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GUIDELINES for . . .
Spacer graphic Developing Stand Density Management Regimes

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Pre-commercial thinning options analysis

      Stand descriptions and management assumptions for coastal and interior scenarios, as they apply to untreated stands, are specified in Table A2-1. For convenience, these examples are based on the default values in TIPSY. Only the bolded information must be entered by the user to replicate the results. Note that some defaults depend on the region and district selected. Since the user can change TIPSY defaults, confirm all input data for untreated stands with Table A2-1 when reproducing these examples. Refer to the TIPSY online manual for detailed information and operating instructions. Note that:

      • all stands regenerate naturally with 10 000 sph
      • operational factors lower potential yields (see OAF values)
      • most yields are based on a minimum diameter of 12.5 cm
      • no cost is incurred for site preparation
      • results may vary slightly if the table range or step is changed.

    Table A2-1. TIPSY input values for untreated stands of coastal hemlock and western interior lodgepole pine


    Spacer graphic Coast Interior Spacer graphic Coast Interior

    Title Untreateda Untreated Harvest system Gr. skid Gr. skid
    Spacer graphic Spacer graphic Spacer graphic Tree-to-truck equation: 17.10 16.10
    Stand specs Spacer graphic Spacer graphic - Slope/100 4.24 4.24
    Spacer graphic Spacer graphic Spacer graphic - Stems/1000 0.70 0.70
    Species W. Hem. Pine - Volume/stems 0.43 0.43
    % 100 100 - Volume/1000 5.41 5.41
    Site index (m) 27 21 - (Distance - 50)/100 0.67 0.67
    Regeneration type Natural Natural - = $/m3 (@ age 80) 14.36 15.66
    Density (sph) 10 000 10 000 Spacer graphic Spacer graphic Spacer graphic
    Regeneration delay (yr) 2 2 Haul distance (km) 100 Spacer graphic
    OAFs 1 & 2 0.90 & 0.95 0.90 & 0.95 Towing/barging ($/m3) 1.93 Spacer graphic
    Thin to density (sph) Spacer graphic Spacer graphic Cycle time (hr) Spacer graphic 3.0
    Table range and step 80/130/5 50/80/5 Off highway? Spacer graphic no
    In relation to Age Age Total haul cost ($/m3) 12.40 6.18
    Merch. limits (cm) 12.5+ 12.5+ Spacer graphic Spacer graphic Spacer graphic
    Spacer graphic Spacer graphic Spacer graphic Milling cost eq'n expo. expo.
    Region Vancouver Pr. George - Sawmill capital ($/MBF) 7.07 7.07
    District Campbell R. Pr. George - Coastal additive ($/MBF) 75.00 Spacer graphic
    Biogeoclimatic zone CWH SBS Total milling cost ($/MBF) 207 144
    Average slope 10 10 Spacer graphic Spacer graphic Spacer graphic
    Distance to support (km) 100 100 Development costs ($/ha) 9 168 1 450
    Spacer graphic Spacer graphic Spacer graphic Overhead costs ($/ha) 13 026 2 229
    Economicb specs Spacer graphic Spacer graphic Annual costs ($/ha) 0 0
    Spacer graphic Spacer graphic Spacer graphic Other harvest ($/ha) 0 0
    Discount rate (%) 4.0 4.0 Other treatment ($/ha) 0 0
    Price increase
    - general (%)
    0.0 0.0 Lumber/chip prices Spacer graphic Spacer graphic
    Cost increase (%) 0.0 0.0 - 2 x 4 ($/MBF) Spacer graphic 387
    - duration (yr) 25 25 - 2 x 6 ($/MBF) Spacer graphic 379
    Analysis base year 0 0 - 2 x 8 ($/MBF) Spacer graphic 383
    Spacer graphic Spacer graphic Spacer graphic - 2 x 10 ($/MBF) Spacer graphic 464
    Surveys ($/ha) 19 16 - chips ($/BDU) Spacer graphic 110
    Site prep. ($/ha) 0 0 Log prices ($/m3) Spacer graphic Spacer graphic
    Brushing costs ($/ha) 0 0 - Grade H 145 Spacer graphic
    Spacer graphic Spacer graphic Spacer graphic - Grade I 114 Spacer graphic
    Spacer graphic Spacer graphic Spacer graphic - Grade J 82 Spacer graphic
    Spacer graphic Spacer graphic Spacer graphic - Grade U 67 Spacer graphic
    Spacer graphic Spacer graphic Spacer graphic - Grade X 63 Spacer graphic
    Spacer graphic Spacer graphic Spacer graphic - Grade Y 62 Spacer graphic

    a Entries shown in bold are not TIPSY defaults (i.e., user must change specifications on screen).
    b All costs and prices are in constant 1996 Canadian dollars.

      Table A2-2 shows the pre-commercial thinning suite of runs that readers are encouraged to duplicate. After completing the untreated case (Table A2-1), select the thinning option in TIPSY, specify the post-treatment density given in Table A2-2, change the age range and steps temporarily and re-run the example. No other changes are needed until you generate the site values at the time of thinning (last row of Tables A2-3 and A2-4).13 To do that, set the "Analysis Base Year" so that discounting stops "At PCT Age." Discount the untreated stands to age 17 or 16 for hemlock and pine, respectively. Note that some calculations (e.g., harvest costs) may change in thinned stands.

    Table A2-2. Treatment options, spacing costs and stand characteristics for coastal western hemlock and interior lodgepole pine density management regimes


    Spacer graphic Coastal western hemlock Interior lodgepole pine

    Initial density (trees/ha) 10 000 10 000 10 000 10 000 10 000 10 000 10 000 10 000
    Thin to: (trees/ha) n/a 1 200 900 600 n/a 1 800 1 400 1 000
    PCT costs ($/ha) n/a 650 660 670 n/a 585 598 611
    PCT age (yr) n/a 17 17 17 n/a 16 16 16
    Spaced at height (m) n/a 6 6 6 n/a 4 4 4

Management assumptions

      The forest estate is managed under a silvicultural system that requires clearcutting at the physical rotation age (culmination of MAI). However, harvesting at the economic rotation age (culmination of site value) will be considered. The stand specifications are shown in the first section of Table A2-1. A minimum DBH of 12.5 cm is assumed for the future harvest. Note that the discount rate is 4%, and no increase in real - excluding inflation - product prices is expected. Costs are incurred for "Surveys" but not "Site Preparation." Pre-commercial thinning costs are given in Table A2-2. The future harvest is expected to use ground skidding equipment. Harvesting, hauling, milling and development costs, and product prices are given in Table A2-1.

      Should stands be pre-commercially thinned - and, if so, to what density? Assume the silviculturist wants to compare the unthinned option with the three residual densities for hemlock or pine shown in Table A2-2.

      13 Note that treatment costs are provided by the "Linear Equation" option.


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Copyright 1999 Province of British Columbia
Forest Practices Branch
BC Ministry of Forests
This page was last updated January 1999

Comments to: Tim Ebata <Tim.Ebata@gems8.gov.bc.ca>