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Harvard Forest Symposium Abstract 2019

  • Title: Wood structure drives secondary growth phenology of Eastern US temperate species
  • Primary Author: Loic D'Orangeville (University of New Brunswick)
  • Additional Authors: Malcolm Itter (Michigan State University); J. William Munger (Harvard University); David Orwig (Harvard Forest); Yude Pan (USDA Forest Service); Neil Pederson (Harvard Forest); Andrew Richardson (Northern Arizona University)
  • Abstract:

    Climate models project warmer summer temperatures leading to increasing drought in temperate forests of Eastern North America (ENA). Such droughts are increasingly documented to affect tree growth, with critical impacts on carbon sequestration, forest dynamics and timber provision. Considering the high sensitivity of growth to the timing of drought events, an accurate species-level understanding of radial growth phenology is crucial to assess the vulnerability of temperate stands to climate change.
    In this study, we use well-replicated dendrometer band data from the Harvard Forest in the Eastern United States to assess the growth phenology of 611 trees from 15 northern temperate species across six years. Radial growth follows a typical logistic shape, with initially low growth rates reaching a maximum in June, then decreasing until process termination. Focusing on the period of rapid growth, we find that diffuse-porous species take 38±8 days to put on 50% of their annual increment, 17-19±10 days less than other wood-structure types. This faster growth rate is associated with a delayed phenology, as diffuse-porous species attain 50% of their annual increment almost a full month (22 to 26±4 days) later than ring-porous and conifer species. When we match the species period of rapid growth with water availability during the six-year study period, we find that diffuse-porous species were subject to a mean 88±19mm of water deficit, compared to 15±35 mm and 30±30 mm for ring-porous and coniferous species. Considering the high climatic sensitivity of growth, these results suggest that the growth of diffuse-porous species may react differently to climate because of its later occurrence in the season, coincidental with higher evapotranspiration and lower water availability.

  • Research Category: Physiological Ecology, Population Dynamics, and Species Interactions; Large Experiments and Permanent Plot Studies

  • Figures:
  • Fig4GrowthWoodStructure.png