DRY-ROT OF INCENSE CEDAR. 7 



tract was not clear cut, the representation of age, diameter breast 

 high, and height classes obtained from the study must not be assumed 

 as an exact expression of the actual conditions. 



Each tree was cut as closely as possible to a stump height of 18 

 inches, then limbed and bucked. The first or butt log was made 

 7 feet long and the others 14 feet long, the number of cuts depending, 

 of course, on the length of the tree. The last cut was always made 

 well in the top near the upper limit of the heartwood. The reason 

 for bucking in 7 and 14 foot lengths was purely a practical one; any 

 sound heartwood could then be utilized for 7-foot posts. The age 

 count at stump height was taken as the age of the tree instead of 

 adding a few years corresponding to the height of the stump, since 

 the aim is to have all figures taken directly comparable. In this 

 case with a minute constant variation no error can be introduced. 

 Trees with wounds which destroy the center at stump height were 

 avoided when possible, since in such cases an accurate age count 

 could not be obtained; hence, trees of this kind are valueless for all 

 further calculations in which the exact age is a factor. The sap width 

 was obtained from an average of six or eight measurements. Three 

 radii were measured to secure the average diameter. Separate 

 measurements were made for the area covered by decay. The dates 

 of occurrence and closure, when healed, were determined for all 

 wounds present. Each log was split at least once in order to reveal 

 completely all decay and internal wounds. Great care had to be 

 observed in splitting the logs in order to be certain not to miss any 

 decay, since the dry-rot occurs in pockets which may be separated 

 in a linear direction by several feet of sound wood. This habit of 

 "jumping" also made it exceedingly difficult to trace the entrance 

 of the decay in certain cases where the decay might be several feet 

 removed from any possible point of entrance. It often became 

 necessary to split log after log into many small pieces. 



In all, 1,075 trees were analyzed, 509 at Sloat, 266 at Strawberry, 

 100 at Cow Creek, and 200 at Crockers Station. 



In all future references in this paper, for the sake of convenience 

 the term " intermediate area" will be used to designate the area at 

 Sloat, since it represents conditions in the intermediate range, and 

 the term ' ' optimum area ' ' to designate the combined areas at Straw- 

 berry, Cow Creek, and Crockers Station, since they represent condi- 

 tions in the optimum range. The results of the field work follow. 



SECONDARY ROTS. 



Under this heading are grouped all decays the causes of which 

 are unknown. Such decays are of various types and are almost 

 invariably found immediately adjacent to open or healed-over 

 wounds, particularly fire scars. Instances were encountered where 



