woods. Furthermore, check scaling, disregarding defect, would still be 

 needed in order to get a measure of breakage, volume table errors, 

 and inaccuracies of measurement. Where defect is not a major source 

 of error, scaling a group of randomly selected logs to arrive at a 

 defect factor is not recommended because the need for check scaling 

 in the woods would not be eliminated. 



Culling for visible defect 



Estimating visible or "detectable" defect in the standing tree and 

 deducting it from the volume is highly recommended. This practice, of 

 course, requires skill and experience and it is not expected that an 

 accurate estimate of defect is possible. Hovi/ever, in many instances 

 considerable improvement can be made in the volume determination by 

 adjusting for defect, A cull tree, for example, that can be identi- 

 fied as such at the time of marking should not be included in either 

 the sample or the tree count. It may or may not be marked for removal 

 depending upon the conditions of the sale contract. A separate tally 

 of cull trees might be desirable from a silvicultural standpoint. 



Volume table errors 



Volume table errors account for a large part of the discrepancy between 

 estimator's and check scaler's volumes. To develop volume tables for 

 universal application, even for a given forest or ranger district, 

 without recourse to such measurements as form class is impossible. 

 Khov/ing how the form and growth habits of a species such as ponderosa 

 pine vary from one site to another, it is not surprising that com.plaints 

 of volume table inaccuracies are common. Until local volume tables 

 can be developed or training given in the use of form class volume 

 tables, discrepancies are difficult to correct. (3) The experienced 

 estimator can, however, make adjustments if he knovjs the basis upon 

 which the volume tables in use were constructed in regard to top dia- 

 m.eter and general form of timber. 



Boe (3^) illustrates comjuon errors in application of volume tables by 

 the following two examples: 



"The first error arising from estimating to a different top 

 diameter than the volume table provides for involves reducing 

 a height estimate to correct for large limbs, crook, or 

 other defect in the top log. The result will be to under- 

 estimate the actual volume. For example, a S4-inch ponderosa 

 pine having five logs to an 11-inch top contains 810 board 

 feet. Suppose that the top log is unmerchantable due to 



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