90 OUR NATIONAL FORESTS 



such a study is being carried on. The purpose of 

 the study for the first two or three years has been 

 to determine the character of the two streams which 

 are to be measured. The forest cover on the two 

 watersheds is practically identical. The results so 

 far obtained indicate that the influence upon the 

 stream flow must be about the same in both cases, 

 and, consequently, a comparison of these streams 

 after the denudation of one watershed will be a 

 very fair test of the influence of the forest cover 

 upon the relative height of the flood stage and low- 

 water stage, the amount of erosion, and the rate of 

 melting of the snow. 



Experimental observations which have been con- 

 ducted since 1908 at the various Forest Experiment 

 'Stations have shown that the forest exercises a de- 

 cided moderating influence upon temperature ex- 

 tremes, wind motion, and evaporation. Likewise, 

 the presence of a forest cover retards the melting of 

 snow in the spring, and in this way huge snowbanks 

 in the forests feed the nearby streams until late in 

 the summer. Forests therefore have been shown 

 to conserve the water supply and also causing this 

 water to run off slowly rather than in sudden floods. 

 Studies have also been conducted on determining 



