Practical Sylviculture 



137 



of good trees. Work carried on in the woodlot in caring 

 for the crop of trees is known by the general term of thin- 

 ning. Thinning 

 may mean ac- 

 tual removal of 

 good trees 

 when the stand 

 is too thick, 

 the removal of 

 defective, poor 

 and worthless 

 trees or the re- 

 moval of any- 

 thing that 

 tends to im- 

 prove the tree 

 growth. The 

 practice of in- 

 telligent thin- 

 n i n g very 

 quickly shows 

 a marked effect 

 on the develop- 

 ment of the 

 trees in a 

 s t a n d. In 

 Europe during 

 a period of 74 

 years, the for- 

 ests have yielded an increase in wood of 300 per cent, or 

 from an annual growth of 20 cubic feet to the acre a year 



Fig. 37. — A good example of woodlot of the selec- 

 tion type. Trees are of all ages, both conifers and 

 hardwoods. 



