54 PRACTICAL FORESTRY IN 



returns by supplementary artificial planting. Some authori- 

 ties question the financial practicability of this on the ground 

 that since spruce is of slower growth it will pay better to use 

 the ground for fir, but the latter is unlikely to be true of 

 bottom land. 



After summing all its advantages, the peculiar merits of 

 spruce for certain purposes should be weighed, for suffi- 

 ciently higher stumpage value will compensate for delay in 

 harvesting the crop. Moreover, Sitka spruce has not been as 

 thoroughly studied by foresters as the more prominent West- 

 ern trees, and while the foregoing notes represent general 

 present opinion, further figures on rate of height growth 

 may be more encouraging. There is no doubt that diameter 

 increase is rapid from the start. Most of the disadvantages 

 mentioned also decrease toward the southern limit of the 

 spruce range, the growth on the Oregon Coast being rapid. 



WESTERN YELLOW PINE (Pinus ponderosa) 



In this species we have the important western conifer which 

 most often permits the selection system of management. 

 With certain exceptions in which the entire stand is mature, 

 the object of conservative logging should be to remove trees 

 past the age of rapid growth and foster those that remain 

 for a later cut. When comprising the entire stand, or at 

 least clearly dominating it, with all ages fairly evenly repre- 

 sented, successful in reproduction, and not so dense as to 

 present mechanical difficulties, it is ideally adapted to this 

 form of management. The important underlying principle is 

 that, since for a period of its life the normal individual tree 

 increases in wood production and then declines, it is bad 

 economy to cut it while it is still growing rapidly or to allow 

 it, after slowing down, to occupy ground which might be used 

 by a tree still in the vigor of production. For example, if at 

 100 years old it contains 500 board feet, it has averaged an 

 addition of 5 feet a year throughout its life. If at 125 years 

 old it contains but 560 feet, the average increment will be but 



