YIELD TABLES 75 



the current annual increment falls from 100, to 

 meet, at which the former culminates and the 

 two are equal. 



The mean annual as well as the current an- 

 nual increment culminates earlier the better the 

 quality of the locality. In quality I the current 

 and mean annual increment of the wood and 

 bark culminate respectively at 40 and 60 years. 

 In quality II they culminate at 50 and 80, and 

 in quality III not until 60 (or thereabouts) and 

 100. 



The culmination of increment of the merchant- 

 able timber takes place later than that in which 

 the entire stem is included. Thus in quality II 

 the culmination for the current and mean an- 

 nual increment occurs for the whole stem with 

 the bark at 50 and 80 years respectively. For 

 the merchantable timber expressed in cubic feet 

 the corresponding points are at 60 and 100 

 years. To compute the growth in height of the 

 various groups as simple a method as possible 

 was employed. The growth in height of all 

 the average trees of the valuation survey 

 groups was plotted on cross-section paper and 

 an average curve was thus obtained for each 

 class. It may be said that the average tree at a 

 given age has not always been the average tree, 

 and that this method is consequently incorrect. 



