Physiographic features

The Sandy 17-20” PZ ecological site is on nearly level to steeply sloping hillslopes, terraces, and alluvial fans.

Table 2. Representative physiographic features

Climatic features

MLRA 64 has a continental climate consisting of cold winters and hot summers, low humidity, light rainfall, and ample sunshine. Extremes in temperature are common in some years. The climate results from MLRA 64 being near the geographic center of North America. There are few natural barriers on the Northern Great Plains. Air masses move freely across the plains and account for rapid changes in temperature.

Average annual precipitation ranges from 17 to 20 inches. The normal average annual temperature is about 47 °F. January is the coldest month with average temperatures ranging from about 21 °F (Wood, SD) to about 25 °F (Hemingford, NE). July is the warmest month with average temperatures ranging from about 72 °F (Hemingford, NE) to about 76 °F (Wood, SD). The range of normal average monthly temperatures between the coldest and warmest months is about 55 °F. This large annual range attests to the continental nature of the climate of this area. Wind speeds are estimated to average about 11 miles per hour annually, ranging from about 13 miles per hour during the spring to about 10 miles per hour during the summer. Daytime winds are generally stronger than nighttime winds. Occasionally, strong storms bring brief periods of high winds with gusts to more than 50 miles per hour.

Growth of cool-season plants begins in early to mid-March, slowing or ceasing in late June. Warm-season plants begin growth about mid-May and continue to early or mid-September. Cool-season plants may green-up in September and October if adequate soil moisture is present.

Table 3. Representative climatic features

Climate stations used

• (1) CRAWFORD [USC00251973], Crawford, NE

• (2) CHADRON 3NE [USC00251578], Chadron, NE

• (3) HAY SPRINGS [USC00253710], Hay Springs, NE

• (4) PINE RIDGE AP [USW00094039], Pine Ridge, SD

• (5) PORCUPINE 11 N [USC00396736], Kyle, SD

• (6) MARTIN 5 E [USC00395285], Martin, SD

• (7) LONGVALLEY [USC00394983], Long Valley, SD

• (8) INTERIOR 3 NE [USC00394184], Interior, SD

• (9) GORDON 6N [USC00253355], Gordon, NE

• (10) CEDAR BUTTE 1NE [USC00391539], White River, SD

Influencing water features

No riparian or wetland features are directly associated with the Sandy 17-20” PZ ecological site.

Wetland description

Not Applicable.

Soil features

The soils in this site commonly have a surface layer of loamy very fine sand to very fine sandy loam 3 to 30 inches thick. Slopes range from 0 to 30 percent. The soils are well drained or somewhat excessively drained. They formed in eolian deposits, alluvium, colluvium, or residuum. The subsurface layer generally ranges from loam to fine sand. This site typically has slight to no evidence of rills, wind-scoured areas, or pedestalled plants. Waterflow paths are broken, irregular in appearance, or discontinuous and obstructed by numerous debris dams or vegetative barriers. The surface of the soil is stable and intact. Subsurface soil layers are not restrictive to water movement and root penetration.
Major Soils Correlated to the Sandy 17-20” PZ Ecological Site: Anselmo, Bayard, Busher, Jayem, Manter, Ponderosa, Sarben, and Tuthill

In MLRA 64, some sandy soils in the 17 to 20 inch precipitation zone have the potential to support conifer (forest-like) plant communities. The Ponderosa soil is on the Pine Ridge escarpment in Nebraska. Other sandy soils that are in the MLRA, adjacent to the Shallow (R064XY040NE) ecological site, and support ponderosa pine may also develop forest-like plant communities.

The soils of this ecological site are susceptible to wind and water erosion. The hazard of water erosion increases on slopes greater than about 15 percent. Loss of 50 percent or more of the surface layer can result in a shift in species composition and production.
More information regarding the soil is available in soil survey reports. Contact the local USDA Service Center or use the Web Soil Survey online for details specific to your area of interest.

