Presented to DTO and ODF, August 4, 2006, Veneta, OR
John Sessions and Pam Overhulser

DTO has been coordinating with ODF’s Coos District and Salem headquarters managers to explore the capacity of the Elliott State Forest to produce harvest schedules with a wood production emphasis. The harvest scheduling is being done by Pam Overhulser, ODF staff Resource Analyst, with assistance from Professor John Sessions, Oregon States University, as needed to provide model modifications to achieve required goals. This exploration is being done to provide DTO and managers with estimates of the maximum sustainable wood flow from the Elliott under various assumptions about the long term sustained yield of the future forest and the conversion period of the existing forest to the future forest.

Background

An initial meeting with District and State Office Managers was held in Veneta on May 20, 2006 to define the assumptions and some preliminary alternatives that might be useful in starting the evaluation. Several harvest scheduling patterns were suggested with the intention of providing a range of alternatives to give direction to a more focused analysis.

The preliminary runs would:

  • Maximize the first 30 year harvest over a 150 year planning horizon (30 5-year periods)
  • Use Forest Practice Act rules
  • Have no minimum harvest age
  • Have an ending inventory, outside the “no harvest” areas, at least equal to that of the regulated forest consistent with the assumptions for that schedule.
  • Net present value would be reported using ODF costs and prices and discount rate (4.5%).
  • Silviculture — Intensive industrial: site prep, plant, release, PCT, fertilize, and thins at least 8 mbf/ac per entry. The modeling runs would use the growth and yield projections ODF has already developed for a Wood Emphasis Alternative. The few prescriptions thinning less than 8 mbf would be flagged as not eligible in the modeling runs. Fertilization is included as an optional treatment, allowing the harvest scheduling model to choose among fertilization and non-fertilization prescriptions to best meet the run objectives.
  • Owls: 17 owl sites that remain static throughout 150 years (existing locations) with no harvest within a 70-acre core area.
  • Murrelets: No reserves
  • Aquatic/riparian strategy would be modeled using no harvest in ODF’s current Wood Emphasis buffers which occupy about 3% of the total acres.
  • Green tree retention – 2 TPA, 14 inch DBH

Steep Areas – No harvest. ODF reviewed the current Steep land allocation and identified only those lands that would fall under the steep, no harvest guidelines of the Forest Practices Act. Unique and visual forested acres remained in the timber base for the Wood Emphasis harvest scheduling runs.

Forest structure over time would be displayed using categories the District has developed to identify structure suitable for older forest species (roosting and nesting habitat for the northern spotted owl, and nesting habitat for the marbled murrelet.)

The results were presented at a July 7, 2006 meeting at the Eastern Lane ODF office in Springfield. During the July 7, 2006 meeting, several additional runs were identified to examine a longer elevated harvest period (50 years) as compared to the initial 30 year period of elevated harvests as well as a broader range of future harvest ages. These harvest schedules were presented at a July 24, 2006 meeting in Veneta. Based upon the July 24, 2006 discussions in Veneta, one additional run was requested to examine a 50 year elevated harvest, transitioning to a 70-year old future forest under a static owl core policy of 250 acres.

The following discussion summarizes the two harvest schedules that DTO would like to present to the Land Board to illustrate the capacity of the Elliott State Forest to produce harvests under a specified set of assumptions, a Baseline and an Intermediate Alternative. For reference purposes, DTO requested the harvest schedule associated with Elliott State Forest’s Proposed Landscape Strategy be displayed on the same graphs. As background, a short introduction to the long term sustained yield harvest level, long term inventory, and forest structure classification is provided for context.

Long Term Sustained Yield

Part of the harvest scheduling process requires identifying the long term sustainable forest inventory and age distribution. To help set the long term goals for harvest volume and standing inventory, the long term sustained yield and forest inventory under a range of rotation ages were developed. The long term sustained harvest yield varied from about 57 million board feet to 64 million board feet depending upon the future rotation age of the regulated forest (Fig. 1). The harvest volume would come from a timber production land base of 81,000 acres. No harvest contribution is assumed from the remaining 12,000 acres of riparian buffers, steep, and unstable lands, owl core habitat (17 cores at 70 acres), and non-forest lands within the Elliott.

The estimate of the inventory on the timber production base (measured after harvest in any 5-year period) varied from about 750 mmbf for a 50 year rotation to about 3200mmbf for a 120 year rotation (Fig. 2). These estimates were based upon prompt site preparation, planting, and release. No thinnings or genetic improvements were assumed. The current forest has a standing inventory of about 2000 mmbf on the 81,000 acres of the timber production base.

For an owl core habitat policy of 250 acres per core, the timber production base would be about 3200 acres lower (78,000 acres versus 81,000 acres) so the existing long term sustainable harvest and inventory on timber producing base would be approximately 4% lower as well.

Forest Structure

Advanced structure from all forested acres on the Coos district contributes toward the advanced structure acres. Advanced structure is divided into three categories. Advanced-1 is a surrogate for roosting habitat for the spotted owl. It must have at least 20 TPA at least 18” DBH that includes at least 10 TPA that are at least 24” DBH. The quadratic mean diameter of trees 8” DBH or over must be at least 15” DBH. The basal area per acre must be between 150 and 325 sq. ft.

Advanced-2, more complex than advanced-1, is a surrogate for the nesting habitat for the spotted owl. In addition to the advanced-1 per acre characteristics it must have at least 8 TPA that are at least 32” DBH.

