CHANGE OF SYSTEM. 309 



It would be problematic to determine the rotation to be 

 adopted for the future coniferous forest. On the other hand, 

 the age should be determined, which the oldest coniferous 

 wood should have reached, when the conversion has been 

 concluded, so as to have, from that moment forward, woods of 

 sufficient age to cut and supply the market. This age 

 determines the period, during which the conversion is to be 

 effected, called the " conversion period." The latter must not 

 be too short, or else there would be no final cuttings for a 

 number of years, after the conversion had been completed. 

 Supposing 60 years were chosen for the period of conversion, 

 then at its close the oldest coniferous wood would have an age 

 of 60 years. 



By dividing the total area by CO, the area is ascertained, 

 which should be converted annually. 



In selecting the areas to be taken in hand year by year, two 

 considerations present themselves : — 



(1.) A suitable arrangement of the future cutting series ; 

 and 



(2.) To begin with cutting over the woods, which are poorest 

 in increment. 



A consideration of both decides the allocation of the annual 

 coupes over the forest area. 



Examph'. — A coppice with standard forest of 1,*200 acres 

 shall, in the course of 60 years, be converted into coniferous 



forest. Every 10 years -— = 200 acres must be taken in 



hand for conversion. In that case the yield during the first 

 10 years would consist oi — 



(1.) The clearing of 200 acres ; and 



(2.) The treatment of 1,000 acres as coppice with standards. 

 During the second 10 years — 



(1.) The clearing of 200 acres ; and 



(2.) The treatment of 800 acres as coppice wath standards. 



During the third 10 years — 

 (1.) The clearhig of 200 acres ; 



