DISTRIBUTION OF AMERICAN FORESTS 
along and carries them to a place where 
the conditions are ill adapted to their 
peculiar nature. The following year 
the wind is propitious and the little 
trees soon start into life. But presently 
the seeds of another tree, whose growth 
is by nature faster, are conveyed to the 
same spot, and the intruders outstrip 
the others in rapidity of growth and 
spread a canopy of foliage that screens 
the smaller trees from the life-giving 
sun and dooms them to destruction. 
Thus only a few of the numberless 
seeds that are produced each year live, 
and fewer still are able to maintain or 
extend the boundaries of the parent 
tree. Sometimes, too, the frugality or 
hardiness of a species may be the rea- 
son for its exclusive occupation of a 
certain locality, since other trees may 
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