Forest Management -27 



PARAGRAPH XXIII. 



COMMON INCREMENT METHODS. 



The increment methods are the oldest and roughest methods of 

 yield regulation. The underlying idea is the following: As long as 

 only the increment is cut — no more, no les« — an overcutting of the 

 forest is impossible. The average production per acre can be ascer- 

 tained from yield tables, by systematic experiments, or, as is the usual 

 practice, by estimating. 



The methods do not pay any attention to normal growing stock, 

 normal age gradation and normal increment. The methods are not 

 applied anywhere, nowadays, in scientifically conducted forestry. 



PARAGRAPH XXIV. 



BRANDIS METHOD. 



The Brandis method was first applied 'by Sir Dietrich Brandis in the 

 Teak forest of Burma. The method ascertains the number of mature 

 trees in a forest as (well as the time "which an equal number of trees 

 styled "immature," next in diameter to the mature class, require to 

 grow as large as the mature trees are, so as to be fit to replace them. 



Dividing the number of mature trees by the period of replacement, 

 the annual possibility of the 'forest is ascertained. The method per- 

 petuates the original 'composition of the forest, calling it normal be- 

 cause natural. 



An illustration 'might be obtained from the data contained in bulle- 

 tin No. 32, Bureau of Forestry, prepared by F. 'E. Olmsted: 

 Diameter of mature trees, 20 inches and over. 

 Number of mature trees, per acre, 4.94. 



Number of immature trees', having 15 inches to 19 inches diam- 

 eter, per acre, 4.99. 

 Number of years required by a 15 inch tree to 'grow mature, 34- 

 The annual possibility, after Brandis, in this case amounts to 



4-94 



= 0.145 



34 

 mature trees per acre, or 145 mature trees for every 1,000 acres. 



After bulletin No. 32, the volume of the trees having 20 inches and 

 over at breast height is 4561 feet b. m. 



The possibility in lumber is, consequently, 



4561 



= 134 



34 



feet b. m. per acre per annum. 



