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Harvard Forest Symposium Abstract 2018

  • Title: Decades to Centuries
  • Primary Author: Loic D'Orangeville (University of New Brunswick)
  • Additional Authors: Malcolm Itter (Michigan State University); David Orwig (Harvard Forest); Yude Pan (USDA Forest Service); Neil Pederson (Harvard Forest)
  • Abstract:

    Tree vigor is strongly sensitive to water deficit in most forest ecosystems. Non-structural carbohydrates are increasingly considered as crucial elements of tree vulnerability to water deficit, as their depletion can potentially cause drought effects to persist in time for multiple years until refilling or completion of hydraulic repairs. Our capacity to predict forest vulnerability to drought is currently limited by our understanding of the additive effects of antecedent water stress on tree vulnerability and the legacy of their impact over time, referred to therein as ecological memory. Recent advances in modelling now allow to explicitly consider antecedent drought conditions on current growth dynamics without any a priori assumption on the persistence and level of influence from antecedent water stress. Further, such approach allows to determine how species traits, biotic or abiotic contexts influence that ecological memory.
    The main objective of this study is to estimate how stand and site factors control water deficit effects. Using ecological memory functions, we will precisely estimate how species, tree size, microsites, and insect defoliation control the persistence and cumulative effect of past water deficit on tree vigor at the monthly scale.
    To reach this objective, we will match seasonal growth from dendrometer bands with local climate data. Going back to 1998 for some trees, these bands monitor the growth of over 1000 Harvard Forest trees, including 600 mapped trees with flux tower footprints. This 20-yr dataset will provide a unique insight into intra-seasonal response of multiple species to disturbances such as water deficit and the impacts of the hemlock woolly adelgid. Such knowledge could inform management strategies, especially our capacity to predict drought-induced mortality according to local stand characteristics.
    We will present preliminary results regarding species seasonal growth trends and recent water deficits.

  • Research Category: Invasive Plants, Pests & Pathogens; Large Experiments and Permanent Plot Studies; Physiological Ecology, Population Dynamics, and Species Interactions