fore, developed great ability for thriving in dry 



soils. 



4. Tolerance. 



The Yell OH Pine is less tele rant of shade 

 than any of its associates, mature trees requiring al- 

 most pure unbroken light. Like D?ost forest trees, 

 the young growing Western Yellow P?ne trees are more 

 tolerant than older trees and the amount of avail- 

 able moisture in the soil determines to a large meas- 

 ure the density of the stand even v;hen a large per 

 cent of the trees are mature. The open sparser 

 stands of Western Yellow Pine found on the lov:er dry 

 slopes is not, therefore, due to the lack of light 

 but to the lack of moisture. Young reproduction is 

 quite tolerant and very dense stands are quite com- 

 mon in moist locations, but after a height of 10 

 feet has been reached the stand thins out very rapidly. 

 Seedlings require some shade for several years until 

 they have established a firm deep root system and 

 then they can stand and make more v j"U*uie growth when 

 they are subject to the direct rayc of -che Sun. 

 5 Grotrth aa d Longevity. 



The rate of growth of Western Yellcw Pine 

 depends entirely upon the quality of the locality. 

 Seedlings in dry localities may not make over 2 to 



-10- 



