THINNINGS AND PRUNING 241 



Foresters usually distinguish between three degrees 

 of thinnings : 



In making light thinnings (coupe sombre des eclair- 

 cies of French, and dunkle Durchforstung of German 

 foresters) only suppressed or dead trees are removed ; 

 in moderate thinnings (coupe moderee, or mdssige 

 Durchforstung) dominated, suppressed, and dead trees 

 are cut out, and in heavy thinnings (coupe claire, or 

 starke Durchforstung) some of the dominant trees are 

 felled as well as the dominated and dead ; but the sup- 

 pressed trees may be taken out or left according to the 

 necessity of giving shelter to the soil. In this operation, 

 although the leaf-canopy should not be materially inter- 

 rupted, it should be considerably lighter. 



In a pure crop of uniform age the thinnings will at 

 first be light, and even these must be done very 

 cautiously at first in a dense crop, the stems of which are 

 thin and lanky, and incapable of standing upright unless 

 supported. In the Tropics generally, where the sunlight 

 is very intense, it will be best to make all the first thin- 

 nings light and to repeat them as often as possible. 

 When the remaining stems are strong enough to do 

 without support the thinnings can be made moderate, 

 and when the trees have reached their full height it will 

 be possible to favour the strongest among the dominant 

 trees by the removal of the more weakly, unsound, and 

 crooked ones ; while the time comes when even among 

 strong and healthy trees some must go, in order to let 

 the remainder attain their full development. In doing 

 so the crowns are slightly isolated, but a certain number 

 of suppressed trees are allowed to stand, or an under- 

 wood is raised, which will shelter not only the soil but 

 also the boles of the trees from direct sunlight. Ulti- 

 mately these thinnings merge into preparatory -fellings. 

 Heyer * illustrates the operations carried out during the 

 rotation of a crop worked according to one of the uni- 

 form methods in the manner indicated in Fig. 83. The 

 circle ABODE represents the rotation of the crop, the 



1 Heyer, JValdbau, p. 290. 



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