Table 4. Representative soil features

Animal community

Wildlife Interpretations:
MLRA 64 is in the drier areas of a northern mixed-grass prairie ecosystem in which sagebrush steppes to the west yield to grassland steppes to the east. Prior to European settlement, this MLRA consisted of diverse grassland and shrubland habitats interspersed with varying densities of depressional, instream wetlands and woody riparian corridors. These habitats provided critical life cycle components for many users. Many species of grassland birds, small mammals, reptiles, and amphibians and herds of roaming bison, elk, and pronghorn were among the inhabitants adapted to this semi-arid region. Roaming herbivores, as well as several species of small mammals and insects, were the primary consumers linking the grassland resources to large predators, such as the wolf, mountain lion, and grizzly bear, and to smaller carnivores, such as the coyote, bobcat, fox, and raptors. The prairie dog was once abundant and remains a keystone species within its range. The black-footed ferret, burrowing owl, ferruginous hawk, mountain plover, and swift fox are associated with prairie dog complexes.

Historically, the northern mixed-grass prairie was a disturbance-driven ecosystem in which fire, herbivory, and climate functioned as the primary disturbance factors, either singly or in combination. Following European settlement, livestock grazing, cropland conversion, elimination of fire, energy development, and other anthropogenic factors influenced species composition and abundance. Introduced and invasive species further affected plant and animal communities. The bison was a historical keystone species but has been extirpated in this area as a free-ranging herbivore. The loss of the bison and the reduction of prairie dog populations and fire as ecological drivers greatly influenced the character of the remaining native plant communities and altered wildlife habitats. Human development reduced habitat quality for area-sensitive species.

Within MLRA 64, the Sandy 17-20” PZ ecological site provides upland grassland cover with an associated forb and shrub component. The site was typically part of an expansive grassland landscape that included combinations of Badlands, Thin Breaks, Clayey, Claypan, Dense Clay, Loamy, Saline, Shallow, Overflow, Subirrigated, and Terrace ecological sites. The site provided habitat for species requiring unfragmented grassland. Important habitat features and components found commonly or exclusively on this site include sharp-tailed grouse leks; upland nesting habitat for grassland birds; forbs and insects for brood habitat; and a forage source for small and large herbivores. Populations are declining for many bird species that nest in grasslands and shrub steppes. Extirpated species include free-ranging American bison, grizzly bear, gray wolf, black-footed ferret, mountain plover, Rocky Mountain locust, and swift fox.

The majority of this ecological site remains intact and provides increasingly important habitat for birds that nest in grasslands and shrub steppes and for small rodents, coyote, and a variety of reptiles, amphibians, and insects. Invasive species, such as Kentucky bluegrass and cheatgrass, have impacted the biological integrity of the site for some grassland birds. Changes to the historic fire regime and domestic grazing have impacted the composition of forbs, shrubs, and grasses.

Bluestem-Prairie Sandreed (1.1) and Prairie Sandreed-Needle and Thread-Blue Grama (1.2): The predominance of grasses plus a high diversity of forbs and shrubs in this community favors grazers and mixed-feeders, such as deer and pronghorn. Insects, including pollinators, play a large role in maintaining the forb community and provide a forage base for grassland birds and other species. The complex plant structural diversity provides habitat for a wide array of migratory and resident birds. Grasshopper sparrow, lark bunting, western meadowlark, and sharp-tailed grouse are common and benefit from the structure and composition this plant community provides. Diverse prey populations are available for grassland raptors, such as ferruginous hawk, Swainson’s hawk, golden eagle, and prairie falcon.

The diversity of grasses, forbs, and shrubs provides high nutritional levels for small and large herbivores, including voles, mice, spotted ground squirrel, desert cottontail, white-tailed jackrabbit, black-tailed jackrabbit, and deer. The higher stature of this plant community provides thermal, protective, and escape cover for herbivores and grassland birds. Predators that use this plant community include coyote, American badger, red fox, and long-tailed weasel. This plant community provides limited habitat for amphibians, mostly toads (i.e., Great Plains, Woodhouse’s, and Plains spade-foot). Prey abundance and shade opportunities may attract multiple reptile species, such as gopher snake, milk snake, prairie rattlesnake, and western ornate box turtle. Several species of sand loving lizards, such as the lesser earless lizard, prairie lizard, many-lined skink, and six-lined racerunner, use this site.

