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Open Access Knowledge and Scholarship

Date of Award

5-2007

Culminating Project Type

Thesis

Degree Name

Geography - Geographic Information Science: M.S.

Department

Geography and Planning

College

School of Public Affairs

First Advisor

Mikhail S. Blinnikov

Second Advisor

David Wall

Creative Commons License

Creative Commons License
This work is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 4.0 License.

Keywords and Subject Headings

Phytoliths, Minnesota, Lakes, Wild Rice, Paleoecology

Abstract

The purpose ofthis study was to develop phytolith analysis as a tool to better understand the presence, abundance and paleodistribution of wild rice (Zizania spp. L.) from paleo lake sediment cores. Thirty-seven dominant study area plant species, divided into 180 plant-parts, were investigated for phytolith production, with extra emphasis on Zizania and Leersia. Zizania palustris was found to produce 23 locally diagnostic phytolith morphotypes that were used to calculate concentration and influx of wild rice phytoliths in modem and paleo lake sediments.

Methodologies optimized for the extraction, concentration and quantification of the phytolith fraction from highly organic lake sediments were developed, utilizing novel and established limnological techniques new to phytolith analysis.

Analysis of 21 modem sediment samples collected along transects across three different wild rice lakes indicated that Zizania phytolith deposition is spatially correlated with stand location and density of wild rice. However, lake morphology and bathymetry can have an effect on depositional patterns.

Analysis of 4 7 paleo lake sediment samples from two Lake Ogechie cores indicated that wild rice may have first appeared in Lake Ogechie approximately 4000 cal yr BP and persisted in relatively low numbers until an apparent population explosion starting approximately 1600 cal yr BP, which peaked at around 800 to 1000 cal yr BP. The archaeological record and oral histories by the Mille Lacs Band of Ojibwe suggest that Lake Ogechie was covered with wild rice; however, wild rice has almost completely disappeared from the lake. Phytolith data indicates that wild rice maintained relatively high abundance for several hundred years and then rapidly declined to present day levels.

Thi-s study d' emonstrated that multiplicity and redundancy of basic phytolith typologies_ in the Poaceae did not limit the establishment of locally diagnostic phytolith morphotypes when three-dimensional observation and descriptors are used.

Methods developed during this study can now be used to better understand the timing of the entry and speciation of Z!Jfnia in North America.

Comments/Acknowledgements

I would like to thank Dr. Richard Rothaus and the Office of Sponsored programs for providing financial support, logistical and field assistance, and NSF grant assistance, without which, this research would not have been possible. I would also like to acknowledge Dr. Matthew Julius, Department of Biology, who generously provided lab space and technical assistance critical to the successful outcome of this thesis. Dr. Mikhail Blinnikov deserves recognition in his ability tp inspire and encourage my creation of the original thesis proposal and NSF grant proposal which lead to this thesis. Dr. Susan Mulholland, Duluth Archaeology Center, and Dr. Linda Scott-Cummings, Paleo Research Institute, were also generous in sharing some of their hard earned phytolith knowledge and laboratory procedures. I finally wish to acknowledge Dr. James Huber, Huber Consulting, for his interest in the antiquity of wild rice utilization in the upper Great Lakes region. His Ph.D. dissertation: "Palynological investigations related to archaeological sites and the expansion of wild rice (Zizania aquatica L.) in northeast Minnesota" inspired me to develop phytolith analysis as a wild rice paleoecological tool.

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