Preliminary office vjork 



Important steps in the operation 



Estimate number of trees by 

 species in the sale 

 a. From cruise data 



b. Alternate system — Divide 

 total volume each species 

 by estimated average 

 volume of single tree 



Key points 



Basic data taken from cruise sheets. 

 Keep species separate. Eliminate 

 all "large" trees, usually about the 

 upper 10 to 20 percent o See page 11 

 of this publication. 



Used if no cruise data available. 

 Average volume of single tree deter- 

 mined from past experience or from 

 previous sale reports on similar 

 areas . 



Estimate coefficient of vari- 

 ation for each species 



See Appendix III of this publication 

 for formulae. For a rough guide to 

 the coefficient of variation for 

 different species and conditions, 

 refer to the following table; 



Coefficient of Variation Q-uide 1/ 



Description 



Species 



of 



Ponderosa pine 



Western 



Douglas fir 



stand 



Engelmann spruce 



white 



V^estern larch 





Grand fir 



pine 



Lodgepole pine 



Uneven aged, large vari- 









ation in tree sizes, 









considerable defect 



0.7-0.8 



0.6"0e8 



0.6-0.8 



Even aged, trees fairly 

 uniform, in size, little 



defect 0.5-0.7 0o5-0o6 0o4-0.6 



1/ Select a coefficient from vathin the range shorn for a parti- 

 cular situation. For more variable timber select values near 

 the top of the range; for less variable timber select values 

 near the lower part of the range o If more precise estimates of 

 the coefficient are desired, use the formula in Appendix III. 



Vftien all large trees are tallied separately, deduct one-tenth 

 unit from the chosen coefficient of variation. 



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