66 FORESTRY 



thinning will be found more satisfactory. The latter system 

 furnishes a greater aggregate production and preserves the 

 yield capacity of the soil better than sudden heavy fellings. 



Pruning 



Natural pruning is the rule in sylviculture. The crowns 

 of the trees in a close wood monopolise the light and compel 

 the lower branches to die through overshading. But there 

 are cases when artificial pruning is required either to en- 

 hance the value of stems so treated, or to prevent young 

 plants being harmed by the branches of larger trees whipping 

 and suppressing them. Trees with strong lower branches, 

 left as shelter or for seed when regenerating forest ground, 

 are often pruned to relieve the young crop at a time when 

 their complete removal would be dangerous. Birch and 

 Aspen occurring accidentally in a rising wood may also be 

 severely pruned with good effect some years before being cut 

 over. Pruning carried out to increase the commercial value 

 of the timber should be restricted to the removal of dead 

 and the lower of the weak green branches. All trees in a 

 wood should not be treated in this way, but only those likely 

 to remain to the end of the rotation. 



Care ought to be taken to remove branches with a clean, 

 sharp cut flush with the stem. The only exception to the 

 latter rule is in the case of strong limbs belonging to shelter 

 trees shortly to be feHed. It is then better to leave a pro- 

 jecting stump, in order to prevent any injury to the tree stem. 

 At other times such shortened branches are very objection- 

 able, for the cut surface heals with great difficulty ; or occlusion 

 may fail altogether, and decay is conducted into the bole. 



Ordinarily, when the pruning is done with a view to the 

 production of good timber, only those branches which are 

 under two inches in diameter should be taken. When a 

 larger branch is pruned from broad-leaved trees, the wound 

 should be painted with coal-tar or other antiseptic material. 



The season for pruning is from October to February, but 

 preferably in the early part of winter. 



