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Pacific Northwest Research Station
Large-Scale Silvicultural Experiments In Western Oregon and Washington
Young Stand Thinning and Diversity Study
Initial Installation Years: 1994-1996
Primary Objectives: Provide scientific information on the biological consequences of thinning. Provide agencies with experience in adaptive management which enhances both the creation of timber-related jobs and increased production and utilization of wood fiber.
Pre-treatment Conditions: 35- to 45-year-old, even-aged, Douglas-fir plantations.
Locations: Christy Flats (43.8857°N, 122.3438°W), Cougar Reservoir (44.1000°N, 122.2500°W), McKenzie Mill (44.1786°N, 122.2708°W), and Tumble Creek (43.8714°N, 122.3333°W).
Initial Treatments: Three thinning treatments and one unthinned control each replicated 1 time at 4 locations.
No Overstory Removal (Control)
Control (1a). No treatment. Provide baseline. Not thinned. Not planted. No woody debris or other initial treatments.
Light Overstory Removal
Light Thin, no gaps (2a). Timber production and wood quality. Thinned 100% of stand to 100–110 tpa. Not planted. No woody debris or other initial treatments.
Light Thin, gaps (2b). Maximum horizontal and vertical heterogeneity. Patch-level approach to creating and enhancing the understory. Thinned 80% of stand to 100–110 tpa. Cut 20% of stand to create 0.5-acre gaps one tree height in diameter (~80 ft at initial treatment). Gaps planted. No woody debris or other initial treatments.
Moderate Overstory Removal
Heavy Overstory Removal
Heavy Thin (4a). Accelerate the development of late-successional habitat. Stand-level approach to creating and enhancing the understory. Thinned 100% of stand to 50–55 tpa. Underplanted. No woody debris or other initial treatments.
Complete Overstory Removal (Clearcut)
Response Variables: Over-, mid-, and understory vegetation; small mammals; birds; snags; woody debris; fungi; soils; social perceptions; wood production, operational factors; forest floor.
Study Plan: No formal study plan found, although several study plan-like files exist. On file with: P. Anderson, U.S. Department of Agriculture, Forest Service, Pacific Northwest Research Station, Corvallis Forestry Sciences Laboratory, 3200 SW Jefferson Way, Corvallis, OR 97331.
(last accessed 2006-12-06)
US Forest Service - Pacific Northwest Research Station