50 ELEMENTS OF SYLVICULTUEE . 



THINNINGS. When the young crop, after succes- 

 sive cleanings, has reached the low pole stage, the 

 time has come to begin periodical thinnings. It is 

 evident that in the last cleaning operations, one may 

 have been compelled to cut a few oak in places where 

 they were too thick, but this is not a true thinning, 

 and generally speaking, the unassisted action of 

 nature would have sufficed to liberate in time those 

 plants that are to form the trees of the future. 



But this remark no longer holds good when the 

 suppressed poles are too long in disappearing of 

 themselves, since the free development of the crowns 

 is an object that must constantly be kept in view. 

 Nevertheless, seeing that the full height of the tree 

 has yet to be attained, the growth of epicormic 

 branches to be prevented, and the soil to be pro- 

 tected as completely as possible, the first periodical 

 thinnings in a crop of pure oak must be moderate, 

 that is to say, only those trees which are on the point 

 of becoming suppressed should be removed, the 

 operation as a consequence being repeated at shorter 

 intervals. 



It is only when the crop has reached the high pole 

 stage, and not before, that we can begin to thin more 

 severely ; but here on the other hand all low shrubby 

 growth should be carefully preserved, even plants of 

 quite secondary importance. However we go to 

 work, we cannot manage without danger to set free 

 the crowns as much as they require, and the almost 

 necessary consequence will be that the trees, though 

 drawn up to a good height, it is true, will be thin 

 out of all proportion and contain soft-grained wood. 



