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Harvard Forest REU Symposium Abstract 2009
- Title: A twenty year study of vegetation dynamics in a virgin Hemlock forest in Sothern New Hampshire
- Author: Brendan R Gallagher (Dickinson College)
- Abstract:
The Pisgah tract, a Harvard Forest property located in Southern New Hampshire, provides a rare opportunity to study virgin forest dynamics. The focus of this study was to study forest succession after a major disturbance, the hurricane of 1938. The tract was first studied by R. T. Fisher in the early 1900’s. The hurricane of 1938 destroyed most of the old growth trees that initially attracted Fisher, principally Tsuga canadensis and Pinus strobus, however, the land was never salvaged or cleared. A vegetation analysis was initially conducted in 1989 and repeated again in 2009 along two transects designed to show variation along a topographic gradient. The two transects combined contained fifty-seven ten by ten meter plots. All stems greater than 2.5 cm DBH were mapped and measured along with the coarse downed wood and stumps. An inventory of all understory vegetation was also taken. Trends since 1989 suggest an increase in overall basal area and a decrease in density. This is indicative of a forest in the “stem exclusion phase” of forest stand development. Both transects had minimal ingrowth, and ingowth trees were principally Tsuga canadensis. In both 1989 and 2009 the forest was dominated by Tsuga canadensis, Acer rubrum, Fagus grandifolia, & Betula spp. Understory vegetation showed twenty-four species in the understory. Highest levels of diversity and coverage were found on the east facing ridge and at the bottom of the transect. The ridge had recently been disturbed by the ice storm in the winter of 2008 and this area had the largest amounts of canopy openness. The bottom of the transect had richer soils and fewer stems which also lead to peaks in diversity and percent coverage.
- Research Category: Historical and Retrospective Studies; Regional Studies
