MEASUREMENTS OF THE EFFECTS OF FOREST 



COVER UPON THE CONSERVATION OF 



SNOW WATERS. 



By W. R. Mattoon. 



The large treeless openings or "parks" in the western yellow 

 pine forests of the southwest, which form a well known char- 

 acteristic, afford an excellent opportunity for a comparative study 

 of the effect of a forest canopy upon local snow conditions. Dur- 

 ing the late winter and spring of 1909, the writer had an excep- 

 tionally favorable opportunity for observing the progress of snow- 

 fall and subsequent melting in a virgin stand of western yellow 

 pine near the base of the San Francisco peaks on the Coconino 

 National Forest in northern Arizona. 



The observations include the measurement of each successive 

 snowfall, and the total depth of snow at intervals of seven days 

 under two entirely different forest conditions, namely, in a virgin 

 stand of mature timber and on an adjacent treeless park, covering 

 an area of several square miles. The observations were taken 

 during the period from February 26 to April 25, at an altitude 

 of approximately 7,500 feet. 



On March 11, the average depth of the snowfall from a two 

 days' storm was 4.0 inches in the park, as compared with 5.0 

 inches in the forest, a difference of 25 per cent, in favor of the 

 forest. A snowfall on March 23 measured 10.8 per cent, deeper in 

 the forest. These may be taken as fair examples of the difference 

 under the two conditions. As an explanation, it seems probable 

 that the sweep of wind across the park carries along a certain ex- 

 cess amount or load of snow from the snow gauge, which under 

 the quieter atmospheric conditions prevailing in the forest is ordi- 

 narily deposited — a phenomenon corresponding in many respects 

 to the well known laws governing the deposition of silt by water 

 currents. Over a forested area broken by parks the maximum 

 deposition occurs at the margin of the parks, the normal deposi- 

 tion in the forest body, and the minimum over the parks and 

 larger openings. 



Contrary to the usually accepted fact, during the early spring, 



