58 GENERAL GROWTH OF STUDIES 



in hardwoods usually ring counts alono can be used, though often 

 these may be checked by the annual nodes, or terminal bud scars. 

 Record the measurements in a table of two columns with ages 

 opposite heights. 



Note. — When the annual nodes are conspicuous it is often possible to obtain a number 

 of height measurements from each individual seedling as follows: 



1. After the total age and the total height of a seedling are determined, subtract one 



from the total age and measure the height to the first annual node below the tip. 



2. In a similar manner determine the values with reference to each of the remaining 



annual nodes. 

 (The same may be done by cutting the seedlings into 6-inch lengths and constructing 

 a height growth table. See Problem 29.) 



4. On a sheet of cross-section paper (Form 1 of Field Notebook) lay otT 



heights as abscissae, and ages as ordinates. Plot the values, in 

 half-foot height classes, draw a smooth curve and read off a table 

 showing the average ages of the heights for each 0.5 of a foot, and 

 label. 



5. Apply this table directly to the stump ages as follows, and record in 



the proper spaces in the data blanks, 

 (a) Look up the stump height of each tree on the front of the Analysis 



Blank (Form 2 A). 

 (6) Determine in the table just constructed the number of years it 



took the tree to grow to stump height. 

 (c) Add this number of years to the age at the stump and record as 



''Total Age." 



PROBLEM 26. (Office.) The Determination of Diameter Growth in Fjver)- 

 aged Stands. 



Explanation. — The object of this exercise is to ilhistrate the fundamental 

 principles involved in all diameter growth studies in even-aged stands. In all 

 cases tables are to be prepared that will show the average diameter a tree 

 may be expected to attain at some one or more points (certain prescribed 

 distances above the ground) along the bole of the tree. The growth at each 

 of these points is determined by a separate study. The method of procedure 



. will be practically the same for all problems involving diameter growth in 

 even-aged stands, as that outlined in the illustration given below. It is cus- 

 tomary to make these studies in ten-year age-periods. 



Illustration. — To Construct a Table of Average Diameter Growth at the 

 Stump for Even-aged Stands, not Thinned. 



A. Data Required. — Stump analysis and total ages. Use Data Series III. 



B. Method. — Plotting the values before averaging. 



Note. — When this problem is completed do not erase any of the plotted points. 

 They will be of use in succeeding problems. When these data are not to be used 



