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Study Area

During the week of April 16, 2007, sound measurements were taken from two different helicopters while they performed typical logging operations on two southwestern Oregon timber sales. The sales were administered by the U.S. Department of the Interior, Bureau of Land Management (BLM), Coos Bay District. The Moon 25 timber sale was located along Moon Creek, approximately 13 miles northeast of Coquille, OR. The Cedar House timber sale was approximately 10 miles northeast of Scottsburg, OR, and about 27 miles northeast of Reedsport, OR (see figure 1).

The forest vegetation on the timber sale areas was typical of western Oregon's mixed conifer forest. The Moon 25 timber sale was primarily western hemlock and Douglas fir. The objective was to thin about 1,100 acres of primarily conifer stands. About 800 acres received density-management thinning; about 200 acres received commercial thinning. Dense stands were thinned to approximately 60 to 80 stems per acre by removing primarily the suppressed, intermediate, and codominant conifers. The dominant and larger codominant conifers were retained (BLM 2003).

The Cedar House sale area was primarily scattered, decadent old-growth and mature Douglas fir with western hemlock, western red cedar, and grand fir intermixed. The objective of the 111-acre timber sale was a regeneration harvest (BLM 1998).

Figure 1. Location of the "Moon 25" and "Cedar House" Timber Sales in SW Oregon (on public land administered by the Bureau of Land Management, Coos Bay District).

Weather was typical for mid-spring in western Oregon, 50 to 60 °F with scattered showers. Table 1 provides details on daily weather conditions (wind, temperature, humidity) during the study period.

For a pdf version of Table 1 - click here.

For HTML version of Table 1—Weather data and notes taken during sound measurements of the KMAX and Vertoil 107 helicopters during helicopter logging operations.

Photos showing the sound measurement data gathering effort of the helicopter logging operations appear in appendix 1.

On October 17, 2007, additional measurements were taken at a timber sale in Detroit, OR. The data is provided in appendix 4.