed seeding mixture (native or non-native) would determine the animal species that would utilize the area. A diverse seed mixture of grasses and forbs would provide similar habitat conditions as described in State 1 Phase 1.2. A diverse seed mixture of grasses, forbs, and shrubs would provide similar habitat conditions as described in State 1 phase 1.1 or 1.3. A monoculture of non-native grass species would not support diverse populations of insects, reptiles, birds, or mammals. Sagebrush obligate animal species would not be supported with a monoculture of grass species. Grassland animal species including western meadowlark, horned lark, savannah sparrow, deer mouse, kangaroo rat, mule deer, and antelope would utilize this site for nesting and/or seasonal foraging. Birds of prey including hawks and falcons may range throughout these areas looking for prey species. Large areas of State 4 with no brush cover would fragment the reference plant community and would reduce the quality of habitat for shrub-steppe obligate animal species.


Grazing Interpretations.
This site is suitable for livestock grazing in the late spring, summer, and fall and winter grazing at lower elevations. Water is often limited in the summer and fall. 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. Calculations used to determine estimated initial stocking rate will be based on forage preference ratings.

Recreational uses

This site offers limited recreational opportunities except for hunting. Occasional off-road vehicle use occurs.

Wood products

None.

Other products

None.

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, Range Management Specialist, IASCD
Brendan Brazee, State Rangeland Management Specialist, NRCS, Idaho
Lee Brooks, Range Management Specialist, IASCD
Kristen May, Resource Soil Scientist, NRCS, Idaho

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

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

DF

Approval

Kendra Moseley, 9/21/2020