468 



Forestry Quarterly. 



The results of the error made by Crew No. i are at once ap- 

 parent. The mean annual growth of veterans is seen to be too 



large compared with the 



QHD Immature 

 \=^ Veterans 



I J ^Mature 3nd 

 Young Merc/i. 



Crew J^o 



C'"ew No 2. 



younger classes, while that of 

 the mature and young is cor- 

 respondingly too small, due to 

 the incorrect balancing of 

 areas. One error has pro- 

 duced another and each tends 

 to show up the other. Com- 

 pared with this the results of 

 Crews 2 and 3 show good 

 judgment and figures which 

 differ from each other only 

 by the margin that may be 

 expected between any two 

 men in solving such a 

 problem. The maps showing 

 the areas assigned to each age 

 class, for the same 20 acres, 

 by each of the three crews, 

 are shown below. The vari- 

 ation in the areas assigned to 

 each age class is due first, to 

 the difference in the number 

 of trees included in these age 

 classes, and second, to differ- 

 ences in judgment as to the 

 proper space to assign to the 

 class. Most of these differences in mapped area are offset or 

 compensated for by differences in the tally. But in case of map 

 No. I, the area mapped to veterans and immature, is seen to be 

 much smaller than the same areas in maps 2 and 3. 



This method as described, is recommended for Western Yellow 

 Pine. With modifications, it may be possible to use it in many- 

 aged stands of spruce, or in mixed stands containing several 

 species. As of interest in this connection the following tables 

 are appended. 



I(^L. 



Crew No 3. 



