A SIMPLIFIED METHOD OF STEM ANALYSIS OD^ 



When the computation sheets have been entered up, the field note- 

 books need not be referred to again. A separate computation sheet 

 may be used for each site and crown class of each species and separate 

 curves drawn for each class. Such classification is not essential and 

 may be varied as desired. To construct average curves for all the trees 

 of each species, the totals of the separate computation sheets of the 

 various classes must be added and general averages secured. If gen- 

 eral curves only are desired, one computation sheet for each species is 

 used. 



The d. b. h., volume, merchantable length, and total height data in 

 columns 4, 5, 8, and 9 are used for the preparation of a volume table 

 by standard methods. These data are transferred to the computation 

 sheet merely to secure their grouping by species. The data are aver- 

 aged arithmetically in merchantable length or total height classes and a 

 single row of points plotted for each class. The volume table based 

 on total height is essential in constructing the volume growth curve. 

 A volume table based on merchantable length is usually considered 

 more convenient for use in estimating and its construction is therefore 

 also provided for. 



All the other columns and also the total height column are added and 

 the totals divided by the number of trees. The average height and age 

 of each section and of the whole tree are plotted as a single row of 

 points to give a height-growth curve from the stump. Allowance must 

 then be made for seedling height growth. The averages of the decade 

 measurements are similarly plotted to give a stump diameter-growth 

 curve, which is converted into a d. b. h. growth curve by the standard 

 method of allowing for the average differences between the stump 

 d. i. b. and the d. b. h. The reduction in labor in these processes as 

 compared to the plotting of every individual tree should be noted. 



The d. b. h. and total height at each decade are now read from the 

 d. b. h. and height-growth curves. The corresponding volumes are 

 read from the volume table, the readings plotted as a single row of 

 plants, and the volume-growth curve drawn through them. 



Graduates of Yale forest school will probably recognize many 

 familiar features in the above description. The original features of it 

 were all worked out in connection with the work at the Yale forest 

 school camps, in the Southern States, and this outline is given with 

 Professor Chapman's consent. The main differences between the sys- 

 tem outlined above and that followed at the Yale camps are twofold. 

 At the Yale camps a d. b. h.-height curve was prepared by the use of 

 hypsometers, and the height-growth curve prepared by relating the 