Continuous season-long grazing, no fire, or no use result in a shift to a prairie sandreed, needle and thread, and blue grama community. The forb and shrub diversity does not substantially decrease. Juniper and ponderosa pine remain a limited component of the plant community and provide little specialized wildlife habitat. The shift from the Reference Plant Community (1.1) to the Prairie Sandreed-Needle and Thread-Blue Grama Plant Community (1.2) does not result in a significant change to the wildlife community.

Continuous seasonal grazing of the grass component results in a shift to a medium to short height plant community. Forb and shrub abundance increases; however, the plant community changes do not significantly change the wildlife community from that of the Reference Plant Community (1.1).

Blue Grama-Sand Dropseed/Threadleaf Sedge/Field Sagewort (2.1): This community results from continuous season-long grazing where blue grama and sedges eventually dominate. Forb abundance is increased compared to the reference state, and forb diversity is relatively unchanged. Shrub and tree abundance and diversity remain relatively unchanged and do not significantly benefit a specific wildlife group.

A shift to shorter plant structure favors prairie dog expansion and associate species, such as ferruginous hawk, burrowing owl, tiger salamander, and swift fox. Species such as horned lark, long-billed curlew, upland sandpiper, white-tailed jackrabbit, and black-tailed jackrabbit increase due to the loss of the tall grass component. This plant community may provide areas suitable for development of sharp-tailed grouse leks. The short stature of this plant community limits thermal, protective, and escape cover. Predators that use this plant community include coyote, American badger, red fox, and long-tailed weasel.

Conifer State (3.0): This state results from no fire and the expansion of ponderosa pine and juniper. Compared to the reference site, forb diversity is decreased and shrub abundance is increased. Juniper and ponderosa pine increase significantly. Grass species decline dramatically. The grass species composition shifts and can become dominated by invasive species. Ponderosa pine and juniper stands provide nesting cover, escape cover, and den sites for a variety of species. Species that increase include mule deer, white-footed mice, bushy-tailed woodrat, black-billed magpie, Townsend’s solitaire, western meadowlark, Bohemian waxwing, dark-eyed junco, nuthatch, black-capped chickadees, brown thrasher, lark sparrow, and white-crowned sparrow. Species such as meadow voles, spotted ground squirrel, thirteen-lined ground squirrel, northern grasshopper mice, and western harvest mice do not use this site. Grassland nesting songbirds are significantly reduced. Raptors, such as the long-eared owl, increase.

If the tree canopy is high enough, then bare ground is likely to increase and excessive runoff, nutrient loads, and sediment loads may impact offsite aquatic habitat.

Grazing Interpretations:
The following list suggests annual, initial stocking rates for average growing conditions. These estimates are conservative and should be used only as guidelines in the initial stages of conservation planning. Commonly, the current plant composition does not entirely match any particular plant community (as described in this ecological site description). Therefore, a resource inventory is necessary to document plant composition and production. More accurate estimates of carrying capacity should eventually be calculated using the following stocking rate information along with animal preference data and actual stocking records, particularly when grazers other than cattle are involved. In consultation with the land manager, a more intensive grazing management program that results in improved harvest efficiencies and increased carrying capacity may be developed.

The following suggested initial stocking rates are based on 912 lb/acre (air-dry weight) per animal-unit-month (AUM) with a 25 percent harvest efficiency of preferred and desirable forage species (refer to USDA-NRCS National Range and Pasture Handbook). An AUM is defined as the equivalent amount of forage required by a 1,000-pound cow, with or without calf, for one month.

Plant Community: Bluestem-Prairie Sandreed (1.1)
Average Production (lb/acre, air-dry): 2,400
Stocking Rate (AUM/acre): 0.66

Plant Community: Prairie Sandreed-Needle and Thread-Blue Grama (1.2)
Average Production (lb/acre, air-dry): 2,000
Stocking Rate (AUM/acre): 0.55

Plant Community: Blue Grama-Sand Dropseed/Threadleaf Sedge/Field Sagewort (2.1)
Average Production (lb/acre, air-dry): 1,400
Stocking Rate (AUM/acre): 0.38

*Plant Community: Ponderosa Pine-Juniper/Shrubs/Herbaceous Understory (VSS: 2-3) (5.1)
Average Production (lb/acre, air-dry): 1,000
**Stocking Rate (AUM/acre): 0.27

Plant Community: All other plant communities identified in this document have variable annual production values and require onsite sampling to determine initial stocking rates.

