cruising approaches area based methods tree based methods
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TIMBER CRUISING METHODS
Cruising Approaches
Area Based Methods
Tree Based Methods
Area Based Methods
Main Types
Strip Cruise Fixed Plot Point Sampling Remote Sensing
Varieties for specific applications
Fixed Count Fixed Count Measure Fixed Plot with 3P
subsample Point Count Measure Point Sampling with 3P
subsample 3P Point Sampling
Tree Based Methods
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
3P
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
Strip Cruising
Strips could be randomly allocated. Hard to stratify without bias.
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.
Strip Cruising
Area Based Methods
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
Remote Sensing
ESTABLISHING PLOTS
Fixed Plot
1. Locate Plot Center
2. Temporarily mark plot centerwith wire flag or paint for instance
3. Plot size targets 4 to 8 trees per plot
4. Use same size plot throughout
5. Plot radius checked with hipchainPacing is less accurate
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%
Slope Correction
Slope Limiting DistanceSLD = HLD X SCF or HLD = SLD/SCF
SCF means Slope Correction Factor
Slope CorrectionFixed plot size (acre) = ¼Plot radius = 58.9 feetMeasured distance to tree face = 59.8 feetDBH = 12.6 inches or 1.05 feetDBH/2 = .525 feetSlope percent = 20Slope correction factor = 1.02Limiting Distance = In or Out =
SLD = (58.9 - 0.525) X 1.02= 58.375 X 1.02 = 59.5
Out by 0.3 feet
Problem Trees – Forked Treesif the boundary passes through the center of the tree at DBH, count as IN
Problem Trees – Leaning Trees
if the boundary passes through the center of the tree at DBH, count as IN
Problem Trees – Broken or Down Treeslocate 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
Must be tallied as having no trees for correct expansion factor to apply to whole site.
Null Plots
DATA RECORDING
Manual Method
Dot-Dash Tally
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
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
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.
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.