26 Characteristics, Structure, Life of Trees 
fir, and hemlock are examples of those which can endure 
considerable shade. 
The practical importance of this fact is exemplified in 
almost every park or yard where groups are planted, 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- 
