CHAP, vi.] Advantages of Mixed Woods 



123 



of long-continued observations in Switzerland, Prussia and 

 Bavaria gave the following results l : 



And of the moisture reaching the soil, Weber calculated that 

 leaving out of account the transpiration of the foliage for which 

 the supplies of moisture are withdrawn by the roots from deeper 

 layers of soil its disposal was as follows : 



Owing to the smaller percentage of precipitations reaching 

 the ground, to the larger evaporation from the soil-covering, and 

 to the strongly hygroscopic nature of the moss, we can easily 

 understand the dried-up appearance that soils under pure 

 Spruce woods sometimes assume in early summer, just at the 

 time when transpiration is becoming most active, and when the 

 greatest necessity exists for a free supply of moisture from the 

 soil so as to permit of the assimilative and productive processes 

 going on to their fullest possible extent. 



In former times, when the work of nature was comparatively 

 uninterfered with, mixed woods almost everywhere formed the 



1 Compiled from data given by Weber, op. cit., pp. 47-49. 



