Stem Breakage of Pinus radiata at Clearfelling and its Effect on Saw Log Yield

Authors: H.M.N. Lees
Publication: New Zealand Journal of Forestry, Volume N.Z.J.For. 1969, Issue N.Z.J.For. 14(1) 1969, pp 68-74, May 1969
Publisher: New Zealand Institute of Forestry

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Abstract: Investigations were undertaken to give a better appreciation of factors that relate standing volume to recoverable sawlog yield.
It was noticed during clearfelling that stems of mature Pinus radiata break at a diameter approximately equal to half breast height diameter. This indicates that volume to a 6 in. top diameter is of little value for estimating sawlog yield.
Using a graphical method of analysis, it was found that, for the d.b.h. range 10 to 24 in., stem volume below the point of break was approximately constant at 86% of total stem volume; but this finding takes no account of additional losses caused by stem malformation or wastage.
The New Zealand Forest Service, Forest Research Institute, carried out a more detailed analysis of the data, and showed a more precise relationship for diameter at break to d.b.h. Total height was also found to be as effective as d.b.h. for estimating the diameter at point of break.
Further developments of this general approach are also suggested.

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