INTRODUCTION 



Forest managers normally recognize and anticipate 

 periodicity in cone production of forest trees. How- 

 ever, variation in cone production among geographic 

 localities and individual trees within localities is 

 largely unexplored, for rarely are cones collected in 

 consecutive years from the same trees. 



In the course of breeding western white pine 

 (Pinus rnonticola Dougl.) for resistance to blister 

 rust (see Bingham, Olson, Becker, and others. 1969 

 and earlier) , 18 years of data on cone and seed yields 

 of individual trees from different geographic local- 

 ities have been accumulated. The protection of cones 

 during development minimized losses due to insects 

 and rodents; therefore, these data simulate the full 

 reproductive potential of young trees in natural 

 stands. Annual variation in cone production among 

 geographic localities and individual trees thus is 

 represented in these data. This information is indis- 

 pensable for practices of seed collection and seed 

 orchard management which rely on knowledge relating 

 to cone yields of individual trees and possibly on 

 yields derived from controlled pollinations. 



MATERIALS AND METHODS 



During the years 1950 to 1967, cone and seed 

 yields were obtained from 179 30- to 50-year-old 

 western white pines. Trees were representative of 13 

 geographic localities (figure 1) within which they 

 varied in elevation by about 400 feet; within two lo- 

 calities, however, trees differed in elevation by about 

 1500 feet. 



Comparisons of yields between seed years, local- 

 ities, and trees within localities were made on the 

 basis of mean yield; statistical analyses were not 

 attempted because yields for each maternal tree and 

 locality were not available for each year. Criteria 

 for including yields of individual trees in the basic 

 data were: (1) five or more years of observation were 



