l8 TREE GROWTH AND RAINFALL— CLOCK 



CONCLUSIONS 



47 



A study of the Holman Pass collection, which came partly from 

 the Transition and partly from the Canadian Life Zones, permits two 

 general conclusions. 



First, the evidence indicates rather clearly that variations in tree 

 growth follow variations of March-July rainfall from year to year 

 very nearly lOO percent at the immediate site of the trees. 



Second, the evidence strongly suggests that changes of internal 

 agreement among the trees and changes of average variation, average 

 departure, and average departure from mean variation can be used 

 as a method to reveal changes in rainfall through the years where 

 amount of rainfall, and hence derived soil moisture, approximately 

 equals that present at the location of the dominant members of the 

 Holman Pass collection. 



