FOREST PATHOLOGY IN FOREST REGULATION. 37 



the cross section enter into the valuation of this factor. In the present 

 study, the lateral extent of decay, the distribution over the cross 

 section, was estimated, as it is in practical scaling. Actual measure- 

 ments are difficult to take, on account of the immense variability of 

 the decay. In Table I, decay which neither in lateral extent nor in 

 degree was considered sufficient to seriously injure the merchanta- 

 bility of the part affected was marked as negligible. The longitudinal 

 decay was taken in linear feet, and the entire length was considered as 

 affected, in order not to complicate the computation too much. We 

 must distinguish between superficial decay of the sapwood and the 

 more serious decay of the heartwood. Figures of superficial decay 

 of sapwood are given in brackets (Table I, column 5). 



The next trees are sound. A negligible decay occurs in a tree 73 

 years old. Its diameter breast high is 11.2 inches; its height 58 feet. 

 The light decay started from an internal scar, caused by fire 23 years 

 ago and healed over in 5 years, but it remained in close proximity 

 to the scar without spreading. Again, a number of sound trees fol- 

 low. Then the first more serious decay appears. 



The tree in question is 84 years old, its diameter breast high only 

 8 inches, height only 45 feet. Both fire and lightning have played 

 havoc with this individual. An open scar extends from the ground 

 21 feet up the bole. The tree is quite evidently not in good health, 

 the sapwood is very narrow, and the crown is lopsided and very short. 

 Even in this case the decay follows more or less the open scar, but it 

 is sufficiently serious to cull the affected parts in so small a tree; in a 

 larger and thriftier one the damage would be called more or less local 

 and a nominal deduction made in the scale. From a lumbering point 

 of view this tree may be disregarded. 



So far, all trees considered had been either thrifty or not very 

 seriously wounded. Here we have an obviously suppressed, un- 

 healthy, and badly wounded tree; it presents at the same time the 

 first case of decay that is not to be called negligible. The following 

 trees are sound ; then follows a negligible trace of decay in an 86-year- 

 old tree, badly suppressed (diameter breast high 4 inches, height 13 

 feet) , grown in dense shade, with a remarkably small crown and with 

 a healed-over frost crack, but no other wounds. After several sound, 

 fairly thrifty trees follows a tree 87 years old, badly suppressed 

 (diameter breast high 7.8 inches, height 39 feet), with a very short 

 crown, wounded badly by fire and lightning (open scar from ground 

 to 18 feet) , and with decay following more or less closely the open scar. 



From these and the following trees, it appeared possible that with 

 increasing age the crown class, or rather the degree of suppression and 

 dominance, played a role with regard to the extent and seriousness of 

 the decay. Preliminary studies on incense cedar had given the same 

 indications. It seemed desirable, therefore, to express this degree of 



