CHAPTER, | Vv; 
THE GEOGRAPHICAL DISTRIBUTION OF FORESTS 
Even the most casual observer, in traveling from 
place to place, notes with interest the various phases 
of forest vegetation. In every region, except where 
the conditions are so inhospitable that nothing can 
grow, various plants are grouped together in the form 
of communities or societies. The species which con- 
stitute these communities have in common the 
ability to endure the peculiar conditions in which they 
live. Every species fills a niche which it holds 
against intruders, in consequence of some peculiar 
advantage or ability which it possesses. These group- 
ings are the result of various warring forces. In 
some places there are deserts which are practically 
devoid of vegetable life; in others, prairies and savan- 
nas, with a few herbaceous plants, especially grasses; 
in others, swamp-lands, and all gradations of forest- 
growth, to the most luxuriant form of vegetation, 
which is the tropical forest. This enjoys constant 
warmth, constant moisture, and suitable soil econdi- 
tions. Although plants have, in the course of time, 
69 
