DRY-ROT OF INCENSE CEDAR. 



In the intermediate range, comprising the northern Sierras and 

 the Coast Ranges, slower growth is the rule, and in the mixed stand 

 where the cedar always occurs it plays a distinctly secondary part 

 and might almost be classed as an understory tree. 



The poorest development is found in the extreme range, which 

 includes stands at the horizontal and altitudinal extremes of the dis- 

 tribution of the species. In such situations the trees are short, 

 scrubby, and relatively of little value. 



With the above facts in mind, it was considered essential to choose 

 areas representative of the intermediate and optimum range; the 

 extreme range could be neglected, since it is of no practical im- 

 portance. 



In the uneven-aged stands care had to be observed to select areas 

 on which all age classes were represented, since if there is a relation 

 between any of the total-loss factors and age of the tree, this would 

 fail to appear if even-aged or nearly even-aged trees alone were con- 

 sidered. 



Observation and a preliminary study by Meinecke 1 showed con- 

 clusively that the total-loss factor of supreme importance in the 

 case of incense cedar is dry-rot caused by Polyporus arnarus. Above 

 all, then, it was essential to select stands in which dry-rot was com- 

 mon, using discretion not to make the selections where loss from, 

 dry-rot was far above or below normal. Other total-loss factors, 

 particularly mechanical injuries, could not be disregarded and were 

 carefully considered. 



With a knowledge of the habits and condition of incense cedar 

 throughout its range, several possible areas were tentatively chosen, 

 a careful examination made in each case, and then the most suitable 

 stands were decided upon. 



DESCRIPTION OF AREAS. 



The area selected to represent the intermediate range is at Sloat, 

 Calif., within the boundaries of the Plumas National Forest, in the 

 northern Sierra Nevada Mountains. In general, the region is one of 

 heavy snowfall, with moderate winter temperatures and a long, 

 dry, warm summer season. Lightning storms are not very frequent. 



The tract has a relative altitude of 4,300 to 4,700 feet. The fairly 

 deep soil is a decomposed lava, normally dry and loose. 



The virgin uneven-aged stand, with a strong representation of 

 mature and badly overmature trees of all species, is principally 

 composed of western yellow pine {Pinus ponderosa), Jeffrey pine 

 (Pinus jeffreyi) , and Douglas fir (Pseudotsuga taxifolia) . Where 



1 The writer wishes to acknowledge his indebtedness to Dr. E . P. Meinecke, who first inaugurated a study 

 of incense cedar in 1912, the data obtained being included in this paper, for advice and direction through- 

 out the course of all the later work. The essential methods followed in this study are outlined by him in 

 United States Department of Agriculture Bulletin 275 (16). 



