WEST VIRGINIA GEOLOGICAL SURVEY. 



41 



The effect upon climate of an individual tree is, of course, 

 not appreciable; but when trees stand together and form dense 

 forests which cover large areas their combined effect is readily 

 seen. When rains fall on bare ground the water quickly runs 

 off or is evaporated and within a short time after it falls, if the 

 sun shines and the wind blows, all signs of it may have disap- 

 peared. In the forest it is not so. The water there is caught by 

 the living and the decaying vegetation which prevent its rapid 

 escape into streams. The trees lessen evaporation by breaking 

 the rays of the sun and by retarding the velocity of winds. We 

 have in the forest, then, a damp, cool atmosphere which is not 

 subject to as rapid changes in temperature and humidity as that 

 • on the outside. This great volume of cool air surrounding the 



mass of green leaves of trees and weeds of the woods, acts as an 

 equalizer of temperature. The soft winds which come out of 

 woodlands during hot, dry days carry the cooler air out into 

 the fields. The air which is held under the canopy of tree tops 

 remains more uniform in temperature, as has been said, and 

 on frosty nights has the effect of warming the air for a consid- 

 erable distance in open areas. In lessening the extremes of 

 temperature in early spring and late fall and in checking evap- 

 oration from cultivated lands the forest exercises two of its 

 most important functions for the farmer. 



It is the common testimony of the older inhabitants of 

 West Virginia that, as the country has been cleared up, there 

 has been a corresponding lengthening of the warmer seasons: 

 that in localities where crops of corn would not ripen in former 

 years they now mature in ample time to be harvested ; that win- 

 ters are shorter and more changeable ; and that both floods and 

 drouths occur more frequently. 



The Forest in Its Relation to Animal Life. 



Mammals, birds and insects make up an interesting and im- 

 portant part of the life of every forest. Some of them are ben- 

 eficial, some are injurious. 



As for the mammals, they do not greatly affect the charac- 

 ter of woodlands although they are frequently important agents 



