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Harvard Forest Symposium Abstract 2009

  • Title: Patterns of grassland development in Colonial New England
  • Primary Author: Elisabeth Almgren (University of Uppsala)
  • Additional Authors: David Foster (Harvard Forest); Wyatt Oswald (Emerson College)
  • Abstract:

    Patterns of grassland expansion in Colonial New England

    European pollen diagrams consistently show indications of human impact on the environment from about 5000 BP. In addition to cereal pollen grains in combination with reduction in forest cover, anthropogenic indicator taxa that largely depend on land management are all used to identify and interpret early European agriculture. Due to the long and consistent history of farming, the human impact part of the European pollen diagrams have been intensely studied.

    In New England the small-scale agriculture practiced by the American Indians is not as easily detected in the pollen diagrams and the start of a clear and consistent indication of human impact is therefore mainly confined to the European Colonial period. This period is however less studies in US pollen diagrams than earlier period of vegetation changes that were caused by climate change or natural disturbances.

    The present study currently compares the Colonial period section of twenty-seven pollen diagrams from across New England, which have all previously been analyzed at Harvard Forest. The aim is to describe patterns and character of grassland expansion and other vegetation changes associated with European Colonial agricultural methods and technology.

    Although most diagrams show rapid expansion of Rumex, Ambrosia, and Poaceae, the expansion pattern differ between sites. The preliminary results show three possible patterns of initial expansion and final dominance of a taxa with e.g. the dominance of Ambrosia only occurring at coastal sites.

    In addition, bracken (Pteridium aquilinum) often increases in response to the first large-scale forest clearances, right before the expansion of Rumex and Ambrosia. As cultivation of corn and wheat starts, the normally very persistent bracken virtually disappears. One interpretation is that it was caused by the use of the new steel-board plow that effectively destroyed the bracken rhizomes and prevented regeneration.

  • Research Category: Historical and Retrospective Studies