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Swiss Needle Cast and Commercial Thinning
Sparse yellow crowns of Douglas-fir in western Oregon damaged by Swiss needle cast
The purpose of the project is to determine the interaction between thinning of older stands (30+ years old) and disease severity and intensity of thinning. The approach includes a combination of a retrospective study of stand growth since thinning with permanent monitoring plots to track future growth.
 
Results from the retrospective study indicated a positive response to thinning in many stands.  These results were incorporated into a revision of the Oregon Department of Forestry Swiss needle cast Strategic Plan (September 2003).  In summary, study results to date indicate that thinning does not increase Swiss needle cast severity and that the average stand showed a positive basal area growth response to thinning regardless of Swiss needle cast severity.  These results are reinforced by initial information from 2 years of current growth data (not retrospective) from the permanent plot portion of the study.  The study will continue, with additional plot measurements and analysis scheduled for 2007.
 
These results are significantly influential to the Tillamook District, where district plans are governed by decisions on Swiss needle cast management.  West Oregon and Astoria Districts were less affected by the research results.  In response to the research findings, actions have already begun or are under consideration to adjust the annual operation plans and implementation plans for the Tillamook district. 
 
At the Annual Operational Plan level:
  • Develop and apply Swiss needle cast stand assessment tool (Currently being tested by Oregon State University and the Oregon Department of Forestry; see descriptions under “Stand Growth Assessment Tool”)
  • Adjust thinning prescriptions to reflect recent research and to meet various objectives.
 
At the Implementation Plan level, and via Harvest and Habitat Model:
  • Incorporate recent Swiss needle cast information into the Harvest and Habitat Model.  Document Swiss needle cast model inputs and assumptions.
  • In initial modeling runs, harvest “severe” Swiss needle cast stands over 20 years.
  • In future modeling, develop some Swiss needle cast “scenarios”.
  • Reflect recent Swiss needle cast findings in a revised Tillamook Implementation Plan.  In the implementation plan, for the purposes of Swiss needle cast management, more stands should be identified as potential candidates for commercial thinning, and fewer stands identified as regeneration harvest candidates.
  • Implementation plans should remain sufficiently flexible to take advantage of new information or a status change in Swiss needle cast.
 
No changes at this time were recommended at the Forest Management Plan level.

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