MACROFOSSIL ANALYSIS AND VEGETATION HISTORY OF THREE FOND DU LAC (NORTHERN MINNESOTA) WILD RICE LAKES

Manoomin (wild rice, Zizania palustris) is a major food staple and a large part of the Ojibwe culture, but the history of its distribution and abundance, and its relationships to other aquatic plants, are not well known. In this study, we used plant macrofossils, such as seeds, leaves, and needles, to reconstruct the history of vegetation around and within wild rice lakes. Transects of cores were collected from Mid Portage, Rice Portage, and Wild Rice lakes, on the Fond du Lac Band of Lake Superior Chippewa Reservation in northern Minnesota. These cores were subsampled at ~30cm intervals and each subsample was sieved at 1mm, 500, 250, and 125 microns. Macrofossils were picked from the larger size intervals under a light microscope and were identified to genus or species where possible. The dominant aquatic vegetation type found was Najas; it is abundant at all sites. Other aquatic plant macrofossils found were from Potamogeton sp., Carex hystericinia, Scirpus cyperinus, Typha sp., Bryales, and Sagittaria sp. There is also evidence of terrestrial flora including Betula papyrifera, Picea sp., Bidens cernua, and Pinus sp. The macroremains found vary from deep water to near shore cores. At most of the sites, there is evidence (glumes and seeds) of Z. palustris within the top 50cm (~300 years) of the cores, with the exception of Mid Portage, where it was found 130cm down (~1000 years). Although we expect that the wild rice plant has been around longer in these lakes, its seeds are not well preserved and we expect to find phytolith evidence (see Misquadace et al., this session) to help confirm this. Hydrologic and topographical differences between the lakes, as well as early 20^th-century ditching, construction of roads around lakes, and the use of copper sulfate to control fish population, have had an impact on the modern state of these lakes and their sedimentary records. Because the site are in close proximity to Lake Superior, and are thus buffered in terms of temperature and precipitation, we do not expect to see major effects of aridity or lake level changes; our study mainly shows the infilling of the lakes over time and the related encroachment of shallow-water vegetation. Continued study of these lakes, along with the analysis of man-made changes in the area, can help us understand and maintain the growth of wild rice for generations to come.