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Harvard Forest REU Symposium Abstract 2006

  • Title: Hemlock Woolly Adelgid Damage Along Headwater Stream Corridors in Central Connecticut and Massachusetts
  • Author: ()
  • Abstract:

    This project focused on locating suitable study sites that will be used to determine the impact of hemlock woolly adelgid (HWA) damage and the death of riparian hemlock trees on headwater stream ecosystems. HWA is a widely-studied invasive pest that has been killing hemlock trees in the New England area, but the effects of hemlock mortality along stream corridors and coupled downstream ecosystems is largely unknown. This research was part of a larger project examining the physical and chemical changes in stream systems during and following hemlock decline. The purpose of this project was to identify severely impacted stream systems in Connecticut and Massachusetts for further detailed study. Damaged sites were identified using aerial photography and ArcView GIS with overlays of hemlock dominance and mortality. Potential sites were identified based on certain criteria and then visited in the field to determine suitability for further study. Severe hemlock mortality was observed in upland areas in Southern Connecticut, but there was surprisingly little HWA damage along stream riparian zones. Large stands of healthy hemlock remained in Connecticut and Massachusetts and there were usually some living hemlock trees in the riparian zones of even the most impacted streams. A large majority of damaged forests also had a considerable amount of deciduous trees that may mitigate the impact of hemlock mortality. As a result, certain physical and chemical changes in the aquatic ecosystem due to hemlock death, such as changes in the light and temperature regime, may not be as severe in a mixed forest as it would if the riparian zone was entirely composed of dying hemlock trees. Streams in Devilís Hopyard State Park in Connecticut represent the best candidate sites for future study of damaged headwater streams. Based on the initial observations of this study, it seems likely that aquatic ecosystems will be impacted more slowly than upland forest ecosystems by HWA damage and the resulting hemlock mortality.

  • Research Category: Invasive Plants, Pests & Pathogens; Regional Studies; Watershed Ecology