STATE REGULATION OF PRIVATE FORESTS 85 



The third way in which forests affect the public is through their indirect 

 influence on rainfall and on the behavior of water. 



Where the influence of forests and forest removal can be directly traced 

 and affects in an appreciable manner agricultural and commercial interests, 

 we have sound constitutional grounds for interference with private actions 

 even to the detriment of the individual, such as are not furnished by the 

 public interest in parks or in timber production. 



These indirect influences of forests are their effect on rainfall and cli- 

 mate, and their effect on the flow of water, soil erosion, streams, navigation 

 and water powers. 



It has been repeatedly denied by many scientists and meteorologists that 

 forests increase the total rainfall in a region or modify the general climate. 

 The forest cover is not without its effect on temperature, evaporation, and soil 

 moisture, but these effects are felt only within the forest or in the immediate 

 vicinity. Such effects may be typified by wind breaks. The influence of a 

 wind break may be beneficial to a distance of ten times the height of the 

 trees, and it is possible to grow better crops in its protection than without it. 

 But the state would not be justified in denying the owner of a woodlot the 

 right to cut his timber on the grounds that his neighbor would be injured by 

 losing the benefit of the wind protection which the grove previously afforded. 

 In the absence of scientific proof of the general beneficial effect of forests on 

 climate and rainfall, since extended research indicates that these influences 

 are not exerted except for infinitesimal distances beyond the forests, the state 

 must seek other grounds for regulating the affairs of the owner of timber 

 lands. But in case this influence is considered a sufficient justification for 

 state interference, it is the woodlot owner to whom regulation should be 

 applied, for it is on the borders of groves and woodlots that these influences 

 are important. 



There remains one strong argument in favor of state regulation. YVTiat- 

 ever may be said to dispute the influence of forests on rainfall, their effect on 

 the flow of streams and on soil erosion has been completely established. 

 Within the forest the presence of a vegetative cover, no matter how slight, 

 tends to catch and delay the flow of rain water, and to increase the porosity 

 and absorptive power of the soil, besides preventing more or less completely 

 the carrying away by erosion of the soil into the streams. Any vegetation 

 cover does this in part, but the forest does it most effectively. The direct 

 effect is a lengthening of the period of flood in the spring or at times of 

 heavy rains, and a great lessening of its severity. The low water stage is 

 aided by the flow of springs, which usually dry up when forest cover is re- 

 moved or destroyed. The water which reaches the streams is usually free 

 from sediment, and the process of silting up of streams is prevented. These 

 facts are well known and their importance to navigation and manufacturing 

 and to agriculture along such streams is evident. (Tnlike the influence on 

 climate, the effects are caused by the influence of larger forest areas often far 

 removed from the ultimate interests affected. The possibility of state regula- 

 tion to prevent the evils resulting from denudation of such areas is worthy 

 of serious consideration. 



Here as elsewhere there must be established a definite connection between 

 cause and effect. It must be shown that the forests designated do have an 

 influence which justifies the interference of the state to prevent their destruc- 

 tion. On lands which are fairly level the influence of the forest in checking 

 the How of water and preventing soil erosion is very small. At the same time 

 agi'iculture becomes possible and cultivation often increases the storage 

 capacity of the soil for moisture to a point equal to or exceeding the capacity 

 of the soil if forested. With increasing slope, cultivation becomes difficult 



