CHAPTER II 
THE EFFECT OF CLIMATE UPON VEGETATION—TYPES 
OF VEGETATION 
THE two most important factors in the plant’s environ- 
ment are climate and soil. In the preceding chapter 
we considered one of these—climate—and we showed 
that the type of climate anywhere prevailing may be 
expressed in terms of two external agencies, variously 
combined—heat and moisture. 
Types of climate operate over wide areas, and if it is 
true that the character of the vegetation varies with the 
climate, it should be possible, in some rough way at least, 
to distinguish broad types of vegetation, just as it is 
possible to distinguish broad types of climate. Let 
us see how this may be done. 
If one were able to survey the vegetation of a country 
as a whole, viewing it from a distance, so as to see its 
broad outlines without being disturbed by details, what 
are the types which would stand out most conspicuously ? 
It would not require great powers of observation to give 
an answer. One person might say woodland, grassland, 
desert. To these another might add marshes, and 
another heath. 
These are types of vegetation regarded as aspects of 
scenery, but how far is it possible to associate them with 
definite conditions of climate ? A marsh is wet, wood- 
lands are generally damp, and grasslands dry; heath 
is very dry, and deserts are almost rainless. But there 
are two types of grassland—one, meadow-land, which 
is wet ; and the other, pasture or prairie, which is dry. 
The term “ woodland ”’ is still more vague, since it includes 
several types easily distinguishable from each other. 
For example, there are evergreen woods and deciduous 
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