DIFFICULTIES AND ERRORS IN STEM ANALYSIS. 



Stem analysis includes two separate series of measurements, 

 namely the determination of increments and of volume. 



The exact procedure and sequence of operations, as carried on 

 under the instructions of the U. S. Bureau of Forestry, differs, 

 depending on the chief of the party, the individuals employed, 

 the kind of timber, and several other variables. The data to be 

 obtained is, however, the same, and the method employed is in 

 general as follows : 



The tree when felled is sawed up into sections. These sections, 

 if the tree is cut solely for the measurements to be taken, should 

 be made short enough to permit a true reading of the growth 

 history of the tree, yet they should not be too short to increase 

 the expense for it makes considerable difference in the cost of 

 investigations if a man spend thirty minutes measuring up a tree 

 or forty-five. The sections must be of equal length, of even 

 feet, preferably even fives in order to facilitate working up of 

 data. 



It will readily be seen that the required length of section should 

 be in relation to the height of the tree. It would be unnecessary 

 finesse to take two foot sections of a 150 foot pine ; again ten 

 foot sections of a 15 foot sapling would be insufficient. 



The Bureau practice is as follows : Seedlings three feet, or 

 under are sectioned every foot above root juncture, saplings 

 between three and ten feet are sectioned every two feet, trees 

 over ten feet in height are sectioned every ten feet, intermediate 

 taper measurements being made every five feet. 



Generally however, merchantable trees are not cut purposely 

 by the Bureau, but measurements are taken on trees as felled and 

 cut in varying lengths by lumberman. 



According to market requirements, these logs may run 10.3, 

 10.4. 10.6, 12.4, 12.5, 16.5, 16.6, 16.7 feet, etc., the choice 

 being with the sawyer, who varies the length so as to get the 

 largest amount of timber out of the tree. The fractions of feet 

 vary with the ])ersonal c(juatioii of the sawyers', a knot in the 