Advanced-3, more complex than advanced-2, is a surrogate for murrelet habitat. In addition to the characteristics of advanced-2 it must have at least 4 TPA that are at least 38” DBH with the quadratic mean diameter of trees 24” DBH or over at least 35.2” DBH.

The structure classes are hierarchical in the sense that acres of Advanced-3 meet the conditions of Advanced-2. Advanced-2 acres meet the conditions of Advanced-1.

Figure 1. Long term sustained yield resulting from a regulated forest of different rotation ages for an 81,000 acre timber production timber base (70 acre owl core)

Definition of Harvest Schedules

Baseline for Comparison: Maximize harvest that can be maintained over a 50 year period transitioning to a future forest with an inventory equal to that of a 50-year old regulated forest. Owl core policy would be to maintain 17 cores at 70 acres each over a 150 year planning horizon.

Intermediate Alternative: Maximize harvest that can be maintained over a 50 year period transitioning to a future forest with an inventory equal to that of a 70-year old regulated forest. Owl core policy would be to maintain 17 cores at 250 acres each over a 150 year planning horizon.

Elliott State Forest (ESF) Proposed Landscape Strategy: Strategy ODF is proposing that develops specific amounts of advanced forest structure per basin to provide for threatened and endangered species while providing a non-declining harvest flow that is substantially higher than the recent past.

Figure 2. Standing Inventory on the timber production base (after harvest basis) resulting from a regulated forest of different rotation ages for a 81,000 timber production base (70 acre owl core).

Harvest Schedule Results

Baseline: (Net present Value = $747 million)

The harvest level over the first fifty years would be about 75 mmbf, dropping to about 53 mmbf, then trending upward to the sustainable harvest level associated with a 50-year old regulated forest of about 58 mmbf (Fig 3). The inventory on the timber production base declines over the first 50 years to about 750 mmbf, a level equal to a forest managed on a 50-year rotation on the 81,000 acre timber base (Fig 4). Acres excluded from the timber base are non-forested, owl cores, steep slopes, and riparian buffers. Total inventory declines over the elevated harvest period, then rises slowly (Fig 5). Annual cash flows generally parallel the harvest flows (Fig 6).

The total advanced forest structure (Fig 7) declines rapidly to about 25% of the advanced forest structure at the beginning of the scheduling period. The highest forest structure (Advanced 3) declines, then increases near the end of the planning horizon as acres outside the timber production base become more complex (Fig 8). All Coos district acres are included in the structure base.

Intermediate Alternative: (Net present Value = $612 million)

The harvest level over the first fifty years would be about 60 mmbf, dropping to about 53 mmbf, then trending upward to the sustainable harvest level associated with a 70-year old regulated forest of about 61 mmbf. The inventory on the timber production base declines over the first 50 years to about 1475 mmbf, a level equal to that of a forest managed on a 70-year rotation on the 78,000 acre timber base (Fig 4). Total inventory remains constant at about the initial inventory level over the elevated harvested period, then slowly increases (Fig 5). Annual cash flows generally parallel the harvest flows (Fig 6). The total advanced forest structure (Fig 7) declines less rapidly than the Baseline to a level about 35% advanced forest structure at the beginning of the scheduling period. The highest forest structure (Advanced 3) remains fairly constant, increasing near the end of the planning horizon as acres outside the timber production base become more complex (Fig 9).

Elliott State Forest (ESF) Landscape Strategy: (Net present Value = $359 million)

The harvest level over the 150 years would be about 40 mmbf. The inventory on the timber production base increases over the planning horizon on the 69,000 acre timber production base (Fig 4) as well as the total forest (Fig 5). Annual cash flows generally parallel the harvest flows (Fig 6). The total advanced forest structure (Fig 7) remains constant for the first 15 years, then increases to a level about 25% higher than the initial level and occupies about 50% of the forest after 50 years. The highest forest structure (Advanced 3) increases rapidly to more than double its existing level (Fig 10).

Figure 3. Harvest output over the 150 year planning horizon. Figure 4. Forest Inventory over the 150 year planning horizon on their respectivetimber production base (Baseline=81,000 acres, Intermediate=78,000 acres, ESF=69,000 acres).
Figure 5. Forest Inventory over the 150 year planning horizon on the District (93,000 acres) Figure 6. Annual net revenues over the 150 year planning horizon
Figure 7. Advanced forest structure over the 150 year planning horizon over District (93,000 acres). Figure 8. Advanced forest structure associated with the Baseline, the 50-year elevated harvest schedule, transitioning to the inventory of a 50-year regulated forest. Note Adv-3 is a subset of Adv-2. Adv-2 is a subset of Adv-1. The upper line represents the total of Adv-1 acres including the 81,000 timber production base plus the 12,000 acres outside the base that include 17, 70-acre owl cores.
Figure 9. Advanced forest structure associated with the Intermediate Alternative, the 50-year elevated harvest schedule, transitioning to the inventory of a 70-year regulated forest. Note Adv-3 is a subset of Adv-2. Adv-2is a subset of Adv-1. The upper line represents the total of Adv-1 acres including the 78,000 timber production base plus the 15,000 acres outside the base that include 17, 250-acre owl cores. Figure 10. Advanced forest structure associated with the ESF Landscape Strategy. Note Adv-3 is a subset of Adv-2. Adv-2 is a subset of Adv-1. The upper line represents the total of Adv-1 acres including all 93,000 acres of the Elliott State Forest.