SYLVICULTURE. 



III. Growing space of a tree. 



In their early youth all species stand or even desire a dense 

 cover overhead. When the food supply stored in the seed shell is 

 consumed, however, the seedling requires light to digest its food. 

 With increasing age, the tree boles getting longer, the crowns ruii 

 and beat one another intensely, swaying pendulum fashion in the 

 wind. As a consequence each crown is surrounded with an air space, 

 the relative width of which depends largely on the length and tin 

 flexibility of the bole. It might be stated that the growing space 

 of a tree is a function of the square of the gradually lengthening 

 bole. 



Trees differ in the ease with which warring neighbors lose their 

 buds and shoots. Oak, for example, loses its May shoots easily, 

 whilst Beech, struggling with Oak, loses a few leaves only along its 

 flexile swaying twigs. In heavy storms Yellow Pine often loses 

 whole branches. White Pine, on the other hand, does not easily 

 lose its shoots. The top shoots of the taller individuals are immune 

 from harm. Thus a tree, once in the lead of its competitors, has a 

 good chance to retain the lead over them. 



IV. Grades of density of cover are: Pressed cover. Close cover. 

 Light cover and Open cover. No strict definition of these tern.s can 

 ^•e given. Obviously the number of stems under pressed conditions 

 is vcrj' lai-ge. 



Indications of a normal cover are: 



a. Relation betw^een length of crown and length of bole. 



b. Normal diameter growth and height growth. 



c. Proper participation of the various diameter classes in the 

 volume of wood at hand. The normal participation in a pure, even- 

 aged wood is for the , 



1st. Diameter class — 40% of total volume. 

 2nd. Diameter class — 24% of total volume. 

 3rd. Diameter class — 17% of total volume. 

 4th. Diameter class — 12% of total volume. 

 5th. Diameter class — • 7% of total volume. 



If cover overhead is too dense, the first class shows over 40% of 

 volume and Aice versa. 



V. In nature, the same causes necessarily have the same result. 

 The causes of timber production are soil and atmospheric food " fall- 

 ing " onto the soil in the shape of sunshine, moisture and air. Hence, 

 whatever the species are, it seems as if the acre of ground, fully 

 stocked, must produce on the annual average the same weight of 

 timber — not the same volume of timber. Thus, ceteris paribus, 



28 



