18 CLIMATIC CYCLES AND TREE-GROWTH 



the differences at different heights are less than the differences between 

 different trees. Of course, in most cases the differences are practically 

 none at all. This subject of taper study or vertical uniformity will be 

 treated on a later page. A boring within a foot of the ground makes 

 one feel that complex and difficult corrections are needed because of the 

 root influence, and the ring record therefore is inferior. On the other 

 hand, if the boring-hole is made over 2 feet from the ground, it 

 may injure slightly the value of the tree for lumber. The average 

 height of pine stumps about Flagstaff is 16 to 20 inches, sometimes 

 going to 2 feet. The lumberman knows that interior defects increase 

 toward the root, and there is always a little waste at the lower end of 

 the butt log. In choosing the exact spot to bore it is better to try a 

 slightly projecting part of the trunk, for there is less danger of encoun- 

 tering absent rings which might render dating difficult. One must be 

 careful in boring fallen trees to note whether they still have roots in 

 the ground and are dry or moist. If they are still rooted or not thor- 

 oughly dried, the sapwood may be distorted with irregular growth or 

 irregular swelling from moisture. 



Root rings — Ring sequences have been identified from roots of 

 trees and in some cases such records seem usable. These, however, 

 have never been included in the averages, from the feeling that root 

 rings, even in large branches of the root, must be subject to other 

 conditions than the trunk and may not be consistent. Sometimes, 

 in well-watered pines, early rings in the lower trunk near the root may 

 be very large.* 



Crown rings — Rings near the top of the tree and in larger branches 

 show close similarity to rings in the lower trunk. Though their 

 actual size is smaller and sometimes microscopic, the sequence of sizes, 

 of the tree record, is nearly the same (see fig. 1, p. 24). 



Boring the sequoia — Using the increment borer on the sequoia 

 has rarely seemed worth while, except for some special purpose, such 

 as tests on young trees for infancy rings, estimates of age, and so 

 forth. The reason is the enormous thickness of bark of the sequoia, 

 especially in the lower 15 feet, and the distortion of rings due to bulges 

 in the same region. With a ladder one could get useful specimens. 



The i-inch tubular borer — The tubular borer so far has not been 

 satisfactory on living trees, not because it hurts the tree but because 

 it is slow and difficult in operation. An 18-inch core from a 350-year 



*This was observed in a tree which once stood in the flat south of the county hospital at 

 Flagstaff, about 2 miles north of town. The tree was cut down in the 1880 's and was renowned for 

 its size. Recently Mr. L. F. Brady copied on paper the rings in the stump, which was badly 

 burned. When I saw it, the stump had been blasted out and thrown away, but fragments showed 

 extremely large and complacent rings near the root. The dating was uncertain, but it was prob- 

 ably nearly 500 years old at time of cutting. 



