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Harvard Forest Symposium Abstract 2017

  • Title: Dendroecological analysis of eastern hemlock stands in the Middlesex Fells Reservation, eastern Massachusetts
  • Primary Author: Jinghan Zhu (Emerson College)
  • Additional Authors: Wyatt Oswald (Emerson College)
  • Abstract:

    We collected and analyzed tree-ring samples from three eastern hemlock (Tsuga canadensis) stands located on the western side of the Middlesex Fells Reservation in the town of Winchester, eastern Massachusetts. In each stand, 10-20 hemlocks occur within a broader forested landscape dominated by hardwood species and white pine. The Hillcrest (HC) stand is located along a small stream to the northwest of Middle Reservoir. Hemlocks in the Meeting House Brook (MHB) stand grow on a rocky slope just south of South Reservoir. The Molly’s Spring (MS) stand, located between the HC and MHB stands, is located on a steep, north-facing slope. The hemlocks in these stands range in size from <10 to 86 cm in diameter. The three largest trees in the stands (>65 cm) had rotten centers, and thus we were unable to determine their ages. However, by applying several plausible growth rates, we estimate that they recruited between 1700 and 1800. Most of the trees in the HC, MHB, and MS stands established between 1900 and 1930, with occasional recruitment in subsequent decades. This large cohort dates to not long after the Middlesex Fells Reservation was protected in 1894 as part of the Metropolitan Park System. Our analysis of tree-ring widths shows that growth patterns have been influenced by drought, with some variability in drought sensitivity across the stands. All three of the study sites feature narrow rings during the drought of the mid 1960s. During the drought and coincident gypsy moth outbreak of the early 1980s, however, the HC and MHB stands exhibited major declines in radial growth, whereas the MS stand had no reduction in tree-ring widths. Trees in the MS stand may have experienced less drought stress than at MC and MHB due to relatively high soil moisture on the north-facing slope. Hemlocks in all three stands have experienced progressively decreasing growth since 2013 as the trees have begun to succumb to the hemlock woolly adelgid.

  • Research Category: Historical and Retrospective Studies

  • Figures:
    • fellshemlock_fig_10mar17.pdf