Table 11 . --Analysis of growth and height in the factorial mating design study 



Source : 



d.£. 



: M.S. 



: Variance 



: : Percentage 



: Value : of total 



Growth between ages 9 and 11 











Elevational zone 



I 



ZzUd 



4.3 



1.4 



Family (Elev.) 



95 



432** 



8.6 



2.7 



Within Family 



1382 



301 



301 .4 



95.9 



Height age 12 











Elevational zone 



2 



7710* 



14.8 



1.9 



Family (Elev.) 



95 



1621** 



59. 9 



7.6 



Within Family 



1382 



716 



715.7 



90.5 



and ** indicate significan 

 respectively. 



ce at the 



5 percent and 1 



percent level , 





Vigor-quality study , --The main reasons for including this study are that the trees 

 are old enough to have reached a stable growth pattern and to show how the results have 

 changed over the years. The mean height of the low elevation families has been consis- 

 tently greater than that of the high elevation families (table 12) . Significant dif- 

 ferences during the early years, ages 4 to 8 (table 13) , probably resulted from the 

 combination of a carryover of nursery differences (Squillace and Bingham 1958) and 

 limited competition on the recently cleared sites. By age 8 competition from the native 

 vegetation was increasing and until age 12 or 14 when most trees were taller than the 

 brush all families probably grew less than their potential. That competition probably 

 was also responsible for keeping the differences between elevational zones relatively 

 constant while between-family and within-plot variation increased more rapidly. After 

 the trees overtopped the brush, their growth potential could be realized more fully. 

 Then height and growth rate differences between the low and high zones again became 

 significant . 



During the last 3 years, differences between the low and high families continued to 

 increase but at a slower rate. At the same time, differences among families within 

 elevational zones became larger, resulting in a decrease in the significance of the 

 elevational difference. The elevational difference exhibited in this study is probably 

 larger than would be found if more stands, and trees, had been sampled. The results from 

 the natural selection study reported earlier indicate that trees of the high elevation 

 stand (White Rock) used in this study produce the slowest growing seedlings of the high 

 elevation stands sampled. Also, most of the low elevation trees are from a stand (Crystal 

 Creek) that produces some of the fastest growing seedlings. Thus, by chance, these 

 results and those of Squillace and Bingham (1958) contrast the poorest high trees we have 

 studied with some of the best low trees. Even then, the best high family has been taller 

 than several of the low families. 



Height growth of the young trees at the two sites was essentially equal until age 

 10 and did not differ significantly until age 16. Interactions between sites and eleva- 

 tional origin of the seedlings were essentially nonexistent even after the height dif- 

 ference between the sites became highly significant. 



15 



