IMPROVEMENT CUTTINGS 145 
exercised so that the bark is not split when the limb 
falls. 
As to just what constitutes the cultural opera- 
tion called a thinning, there is considerable diversity 
of opinion. I have already defined a cleaning as the 
removal of all dead, dying, diseased, and distorted 
stems and weeds. A thinning consists in lessening 
the crowded condition of the crowns of the good 
trees in a canopy, so as to provide room for those 
which remain, as they grow older and larger. Con- 
siderable depends, however, upon the meaning of 
the word “ good” in this connection. The good trees 
may not always be the tallest and biggest. What is 
good depends upon the nature of the management, 
and the kind of wood desired. Thinnings should be 
frequent so that the canopy may be lightly and grad- 
ually opened, and not interrupted. As the forest 
grows in age, the number of trees it is capable of sup- 
porting decreases proportionately. As they crowd 
one another some are strangled and in time become 
suppressed and die. Nature will do her own thin- 
ning in her own way. Man, however, can hasten 
and improve the process. He aids her in such a way 
that she can produce better materials in larger quan- 
tity and in a shorter length of time. 
The difference between a cleaning and a thinning 
may be rendered clear by the following example: If 
