APPLICATION OF THE METHOD. 73 



To effect this, contrary to the rules that hold good 

 for thinning a crop composed of a single species, all 

 beech trees that immediately overtop the oak must 

 be got rid of, while they that are themselves over- 

 topped by the oak must be preserved. They must 

 therefore be commenced early, because if any length 

 of time is allowed to elapse after a crop has once 

 entered the pole stage, every overtopped beech will 

 have died a natural death. 



The same course must be pursued in all subsequent 

 thinnings, and beech seedlings that spring up under 

 an already high canopy must be looked after and 

 preserved. These seedlings will constitute an 

 under story, most favourable to the growth of the 

 oak. 



But this advantage must not tempt us to endeavour 

 to obtain them in a uniform and absolute manner at 

 a given moment, for that would cause gaps in the 

 oak. The thinnings must be severe round the 

 oak, and of a medium strength over the rest of the 

 crop. 



When the associated trees are oak and hornbeam, 

 or oak, hornbeam and beech, the operation of thinning 

 is rendered much more easy. The tree to preserve 

 round the oak is the hornbeam. The only thing to 

 remember is that the hornbeam requires a moderate 

 thinning sooner than the beech. The difference in 

 longevity between the oak and the hornbeam need 

 not trouble us. The gradual extraction of the horn- 

 beam, as it arrives at maturity, will allow seedlings 

 of this tree to establish themselves, as a consequence 

 of the leaf-canopy becoming more and more open. 



