T246 Wetlands: Form, Function and History (Posters)

Wednesday, 7 November 2012
9:00 AM - 6:00 PM
Hall B

THE HISTORICAL PRESENCE OF WILD RICE DEMONSTRATED BY LAKE CORE PHYTOLITHS

Paper number: T246-8
Program: Technical Sessions
Time: 9:00 AM – 6:00 PM

Authors

Abstract

Phytoliths recovered from sediments in lake cores support the hypothesis that Rice Portage Lake, Cranberry Lake, and Triangular Feature (TF), located in Fond du Lac Band of Lake Superior Chippewa Reservation and Ceded Territories, sustained wild rice (Zizania palustris) in the recent past. The Ojibwe or Anishinaabeg have formed their communities around this grain-producing grass and culturally significant food for thousands of years. Traditional knowledge, historical records, and paleobotanical data indicate that the range of wild rice has decreased due to recent land use change and other human activities.

One indication of past wild rice populations is phytoliths, silicified plant cells. Multiple spatially distributed cores at Rice Portage Lake and TF, both located on the Fond du Lac Reservation, were analyzed. Rice Portage Lake was ditched for drainage in the early 20th century and lost much of its wild rice. Restoration of Rice Portage Lake could be achieved by removing areas of floating sedge mats and increasing the lake level with new dams. TF is a floating bog that may have sustained wild rice in the past. Quantitative slides using Battarbee evaporation trays were also prepared from a single lead-210 dated core from Cranberry Lake, which is located on the Mesabi Iron Range of NE Minnesota.

The recovered phytoliths from all three sites include morphologies that are characteristic of grasses, as well as locally diagnostic wild rice morphologies. The data support efforts to restore wild rice in Rice Portage Lake. It also establishes the historical range of wild rice in the area and a botanical history for Cranberry Lake – a lake at risk for high sulfate levels due to proposed metal sulfide mines.