Physiographic features

The Loamy Terrace ecological site occurs on nearly level to gently sloping alluvial fans and low terraces.

Table 2. Representative physiographic features

Climatic features

MLRA 64 is considered to have a continental climate consisting of cold winters and hot summers, low humidity, light rainfall, and ample sunshine. Extremes in temperature may also abound. The climate is the result of the location of MLRA 64 near the geographic center of North America. There are few natural barriers on the Northern Great Plains, and air masses move freely across the plains and account for rapid changes in temperature.
Annual precipitation ranges from 14 to 20 inches per year.

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 temperatures averaging from about 70°F (Keeline 3 W, WY – 1953-1986) 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. Hourly winds average about 11 miles per hour annually, ranging from about 13 miles per hour during the spring to about ten miles per hour during the summer. Daytime winds are generally stronger than nighttime and occasional strong storms may 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. Green-up of cool-season plants may occur in September and October when adequate soil moisture is present.

Table 3. Representative climatic features

Climate stations used

• (1) HARRISON 20 SSE [USW00094077], Harrison, NE

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

• (3) ALLIANCE 1WNW [USC00250130], Alliance, NE

• (4) HARRISON [USC00253615], Harrison, NE

• (5) HEMINGFORD [USC00253755], Hemingford, NE

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

• (7) MARTIN [USC00395281], Martin, SD

• (8) WOOD [USC00399442], Wood, SD

• (9) LUSK 2 SW [USC00485830], Lusk, WY

• (10) TORRINGTON 29N [USC00488997], Jay Em, WY

Influencing water features

The Loamy Terrace ecological site occurs adjacent to lowland and overflow sites along stream corridors.
Stream Type: B6, C6 (Rosgen System)

Wetland description

Not Applicable.

Soil features

The soils in this site are well-drained and formed in alluvium with slopes that range from zero to three percent. Soils are deep with a very fine sandy loam to silty clay surface layer, 3 to 25 inches thick. Subsurface textures range from very fine sandy loam to silty clay. The soils have slow to moderate infiltration rates. This site should show no evidence of rills, wind-scoured areas, or pedestalled plants. Water flow patterns are broken, irregular in appearance, or discontinuous with numerous debris dams or vegetative barriers. The soil surface is stable and intact.

Soils correlated to the Loamy Terrace site: Bigbend, Bridgeport, Craft, Haverson, Lohmiller, and McCook.

Soils with multiple ecological site correlations including Loamy Terrace: Haverson, Lohmiller, and McCook.

These soils are mainly susceptible to water erosion. The hazard of water erosion increases where vegetative cover is not adequate. A drastic loss of the soil surface layer on this site can result in a shift in species composition and production.

More information can be found in the various soil survey reports. Contact the local USDA Service Center or use Web Soil Survey online for soil survey reports that include more detail specific to your area of interest.

Table 4. Representative soil features

Animal community

Wildlife Interpretations:
MLRA 64 lies within the drier portion of northern mixed-grass prairie ecosystem where sagebrush steppes to the west yield to grassland steppes to the east. Prior to European settlement, this area 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 of its users. Many species of grassland birds, small mammals, reptiles, 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 small mammal and insect species, were the primary consumers linking the grassland resources to predators such as the wolf, mountain lion, and grizzly bear, and smaller carnivores such as the coyote, bobcat, fox, and raptors. The prairie dog was once abundant; however, the species 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 with fire, herbivory, and climate functioning 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 impacted 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 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 has reduced habitat quality for area-sensitive species.

Within MLRA 64, the Loamy Terrace ecological site provides upland grassland cover with an associated forb, shrub, and tree component. It was typically part of an expansive grassland landscape that included combinations of Badlands, Thin Breaks, Clayey, Claypan, Dense Clay, Loamy, Saline, Sandy, Shallow, Overflow, and Subirrigated ecological sites.

This ecological site can support an abandoned floodplain plant community and may be associated with an adjacent riparian plant community. The abandoned floodplain plant community may be composed of mature cottonwood and various age classes of elm, green ash, and boxelder; with a shrub component of chokecherry, wild plum, western snowberry, silver sagebrush, wild rose, etc. The presence or absence of this tree/shrub component is an important factor influencing wildlife species composition. Rare flooding events deposit silt on the site which may allow the potential sprouting of plains cottonwood. However, due to the doughtiness of this site, cottonwood establishment does not occur. This site is subject to invasion of grass species such as Kentucky bluegrass, smooth brome, and cheatgrass. Woody species such as Russian olive, Tamarisk (saltcedar), and eastern redcedar may invade this site.

