TRACING THE HISTORY OF FOND DU LAC RESERVATION'S WILD RICE (ZIZANIA PALUSTRIS) LAKES THROUGH PHYTOLITHS

Wild rice is a central part of Anishinaabe culture, with a long history of use in northern Minnesota. It is particularly important to the Fond du Lac Band of Lake Superior Chippewa, whose representatives chose its current reservation boundaries for the 1854 treaty based on the abundance of wild rice producing lakes. Archeological evidence shows that Z. palustris has been used regionally for more than 3000 years, but it is unknown how long it has been growing in the region, or what the variability in its abundance has been. Wild rice requires a restrictive set of environmental conditions, which have been disrupted in many of the Fond du Lac rice lakes. The history of wild rice in the lakes is critical to helping to manage this resource. Each rice plant contains millions of phytoliths, cells encased in amorphous (opaline) silica. Some phytoliths can be identified as belonging to groups of plants such as grasses, reeds, or sedges, while others can be identified to species. Wild rice produces some of these unique cell types, and we utilized three of them: indented rondels, multiple indented rondels, and crosses. Reeds produce concave bottom rondels, and sedges produce unique cone-shaped cells. We focused on three lakes in the Fond du Lac reservation: Dead Fish, Perch Lake and Rice Portage. Ten samples were collected from the topmost core section at each lake at a 16 cm interval (about every 25-100 years). Pollen preparations were made at each of these intervals as well, to allow comparison of grass pollen vs. wild rice phytolith abundance. Each sample was processed to remove organic material and diatoms and concentrate phytoliths, and a quantitative microsphere spike was added so that abundance could be calculated. The variation in these assemblages, and the abundance of phytoliths, reflect the presence and abundance of wild rice. Wild rice abundance has varied in the lakes, and an important characteristic of phytoliths for core interpretation has been identified. Pollen, and especially grass pollen thought to represent wild rice, is abundant in the surface levels of lake sediments. Phytoliths are scarce in these levels, having apparently migrated downward in the organic rich, watery, fine-grained sediment. This has implications for the interpretation of phytoliths representing the first occurrence of any plant in lake sediments.