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Harvard Forest Symposium Abstract 2011

  • Title: Effects of warming on tree species' recruitment in deciduous forests of the eastern USA
  • Primary Author: Sarah Butler (Marine Biological Laboratory)
  • Additional Authors: Frank Bowles (Research Designs); James Clark (Duke University); Jerry Melillo (Marine Biological Laboratory); Jacqueline Mohan (University of Georgia); Carl Salk (Duke University); Lindsay Scott (Marine Biological Laboratory); Rose Smith (Marine Biological Laboratory)
  • Abstract:

    Climate change is predicted to alter the composition and structure of the forests of the United States over the coming century with projected increases in temperatures of between 2 and 8°C and associated changes in soil moisture. These environmental changes will likely affect various aspects of tree recruitment, including germination, growth and mortality. To examine the effects of warming on these sensitive stages of development, we are conducting air and soil warming experiments in two eastern deciduous forest sites; one at the Harvard Forest in central Massachusetts, and the other at the Duke Forest in the piedmont region of central North Carolina. At each site, we planted seeds of select tree species near their northern or southern range limits in temperature controlled, open-top chambers. The experimental chambers span two light regimes (closed forest canopy and gap conditions), three temperature regimes (ambient, 3°C, 5°C) and three moisture regimes (upslope, midslope, downslope). By measuring germination, growth, survival and phenology we hope to discern how warming will affect changes in species distribution and light and temperature interactions within and amongst species. Preliminary results show that germination and budburst occur earlier with warming for nearly all species. However, species’ sensitivity decreases as temperatures increase. Thus, warming leads to plants’ leafy season beginning and ending in warming temperatures. This suggests that trees’ growing seasons will fall increasingly short of the meteorological growing season as global warming progresses, constraining their ability to act as bigger carbon sinks in a warmer future.

  • Research Category: Large Experiments and Permanent Plot Studies