20 Characteristics, Structure, Life of Trees 



growth of buds and foliage. Hence a deficiency in food 

 elaboration or defoliation in one year may, according to the 

 time when it occurs, influence the growth and health of that 

 and the next year; or the unfavorable season of one year 

 may not show its effects until the following season. 



Besides food, a tree, like an animal, needs air or oxygen 

 for respiration. The importance of this fact is perhaps 

 very imperfectly realized by the uninitiated. Yet not only 

 the leaves but also the twigs, branches and bole, and even 

 the roots have breathing pores in the developed fissures 

 of the bark, for the purpose of conducting air into the 

 interior. 



That the roots must breathe is often forgotten, as when 

 trees are planted too deep, or when ground is filled in on 

 top of them. Many a tree is lost by this ignorance. The 

 more compact the soil and the deeper the cover, the surer 

 and quicker the result; the tree dying from suffocation. The 

 same result is induced by flooding, or even a very rainy sea- 

 son may, on compact soil, so reduce the aeration of the roots 

 as to kiU them. Trees growing in swamps have adapted 

 themselves gradually to the difficulty of root respiration, 

 and the ground around trees grown in such conditions may 

 be filled up without the same detriment that would come to 

 trees not so adapted. 



Whenever there is a change made in the surroundings, 

 especially in soil and in light conditions, there must take 

 place an adaptation of the root system to the change. The 

 tree, however, can make this adaptation only gradually, 

 hence any contemplated change in the en\ironment must be 

 made by degrees or else the tree will suffer. 



It appears from the brief description of the household 

 economy of the tree, that the requisites for tree life are, 

 like that of other plants, first of all, at the root: — 



