CHAPTER XI 



THE CONSTRUCTION OF STANDARD VOLUME TABLES FOR 

 TOTAL CUBIC CONTENTS 



131. Steps in Construction of a Standard Volume Table. The 

 steps in the construction of a standard volume table, whether for total 

 cubic contents, or for any form of product, are practically the same. 

 They are : 



1. Selection of felled trees in sufficient number, and representing 

 the complete range of diameter and height classes of the species or 

 locality. 



2. Measurement of each tree to secure all the data needed for the 

 construction of the volume table. 



3. Computation of volume of each tree. 



4. Classification of tree volumes according to diameter and height 

 classes. 



5. Averaging the volumes of trees of each separate diameter and 

 height class. 



6. Elimination of iri-egularities in final table by graphic plotting 

 and curves. 



132. Selection of Trees for Measurement. As only felled trees 

 can be measured with the accuracy needed for construction of volume 

 tables, the choice is presented of utilizing timber already felled, either 

 by wind, or by loggers, or of felling the trees for measurement. Wind- 

 fallen trees are usually of the larger sizes, and scattered individually 

 or in groups, and are measured more as a check on rough methods 

 of estimating than in the systematic construction of tables. A logging 

 job presents the opportunity to secure trees of all diameters except 

 those below merchantable size. The operation may be too local in 

 extent to embrace the extreme forms desired, and a standard table 

 covering the extremes of diameters and complete range of heights 

 should be based on trees cut from several different operations covering 

 the range of altitude and soil qualities for the species or type. 



The influence of soil, altitude, age and other factors upon the form 

 of trees of the same diameter and height class is discussed in Chapter 

 XVI. When it can be shown that differences in volume can be cor- 

 related with age, or site, separate standard tables may be constructed 

 for trees of the specified classes or sites. In this case, the same principle 



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