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Harvard Forest Research Project 2022

  • Title: Woody Species Phenology, Prospect Hill Tract, Harvard Forest
  • Principal investigator: John O'Keefe (jokeefe@fas.harvard.edu)
  • Institution: Harvard Forest
  • Primary contact: Audrey Barker Plotkin (aabarker@fas.harvard.edu)
  • Team members: Mark Friedl; Andrew Richardson
  • Abstract:

    We initiated the ongoing investigation of the timing of woody vegetation development (phenology) during the growing season in 1990. Data are available at - http://harvardforest.fas.harvard.edu:8080/exist/xquery/data.xq?id=hf003. For the first twelve years we observed bud break, leaf development, flowering, and fruit development on three or more individuals of 33 woody species at 3-7 day intervals from April through June. These observations documented substantial (up to three weeks difference) inter-annual variation in the timing of spring development, but good relative consistency among species and among individuals within species during these twelve years.

    Therefore, starting in 2002 we maintained the same observation schedule, but reduced the number of species observed through full development to nine, including red maple (Acer rubrum), sugar maple (A. saccharum), striped maple (A. pensylvanicum), yellow birch (Betula alleghaniensis), beech (Fagus grandifolia), white ash (Fraxinus americana), witch hazel (Hamamelis virginiana), red oak (Quercus rubra), and white oak (Q. alba). An additional seven species, including shadbush (Amelanchier sp.), black birch (B. lenta), paper birch (B. papyrifera), alternate-leaved dogwood (Cornus alternifolia), hawthorn (Crataegus sp.), black cherry (Prunus serotina), and black oak (Q. velutina), continue to be observed through bud break. This subset of important, representative species has allowed us to continue to characterize leaf development each spring and document inter-annual variability while reducing the resources required for the study significantly.

    We have also recorded fall phenology since 1991, with the exception of 1992. Approximately weekly observations of leaf coloration and leaf fall begin in September and continue through leaf fall. In 2002 the number of species observed in the fall was reduced to fourteen, including red maple (Acer rubrum), sugar maple (A. saccharum), striped maple (A. pensylvanicum), shadbush (Amelanchier sp.), yellow birch (Betula alleghaniensis), black birch (B. lenta), paper birch (B. papyrifera), beech (Fagus grandifolia), white ash (Fraxinus americana), black gum (Nyssa sylvatica), black cherry (Prunus serotina), white oak (Quercus alba), red oak,(Q. rubra) and black oak (Q. velutina).

    All individuals are located within 1.5 km of the Harvard Forest headquarters at elevations between 335 and 365 m, in habitats ranging from closed forest, through forest-swamp margins, to dry, open fields.