Walt Kastner and Charlie Thompson, Bureau of Land Management, Salem, OR

Density Management studies conducted on BLM lands in western Oregon under the direction of Dr. John Tappeiner may provide insights into the kinds of treatments that could set stands on a trajectory to develop some important late-successional forest characteristics. Such treatments being tested in these studies include various levels of overstory retention combined with small patch-cut openings, underplanting, retention of existing snags and down wood, and unthinned "leave" islands. The Phoenix Density Management Project represents a practical application of some of the concepts being investigated in these studies.

The Phoenix Density Management Project is a 50-acre commercial thinning located in the upper Nestucca River watershed, about 20 miles inland from the Pacific Ocean, and just west of the Oregon Coast Range summit. The project is in the Northern Coast Range Adaptive Management Area, but has a Late-Successional Reserve (LSR) land-use designation in addition because of concerns for the marbled murrelet (a robin-sized sea bird listed as threatened under the Endangered Species Act). No Riparian Reserves occur within the treatment area.

LSR Standards and Guidelines apply. Treatments in LSR's must be beneficial to the attainment of late-successional forest conditions. The Nestucca River Watershed Analysis identified lack of late-successional habitat as the major factor contributing to declining population viability of many wildlife species in the watershed. About 60% of the Nestucca River Watershed Analysis area is in early seral habitat and 40% is in early- to mid-seral habitat, with less than 1% of the stands more than 130 years old.

The objectives of the treatment were to accelerate development of some late-successional forest habitat features, including large trees with large crowns and limbs, gaps in the canopy, snags and down logs, various levels of overstory tree density, and a variable degree of establishment and growth of understory species. In addition, implementation of the prescription was expected to set the stage for future treatments that could continue this process. The project proposal was reviewed by the Regional Ecosystem Office (an interagency Northwest Forest Plan oversight group) and determined to be consistent with the Standards and Guidelines for LSR's in the Northwest Forest Plan.

The area was selected for treatment because the majority of it consisted of a relatively dense, single-storied stand that was of an age and condition expected to respond favorably to density management (thinning). The stand was also situated in a relatively isolated patch of forest habitat in a highly fragmented portion of the Nestucca River watershed where the potential short-term adverse impacts to species listed as threatened or endangered were considered to be very low. Without treatment or some other form of disturbance, development of late-successional forest structure in this area was anticipated to be very slow for at least the next 50 years or more.

At the time the area was proposed for treatment, it was dominated by a 70-year-old, even-aged Douglas-fir stand. There were, however, a few widely spaced pockets of 90-year-old Douglas-fir trees. For the most part, the trees were fairly uniform in size and in spacing, and formed a single canopy layer. There was a small amount of western hemlock advance regeneration in the understory, and the density of the understory shrubs varied throughout. Small scattered patches of Douglas-fir beetle-caused mortality associated with root disease also occurred.

Most relatively sound snags (decay classes 1 and 2) were from Douglas-fir beetle-caused mortality in root disease pockets. Scattered soft snags (decay classes 4 and 5) occurred throughout. Pre-treatment down wood levels were fairly high (averaged 3,154 cubic feet/acre), but the majority (71%) was in the advanced stages of decay (decay classes 4 and 5). Concentrations of down wood occurred in root disease pockets and in a small patch of windthrow along an existing clearcut edge.

The prescribed treatments were:

• Reduce stand density in a "variable-spaced" manner to an average of about 70 trees per acre, but ranging from about 50 to 90 trees per acre, by removing mostly the smaller-diameter trees.
• Retain approximately 10% of the stand in unthinned areas.
• Exclude existing small, snag-containing canopy openings (mortality patches) created by Douglas-fir beetles and root disease.
• Leave clumps of two or three up to a dozen trees scattered throughout.
• Girdle the tops of one tree/acre in the live crown to create snag-topped trees.
• Occasionally reserve pairs of trees spaced four feet apart or less to provide an opportunity to develop "protected" snags in the future.
• Reserve hardwood trees larger than 10 inches dbh.
• Do not fell unmerchantable trees.
• Surround advance western hemlock regeneration in a small leave-tree clump and thin wider around the clump.
• Surround selected soft snags in a small leave-tree clump.
• Retain large trees with deformities.
• Reserve snags not considered a safety hazard and all existing down logs.
• Retain four of the larger leave trees cut to create each skyline corridor on site for down wood.
• No felling or yarding during the critical marbled murrelet breeding period (April 1 to August 6).
• Plant selected Douglas-fir mortality patches (gaps) and openings around landings with western hemlock and western redcedar.

As a result of implementing the prescription, the timber volume harvested was 1,070,000 board feet or 21,400 board feet/acre. The sale was purchased at the appraised price of $221 per MBF (1,000 board feet), for a total sale price of $236,470. All harvesting was done with a skyline logging system. Harvesting was completed in December 1998.

There was very little residual tree damage or soil disturbance associated with the thinning. Permanently located 0.2-acre monitoring plots were established in each of the residual density levels, including an untreated area, to help evaluate the progress toward achieving project objectives. Since completion of the project in December 1998, 28 additional Douglas-fir trees died in the unit (or in a few cases, within about 150 feet of the unit boundary). Most of the mortality (89%) was associated with Douglas-fir beetles and/or Douglas-fir beetles combined with root disease. Only 11% of the mortality was associated with root disease alone.

Four factors were primarily responsible for the success of this project: (1) the team members involved in planning the project participated in project implementation, (2) there was a high level of enthusiasm among the team members throughout the entire process, (3) we were able to have open and productive dialog with the Regional Ecosystem Office during their review of the project proposal, and (4) the logger was experienced in logging sales in Late-Successional Reserves under the Northwest Forest Plan.

Keywords: thinning, density, management, Douglas-fir.