This site provides habitat for grassland- and shrub-thicket-nesting birds, small rodents, bats, mammalian predators, and a variety of reptiles, amphibians, and insects. Within the MLRA, this site provides suitable habitat for numerous riparian-associated species. This site provides foraging and brood-rearing habitat for upland game birds, such as the sharp-tailed grouse. However, due to the presence of invasive grass and woody species, reproduction of ground nesting birds is reduced.

Rhizomatous Wheatgrass-Needle and Thread-Big Bluestem/Shrubs/Scattered Trees (1.1): This site is dominated by western wheatgrass, needle and thread, and big bluestem. Shrub community generally dominated by silver sagebrush, American plum, rose, chokecherry, western snowberry, false indigo, and silver buffaloberry, favoring grazers and mixed-feeders, such as deer. Plant communities associated with shrub thickets and low shrubs provide habitat for songbirds such as brown thrasher, yellow warbler, gray catbird, Say’s phoebe, loggerhead shrike, Lazuli bunting, and yellow-breasted chat. Raptors such as red-tailed hawk, Ferruginous hawk, Swainson’s hawk, American kestrel, and great horned owl may use this site. Insects, such as pollinators, play a limited role in maintaining the forb community but do provide a significant forage base for birds and various bats, especially species such as the Western small-footed Myotis, the fringe-tailed Myotis, and the Townsend’s big-eared bat. Diverse prey populations are available for grassland raptors and mammalian predators, especially bobcat. Other mammalian predators utilizing this plant community include the coyote, mink, long-tailed and least weasels, and spotted and striped skunks.

The Loamy Terrace ecological site provides a diversity of grasses, forbs, and shrubs for small and large herbivores including shrews, voles, mice, spotted ground squirrel, desert cottontail rabbit, white- and black-tailed jackrabbits, and deer. This site provides excellent nesting and brood-rearing habitat for sharp-tailed grouse and turkey. This ecological site provides excellent fawning habitat for white-tailed deer. The relatively tall stature of this plant community provides suitable thermal, protective, and escape cover for small and large mammals. This plant community provides habitat for amphibians, mostly toads (i.e., Great Plains, Woodhouse’s, and plains spadefoot). Prey abundance and shade opportunities may attract multiple reptile species such as gopher snake, milk snake, prairie rattlesnake, and western ornate box turtle to this site along with lesser numbers of various lizard species. Introduced bird species such as European starling, ring-necked pheasant, and gray partridge will use this site.

Blue Grama-Rhizomatous Wheatgrass/Shrubs/Scattered Trees (1.2): Resulting from continuous seasonal grazing or haying, blue grama will become dominant. Forb, shrub, and tree diversity and abundance decrease. If the decrease results from haying, then shrub dependent wildlife species will decline. However, songbirds such as brown thrasher and raptors such as red-tailed hawk, Swainson’s hawk, American kestrel, and great horned owl will continue to use this site. This site will continue to attractor pollinators and other insects, thereby still providing a suitable forage base for birds and bats. This plant community will continue to provide areas suitable for sharp-tailed grouse. Species such as the horned lark, long-billed curlew, upland sandpiper, and white-tailed jackrabbit will increase in locations where shrub species decline. This site continues to provide suitable habitat for various snakes, toads, and lizards. The interspersion of short and tall vegetation provides adequate thermal, protective, and escape cover. Predators utilizing this plant community include the coyote, American badger, red fox, and long-tailed weasel.

Early Seral State (2.0): Resulting from heavy, continuous season-long grazing over many years or frequent and severe defoliation, threeawn and annuals will dominate. The forb abundance has increased; however, forb diversity has substantially decreased, and shrub abundance has increased. A shift to short plant structure and relatively high percentage of bare ground will favor prairie dog expansion with prairie dog town sites and associate species such as swift fox, ferruginous hawk and burrowing owl. Species such as horned lark, long-billed curlew, upland sandpiper, and white-tailed jackrabbit will increase. Species such as desert cottontail and grassland-nesting birds requiring moderate cover height will rarely use this site. The short stature of this plant community limits suitable thermal, protective, and escape cover. Prey populations are reduced and are more vulnerable to raptor and mammalian predation. Predators utilizing this plant community include the coyote, American badger, red fox, and long-tailed weasel. Extreme impairment of the ecological processes impacts offsite aquatic habitats through excessive runoff, nutrient, and sediment loads. Elevated surface temperatures resulting from reduced cover and litter will greatly reduce habitat for most amphibian species, grassland birds, and mammals.

Plant Community 3.1: Rhizomatous Wheatgrass-Needlegrass-Non-Native-Cool-Season Grasses/Shrubs/Scattered Trees: Resulting from non-use or long-term light grazing, and the invasion of non-native cool-season grasses. This plant community can develop excessive litter and exhibits a reduction in plant density. If managed to maintain species diversity and structural/function groups, this plant community will provide similar habit and wildlife value at the Reference Plant Community (1.1).

