THE ART OF THE SECOND GROWTH 



the same age, the poorer these factors are 

 Pine Forests: 



Xuiiiber of trees per acre. 



Soil. Boles 75' long. Diameter 12". 



I qmility... 320 240 



II quality... 240 215 



III quality... 190 190 



For e.xample — Yellow 



Age 60 y IS. 

 380 

 4G0 

 540 



During the pole stage and tree stage, shade bearers exhibit per 

 acre of ground about 507o more trees than light demanders. 



The following curve illustrates the interdependence between age 

 and number of trees 'ler acre: 



of 



trees 



per 



10,000 



5,000 



2,500 



1,000 



900 



800 



700 



600 



.500 



400 



300 



200 



100 







10 20 30 40 50 60 



When the forest is 



rO 80 90 100 120 130 140 1.50 160 170 180 

 years old. 



III. Growing space of a tree. 



In their earliest youth nil 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 rub 

 and beat one another intensely, oscillating in the wind. As a con- 

 sequence each crown is surrounded with an air space, the relative 

 width of which depends largely on the length and the 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 but a few leaves along its 



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