58 



A PRIMER OF FORESTRY. 



land, whether liat, hilh^, or tnountainous, and the char- 

 acter of the surface covering. These are all connected 

 with the temperature in a special manner. Lastly, it 

 is affected b}^ the winds and the moisture of the atmos- 

 phere. Now, it is clear that of all these factors of 

 climate the forest can influence only the wind, the 

 moisture, and the surface covering; but heat (with 



Fig. 39.— The forest cover. Oregon, 



which the curface covering has so much to do), mois- 

 ture, and wind are the three things which change when 

 we say that the weather changes. These are just the 

 points where a change due to the forest would have 

 most effect on daih^ life. The influence of the forest 

 is exerted upon them in two ways: 



First. The forest cover intercepts the rain and the 

 rays of the sun, checks the movement of the air, and 

 reduces the radiation of heat at night. 



