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 



stand. 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 



G - 37. A good example of woodlot of the selec- 

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



hardwoods. 



