SYLVICULTURE 



inclien in diameter affect the lumber price only slightly. The pre- 

 vention of dead knots is, therefore, most important. No topslioot 

 is formed without side shoots, and no section of a tree bole is 

 free from brancnes and free from branch knots. Hence the advisa- 

 bility of pruning the boles oi such species which develop branches 

 of large diameter and of great persistence when dead. Branches 

 (excepting adventitious branches) invariably start from the central 

 core. 



II. Increased height growth. 



III. The production of cylindrical boles of high form figure 

 (Pressler's law of bole formation). (H)viously, " II" and " III" are 

 obtained only by removing live branches. 



IV. The reduction of the sliarle falling on a young, promising 

 undergrowth. 



V. The reduction of cianger from fire in coniferous woods close 

 to public roads. 



B. bpecies: Hardwdods suffer less from the removal of green 

 branches than softwoods. Green branches of over five inches in 

 diameter should not be removed at all, except in case " IV," owing 

 to the certainty of subsequent disease. 



Oak heals the wound inflicted by pruning best; Ash is likely 

 to split; Maple is slow in closing a wound; Birch soon shows dis- 

 ease; Yellow Pine covers the wound quickly with rosin. 



C. Actual European practice: 



The practice restricts pruning to the case " I " and m ithin case 

 "I" to: 



I. Dead branches. 



II. Polewoods forty years to sixty years old. 



HI. Limited numbers of poles (say 100) per acre, namely, to the 

 specimens presumably predestined to reach the end of the rotation. 



Pruning extends to a height reaching up to forty feet, is done 

 by help of ladders, of a climbing apparatus (not climbing irons) 

 or of saws attached to very long poles. The best saw is the 

 ■'Alers " construction. 



In ±iTance, sharp, curved blades are preferred to saws, since 

 they produce a smoother cut. 



The branch is cut off as close to the bole as possible. Large 

 branches are cut off in sections to prevent the bole from being 

 scarred. In the case of broad-leafed species and in the case oi 

 live branches, large v.'ounds are always tarred. Tarring in spring 

 is impossible. 



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