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Timber Cruising Methods

Timber Cruising Methods. Cruising Approaches. Area Based Methods Tree Based Methods. Varieties for specific applications. Area Based Methods. Fixed Count Fixed Count Measure Fixed Plot with 3P subsample Point Count Measure Point Sampling with 3P subsample 3P Point Sampling. Main Types.

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Timber Cruising Methods

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  1. Timber Cruising Methods

  2. Cruising Approaches • Area Based Methods • Tree Based Methods

  3. Varieties for specific applications Area Based Methods • Fixed Count • Fixed Count Measure • Fixed Plot with 3P subsample • Point Count Measure • Point Sampling with 3P subsample • 3P Point Sampling Main Types Strip Cruise Fixed Plot Point Sampling Remote Sensing

  4. 3P Tree Based Methods • Small or irregular shaped harvest units • Widely scattered trees • Very large stands • Used where a wide volume range occurs within a species group • Measure as few trees as possible • Cut tree marking • Not used in this region Sample Tree Method For stands too variable in density to plot cruise or where trees are not suitable for cruising by other methods Examples – partial cutting, small clearcuts, stratification by species or size class is desired

  5. Strip Cruising Strips could be randomly allocated. Hard to stratify without bias.

  6. Area Based Methods Strip Cruising Disadvantages of strip cruising: 1. Inaccurate estimation of strip width may lead to errors. 2. Difficult to maintain a straight strip centerline. 3. Brush and windfall are more of a hindrance in this system. 4. Spot-checking the cruise is difficult: strip centerline is rarely marked.

  7. Remote Sensing • Best for low value products • Best for even-aged, single canopy and species stands (tree farms) • Needs recent high resolution photos • Pre-sampling needed to establish relationships i.e. volume versus canopy cover estimates • Photos must be geo-referenced

  8. Remote Sensing

  9. Establishing Plots

  10. Fixed Plot • Locate Plot Center • Temporarily mark plot centerwith wire flag or paint for instance • Plot size targets 4 to 8 trees per plot • Use same size plot throughout • Plot radius checked with hipchain Pacing is less accurate

  11. Determination of “IN” Trees • Plot center to tree center • Horizontal Limiting DistanceHLD = Plot Radius – (0.5 X DBH/12) • Must be corrected for slope if steeper than 10%

  12. Slope Correction • Slope Limiting DistanceSLD = HLD X SCF or HLD = SLD/SCF • SCF means Slope Correction Factor

  13. Slope Correction Fixed plot size (acre) = ¼ Plot radius = 58.9 feet Measured distance to tree face = 59.8 feet DBH = 12.6 inches or 1.05 feet DBH/2 = .525 feet Slope percent = 20 Slope correction factor = 1.02 Limiting Distance = In or Out = SLD = (58.9 - 0.525) X 1.02 = 58.375 X 1.02 = 59.5 Out by 0.3 feet

  14. Problem Trees – Forked Trees if the boundary passes through the center of the tree at DBH, count as IN

  15. Problem Trees – Leaning Trees if the boundary passes through the center of the tree at DBH, count as IN

  16. Problem Trees – Broken or Down Trees locate breast height at 4 and 1/2 feet above the root collar as the tree lies on the ground. If this point lies on or inside the plot boundary, the tree is IN

  17. Null Plots Must be tallied as having no trees for correct expansion factor to apply to whole site.

  18. Data Recording

  19. Manual Method • Dot-Dash Tally

  20. Field Aids • Species Codes • Tree Codes • Location Codes • Tree and Log Grading Rules • Percentage Deduction Tables • Standard upper limit Diameter Outside Bark (DOB) by species • Limiting distance tables for point-sampling • Stratification guides

  21. Recording Equipment • Compass and/or GPS • Clinometer or laser to determine slope • D-Tape • 100 foot tape or hipchain • Flagging and/or paint • Prism or angle gauge for point cruising • Hypsometer • Pencil and paper or Data Recorder

  22. Forms • Date = 8/19/2013 Size = 1/10th acre Forest Cover Type = • Stand Size and Condition = Stand Age = Stocking or Density Class = • Site Index = Slope = Soil Classification = • Understory Vegetation = Treatments needed = • Plot = 1 • Tree Species DBH Form Class Height Grade Crown Class Notes • 1 RO 14 78 1.5 2 • 2 SP 16 80 2 2 • 3 YP 18 82 2.5 1 • Plot = 2 • Etc.

  23. Electronic Data Recorders • Pocket Dog • FS Cruiser • If your field data recorder has built in GPS – even better. Can include location in tally data for periodic rescaling, etc.

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