DETERIORATION OF WESTERN YELLOW PINE. 7 



exactly similar to those of a great part of the yellow-pine belt of 

 eastern California, Oregon, and Washington, and not markedly at 

 variance with conditions in other western yellow-pine regions in 

 North America. 



These results should prove generally applicable, with minor varia- 

 tions, on control projects in western yellow pine. Timber averaging 

 smaller than that studied here will deteriorate more rapidly, while 

 the deterioration in larger timber will, of course, be slower. 



The felled and barked trees were completely sap-stained by the 

 end of the first season of exposure. If sap-stain is considered a 

 defect serious enough to make discolored wood worthless for lumber, 

 there is such a large loss the first season that utilization by mid- 

 summer is imperative. However, as a rule, stained lumber is only 

 degraded and not culled. 



Deterioration is very rapid and is chiefly caused by decay, par- 

 ticularly the very rapid decay of the sapwood, followed more slowly 

 by the breaking doAvn of the heartwood. The resulting loss is so 

 high by the end of the second season that felled trees must be utilized 

 by the beginning of the second season, or else the volume of mer- 

 chantable wood obtained is so small as to be of little commercial 

 importance. Consequently, the timber in most of the trees cut on a 

 control project becomes a complete loss, since under present economic 

 conditions it is usually not possible to utilize scattered trees over a 

 large area within such a limited period of time. 



