FORESTRY 429 



and this differs for different trees. The spacing should be a 

 little greater than the natural spread of a tree ; for example, 

 the following spacings are recommended : white elm, 50 

 feet ; maples, 40-45 feet (dependent on the kind) ; linden, 

 40 feet ; Carolina poplar, 30 feet. 



The selection of trees is important, and the judgment of 

 different people will vary. The primary choice is between 

 a fast-growing tree and a slow-growing tree. The former 

 brings results quicker, which mean beauty and shade, but 

 it is usually a short-lived and brittle tree. The latter de- 

 velops beauty and shade very slowly, but it is usually long- 

 lived and tougher. It would seem wise to select for city 

 streets the slow-growing and long-lived trees, the most popu- 

 lar of which is the white or American elm. The rapid-grow- 

 ing trees, which impatient people select, are usually Carolina 

 poplar, willow, box elder, or silver maple. 



134. Planting street trees. The space for soil prepara- 

 tion is very restricted, so that instead of breaking up the 

 soil in the usual way for a crop, large holes are dug and 

 filled with proper soil, which in this case means a pulverized 

 soil thoroughly mixed with fine manure. Great care must 

 be taken to see that there is proper drainage, and often a tile 

 drain has to be laid. The young trees are usually obtained 

 from a nursery, and before they are " set," they are pruned, 

 so that the stem system may balance better the more or 

 less injured root system. In case the root system is com- 

 plete, no trimming is necessary, but it would be a rare 

 amount of care that could transplant a young tree without 

 injuring the roots more or less. In the bottom of the hole 

 a bed of fine soil is placed, the tree is settled in place care- 

 fully and watered, and the hole filled up. Of course trees 

 must be transplanted while they are dormant, and this 

 means either spring-planting or fall-planting, the former 

 being the better. Sometimes very large trees are trans- 

 planted, but the larger the tree, the greater the danger. 



