52 FIRST BOOK OF FORESTRY 



endures longest; while for poplar, birch, and willow it 

 should not be over twenty-five years. 



Since large trees are not furnished by the coppice woods, 

 and since it is often desirable and profitable to raise larger 

 trees for timber and lumber, many people have modified 

 their coppice in this way. 



Suppose our farmer has sixty acres of coppice and cuts 

 about two acres each year. Instead of cutting all trees 

 he leaves standing on each acre from fifty to a hundred 

 of the very best trees. These trees go on growing and 

 are cut thirty years later, so that they live through two 

 rotations of the coppice woods. By that time they are 

 sixty years old and of considerable size. These we call 

 standards and this kind of coppice woods a standard cop- 

 pice. Sometimes the standards are not all cut down at 

 the end of the second rotation, but some are left for a 

 third or even a fourth rotation, and thus get to be quite 

 large. But it is usual to cut part of the standards each 

 time the particular piece of woods is cut over. 



Since too much shade would hinder the starting as well 

 as the growth of the sprouts, the trees left over for stand- 

 ards at any one time should not shade more than about 

 one third to one fourth of the ground. Usually a thirty- 

 year-old tree in good coppice woods has a crown covering 

 about fifty to a hundred square feet, and it nearly doubles 

 this every thirty years. Since an acre has 43,560 square 

 feet, and about a fourth may be covered by the standards, 



