PLENARY THINNINGS. 483 



various component individuals considered together can bear further 

 isolation and the undercrop requires brighter illumination. At 

 first the plenary thinnings will be comparatively light, since dur- 

 ing the period of their execution the lower crop has still to be well 

 sheltered, the soil carefully protected and the individuals of the 

 upper crop (too young to have yet attained their full length of 

 bole or to be free from the danger of becoming overgrown with 

 epicorms) kept close together. For the same reasons that the 

 first plenary thinnings should be lighter than the subsequent ones, 

 their periodicity should be shorter. In oak forests in Germany 

 treated under the system, this periodicity ranges from 5 to 10 

 years, while that of the later thinnings varies from 10 to 15 years. 

 In choosing the trees to be preserved in order to attain exceptional 

 dimensions no account should be taken of the manner of their dis- 

 tribution ; they should be selected solely for their vigour and 

 future value as timber trees. 



This method of plenary thinnings is specially suited for shade- 

 avoiding species. 



4. The young crop obtained ivitli coppice. 



The conditions of this method are completely fulfilled in stored 

 coppice worked on long rotations and with numerous standards. 

 In the underwood there should be an abundance of some species 

 capable of forming a close growth. 



5. Selection of the trees and execution of the thinnings. 



Considering the small number of trees to be left and that they 

 must be the very best of the entire crop, their selection and ex- 

 ploitation call for even greater care and solicitude than the same 

 work requires in ordinary thinnings. Obviously it is the trees to 

 be preserved that must be marked, and as the felling, conversion 

 and removal of produce are to be effected under the constant per- 

 sonal direction and supervision of the regular staff, it will suffice 

 to mark the the trees merely with a ring of white paint. 



The selection should be effected in several operations, every tree 

 likely to be fit for reservation being closely examined from several 

 points of view, and carefully compared with its neighbour, if two 

 or more such trees stand together. The work of selection should 

 not be considered complete until the marking officer has traversed 

 the coupe in every direction and thoroughly assured himself that 

 no mistake has been made. The following procedure may be re- 

 commended as giving the best guarantee against a faulty selection 



