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. 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.
It spans four states Iowa, 53 percent; Missouri, 32 percent; Nebraska, 12 percent; and Kansas 3 percent , encompassing over 14, square miles Figure 1. Local relief varies from 10 to 20 feet in the major river floodplains, to 50 to feet in the dissected uplands, and loess bluffs of to feet along the Missouri River. Loess deposits cover most of the area, with deposits reaching a thickness of 65 to feet in the Loess Hills and grading to about 20 feet in the eastern extent of the region.
Pre-Illinoian till, deposited more than , years ago, lies beneath the loess and has experienced extensive erosion and dissection. The vegetation in the MLRA has undergone drastic changes over time. Spruce forests dominated the landscape 30, to 21, years ago. As the last glacial maximum peaked 21, to 16, 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, and as the warming continued, spruce trees were replaced by deciduous trees Baker et al. Not until approximately 9, years ago did the vegetation transition to prairies as climatic conditions continued to warm and subsequently dry. Between 4, and 3, 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.
Deep Loess Upland Prairies are generally located within the green areas on the map Figure 1. They occur on summits and shoulders on slopes less than fifteen percent. Soils are Entisols, Inceptisols, and Mollisols that are well-drained and very deep, formed from leached loess with a strongly acid to moderately alkaline increased pH environment.
