84 TREES AS GOOD CITIZENS 



In some streets the entire sidewalk surface is needed 

 for traffic, and this makes it impossible to sacrifice the 

 space that is required. In a case of this kind, a sidewalk 

 grating may be employed, permitting pedestrians to use 

 the sidewalk up to the very base of the tree and still 

 providing breathing room for the tree itself. This grating 

 is level with the surface of the sidewalk, and the ground 

 underneath slopes away from the tree, forming a pit or 

 basin, which collects water, and is therefore useful in 

 supplying moisture to the roots. The grating is so set 

 as to be easily removed for cleaning the space underneath. 

 In dense traffic the grating is essential, but where it is 

 possible to provide a space free from paving, without the 

 use of the grating, this should be done in the interest of 

 the tree's best development. 



Irrigation and drainage are essential to the life of the 

 tree. The ideal means of providing water is by having the 

 tree so placed that the soil surrounding the roots may be 

 loosened from time to time, in order that surface watering 

 may penetrate the earth and reach the roots in abundant 

 supply. This is possible where trees are planted in space 

 free from paving, such as a strip of gravel or grass be- 

 tween sidewalk and curb. If a grating is used, it should 

 be taken up occasionally and the soil underneath made 

 loose by cultivating. One of the most important features 

 of the grating is that it allows this cultivation, in addition 

 to preventing the traffic from packing the surface, as would 

 occur if foot-traffic were allowed to use the space immedi- 

 ately surrounding a tree without the protection afforded 

 by the grating. 



If the natural drainage fails to prevent water from 

 collecting at the roots, artificial drainage may be supplied 

 by using tile drains, 3 or 4 feet below the surface, 

 to carry surplus water to the nearest sewer. This is 





