CLASSES OF GROWTH DATA, CHART GROWTH STUDIES 329 



stands, or to the effort to predict the growth of stands from that of 

 the trees which they contain. As a result of similar actual records 

 of production the working plans for some European forests dispose of 

 the subject of growth quickly, stating substantially that the growth 

 in this class of forest is known, from past records covering (perhaps) 

 200 years, to be about so much. 



In the chart, on pages 328-333, eleven main lines of investigation 

 of growth are listed, as a guide to the discussions in the following chap- 

 ters. The object of a study should first be understood, and the con- 

 dition of the stands to which it is to be applied, as indicated in the 

 three columns under " Purpose of Growth Study." In the column 

 under " Basis " the principles on which the solution of the problem 

 depends are outlined. 



The remaining columns are self-explanatory. Column 6 shows the steps 

 by which the study can be applied to large areas of forest land, thus secur- 

 ing the data for which the preceding steps are merely preliminary. 



By using this chart as a guide, and consulting the references to 

 discussions of principles and methods, under each step, one may hold 

 the purpose of growth studies clearly in mind and choose the best 

 method of accomplishing the desired object. 



The relative importance and reliability of the methods given are 

 indicated by the quality of type used in the table. 



Growth Studies 



Office records 



Final data obtained 



Application to forest 

 areas 



Data derived from the 

 investigation 



1. Area of sample plots — 

 §308 



2. Volumes of trees (vol 

 ume tables)— § 131 



3. Age of sample trees — 

 § 256, § 257 



4. Height of dominant 

 trees— § 310, § 311, 

 §312 



1. Volume per acre — 

 §306 



2. Age of stands — § 256 



3. Height of stands 



Classification of site qual- 

 ities— § 294, § 345 



1. On basis of height 

 growth— §§ 296-310 



2. On basis of volume 

 growth— § 295, § 312 



1. Mean annual growth 

 —§245 



2. Number of trees per 

 acre 



3. Basal area per acre 



4. Maturity of stands — 

 § 244 (rotation) 



5. Maximum yields 



1. Area of stand or age 

 class 



2. Volumes of trees (vol 

 ume tables) § 131 



3. Age of sample trees — 

 § 256, § 257 



4. Average volume per 

 acre for age class 



Reduction per cent or 

 relative volume de- 

 rived from this com 

 parison — § 317 

 Empirical yield table 

 based on this reduc 

 lion— §§ 304-316 



1. Empirical yield table to 

 predict future growth 

 on each age class 



2. Correction for i n - 

 fluence of number of 

 trees per acre at differ- 

 ent ages — §§ 301-317 



Future yields based on 

 actual stocking — 

 § 301, § 343 



2. Losses due to natural 

 agencies — § 293 



Gains possible from 

 protection and silvi- 

 culture 



