Natural Resources
Conservation Service
Ecological site R107XB006MO
Calcareous Loess Exposed Backslope Prairie
Last updated: 5/21/2020
Accessed: 11/21/2024
General information
Provisional. A provisional ecological site description has undergone quality control and quality assurance review. It contains a working state and transition model and enough information to identify the ecological site.
Figure 1. Mapped extent
Areas shown in blue indicate the maximum mapped extent of this ecological site. Other ecological sites likely occur within the highlighted areas. It is also possible for this ecological site to occur outside of highlighted areas if detailed soil survey has not been completed or recently updated.
MLRA notes
Major Land Resource Area (MLRA): 107X–Iowa and Missouri Deep Loess Hills
The Iowa and Missouri Deep Loess Hills includes the Missouri Alluvial Plain, Loess Hills, Southern Iowa Drift Plain, and Central Dissected Till Plains landform regions (Prior 1991; Nigh and Schroeder 2002). It spans four states (Iowa, 53 percent; Missouri, 32 percent; Nebraska, 12 percent; and Kansas 3 percent), encompassing over 14,000 square miles (Figure 1). The elevation ranges from approximately 1,565 feet ASL on the highest ridges to about 600 feet ASL along the Missouri River near Glasgow in central Missouri. Local relief varies from 10 to 20 feet in the major river floodplains, to 50 to 100 feet in the dissected uplands, to 200 to 300 feet in the loess bluffs along the Missouri River. Loess deposits cover most of the area, with deposits reaching a thickness of 65 to 200 feet in the Loess Hills and grading to about 20 feet in the eastern extent of the region. Pre-Illinoian till, deposited more than 500,000 years ago, lies beneath the loess and has experienced extensive erosion and dissection. Pennsylvanian and Cretaceous bedrock – comprised of shale, mudstones, and sandstones – lie beneath the glacial material (USDA-NRCS 2006).
The vegetation in the MLRA has undergone drastic changes over time. Spruce forests dominated the landscape 30,000 to 21,500 years ago. As the last glacial maximum peaked 21,500 to 16,000 years ago, they were replaced with open tundras and parklands. The end of the Pleistocene Epoch saw a warming climate that initially prompted the return of spruce forests, but as the warming continued, spruce trees were replaced by deciduous trees (Baker et al. 1990). Not until approximately 9,000 years ago did the vegetation transition to prairies as climatic conditions continued to warm and subsequently dry. Between 4,000 and 3,000 years ago, oak savannas began intermingling within the prairie landscape. This prairie-oak savanna ecosystem formed the dominant landscapes until the arrival of European settlers (Baker et al. 1992).
Classification relationships
Major Land Resource Area (MLRA): Iowa and Missouri Deep Loess Hills (107B) (USDA-NRCS 2006)
USFS Subregions: Central Dissected Till Plains Section (251C), Loess Hills (251Cb) Subsection; Nebraska Rolling Hills Section (251H), Pawnee City-Seneca Rolling Hill (251Hd) (Cleland et al. 2007)
U.S. EPA Level IV Ecoregion: Steeply Rolling Loess Prairies (47e), Nebraska/Kansas Loess Hills (47h), Western Loess Hills (47m) (USEPA 2013)
Biophysical Setting (LANDFIRE 2009): Central Tallgrass Prairie (4214210)
Ecological Systems (National Vegetation Classification System, Nature Serve 2015): Central Tallgrass Prairie (CES205.683)
Eilers and Roosa (1994): Loess Hills
Iowa Department of Natural Resources: Loess Hills Prairie
Missouri Natural Heritage Program (Nelson 2010): Dry Loess/Glacial Till Prairie
Nebraska Game and Parks Commission (Steinauer and Rolfsmeier 2010): Northern Loess/Shale Bluff Prairie
Plant Associations (National Vegetation Classification System, Nature Serve 2015): Schizachyrium scoparium – Bouteloua curtipendula – Bouteloua hirsuta – (Yucca glauca) Herbaceous Vegetation (CEGL002035)
Rosburg (1994): Dry Mid-Grass Community
White (1983): Gravel Hill
Ecological site concept
Calcareous Loess Exposed Prairies are mapped in complex with Calcareous Loess Protected Backslope Savannas and are located within the green areas on the map (Figure 1). They occur on south- and west-facing shoulders with slopes greater than fifteen percent. Soils are Entisols that are well-drained and very deep to bedrock. These sites are developed from loess with a significant component of carbonates at or near the surface, resulting in an alkaline (increased pH) environment. These fine-silty, fertile soils have high soil uniformity resulting in increased nutrient-holding capacity, increased organic matter retention, and good soil aeration that allows deep penetration by plant roots, which generally results in high plant productivity (Catt 2001). These sites reside downslope from and adjacent to other calcareous loess ecological sites.
