Authors: Chelsea Teale*, Humboldt State University
Topics: Paleoenvironmental Change, Biogeography, Agricultural Geography
Keywords: Fabacaeae, legume, settlement horizon, pollen, paleoecology
Session Type: Poster
Presentation File: No File Uploaded
European land-use indicators in northeastern North America typically include ragweed (Ambrosia), sorrel (Rumex), plantain (Plantago), and grasses (Poaceae). Although grasses can include cultivated cereals, paleoecologists interpret most of these taxa as introduced weeds in ruderal environments. A potential complement to this list is the legume family (Fabaceae), members of which were also introduced by colonists. Native legumes are present in the region, but historical records show that white clover (Trifolium repens) was widespread from the earliest days of settlement, both intentionally sown and spreading through manure and tillering. By 1820, several other Eurasian legumes were also introduced as livestock fodder. As an insect-pollinated family, Fabaceae is usually excluded from reconstructions due to low pollen counts, but it may be beneficial to include when the settlement horizon is vague. For example, a recent study demonstrated the difficulty paleoecologists can have when identifying the settlement horizon—even when multiple taxa are available. This research used the R neotoma package to retrieve pollen data from the Neotoma Paleoecology Database and displayed it over the past millennium. Results for 59 sites reporting Fabaceae show a similar trend as the traditional indicators, and most closely resembles Plantago (which is similarly represented by low pollen amounts owing to partial pollination by insects). Two case studies with good chronological control illustrate how all five taxa can be found at the settlement horizon across the study area and over time: a PB210-dated pond in Connecticut impacted by 1700, and a varved lake in Ontario impacted by 1840.