76 SYLVICULTURE. 



poles or young trees may be roughly classified as (1) dominant, 

 (2) dominated, and (3) suppressed. Suppressed stems that are 

 dead or dying should always be thinned out as soon as con- 

 venient, and the thinning must go further than this to be of 

 any use in stimulating the rate of growth of the crop. 



As the object of thinning is to try and produce the best 

 ultimate crop, the thinnings should from time to time (about 

 once every five years, if practicable) eliminate one or more of 

 the following : 



(1) All dead, dying, and badly diseased or insect-infested poles. 



(2) Badly-grown poles (e.g., of crooked or forked growth), and poles 



of inferior kinds of trees interfering with the growth of more 

 valuable kinds. 



(3) Poles of the better kinds of trees interfering with the growth of 



more valuable poles, whether of their own species or of other 

 valuable kinds. 



Even the lightest thinning should remove all poles of class 

 (1) ; but how far, if at all, those of classes (2) and (3) can with 

 advantage be cut out, depends upon the existing condition of 

 the plantation or wood as to density and demand for light and 

 growing-space e.g., Larch, Scots Pine, and other light-demand- 

 ing Conifers need somewhat freer and heavier thinning than 

 Douglas Fir, Spruce, Silver Fir, and Eed Cedar ; and Oak and 

 Ash more than Beech or Sycamore. The best general rule is, 

 thin early, lightly, and often ; but what this may mean in any 

 given case depends greatly on the kind of crop and its condition. 

 The time when thinning should be heaviest and repeated most 

 often is when pole-woods are getting past their most active 

 rate of growth in height, for their crown-expansion sidewards 

 becomes more necessary than before ; and, of course, this need 

 for expansion of crown- and root-system is greatest in light- 

 demanding trees. 



Thinning out of standards in copse only takes place at each 

 fall of the underwood, and is then part of the regular clearance 



