Natural Resources
Conservation Service
Ecological site R107XB013MO
Calcareous Loess Protected Backslope Savanna
Last updated: 5/21/2020
Accessed: 11/13/2024
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 (MLRA 107B) 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 above sea level (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, and loess bluffs of 200 to 300 feet 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): North-Central Interior Oak Savanna (4213940)
Ecological Systems (National Vegetation Classification System, Nature Serve 2015): North-Central Interior Oak Savanna (CES202.698)
Iowa Department of Natural Resources (INAI 1984): Loess Hills Savanna
Missouri Natural Heritage Program (Nelson 2010): Dry-Mesic Loess/Glacial Till Savanna
Plant Associations (National Vegetation Classification System, Nature Serve 2015): Quercus macrocarpa – (Quercus alba, Quercus stellata)/ Andropogon gerardii Wooded Herbaceous Vegetation (CEGL002159)
Rosburg (1994): Bur Oak Woodland
Ecological site concept
Calcareous Loess Protected Backslope Savannas are mapped in complex with Calcareous Loess Exposed Backslope Prairies and are generally located within the green areas on the map (Figure 1). They occur on north- and east-facing backslopes with slopes greater than fifteen percent. Soils are Entisols that are well-drained and very deep, formed from loess with a significant component of calcium carbonates at or near the surface, resulting in an alkaline (high pH) environment. These fine-silty, fertile soils have high soil uniformity resulting in increased nutrient- and water-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, with oaks interspersed across the landscape. Little bluestem (Schizachyrium scoparium (Michx.) Nash) , sideoats grama (Bouteloua curtipendula (Michx.) Torr.), and chinquapin oak (Quercus muehlenbergii Engelm.) represent the indicator species, while big bluestem (Andropogon gerardii Vitman), American hazelnut (Corylus americana Walter), and bur oak (Quercus macrocarpa Michx.) are the dominant species of their respective canopy class (Nuzzo 1994; Whitney 1994; Nelson 2010). Forb species typical of an undisturbed plant community associated with this ecological site include white prairie clover (Dalea candida Michx. ex Willd.) and rattlesnake master (Eryngium yuccifolium Michx.) (Drobney et al. 2001; Ladd and Thomas 2015). Wild plum (Prunus americana Marshall), leadplant (Amorpha canescens Pursh), and roughleaf dogwood (Cornus drummondii C.A. Mey.) are common shrubs that can be found scattered throughout the savanna. Fire was the primary disturbance factor that maintained this site, while drought and native large mammal grazing were secondary factors.
Relative to other calcareous loess prairie ecological sites in the MLRA, Calcareous Loess Protected Backslope Forests occur downslope from Calcareous Loess Upland prairies and adjacent to Calcareous Loess Exposed Backslope Prairies. They support similar shrub and herbaceous species found in the prairie ecological site but due to the protected north- and east-aspects contains an open canopy of bur oak.
Associated sites
R107XB012MO |
Calcareous Loess Upland Prairie Calcareous loess soils on upland summits and shoulders on slopes less than 15 percent, including Dow and Ida |
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R107XB006MO |
Calcareous Loess Exposed Backslope Prairie Calcareous loess soils on slopes greater than 15 percent with south and west aspects, including Dow, Hamburg, and Ida |
Similar sites
R107XB003MO |
Deep Loess Exposed Backslope Savanna Deep Loess Exposed Backslope Savannas are similar in landscape position but only occur on south- and west-aspects and are dominated by white oaks |
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Table 1. Dominant plant species
Tree |
(1) Quercus macrocarpa |
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Shrub |
(1) Corylus americana |
Herbaceous |
(1) Andropogon gerardii |
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