184 OUTLINES OF FORESTRY. 



be, or what the amount of light and heat such soil 

 receives, vegetation will be entirely absent, and 

 the region will become a desert. 



Where rain falls during one part of the year, 

 and the rest of the year is dry, steppe regions 

 occur. Such regions are covered by vegetation 

 during the wet season, but resemble deserts during 

 the dry season. 



Meadows and prairies occur where the rainfall 

 is well distributed throughout the year, and the 

 quantity is not very great. 



Forests occur where there is an abundant rain- 

 fall well distributed throughout the year. 



Forests cannot exist in any part of the North 

 Temperate Zone where the rainfall is absent for 

 a considerable length of time, because the trees 

 would die during the dry season, and there would 

 be no germs for a new crop of trees to start grow- 

 ing from on the appearance of the rainy season. 



In certain parts of the tropics forests may exist 

 despite long periods of drought, because in such 

 regions the growth of the trees is either considera- 

 bly retarded, or the trees obtain their liquid nour- 

 ishment from copious dews or directly from the 

 vapor of the air. 



A certain depth and character of soil are neces- 



