APPLICATION OF THE METHOD. 49 



back down to the ground, unless indeed they are only 

 few and far between ; the leaf-canopy is thus com- 

 pletely preserved down below, and natural pruning 

 goes on among the small branches, which then fall 

 off without leaving any appreciable knots on the bole. 



It is often necessary to repeat the cleanings, 

 especially if the first operation was judiciously and 

 cautiously performed, but we must not postpone 

 felling the soft-wood trees until they have attained 

 a certain commercial value ; it should never be for- 

 gotten that the operation is urgent, and that the 

 more the oak stands in need of light, the faster will 

 it wither away. In short, cleanings must be made 

 whenever and wherever they are necessary, without 

 giving a thought to the produce they may yield. 



Among the trees of rapid growth which often in- 

 vade a crop of oak seedlings > the birch claims our 

 special attention. This tree has a very light cover, 

 and its leaf-blades hang vertically ; hence it does but 

 little injury to the oak unless it forms a complete 

 canopy above. Indeed it is often useful to the oak, 

 if the final cutting was made too soon, by providing 

 shelter against spring frosts. We must therefore 

 remove the birch gradually, felling only a few at a 

 time, and selling the produce either for faggot bands, 

 or cask-hoops, or for any other purpose that may 

 chance to occur. Moreover it should not be forgot- 

 ten that there is a large demand for birch wood in 

 certain industries, and that as far as the quality of 

 the oak is concerned, its association with this tree 

 is far preferable to pure oak. The preceding remarks 

 often hold good for the aspen as well. 



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