26 Characteristics, Structure, Life of Trees 



fir, and hemlock are examples of those which can endure 

 considerable shade. 



The practical im])ortance of this fact is exemplified in 

 almost every park or yard where grou[)s are j)lanted, either 

 by the failure of the designer to group trees with reference 

 to their characteristics, or by failure of the manager to cor- 

 rect in time such changes of relationship, and by allowing 

 the "stronger" to damage or kill out the "weaker." 



The knowledge that this strength or weakness is merely 

 in the light requirements can be used, first, in restraining 

 the stronger by proper pruning, if the two are to be kept 

 together; second, if it becomes necessary to plant between 

 existing groups, in choosing a species capable of bearing the 

 shade of its neighbors; and finally, in pruning individuals 

 of the light-needing kind so as to give more light to the 

 interior of the crown, making it fuller and more compact 

 by the development of dormant buds. 



Recuperative Capacity. There is one other feature in 

 the economy of the tree, important to the tree-warden, by 

 which it differs from the animal household (with exceptions), 

 namely, its ability to replace lost parts. This is due to the 

 fact that it produces and keeps alive many more buds or 

 growing points than it can develop in a season. As we 

 have seen, only a few of the many buds formed each season 

 grow into shoots and make leaves; the majority die, are 

 killed by insects, or dry out, while a number remain living 

 but undeveloped, keeping dormant until needed. 



Let a tree be defoliated again and again by insects in a 

 single season and the dormant buds will replace the lost 

 foliage as long as there are stored food materials at hand to 

 feed them; let a twig or branch be cut off, and several dor- 

 mant buds near the cut base will vie with each other to 

 replace it; cut off the whole tree and with most deciduous- 



