THINNING 145 



dead and sickly trees ; with a view to aiding the suppression 

 of insect and fungoid attacks, and of fire.* 



Then again, in natural regenerations or when artificial 

 sowing has taken place, it will often be necessary to clean out 

 much of the young crop to prevent overcrowding and to 

 prevent the seedlings from becoming too spindly, in which 

 case, they might be unable to support their own weight when 

 they were a few years older, and so get bent over by the 

 wind. This cleaning on natural regeneration areas is some- 

 times done by freeing individual trees, and sometimes by 

 cutting narrow strips 2 feet wide ; in this latter case the trees 

 on the edges of the strips become stronger and so free them- 

 selves. 



THINNING. 



The primary object of thinning is to aid the more 

 valuable trees in that struggle for existence, which results in 

 the survival of the fittest, when Nature alone has her 

 course. 



In the latter stages of a rotation heavy thinnings are 

 often made in order to increase the quarter-girth measure- 

 ment and for the production of timber of larger dimensions. 

 Such thinnings are, however, really partial clearances. 1 



Now, with reference to thinnings in the early stages of a 

 rotation : 



After an area has been planted or raised from seed, there 

 is always a period of risk and uncertainty, especially if there 

 is no shelter-wood over the young crop, until the young crop 

 has closed in overhead and close canopy has been formed. 



When this has taken place much anxiety is removed. 

 From this time onwards the trees are struggling with each 

 other for supremacy. If artificial aid is not forthcoming this 

 struggle is continued to a dangerous extent ; the trees 

 become too thin and lanky, and, when ultimately any 

 thinning takes place, the trees left will be unable to with- 

 stand gales of wind or heavy falls of snow. 



On poor soil this prolonged struggle is especially notice- 



1 Vide Chapter VIII. 



K 



