2 t^^enerat. considerations 



Climate as effecting Agriculture 



The growth of wild plants is determined by two 

 sets of factors, those connected with the soil and 

 those connected with the climate. Cultivated plants 

 are also subject to these same conditions except in 

 so far as these may be modified by human effort. 

 Cultivation is the collective name for all those pro- 

 cesses by which man seeks to alter these environ- 

 mental conditions, tlius making them more favorable 

 for his crops. It is easier to modify soil conditions 

 than climatic conditions, hence the climate of any 

 region must always profoundly influence its agri- 

 culture. Climate depends on the two factors of 

 temperature and humidity. A climate may be hot 

 or cold, wet or dry, and the kinds of crops that can 

 be grown will vary accordingly. These factors 

 depend in turn on three others, — latitude, altitude, 

 and topography. 



Latitude as effecting Climate. — If we start with 

 the land of perpetual snow in the Arctic regions and 

 travel southward, the climate will become gradually 

 warmer and warmer until we reach the perpetual 

 summer of the tropics. Each change in temperature 

 will be accompanied by corresponding changes in 

 plant and animal life. These changes are so well 

 marked and conspicuous that naturalists are able to 

 mark off a number of well-defined areas called life 

 zones, each of which is characterized by the plants 

 and animals found in it which do not occur either 

 farther north or farther south. Other plants and 

 animals have a wider range of adaptability and may 



