32 



A PRTMER OF FORESTRY. 



twenty years before. The yield of the whole forest in 

 spruce for a single } T ear may be cut each year from 

 one-twentieth of the whole area. If all the divisions 

 were cut over five times in the life of a mature tree, 

 then one-fifth of the standing timber would be taken 



FIG. 19. Group of spruce under beech. Germany. 



from each division at each cutting. Thus, if it took 

 one hundred } T ears for a tree to become ripe for the ax, 

 the cutting (at intervals of twenty years) would return 

 five times during the life of the tree, at its twentieth, 

 fortieth, sixtieth, eightieth, and one hundredth 3 r ears. 