The historic pre-European settlement vegetation on this site was dominated by tall- and midgrass prairie species adapted to dry habitats. The site is a relatively even mixture of tall and midgrass species where the tallgrass species represent the greatest relative biomass and the midgrasses support the highest relative frequency. Little bluestem (Schizachyrium scoparium (Michx.) Nash) and sideoats grama (Bouteloua curtipendula (Michx.) Torr.) represent the dominant midgrass species, big bluestem (Andropogon gerardii Vitman) is the dominant tallgrass species, and prairie sandreed (Calamovilfa longifolia (Hook.) Scribn.) is a diagnostic component (Rosburg 1994; Nelson 2010). Forb species typical of an undisturbed habitat associated with this ecological site include tall false foxglove (Agalinis aspera (Douglas ex Benth.) Britton), lotus milkvetch (Astragalus lotiflorus Hook.), aromatic aster (Symphyotrichum oblongifolium (Nutt.) G.L. Nesom), and western silver aster (Symphyotrichum sericeum (Vent.) G.L. Nesom) (Drobney et al. 2001). Leadplant (Amorpha canescens Pursh) and prairie rose (Rosa arkansana Porter) are common shrubs that can be found lightly scattered throughout the prairie. Fire was the primary disturbance factor that maintained this site, while drought and native, large mammal grazing were secondary factors (LANDFIRE 2009; Nelson 2010).
Relative to other calcareous loess prairie communities in the MLRA, the south- and west-facing slopes of Calcareous Loess Exposed Backslope Prairies are generally warmer and drier due to the greater exposure to solar radiation and increased evapotranspiration, resulting in a plant community dominated by xerophytic species. The steeper slopes also allow for increased runoff, thus limiting the amount of infiltration within the ecological site. Herbaceous production and forb diversity are less on this ecological site compared to that of prairies found on calcareous till sites. Lastly, unlike similar loess prairie ecological sites with a higher clay content, this ecological site has a lower soil moisture and higher coefficient of wetness as evidenced by the presence of mostly obligate upland species (Drobney et al. 2001).
Associated sites
R107XB003MO |
Deep Loess Exposed Backslope Savanna Calcareous loess soils on slopes greater than fifteen percent on north and east slopes, including Dow and Ida |
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R107XB012MO |
Calcareous Loess Upland Prairie Calcareous loess soils on slopes less than fifteen percent, including Dow and Ida |
Similar sites
R107XB027IA |
Calcareous Till Upland Prairie Calcareous Till Upland Prairies are similar in landscape position but parent material is glacial till |
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R107XB007MO |
Loess Upland Prairie Loess Upland Prairies are similar in supporting a prairie plant community but parent material contains no carbonates and a higher clay content |
R107XB012MO |
Calcareous Loess Upland Prairie Calcareous Loess Upland Prairies are similar in composition but frequency and production of tallgrasses are greater in this ecological site; occurs only on summits |
R107XB002MO |
Deep Loess Upland Prairie Deep Loess Upland Prairies are similar in supporting a prairie plant community but parent material contains no carbonates and a higher clay content |
Table 1. Dominant plant species
Tree |
Not specified |
---|---|
Shrub |
Not specified |
Herbaceous |
(1) Schizachyrium scoparium |
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