METHODS OF MAKING THINNINGS 171 



Interlucation or Accretion Cuttings. — Accretion cuttings are 

 classed as the heaviest grade of thinnings and like other thin- 

 nings are not intended to make permanent gaps in the cover. 

 Their purpose is to obtain exceptionally rapid diameter growth 

 of individual trees, not attainable with lighter thinnings. 



Fig. 



The same stand as shown in Fig. 66, but immediately after a D grade thinning, 

 removing overtopped, intermediate and many co-dominant trees. Note that 

 the crown canopy has been opened and every one of the remaining trees given 

 increased room on one or more sides. Compare with Figs. 67 and 77. 



They are needed particularly with light demanding species, 

 for shade enduring trees grow rapidly following lighter thin- 

 nings. In making accretion cuttings there is great danger of 

 reducing the volume production per acre, although the in- 

 creased value of the large trees may offset financially any such 

 reduction. 



