22 ELEMENTS OF SYLVICULTURE. 



year according to the cultural requirements on each 

 occasion. 



Again there are cases, as for instance in high forests 

 worked on the selection system (see infra) when 

 the exact calculation of the annual yield is of less 

 importance than the object with which the selection 

 system is adopted in any particular case. Here it 

 is considered sufficient to cut over very nearly equal 

 areas every year, removing a fixed number of trees 

 per acre. In this method, therefore, our annual 

 yield is expressed in the number of trees. If the 

 forest has been divided into a convenient number of 

 working circles, large fluctuations in the yield from 

 one year to another need not be feared, and the forest 

 is gradually brought into the most favourable 

 condition for the proprietor. 



PART II. 



HIGH FOREST. 



INTRODUCTORY REMARKS. In growing high forest 

 the object in view is generally to produce large tim- 

 ber, and to obtain natural reproduction by seed as a 

 direct consequence of the cultural operations. 



We recognise three principal methods of treating 

 high forest. 



1. The selection method, which, more than any 

 other method, resembles the action of nature, and 

 consists in cutting over rather extensive areas every 



