SECTION X— STUDIES IN GROWTH PER CENT 



Explanation. — Growth per cent is chiefly' useful in the prediction of volume 

 growth for short periods, and is a method used in connection with the prepa- 

 ration of working plans for even-aged stands, and in the determination of 

 the final volume to be cut. Equipment required for field work is not listed 

 with the exercises of this section. The chief of party will in each case be 

 held responsible for checking out the necessary equipment. 



PROBLEM 36. (Field.) The Determination of Futuhe Volume by 

 Means of Growth Per Cent Calculated Frotn Felled Sample Trees. 



Explanation. — This exercise aims to illustrate three of the fundamental 

 methods. For purposes of comparison it is suggested that all of them be 

 carried out on the same sample plot. 



IL1.USTRATION. — To Determine What the Volume in Cubic Feet of a 40-acre 

 Tract (area assumed) Will Be 10 Years Hence. 

 Method 1. — By comparing the Average Volume Growth for the past ten 

 years as interest to the Volume 10 years ago as Principle. 



Directions: 



A. Formula. 



V-v 



:v = p:100, 



n 



V-v 



p = xioo 



vn 

 where p = growth per cent; 

 V = present volume ; 

 «; = volume 10 years ago; 

 n = 10 years. 



B. Parties. — 3 men in each. 



C. Method of Procedure. 



1. Select and carefully lay out an average plot of j acre. 



2. Proceeding as in the Mean Sample Tree Method, determine the volume 



of the plot and the average tree. 



3. Select and fell three average trees for measurement. 



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