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Harvard Forest REU Symposium Abstract 2009

  • Title: Long-term dynamics of hemlock in western Massachusetts
  • Author: Adriana G Marroquin (Emerson College)
  • Abstract:

    Lake-sediment records provide a long-term perspective on the relationship between climate change and ecosystems. With this study we intend to create a record of the history of the vegetation surrounding Guilder Pond in Berkshire County, Massachusetts. Comparison of pollen assemblages before and after European settlement allows us to better understand the recent dynamics of the supposedly old hemlock stand that surrounds the pond and the effects of any human disturbance. We used data from two sites in Berkshire County—Guilder Pond and Benson Pond—as historically this area had the highest hemlock abundance in the Northeast. To date we have measured the organic content of the Guilder Pond sediments and have counted pollen for the upper 120 cm of the core. The organic content data for Guilder correlated with that of Benson Pond, suggesting similar reactions to regional climate changes; a series of peaks in organic content for both ponds imply shallow waters, which in turn suggest periods of drought. The pattern of hemlock in the surface core also correlated with the middle-Holocene increase in hemlock abundance seen in Benson’s pollen record, which dates to ~4000 yr BP. A drop in hemlock pollen in the uppermost samples, and an increase of ragweed pollen at the same level, correspond to European settlement and suggest that the Guilder area experienced some logging. Future research with tree-ring samples and a more detailed pollen record for the uppermost 50 cm will help provide a better understanding of the current hemlock stand and the possibility that it is not a pristine old-growth forest, but instead has been subject to human disturbance.

  • Research Category: Historical and Retrospective Studies