Some Permanent Sample Plot Studies 



123 



with No. 12, (id. copper nails. On old mature trees they were 

 driven in their entire length but on small growth or where the 

 bark was thin, they were driven in to only about one-half inch 

 from the head to allow for the growth of the next five years 

 since the growth study plots are to be remeasured at the end 

 of periods of that length. 



The total heights of twenty percent of all the trees were 

 measured with a Forest Service standard hypsometer; the 

 distance from the base of the tree in each case was carefully 

 measured with a tape. The clear length to the first living 

 limb and the merchantable length to an estimated eight-inch 

 limit was also measured far these trees. The age was esti- 

 mated from figures obtained from analyses of about one hun- 

 dred stumps. The results of these measurements were aver- 

 aged by a series of curves from which the following table was 

 constructed in order to show the relation between the dia- 

 meter, height, merchantable and clear length, and age of 

 Jeffrey Pine and White Fir: 



TABLE 4. 



RELATION OF DIAMETER TO HEIGHT, MERCHANTABLE 

 AND CLEAR LENGTH, AND AGE. 



