SHAPE OF TREES. 



119 



9. Shape of Trees. 



Every tree has three parts, the bole, roots, and crown. In 

 youth, the roots and crown preponderate over the bole, the 

 formation of which begins at the 15th or 20th year. By 

 silvicultural means a forester can regulate the proportion 

 between the bole, crown and roots of a tree. Open growth 

 favours crown and roots at the expense of the bole ; density 

 of growth increases the bole at the expense of the crown and 

 roots. 



On good soil, the bole and crown become relatively large, 

 the former in a less degree than the latter. Other 'conditions 

 being equal, crops of trees produce more volume per acre on 

 good soils, which favour stem-timber, though more numerous 

 but smaller trees grow on an acre of poor soil. Usually in 

 close, mature woods, only 10 to 20 per cent, of the volume is 

 lop-and-top (under three inches in diameter). Individual species 

 vary in the proportion of bole and crown in accordance with 

 the following statement. 



Spro 



Lan-hcs. 

 Douglas lii'. 



Si Ivor-fir. 



in runs up to the 

 topmost Idid of the 

 tree and height, growth, 

 except in silver-Mr, con- 

 tinues us long as the 

 tree lives. The branches 

 are small. 



I'll 



.:as. 

 Cyj/i 



; of Stem depends 



on climate ami locality. 

 In open growth or in 

 old age, the stem divides 

 into .several large 

 boughs. 



I! road leaved trees resem- 

 ble pines in their growth, 

 but stem preponderates 

 in the following : 



niiereus palustris. 



Poplars. 



Tulip-tree. 



Alder. 



Birch, 



Ash, 



-sile oak. 



Aspen. 



Also in beech and other 

 broadleaved trees, 

 when grown in dense 

 crops. 



The following statement is compiled from results given by 

 Pfeil and M. Hartig, with which those given by Pressler and 

 Burckhart have been compared. In the case of dense crops 

 grown in high forest to an advanced age in good localities, 



