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Pacific Northwest Research Station
Large-Scale Silvicultural Experiments In Western Oregon and Washington
Density Management Study, Re-Thinning
Initial Installation Years: 1996-2007
Primary Objectives: Evaluate effects of alternative forest density management treatments on important stand and habitat attributes in stands thinned 25-30 years earlier to >100 tpa. Determine treatment effects on selected plant and animal taxa. Use these sites to develop operational approaches to implementation of new prescriptions, improve methods for effectiveness monitoring of plant and animal taxa, and to share results of on-the-ground practices and findings with land managers, regulatory agencies, policymakers, and the public.
Pre-treatment Conditions: 60- to 90-year-old stands.
Locations: Blue Retro (43.2803°N, 124.0825°W), Little Wolf (43.4222°N, 123.6292°W), North Ward (43.7689°N, 123.2014°W), Perkins Creek (43.7142°N, 122.9131°W), and Sand Creek (44.8347°N, 123.5906°W).
Initial Treatments: 1 thinning treatment and 1 unthinned control each replicated 1 time at 5 locations.
No Overstory Removal (Control)
Unthinned Control (1a). 25–30 years prior to initial DMS_RT treatments, overstory density reduced to >100 tpa in a single commercial thinning. Initial DMS_RT thinning: not thinned. Not planted. No woody debris or other initial treatments.
Light Overstory Removal
Moderate Overstory Removal
Re-Thin (3a). 25–30 years prior to initial DMS_RT treatments, overstory density reduced to >100 tpa in a single commercial thinning. Initial DMS_RT thinning: thinned 100% of stand to a clumpy distribution of 40–60 tpa. Not planted. No woody debris or other initial treatments.
Variable Density Retention (3b). Thinned 10% of stand to 40 tpa, thinned 25-30% of stand to 80 tpa. Thinned 25-30% of stand to 120 tpa. Cut 10% of stand to create circular gaps (0.25, 0.5, and 1.0 acres). Left 10% of stand in circular leave islands (0.25, 0.5, and 1.0 acres). Left 15-20% of stand as unthinned riparian buffers. Planted gaps and underplanted 40 tpa overstory areas with western hemlock, Douglas-fir, western redcedar, and grand fir. No woody debris or other initial treatments.
Heavy Overstory Removal
Complete Overstory Removal (Clearcut)
Response Variables: Over-, mid-, and understory vegetation; snags; woody debris; forest floor.
Study Plan: Cissel, J.H.; Anderson, P.D.; Berryman, S.; Chan, S.S.; Olson, D.H.; Puettmann, K.J.; Thompson, C. 2006. BLM Density Management and Riparian Buffer Study: establishment report and study plan. Scientific Investigations Report 2006–5087. Reston, VA: U.S. Department of the Interior, Geological Survey. 144 p.
(last accessed 2006-12-06)
US Forest Service - Pacific Northwest Research Station