84 report of the 



The Draudt Method. 



By this method the sample trees when placed together present an exact model of 

 the stand and show the relationship of size classes as to number of trees. In tiie 

 sample trees all diameter classes of the stand are represented and the same relation- 

 ship exists between the sample trees of the different diameter classes as exists 

 between the diameter classes themselves. 



It is first decided what proportion the whole number of sample trees shall bear to 

 the whole number of trees of the stand. The percentage may either be chosen 

 directly, that is, we may say that there shall be felled as sample trees i, or 2, or 3, 

 etc., per cent of the whole number of trees. Or the total number of sample trees to 

 be felled may be decided upon and then from a consideration of these and the total 

 number the percentage can be reckoned. 



Suppose for example the number of trees of the stand to be 1,780 and that 25 

 sample trees are to be felled. Then, 



1,780 : 25 :: 100 : /. 



The number of sample trees for each diameter class is then found by multiplying 

 the number of trees of each class by /. Fractions of .5 or over, resulting from the 

 mliltiplication are reckoned as a full inch, and those under .5 are discarded. Should 

 several neighboring classes furnish no sample tree each, or rather only a fraction 

 imder .5, several classes may be grouped together according to the size of the frac- 

 tions. Finally the sample trees should be added together to see if these agree with 

 the whole number decided upon at first. Differences which are caused by rounding 

 off the fractions are then balanced. In order to avoid too many fractions of sample 

 trees, the diameter classes need not be made too small. 



Sample trees are then according to sizes and number selected in the forest. 

 After being felled, they can either be cut into sections, say, 4 feet long, and their 

 volume accurately measured ; or they can be worked up in the usual way for sale. 



According to the principle of the method, the sample \Vood likewise presents the 



■chosen per cent of the volume of the stand. The volume of the stand, then, is to 



be reckoned by the formula, 



vY. 100 



V ■ 



P 



On account of the rounding of the fractions, due to fixing upon the number of 

 sample trees, this relation does not exactly hold, and instead of the quotient -— 7- 

 according to Draudt's proposition that of 



