10 BULLETIN 816, U. S. DEPARTMENT OF AGRICULTURE. 
it is short lived in order to make room for a good one that will be 
permanent does not appeal to the average citizen. Where trees 
which have been planted by the property holder come under city 
control a strong feeling of proprietorship still remains, which is 
outraged by the suggestion of the removal of even poor trees. Where 
all the work is under city control good work is often hampered by a 
strong public sentiment against the removal of trees, even though they 
are poor or crowding. 
Because of this difficulty it is extremely important that young 
trees be planted farther apart than at that time seems reasonable. 
If they are planted as far apart as is proper for mature trees the 
distance will be so great as to make planting seem a joke. If they 
are planted half the distance apart they should be when mature, 
good results would follow if the intermediate trees were removed 
when they nearly touch those to be left. As the intermediate 
trees would probably not be removed, or not until too late for the 
good of the remaining ones, planting had better be sufficiently 
far apart in the beginning to avoid the necessity of later removals. 
In the beginning the trees will be too far apart and when mature 
too close together, but it seems to be the alternative imposed by a 
misguided public opinion. 
There is scarcely a community that would permit the removal of 
interplanted trees from a street of fine elms, oaks, or other worthy 
varieties without a protest that would be the almost sure political 
death of the administrative authorities responsible, no matter how 
great the need or how much expert support they might have. If 
short-lived intermediate trees were used they would not be likely to 
be taken out before they died, and they probably would not die before 
they had irreparably injured the permanent trees. The removal of 
surplus or interplanted trees can be made with least shock to the 
community by gradually narrowing the tree tops by severe pruning 
from year to year on the sides next the permanent trees until finally 
they are so narrow they may be removed and leave only small 
openings between the permanent trees. LHven this method will not 
materially lessen the public protest at the final removal. 
A common practice is to set street trees 35 feet apart. If it were 
practicable to remove one-half the trees at the proper time this would 
be a good distance, but in the eastern half of the United States and 
on the Pacific slope 50 feet apart is close enough for most varieties, 
and for the larger growing trees 60 to 70 feet would be better. 
CONDITIONS FOR TREE GROWTH. 
In order to grow, trees must have a soil of suitable texture, in 
proper mechanical condition, that contains sufficient available mineral 
elements and plenty of organic matter, and, last but not least, a con- 
stant supply of moisture and air. In addition to these there must 
