1 78 FORESTRY IN NEW ENGLAND 



tree in percentage falls with increasing age, in spite of the fact 

 that it lays on more wood each year even if the width of the rings 

 remains the same. Although the actual amount of wood made 

 may increase, this increase is an ever-decreasing proportion of 

 the total volume of the tree. Suppose, for example, that the 

 red oak mentioned above grew 3 cubic feet during the decade 

 between sixty and seventy years, the percentage of growth would 



be ~ or 35 per cent. 

 5.4 



B. GROWTH OF STANDS. 



Thus far the growth of individual trees has been considered; 

 it is important for many purposes to ascertain the growth of 

 stands or whole forests. Forest management depends very 

 largely on this knowledge, especially the more intensive forms 

 of management, such as are in use in Europe. In Austria, for 

 example, the policy is to cut and reproduce a stand as soon as 

 it ceases to yield a satisfactory rate of interest. This is called 

 the financial maturity of the stand. In Baden and other coun- 

 tries the forest working plans prescribe the cutting of an equal 

 amount of wood each year, while in Wiirttemberg, an equal area 

 is cut over annually. A knowledge of the growth of the different 

 stands is essential for the Baden system. In our own country, 

 forestry which aims at a permanent income must rest on tliis 

 kind of knowledge. 



Just as we have considered the growth in diameter, height 

 and volume of individual trees, so the growth of whole stands 

 should be discussed under similar headings. 



I. Age of Stands. 



The age of a stand is usually considered to coincide with the 

 age of the tree of average size in the stand. Such a tree is 

 selected and its age ascertained as already described. This 

 result is taken as the average age of the stand. Such a figure 

 has more value in even-aged than in uneven-aged stands. 



