Pruning and Trimming 83 
erowing naturally in the swamp promise well. In addi- 
tion, a certain space, say one and one-half by two yards, 
should, if practicable, be left unpaved around the base of 
the tree, and this space should be kept open, stirred and 
fertilized from time to time. Where this is not practicable, 
a smaller space left unpaved may be covered by a grill or 
iron grating, supported on wooden pegs driven in the ground. 
Such grills are found in Paris, Berlin, and London (see 
page 119), and permit of watering the trees. This treat- 
ment is, to be sure, applicable only with new plantings, 
when the trees will adapt themselves to the conditions. 
Where old established trees are concerned, it is doubtful 
whether they can be permanently maintained when a tight 
pavement is placed over their roots. 
Pruning and Trimming. Next in importance to atten- 
tion to soil conditions, there is nothing of more value for 
avoiding and correcting trouble in tree economy than prop- 
erly applied surgery. 
There is competition everywhere in the living world, 
and not only do the individual trees compete with each 
other for root and air space, water and light, but each leaf, 
each bud, each shoot competes with its neighbor, although 
only a limited number can develop. 
As we have seen, trees prune themselves, 2.¢., some of 
the buds and branchlets die every year and are broken off 
by the wind. This natural pruning is the result of the 
struggle for existence, 7.¢., for food and light supply, between 
the buds or branchlets, and an adjustment in the economy 
of the tree, keeping the balance between income and expend- 
iture. “By reducing the number of mouths to be fed the 
remaining are better fed. There is, therefore, not neces- 
sarily any apprehension to be had if some twigs and branches 
die in response to the perfectly normal need of adjusting 
