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(N$ STATE BOARD OF FORESTRY 



Floods which are produced by exceptional meteorological condi- 

 tions cannot be prevented by forests, but without their mitigating 

 influence the floods are more severe and destructive. 



CONCLUSIONS. 



The extent of forest land necessary for the regulation of stream- 

 flow and the protection of the soil against erosion must be not less 

 than from one-fifth to one-third of the total area of the country. 



Forests must be protected, not so much in localities which already 

 suffer from lack of moisture, as in regions which lie in the path ot 

 prevailing winds and are still abundantly supplied both with ground 

 water and precipitation. 



In the dry regions large bodies of forest may have an unfavorable 

 effect upon the available water supply. There rows of trees or wind- 

 breaks surrounding fields and orchards, by preventing the drifting of 

 the snow and increasing the activity of the wind, will act more as 

 conservers of moisture in the soil than solid bodies of timber. 



The care with which forests should be protected in the eastern 

 half of the United States must increase from north to south and 

 from west to east. 



In the Atlantic plain and southern Appalachians, which are the 

 gateway for the prevailing winds from the Gulf of Mexico and the 

 Atlantic Ocean, forests must be especially conserved if the humidity 

 of the Central States and the prairie region is to be maintained. 



If the clearing of the forest in the Atlantic plain and southern 

 Appalachians is a necessity, it should be done only under condition 

 that the cleared land is to be devoted to intense cultivation, as, after 

 forests, crops contribute most to the moisture of the air. 



The highest organic production is in harmony with the safeguard- 

 ing of the humidity in the regions which lie in the path of the pre- 

 vailing winds. Cleared land which becomes waste or poor pasture or 

 grows up to weak vegetation means so much evaporation lost to the 

 piassing air currents. 



