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Hemlock Removal by Logging or Hemlock Woolly Adelgid

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Arrival of the hemlock woolly adelgid to New England is generating two substantial but contrasting impacts across the New England landscape:

  • gradual mortality of hemlock due to the direct impact of the insect
  • widespread logging of hemlock in advance of mortality or infestation

Although both processes affect thousands of acres of forest annually we have only a limited understanding of their effects on forest ecosystem function and productivity and the nature of the subsequent forest community. We anticipate that harvesting will yield different consequences than gradual mortality from the insect. Therefore we have designed an experiment to simulate the impact of both in order to contrast them. To simulate some of the effects of the adelgid (e.g., progressive mortality, retention of the wood on the site) we are girdling all hemlocks in a hemlock-dominated stand. In the adjacent area we are conducting a commercial harvesting of hemlock. Results from both experimental treatments will be compared to the changes observed in forests that are being infested by the adelgid.

This experiment began in 2005 and continues as part of the Harvard Forest Long-Term Ecological Research program.