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.