58 



meast:rement of whole woods. 



Urich's method is thus a combination of Draudt's method 

 with that of the arithmetical mean sample tree for each 

 group. 



The degree of accuracy depends on the number of groups, 

 which are formed, and on the number of sample trees 

 measured in each. Too large a number of groups is, however, 

 inconvenient, as it involves repeated separation of the original 

 diameter classes. 



The method has the disadvantage, that the basal areas must 

 be calculated before the sample trees can be selected. Urich 

 proposes to avoid this by estimating the sizes of the sample 

 trees in the several groups, a procedure which may lead to 

 inaccuracies. 



Example. ^^ee pages 56 and 57. 



Measukement of Volume according 



