A PRIMER OF FORESTRY. 



process is called natural pruning, and from the time 

 when it begins the existence of the young forest, unless 



it should be overtaken by 

 fire or some other great 

 calamity, is practically se- 

 cure. 



GROWTH IN HEIGHT. 



At this time, as we have 

 seen, the crowns of all the 

 young trees are growing 

 faster at the tops than at the 

 sides, for there is unlimited 

 room above. (See fig. 51.) 

 But some are growing faster 

 than others, either because 

 their roots are more devel- 

 oped or in better soil than 

 those of the trees about 

 them, because they have 

 been freer from the attacks 

 of insects and other ene- 

 mies, or for some similar 

 reasons. Some trees have 

 an inborn tendency to grow 

 faster than others of the 

 same species in the same 

 surroundings, just as one 

 son in a family is often 

 taller than the brothers with 

 whom he was brought up. 

 Eapid growth in height, from whatever cause it pro- 

 ceeds, brings not only additional light and air to the 



FIG. 51. Large saplings and small 

 poles. Western Larch and Western 

 White Pine. Priest River Forest 

 Reserve, Idaho. 



