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Pacific Northwest Research Station
Large-Scale Silvicultural Experiments In Western Oregon and Washington
Capitol Forest Study
Initial Installation Years: 1998-2004
Primary Objectives: Create on-the-ground examples of a number of contrasting silvicultural systems (i.e., a range of disturbances and levels of retention) that can be evaluated for effectiveness in reducing visual and other environmental impacts of forestry operations, while providing high timber outputs over time. Monitor development of stands under these contrasting systems over an extended time period with procedures that will provide quantitative estimates of vegetation change and timber outputs, and statistically sound tests of differences between systems.
Pre-treatment Conditions: 40- to 70-year-old, even-aged Douglas-fir stands.
Locations: Blue Ridge (46.8500°N, 123.1500°W), Copper Ridge (47.0333°N, 123.0667°W), and Rusty Ridge (46.9500°N, 123.2000°W).
Initial Treatments: 5 thinning treatments and 1 unthinned control each replicated 1 time at 3 locations.
No Overstory Removal (Control)
Control (1a). Provide a comparison with gains obtainable by the repeated thinning regime when some stands are held on an extended rotation as a means of adjusting currently unbalanced age distributions and reducing visual impacts on the landscape. Not thinned. Not planted. No woody debris or other initial treatments.
Light Overstory Removal
Repeated Thinning (2a). Extended rotation with repeated, light, commercial thinnings. Thinned 100% of stand to RD 40–50. Not planted. No woody debris or other initial treatments.
Moderate Overstory Removal
Group Selection (3a). Group selection uneven-age management, producing a unit consisting of five age classes on an approximately 50- to 75-year rotation. Thinned 80% of stand to RD 45 as needed. Cut 20% of stand in groups ranging from individual trees to groups of trees not larger than 1.5 acres in size on a 10- to 15-year cycle. Harvest groups dispersed throughout stand. Planted openings larger than 0.10 acre to Douglas-fir. Control competing vegetation as needed. No woody debris or other initial treatments.
Patch Cut (3b). Patch-wise uneven-age management, producing a unit consisting of five age classes on an approximately 50- to 75-year rotation. Thinned 80% of stand to RD 45 as needed. Cut 20% of stand to create somewhat irregularly shaped 1.5-acre to 5.0-acre patches on a 10- to 15-year cycle. Harvest patches dispersed throughout stand. Patches planted to Douglas-fir and/or a mix of Douglas-fir and other species. Control competing vegetation as needed. No woody debris or other initial treatments.
Heavy Overstory Removal
Two-Age (4a). Reserve shelterwood resembling a conventional shelterwood but with the overwood, or a portion of it, carried through the second rotation to provide large diameter trees and high-quality material. Thinned 100% of stand to 15 tpa (leave trees selected for spacing, vigor, and stem quality). Underplanted Douglas-fir. Control competing vegetation as needed. No woody debris or other initial treatments.
Complete Overstory Removal (Clearcut)
Clearcut (5a). Provide a direct quantitative comparison of clearcut costs and outputs with those of the other regimes. Clearcut 100% of stand, except for scattered groups of leave trees as needed to meet Washington Department of Natural Resources (WADNR) rules. Plant according to current WADNR practices. Control competing vegetation as needed. No woody debris or other initial treatments.
Response Variables: Over-, mid-, and understory vegetation; lichens, mosses, and bryophytes; birds; snags; social perceptions; wood production; economics; operational factors; forest floor.
Study Plan: Curtis, R.O.; Clendenen, G.W.; DeBell, D.S.; DeBell, J.; Shumway, J.; Poch, T. 2001 (revised; originally 1997). Silvicultural options for harvesting young-growth production forests. Part I. The stand-level silvicultural experiment. Study plan (silviculture). On file with: R. Curtis, U.S. Department of Agriculture, Forest Service, Pacific Northwest Research Station, Olympia Forestry Sciences Laboratory, 3625 93rd Avenue SW, Olympia, WA 98512.
(last accessed 2006-12-06)
US Forest Service - Pacific Northwest Research Station