NO, I GROWTH LAYERS IN TREE BRANCHES — CLOCK ET AL. 205 



RELATIONS AMONG BRANCHES OF THE SAME TREE 



A lack of consistency in the unity or multiplicity in growth layers of 

 corresponding years in different branches has been mentioned when 

 pertinent heretofore. Such lack is to be expected and may be charac- 

 teristic of trees grown in the extreme lower forest-border region. Sev- 

 eral questions arise from a study of branch materials: (i) Do the 

 branches within a single tree correspond with each other; and if so, 

 to what extent? (2) Does the amount of correspondence vary from 

 tree to tree under the same general environment? (3) Is there a 

 similarity among branches according to the year? (4) What is the in- 

 fluence of the environment? 



Before details are given, several points should be reemphasized : 

 (i) "Serial" sections were taken at unequal intervals along the 

 branches; (2) sections were taken on different dates, from 1939 to 

 19455 (3) sections contained different series of growth layers; and 

 (4) the trees grew at the extreme lower forest border. 



The first question mentioned above was, "Do the branches within a 

 single tree correspond with each other; and if so, to what extent?" 

 Much detail could be given because, in fact, each section of every 

 branch was examined, dated, and all growth layers identified and de- 

 scribed. All these results exist in charted form. From them the fol- 

 lowing typical examples are abstracted. 



In addition, the tables here given show the nature and amount of 

 multiplicity and the variation longitudinally on the different branches. 

 Some details of certain branches may not seem to agree with those 

 given heretofore; this disagreement is due to the uniting of certain 

 growth-layer types or to selecting certain types for emphasis. 



G^nsider the year 1940, for Con T i (table 142) : four branches 

 have multiplicity; the year 1941 : three branches have unity and five 

 have multiplicity; the year 1942; six branches have unity and two 

 have multiplicity. If we multiply the number of branches by the num- 

 ber of years in those branches, we obtain the number of branch-years. 

 This gives 20 branch-years, of which 9 have unity and 11 have mul- 

 tiplicity. Thus, 90 percent of the branch-years (i.e., 9 unity plus 9 

 multiplicity, making 18 out of the total 20 branch-years) offset each 

 other in respect to unity and multiplicity — they cancel. The remaining 

 2 out of 20 branch-years, or 10 percent, represents the amount of 

 agreement. 



The year 1938 for TTAp 2 (table 143) has all four branches mul- 

 tiple; 1939, all four branches multiple. Agreement is 100 percent, 

 that is, all branches have multiple growth layers for all years. 



