List Of Cruising Methods

Tree Based Cruising Methods

100 Percent Cruise (100)

• This cruise method is where every member of the population is visited and measured.

Sample Tree with Complete Tally (STR)

• Is a method where single trees are sampled with equal probability of selection.

Probability Proportional to Prediction (3P)

• This method involves visiting each tree to be sold on a timber sale and estimating the tree volume or value.

Sample Tree with Probability Proportional to Prediction (S3P)

• A Two-stage sampling method. First stage is an equal probability sample where the probability of a tree being selected as a sampling unit is proportional to the tree frequency in the population. The second stage is a 3P sample of the trees selected in the first stage.

Plot Based Cruising Methods

Fixed Plot (FIX)

• This is an area sampling method using plots of a specific area so trees in the population are selected with equal probability.

Fixed Plot Count/Measure (FCM)

• This cruise system is applicable in stands where there is a large variation in tree counts per plot and there is little variation in tree size.

Fixed Area Plot with 3P Subsampling (F3P)

• This is a two-stage sampling system. The first stage is a fixed area sample where the probability of a tree being selected as a sample unit is proportional to the tree frequency in the population. The second stage is a 3P sample of the sample trees on the fixed area plots.

Fixed Count Plot Method (FIXCNT)

• This method is designed to estimate the number of trees per acre in an area. The sampling method uses fixed plots of a specified area and shape.

Point Sampling (PNT)

• The probability of a tree being selected as a sample unit in point sampling is proportional to its basal area.

Point Count Measure (PCM)

• In ratio double sampling, count all sample trees at all points but measure volume a proportion of the trees. Use the data from the sample trees estimate a ratio of volume to basal area.

Point Sampling with 3P Subsampling (P3P)

• This is a two-stage sampling system. The first stage is a point sample where sample trees are selected in proportion to tree basal area. The second stage is a 3P sample of the point-sampled trees.

Point Sample with 3P Cluster Subsampling (3PPNT)

• This is a two-stage sampling system. The first stage is a variable plot sample where the probability of the point being selected as a sample point is proportional to the estimate of the cubic foot per acre within the point sample. The second stage is a 3P sample of the estimated cubic volume per acre on the variable plots.

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The above definitions are pulled directly from the Timber Cruising Handbook (FSH 2409.12).