* Total annual production and stocking rates are highly variable and require onsite sampling.

** Total onsite annual production may contain vegetation deemed undesirable or untargeted by the grazing animal. Therefore, AUM values may have been reduced to reflect only preferred or desirable forage species.

Grazing by domestic livestock is one of the major income-producing industries in the area. Rangeland in this area may provide yearlong forage for livestock. During the dormant period, the forage for livestock likely has insufficient protein to meet livestock requirements. Added protein allows ruminants to better utilize the energy stored in grazed plant materials. A forage quality test (either directly or through fecal sampling) should be used to determine the level of supplementation needed.

Hydrological functions

Water is the principal factor limiting herbage production on this site. Soils on this site are in Hydrologic Soil Groups A and B. The infiltration rate is moderate. Runoff potential varies from moderate to high, depending on soil hydrologic group and ground cover. In many cases, areas that have greater than 75 percent ground cover have the greatest potential for high infiltration and lower runoff. An exception occurs where shortgrasses form a dense sod and dominate the site. Areas where ground cover is less than 50 percent have the greatest potential to have reduced infiltration and higher runoff. Refer to the USDA-NRCS National Engineering Handbook, Part 630, for hydrologic soil groups, runoff quantities, and hydrologic curves.

Recreational uses

This site provides opportunities for hunting upland game species. The wide variety of plants that bloom from spring until fall have an aesthetic value that appeals to visitors. A wide diversity of species for birders is also appealing.

Wood products

The Pine Ridge escarpment is the primary source of wood products in MLRA 64. Some soils in this area may produce marketable ponderosa pine. Steep slopes, however, may make this resource inaccessible to modern timber harvesting equipment. Management of this forest resource for watershed protection, grazing, wildlife, recreation, and timber harvest may be the most critical issues land managers and owners currently face.

Before the 1950s, ponderosa pines covered approximately 250,000 acres of the Pine Ridge escarpment. Wildfires have reduced that to less than 120,000 acres. Much of the remaining acreage is also at risk of catastrophic fire because dense stands of pine and cedar have created dense stands of fuel (Gaarder, 2013). Forest and grazing land specialists stress the need to create and manage fire-tolerant forests on a landscape basis. They recommend fuel-mitigation treatments through grazing management, forest thinning, prescribed burning, and timber harvest management. They also recommend additional access roads for fire protection, the expansion of defensible space around homes and building, and education on “Fire Wise” practices (Nebraska Forest Service, 2014).

Other products

Harvesting the seeds of native plants can provide additional income on this site.

Other information

Revision Notes: “Previously Approved” Provisional
This Provisional ecological site description (ESD) has passed Quality Control (QC) and Quality Assurance (QA) to ensure the it meets the 2014 NESH standards for a Provisional ecological site description.

This ESD is an updated “Previously Approved” ESD that represented a first-generation tier of documentation that, prior to the release of the 2014 National Ecological Site Handbook (NESH), met all requirements as an “Approved” ESD as laid out in the 1997 National Range and Pasture Handbook (NRPH). The document fully described the Reference State and Community Phase in the State-and-Transition model. All other alternative states are at least described in narrative form. The “Previously Approved” ESD has been field-tested for a minimum of five years and is a proven functional document for conservation planning. The “Previously Approved” ESD may not contain all tabular and narrative entries as required in the current “Approved” level of documentation, but it is expected that it will continue refinement toward an “Approved” status.

Site Development and Testing Plan
Future work, as described in an official project plan, is necessary to validate the information in this provisional ecological site description. The plan will include field activities for low-, medium-, and high-intensity sampling, soil correlations, and analysis of the data. Annual field reviews should be done by soil scientists and vegetation specialists. Final field review, peer review, quality control, and quality assurance reviews are required to produce the final document.

