h{fiuence of Forests on Health. ' 159 



INFLUENCE OF FORESTS ON HEALTH. 



BY JOHN A. WARDER, M. D. 



A medical friend*, who has strenuously advocated the preservation of for- 

 ests for their hygienic influence, in a recent paper presented before the 

 American Forestry Congress, took for his thesis the following proposition : 

 " Trees conduce to health, and the more trees the more health." 



He takes and maintains the position that trees notably modify the climate 

 by arresting the currents of air, the winds, which constitute an important 

 element in climate, the influence of which, he thinks, has been far too much 

 overlooked by writers on hygiene. He asserts that "a windy climate is a 

 bad climate — wind interferes with health as well as Comfort; it punishes 

 hearty persons and is ruinous to invalids; it interferes with good ventila- 

 tion, and with the moderate, uniform warmth that should prevail in our 

 houses. A windy climate is a climate of shivers and snuffles, and colds and 

 consumption. Therefore, I say, the more trees the less wind, the more trees 

 the more health." 



He also advocates the effects of forests on the score of temperature. Ad- 

 mitting that the mean average temperature may be the same in wooded as 

 in open regions, he claims that " the annual means have little to do with 

 health. What concerns the physician and the sanitarian most is the extent 

 and the rapidity of the oscillations of temperature ; here the influence of for- 

 ests is eminently conservative." From which the writer will not demur, but 

 proceeds : 



CLIMATIC INFLUENCES OF FORESTS. 



While it will not be insisted upon that the general rainfall will be increased,, 

 as is so generallj' supposed, the forests do undoubtedly exert an important in- 

 fluence upon the climatic conditions. The general storms of our country 

 may be dependent upon the relative configuration of land and water, as well 

 as upon the lines of elevations. These are conditions that are arranged on a 

 plan of grand proportions. They cover continental areas ; still, it may safely 

 be asserted, that the fortunate or judicious distribution of forests in prairie 

 regions, and even on our great western plains, can not fail to exert a control- 

 ing influence of vast importance and of greater or less extent. Certainly the 

 local climate will be aftected by the woodlands, which act upon it in the fol- 

 lowing manner: 



First — By checking the force of the currents of air, woodlands will, in a 

 great measure, prevent excessive evaporation, and the moisture thus permit- 

 ted to remain in the soil will prove as valuable as an equal amount in rain- 

 fall. 



Second — The forests are of great value in a similar way by the influence of 

 their shade, which prevents the fierce rays of the sun from exercising an ad- 



*Dan. Milliken, M. D., Hamilton, Ohio. 



