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Harvard Forest Symposium Abstract 2016

  • Title: Holocene history of Atlantic white cedar on Naushon Island, southeastern Massachusetts
  • Primary Author: Wyatt Oswald (Emerson College)
  • Additional Authors: Elaine Doughty (Harvard Forest); David Foster (Harvard University); Barbara Hansen (University of Minnesota - Twin Cities); Bryan Shuman (University of Wyoming)
  • Abstract:

    Atlantic white cedar (Chamaecyparis thyoides), a species of significant ecological and conservation interest, occurs in freshwater wetlands along the coast of the eastern United States. To improve our understanding of the long-term history of this species, we analyzed pollen in sediment cores from two kettle ponds on Naushon Island, the largest of the Elizabeth Islands, located a short distance southwest of Cape Cod in southeastern Massachusetts. Diaries of early European explorers describe thick cedar stands on Cape Cod and the Elizabeth Islands, but logging has greatly reduced its prevalence along the Massachusetts coastline. The sediment cores were collected from Blaney’s Pond (41.472°N, -70.765°W, 3 m above sea level) and Duck Pond (41.495°N, -70.714°W, <1 m above sea level). Blaney’s Pond is located on the southern half of Naushon, 0.4 km from the ocean on the Vineyard Sound side of the island. Duck Pond is located in a large, coastal wetland, known as the Great Swamp, on the northern half of the island, also 0.4 km from Vineyard Sound (Figure 1a). The base of the Blaney’s Pond record dates to 13,500 calibrated radiocarbon years before present (cal yr BP); the record from Duck Pond begins at 5000 cal yr BP. In both pollen records, cedar is rare until the late Holocene, but its pollen influx values increase dramatically at 3500 cal yr BP at Blaney’s Pond and at 3000 cal yr BP at Duck Pond (Figure 1b). Pollen records from elsewhere in the northeastern US indicate that Atlantic white cedar had migrated back to the region from glacial refugia as early as 10,000 cal yr BP at some sites, but not until after 500 cal yr BP in other areas. On Naushon Island, its expansion may have been linked to sea-level rise, as sea level appears to have reached the elevation of the sediment-water interface of these ponds just prior to the increases in cedar abundance (Figure 1c). Rising sea levels would have lifted the lens of groundwater, inundating soils surrounding the ponds and thus allowing for the establishment of stands of Atlantic white cedar.

  • Research Category: Historical and Retrospective Studies

  • Figures:
    • Oswald_Fig1.pdf