782 JOURNAL OF FORESTRY 



irregular flattening of curves B and C, in figure i, between diameters 

 12 and 1 6 may be explained by the increase of size of limbs at a faster 

 rate than the radial overgrowth of the tree bole. The diameter of the 

 limb is determined by the amount of light reaching it in its position on 

 the tree bole, while the diameter growth of the tree bole is determined 

 largely by the height and size of the total crown and is not directly re- 

 lated to the development of an individual limb. It is in fact apparent 

 that the period of time elapsed from the death of the limb is quite as 

 important, if not more so, than the size attained at this point on the bole. 



From the curve D it can be noted that the live crown is very low on 

 the smaller trees, so that the live knots will be incorporated in the center 

 of all butt logs. These knots change to dead knots before they are 

 finally healed over. Points read from the curves in figure i were plotted 

 on the tree diagram in figure 2. This diagram was constructed from 

 taper tables in Department of Agriculture Bulletin 544, after they had 

 been adjusted to conform to the heights shown for each diameter in 

 curve E, figure i. Height of the various diameter classes in figure 2 

 is shown on the vertical co-ordinate. The difference in source of the 

 taper tables used in the construction of the tree diagram and data on 

 live crown obliterates the relation which might be shown between the 

 rise of crown and increase of size of bole at the base of the crown. 



Similar data taken at Brandreth on the position of knots show no 

 difference in height of the clear zone to the ii-inch diameter class. 

 Above that point there is a gradual rise, reaching 2 feet at the 22-inch 

 class, which makes the total clear length for 22-inch trees 15 feet. The 

 top of the inch-knot zone corresponds very closely to that shown in the 

 diagram, and the top of the dead-knot zone is about 4 feet higher. The 

 purpose of the diagram is to show graphically the proportionate amount 

 of the tree bole in the various diameter classes which is clear of all 

 knots (zone i), the amount which contains dead knots (zones 2, 3, 4), 

 and the zone of live knots (5). The large amount of the best grade of 

 lumber which is left in the woods in high stumps is also made apparent. 



Dimensions read from figure 2 have been plotted in figure 3, showing 

 diameter less exaggerated in proportion to the length of the log. The 

 first 28 feet of the tree only are shown, since the quality of the lumber 

 above that point renders it of slight interest. Data are submitted in this 

 diagram for the construction of a graded board volume table. Certain 

 variable factors controlling results in such tables must be determined 

 and applied. Saw kerf, dimension limits of lumber, location and size 

 of knots specified in the grading of lumber, alignment of logs on the 

 carriage, and method of cutting (rift or slash sawing) are the chief 



