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Influence of cutting block size on the efficiency of several 3-P sampling variations as compared to point sampling

University of British Columbia

For 3-P sampling, an ocular prediction of volume must be made on every tree in a cutting block, which casts doubt on its efficiency in larger blocks. However, it has three main advantages over the standard BCMF prism cruising procedures. First, individual trees are the sampling units, not plots of trees, so greater precision may result for a given sample size, second, no height/dbh regressions need be calculated, third, it potentially avoids volume equation biases when it is used in conjunction with dendrometry. A simpler sampling procedure, ratio estimation, differing from 3-P in that sample trees are selected with equal probability, may also prove advantageous. A study was conducted in the UBC research forest in which several blocks were cruised using all three of these methods. A volume equation, the wide-scale relaskop, and the Barr and Stroud dendrometer type FP-12 were tested as tree measurement methods for use with 3-P and ratio estimation. Results indicate that 3-P is more efficient than point sampling in blocks ranging in size up to between 5 and 14 hectares, depending on the tree measurement method chosen and the height/dbh regressions deemed necessary for use in the standard cruise. Ratio estimation is more efficient than point sampling in block sizes ranging up to 14 hectares depending on the same factors as 3-P.

Text

2010-06-30

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http://hdl.handle.net/2429/26095

Forestry

University of British Columbia

Graduate