10 



MISSOURI AGR. EXP. STA. RESEARCH BULLETIN 41 



number of years required to make an increase of 1 inch in di- 

 ameter of wood (not including bark growth). It is computed 

 from the second column. The fourth column shows the average 

 double thickness of bark for each inch class of wood diameter. 

 The initial value in the fifth column is derived from field data but 

 all subsequent values are derived in turn by adding to the value 

 in column five the value in column three. The last column is 

 the diameter outside the bark and is the sum of the first and 

 fourth columns. It is the value obtained in calipering standing 

 trees at breast-height (D. B. H.). When plotted the data in col- 

 umns five and six give the curves shown in Figure 3. 



Height-Growth. The relation between diameter at breast- 

 height outside the bark and the total height of the tree as comput- 

 ed from the field data is shown in Figure 4. It will be noted on 

 this figure that the course for white oak, post oak and black jack 1 

 oak coincide below 15 feet and the curves for post oak and black 

 jack coincide below 40 feet. 



Volume Growth. The volume of a tree is either its total 

 gross volume or that portion of its gross volume which is used 



TABLE II. DIAMETER GROWTH AT BREAST-HEIGHT BLACK JACK OAK. 



