The study of fossil pollen preserved in lakes reconstructs abundance shifts of plant species in response to climate changes, as each species has its particular tolerances for temperature and moisture. Although Michigan has an abundance of inland lakes (~11,000) and hence is a prime area for pollen research, there has been a scarcity of pollen studies, especially in the southeastern portion of the state south of the Tension Zone. Moreover, many of these previous studies were conducted at a poor temporal (centennial) resolution, and therefore do not capture subtle vegetation changes, such as those in response to the Medieval Warm Anomaly (MWA; ~1150-750 cal yr BP) and Little Ice Age (LIA; ~550-150 cal yr BP). The intent of this thesis research was to conduct pollen analysis of a sediment core from Otter Lake, Michigand at high-resolution (~33 years) for the last 2000 years to capture shifts in tree species dominance associated with the MWA and LIA. This research involved several laboratory procedures, which resulted in a pollen diagram that detailed vegetation change over time. The data suggest a weak signal for greater warmth and dryness during the MWA, as evidenced by an increase in the more xeric-adapted Quercus (oak) and Pinus (pine) at the expense of mesic-adapted species like Fagus (beech). A stronger signal was detected for decreased temperatures during the LIA, as indicated by greater abundance of Pinus and Picea (spruce), but the signals for moisture were conflicting. Dramatic decreases in all tree taxa abundance, along with a seven-fold spike in Ambrosia (ragweed), are indicative of land clearing by Euro-American settlers into the area.
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