Pacific Northwest Research Station

PNW > Research > Large Scale Siviculture Experiments > Demonstration of Ecosystem Management Option Study

Large-Scale Silvicultural Experiments In Western Oregon and Washington

Demonstration of Ecosystem Management Options Study

Initial Installation Years: 1994-1995

Primary Objectives: Determine how the level of retention following overstory removal influences biological values and social perceptions of mature, coniferous forests. Determine whether, for a particular level of retention, spatial pattern of retention important. Determine whether a 15% level of retention is sufficient to maintain the organisms and processes that characterize late-seral forests in the Pacific Northwest. Determine which species or groups of organisms are most sensitive to variation in the amount or spatial pattern of retention.

Pre-treatment Conditions: 65- to 170-year-old stands.

Locations: Butte (46.3720°N, 121.5920°W), Capitol Forest (46.8880°N, 123.1230°W), Dog Prairie (43.1960°N, 122.3060°W), Little White Salmon (45.8580°N, 121.7020°W), Paradise Hills (46.0030°N, 122.0430°W), and Watson Falls (43.2620°N, 122.2460°W).

Initial Treatments: 5 overstory removal treatments and 1 unthinned control each replicated 1 time at 6 locations.

No Overstory Removal (Control)

100% Retention (1a). Provide untreated control. Not thinned. Not planted. No woody debris or other initial treatments.

Light Overstory Removal

75% Aggregated Retention (2a). High retention in aggregated fashion. 3 circular 2.471-ac (1-ha) patches harvested in an evenly spaced triangular array removing 25% of the stand basal area. 2.6 snags/ac created in harvested areas from dominant/co-dominant trees. Planted ~165 to 300 tpa to achieve minimum stocking; mix comprised of 2-5 species which varied by geographic location. No additional woody debris or other initial treatments.

Moderate Overstory Removal

40% Aggregated Retention (3a). Moderate retention in aggregated fashion. 5 undisturbed 2.471-ac (1-ha) circular patches are retained evenly spaced within the harvest unit. Planting and snag treatments identical to DEMO treatment 2a. No additional woody debris or other initial treatments.

40% Dispersed Retention (3b). Moderate retention in dispersed fashion. Dominant and co-dominant trees are retained in an even distribution throughout the treatment unit; total basal area equivalent to that retained in DEMO treatment 3a. Planting and snag treatments identical to DEMO treatment 2a. No additional woody debris or other initial treatments.

Heavy Overstory Removal

15% Aggregated Retention (4a). Low retention (NWFP minimum) in aggregated fashion. 2 undisturbed 2.471-ac (1-ha) circular patches are retained at diagonally opposite positions within the harvest unit. Planting and snag treatments identical to DEMO treatment 2a. No additional woody debris or other initial treatments.

15% Dispersed Retention (4b). Low retention (NWFP minimum) in dispersed fashion. Dominant and co-dominant trees are retained in an even distribution throughout the treatment unit; total basal area equivalent to that retained in DEMO treatment 4a. Planting and snag treatments identical to DEMO treatment 2a. No additional woody debris or other initial treatments.

Complete Overstory Removal (Clearcut)

None.

Response Variables: Over-, mid-, and understory vegetation; lichens and bryophytes; arboreal mammals; small mammals; bats; birds; arthropods; amphibians; mollusks; woody debris; fungi; microclimate; hydrology; social perceptions; forest floor.

Study Plan: U.S. Department of Agriculture, Forest Service. 1996. Demonstration of Ecosystem Management Options: a study of green-tree retention levels and patterns in western Oregon and Washington. Unpublished study plan. On file with: U.S. Department of Agriculture, Forest Service, Pacific Northwest Research Station, Portland Forestry Sciences Laboratory, 620 SW Main Street, Suite 400, Portland, OR 97205.

Website: http://www.cfr.washington.edu/research.demo/

(last accessed 2006-12-06)

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USDA Forest Service - Pacific Northwest Research Station
Last Modified:  Tuesday, 29 January 2008 at 17:12:37 EST