Date of Graduation

12-2018

Document Type

Thesis

Degree Name

Master of Science in Crop, Soil & Environmental Sciences (MS)

Degree Level

Graduate

Department

Crop, Soil & Environmental Sciences

Advisor/Mentor

Kristofor R. Brye

Committee Member

David M. Miller

Second Committee Member

Lisa S. Wood

Third Committee Member

Edward E. Gbur

Abstract

Native tallgrass prairies were once considered to be the dominant pre-settlement vegetation type in the eastern third of the Great Plains, but are now designated as America’s most endangered ecosystem due to conversion to agricultural land. Prairie mounds are unique soil features still present in remnant native tallgrass prairies across the United States. The main objective was to determine the effects of soil moisture regime (i.e., aquic and udic), mound position, (i.e., mound summit, backslope, toeslope, inter-mound), soil depth (i.e., 10-cm intervals from 0 to 90 cm), and their interactions on soil physical, chemical, and hydraulic properties in a mounded native tallgrass prairie in the Ozark Highlands region of northwest Arkansas. The secondary objective was to evaluate the effects of soil depth (i.e., 10, 20, 30, and 50 cm), mound position (i.e., mound summit and inter-mound), soil moisture regime (i.e., udic and aquic), and their interactions over time and to quantify the effects of soil moisture regime (i.e., udic and aquic), mound position (i.e., mound summit and inter-mound), sample date, and their interactions on prairie vegetation. Soil samples were collected in mid-April 2017, volumetric water content measurements were collected continuously from April 2017 – June 2018, and vegetation was sampled in June and August 2017 and in May and August 2018. Soil clay concentrations in the mound summits roughly doubled from 0-90 cm while the clay concentrations in the backslope, toeslope, and inter-mound increased by three to six times from 0-90 cm. The maximum soil volumetric water content for selected rainfall events was approximately 2.5 times greater at the 10-cm depth in the aquic inter-mound compared to the udic mound at 30 cm. Total aboveground dry matter was numerically largest (8489 kg ha-1) at the aquic summit in August 2018 and numerically smallest (1280 kg ha-1) at the aquic inter-mound in May 2018. The results of this study provide insight regarding soil nutrient contents and water dynamics of prairie mounds and inter-mound areas, which are important for plant growth. Results clearly demonstrate that prairie restoration/management activities need to account for mound topography and differing soil moisture regimes to be most successful.

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