Inventory data references

Information presented here has been derived from NRCS clipping data and other inventory data. Field observations from range-trained personnel were also used. Those involved in developing this site include: Stan Boltz, range management specialist (RMS), NRCS; Jill Epley, RMS, NRCS; Rick Peterson, RMS, NRCS; David Steffen, RMS, NRCS; Jeff Vander Wilt, RMS, NRCS; Phil Young, soil scientist, NRCS; Kent Cooley, resource soil scientist, NRCS; George Gamblin, RMS, NRCS; Dr. James O’Rourke, emeritus professor, Chadron State College, and range professional and rancher; Wade Anderson, range professional and rancher; and Jack Butler, scientist emeritus, USDA-Forest Service, Rocky Mountain Research Station, Rapid City, South Dakota.

Other references

Cleland, D.T., J.A. Freeouf, J.E. Keys, G.J. Nowacki, C.A. Carpenter, and W.H McNab. 2007. Ecological subregions: Sections and subsections of the conterminous United States. USDA Forest Service, General Technical Report WO-76D. https://www.fs.fed.us/research/publications/misc/73326-wo-gtr-76d-cleland2007.pdf (accessed 31 January 2019).

U.S. Environmental Protection Agency. 2018. EPA level III and level IV ecoregions of the conterminous United States. https://www.epa.gov/eco-research/level-iii-and-iv-ecoregions- conterminous-united-states (accessed 26 April 2018).

High Plains Regional Climate Center, University of Nebraska. 2018. http://www.hprcc.unl.edu/ (accessed 6 April 2018).

Steele, Ken, M.P. Fisher, and D.D. Steele. 2018. Fort Laramie and the Hartville Uplift. In: Geology of Wyoming. https://www.geowyo.com/fort-laramie--hartville-uplift.html (accessed 14 November 2018).

U.S. Department of Agriculture, Natural Resources Conservation Service. 2018. Electronic field office technical guide. https://efotg.sc.egov.usda.gov (accessed 12 April 2018).

Soil Survey Staff. 2018. Official soil series descriptions. USDA Natural Resources Conservation Service. https://www.nrcs.usda.gov/wps/portal/nrcs/detail/soils/home/?cid=nrcs142p2_053587 (accessed 12 April 2018).

Soil Survey Staff. 2018. Web Soil Survey. USDA Natural Resources Conservation Service. https://websoilsurvey.sc.egov.usda.gov/App/WebSoilSurvey.aspx (accessed 12 April 2018).

U.S. Department of Agriculture, Natural Resources Conservation Service. 2006. Land resource regions and major land resource areas of the United States, the Caribbean, and the Pacific Basin. Agriculture Handbook 296. https://www.nrcs.usda.gov/Internet/FSE_DOCUMENTS/nrcs142p2_050898.pdf (accessed 17 January 2018).

U.S. Department of Agriculture, Natural Resources Conservation Service. 2014. National ecological site handbook, 1st Ed. https://www.nrcs.usda.gov/wps/portal/nrcs/detail/soils/ref/?cid=nrcseprd1291232 (accessed 27 January 2018).

U.S. Department of Agriculture, Natural Resources Conservation Service. 2012. National engineering handbook, part 630. Hydrology chapters from e-Directives. https://directives.sc.egov.usda.gov/viewerFS.aspx?hid=21422 (accessed 17 January 2018).

U.S. Department of Agriculture, Natural Resources Conservation Service. 2018. Climate data. National Water and Climate Center. http://www.wcc.nrcs.usda.gov/ (accessed 12 April 2018).

U.S. Department of Agriculture, Natural Resources Conservation Service. 1997. National range and pasture handbook, rev. 1, 2003. https://www.nrcs.usda.gov/Internet/FSE_DOCUMENTS/stelprdb1043055.pdf (accessed 7 November 2018).

U.S. Department of Agriculture, Natural Resources Conservation Service. 2018. National Soil Information System, Information Technology Center. http://nasis.nrcs.usda.gov (accessed 7 November 2017).

U.S. Department of Agriculture, Natural Resources Conservation Service. 2018. PLANTS database. National Plant Data Team, Greensboro, NC. http://plants.usda.gov (accessed 12 April 2018).

Contributors

Rick L. Peterson
Stan C. Boltz

Approval

Suzanne Mayne-Kinney, 12/16/2024

Acknowledgments

This ecological site was reviewed and approved at the Provisional Level by David Kraft, Regional ESS, Salina, KS on 2/15/2019.

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