Invaded State (4.0) and Disturbed Rangeland State (5.0): This group includes separate vegetation states that are highly variable in nature. They are derived through distinct management scenarios. These plant communities have been or are highly susceptible to invasion of annual bromegrasses, bluegrasses, crested wheatgrass, and other nonnative species. Since secondary succession is highly variable, plant and wildlife species will vary. This plant community provides habitat for generalist or early successional species. In addition, these communities may contain prairie dog towns. Prairie dog towns are sites of high plant and wildlife diversity.

The Invaded State (4.0) includes areas that have been invaded and are dominated by species such as smooth brome, Kentucky bluegrass, crested wheatgrass, non-native thistles, field bindweed, knapweeds, leafy spurge, hoary cress, and other introduced species. These sites greatly reduce forage, reproductive, and escape cover for grassland-nesting bird species.

The Go-back Plant Community (5.1) can be reached whenever severe mechanical disturbance (i.e., abandoned farmland) is eliminated. Early successional plant communities include annual and perennial weedy type species first to occupy the site. These sites provide diverse forage, reproductive, and escape cover that favors multiple edge species. This pioneer plant community provides abundant opportunity for insect, bird, and small mammal foraging due to abundant flowers and seed sources.

The Seeded Plant Community (5.2) provides increased forage, and, therefore, a potential for increased herbivore populations such as deer, pronghorn, and various small mammals. These sites provide diverse forage, reproductive, and escape cover favoring multiple edge species.

Grazing Interpretations:
The following list provides annual suggested initial stocking rates with average growing conditions. These are conservative estimates that should be used only as guidelines in the initial stages of conservation planning. Often, 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 carrying capacity estimates 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. With consultation of the land manager, more intensive grazing management may result in improved harvest efficiencies and increased carrying capacity.

The following initial suggested stocking rates are based on 912 lbs./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: Rhizomatous Wheatgrass-Needle and Thread-Big Bluestem/Shrubs/Scattered Trees (1.1)
Average Production (lbs./acre, air-dry): 2,600
Stocking Rate (AUM/acre): 0.71

Plant Community: -Blue Grama-Rhizomatous Wheatgrass/Shrubs/Scattered Trees (1.2)
Average Production (lbs./acre, air-dry): 1,600
Stocking Rate (AUM/acre): 0.44

*Plant Community: Blue Grama/Sedge (2.1)
Average Production (lbs./acre, air-dry): Variable
Stocking Rate (AUM/acre): Variable

Plant Community: Rhizomatous Wheatgrass-Needlegrass-Non-Native Cool-Season Grasses/Shrubs/Scattered Trees (3.1)
Average Production (lbs./acre, air-dry): 2,400
*Stocking Rate (AUM/acre): 0.66

*Plant Community: Kentucky Bluegrass (>30%)-Smooth Brome (4.1)
Average Production (lbs./acre, air-dry): 1,100
Stocking Rate (AUM/acre): 0.30

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

* Total annual production and stocking rates are highly variable and will require on-site sampling.

Total annual production on-site 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 will likely be lacking protein to meet livestock requirements, and added protein will allow 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. The site is dominated by soils in hydrologic groups B and C. Infiltration and runoff potential for this site varies from moderate to high depending on soil hydrologic group, slope, and ground cover. In many cases, areas with greater than 75 percent ground cover have the greatest potential for high infiltration and lower runoff. An exception would be 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 for hydrologic soil groups, runoff quantities, and hydrologic curves, Part 630.)

Recreational uses

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

Wood products

No appreciable wood products are present on the site.

Other products

Seed harvest of native plant species can provide additional income on this site.

Other information

Revision Notes: “Previously Approved” Provisional
This Provisional ecological site concept has passed Quality Control (QC) and Quality Assurance (QA) to ensure that the site meets the 2014 NESH standards for a Provisional ecological site description. This is an updated “Previously Approved” ESD that represents 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 (rev.1, 2003) 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 does not contain all tabular and narrative entries as required in the current “Approved” level of documentation, but it is expected that the “Previously Approved” ESD will continue refinement toward an “Approved” status.

Site Development and Testing Plan:
Future work, as described in a Project Plan, is necessary to validate the information in this Provisional Ecological Site Description. This will include field activities to collect low-, medium-, and high-intensity sampling, soil correlations, and analysis of that data. Annual field reviews should be done by soil scientists and vegetation specialists. The final field review, peer review, quality control, and quality assurance reviews of the ESD will be 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; and George Gamblin, RMS, NRCS.

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 Approved Level by David Kraft, Regional ESS, Salina, KS on 6/06/2019.

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