STATE HORTICULTURAL SOCIETY. 225 



Regarding forests, it would perhaps be interesting to give some of the results ©f 

 observations taken during the ,year just past at stations of tlie State Weather Service 

 on their influence as a modifying agent of the climate of Minnesota. 



Scientists agree that while the evidence at present available does not fuU^' estab- 

 lish the fact that forests increase rainfall, other than to a slight extent, yet no fact 

 is more apparent than that they serve a most important part in the economy of 

 nature, by averting extreme and sudden changes in temperature, and more partic- 

 ularlv by protecting the earth from the direct rays of the sun and drying winds, to 

 check excessive evapoi-ation and husband the rainfall, permitting it to gradually 

 sink into the ground only to again appear in the form of springs which feed the 

 rivers*; a full and constant volume of which is so necessary to the economical pros- 

 perity of the Stale. As an instance of the important part played by the forests of 

 Minnesota on the volume of water in two of its principal rivers, it may be stated 

 that the Minnesota river has a drainage area of 19,000 square miles, nearly destitute 

 of timber. The Mississippi, above their junction, a drainage area of 23,000 square 

 miles, nearly all forested. As a result, at the confluence of these two streams the 

 Mississippi drainage area furnishes at least seven times as much water as the Minne- 

 sota area. Let the present rapid deforesting of Northern Minnesota be continued , 

 and aside from the influence of the government reservoirs, the amount of water in 

 that stream will ultimately assume insignificant proportions and become practicall}^ 

 unavailable for manufacturing purposes. 



The beneficial efl'ects of what arc called the "Big Woods" in arresting sweeping 

 air currents and gales, a result so much to be desired in this climate, will be appre- 

 ciated when it is understood that Bird Island on their windward side has in round 

 numbers a movement of 8,500 miles of wind each month, and St. Paul on the lee- 

 ward side only 4,000, less than half as much as it will have when that forest is 

 cleared away, as it surely will be unless the people of this State awake to the im- 

 portance of its preservation. 



Another undoubted influence which the Big Woods have is by their resistance to 

 the free movement of the air. to cause many of those bodies of frigid air called 

 "eold waves," which sweep down from the north, to be deflected over the broad 

 treeless plains of Dakota and Nebraska and, as was instanced last autumn, to be 

 often felt at St Louis, Mo., before they were, if at all, at St. Paul. They, with 

 Lake Superior, cause the winter isotherms or lines of equal heat to extend nearly 

 north and south instead of east and west, and thus make Duluth and Minneapolis 

 nearlj^ if not quite as warm as Sioux City and Yankton. Similar instances of the 

 mild and genial influences which this forest exerts on the climatolog}' of this State 

 could be multiplied indefinitely. But we will close this paper by expressing the 

 hope that the people of Minnesota will in the near future supplement those at pres- 

 ent in force by a code of forest laws looking to the preservation of a proper per- 

 centage of the existing forests, and their extension over the treeless part of the 

 State; tliese laws to be based on an intelligent conception of the necessities of the 

 present and the demands of the future. 



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