99 



run-off. All added advantage is also olitained m tliat the force of the 

 raiiidroiis is diiiiiiiislied and prevents the soil from becoiuiiig hard and 

 compact, thus reducini; its absorbtive pnwer. It must not be forgotten, 

 however, that the blanches of the trees catch from S-10 per cent, of the 

 rainfall, and this is, of course, immediately evaporated. 



The character of the soil has much to do with the distriI)utiou of the 

 fallen water. Many experiments have been made concerning the con- 

 ductivity of certain soils, but as many of these have led to contradictory 

 results, no attempt will here be made to discuss them. It is fair to say, 

 however, that the forest soil is well adapted t(i alisorb a great deal of 

 water. The humus and litter of leaves, limbs, etc., serve to keep the 

 soil in a loose, spongy condition, which undoulitediy assures a great ab- 

 sorbing capacity. The great mass of roots also aids in this and facili 

 tates the passage of the water down through the soil. It may be true, 

 however, that after a long continued rain the forest soil will become so 

 saturated that the water will run off as freely as from bare soil. The 

 forest floor oft'ers niiny obstructions and obstacles to the water that is 

 not immediately absorbed as it runs over the surface of the ground. 

 These retard its passage and thus more is taken into the soil. 



In the case of bare land, the water is gathered into little rivulets 

 which form larger and larger ones, which flow with constantly increasing 

 velocity with the result that very little water gets into the soil. 



Forests also have a great power in conserving snow water. Mattoon 

 (21) in Northern Arizona has shown that the forest retains the snow 

 later in the spring than does the open parks. The snow melts more 

 slowly and more is taken into the earth. A layer of ice which kept 

 the water from entering the soil was formed above the soil and under 

 the snow in the park, while this was absent in the forest. 



By retaining the rainfall the forest is a benefit in two ways. It tends 

 to prevent disastrous and destructive floods, and holds the water until 

 long after precipitation and gives it out slowly to streams, springs, etc., 

 in times of drouth. Many, however, do not concede the regulating effect 

 of the forest and much discussion has arisen concerning the subject. 

 Professor Engler reports that at the Swiss Station experiments made for 

 three years show that the springs in times of drouth continued to give 

 out water for a longer period in a forested region than in au unforested 

 one. Buffault (4) discusses the evidence reported at the Navigation 



