334 REPORT OF THE FOREST, FISH AND GAME COMMISSIONER. 



The oldest compartments are allotted to period number one; the next 

 oldest to periodnumber two, etc. The total acreage allotted to each periodical 

 column is found by addition and compared with the average contents of a 

 column. If a column contains too much acreage, the surplus is shifted back- 

 ward or forward into adjoining columns. Compartments growing vigor- 

 ously are shifted backward into later periods and vice versa. After shift- 

 ing, each column contains in toto, approximately, an equal number of acres. 



By valuation surveys or yield tables, the volume contents of the 

 compartments allotted to the first period are ascertained; and the contents 

 are increased by the probable volume increment of these compartments 

 expected during half a period. The total contents are then divided by 

 the number of years comprised by the period. The result is the annual 

 " sustained yield." Obviously, the sustained yield is apt to change at 

 the end of each period. 



The installation period comprises a whole rotation. At the end of a 

 rotation the forest is sure to exhibit a more normal age gradation. . 



This method is in use in Prussia, Bavaria, etc., and has been working 

 in almost all European forests since 1780. The method is not applicable 

 to selection forests. It might be improved by replacing the " Statement 

 of Ages " by a " Statement of Indicating Percentages." 



Volume Aetfjod 



A statement of ages is prepared, each compartment being allotted to 

 a periodical column according to the number of years which separates it 

 from maturity. The compartmental entries made in the statement of ages 

 are, in this case, however, the final volumes expected at maturity, and not 

 the compartmental acreages. 



The totals for each period are drawn and compared with the average 

 volume expected from each periodical column. Again, by shifting com- 

 partments onward and backward, surpluses are shifted into columns showing 

 a deficit, under adequate allowance for changed yields. The possibility 

 is obtained by dividing the total of the first column, as it stands after 

 shifting, by the length of a period. 



The method does not work towards normal age gradation. The 

 shifting of volumes is times taking, and the method is not in use nowadays. 



