68 ECONOMICS OF FORESTRY. 



In other words, while the quality of the influence 

 remains the same, its degree, and especially its 

 effective and appreciable value, must vary as much 

 as there are varying local conditions possible. The 

 size and character of the forest, its density, height, 

 situation, and composition, are of more importance 

 in determining its influence than is usually realized 

 by those who discuss the question. 



Another matter which it is also necessary to 

 accentuate, because it is usually overlooked, is that 

 the influence, if any, can only be of local charac- 

 ter, it must therefore be discussed only with refer- 

 ence to given local conditions. It cannot be put 

 in comparison with that of the large oceans, the 

 great air currents, the extensive mountain ranges, 

 which determine the general or cosmic climate. 

 The forest can modify only locally the effects of 

 this general climate, in about the same manner as 

 we modify it by building houses around us and 

 heating them, whereby we change the temperature 

 and moisture conditions at least in our habitation ; 

 or by building cities, which we know differ, as far 

 as our feeling is concerned, from the climate of 

 the adjoining country. 



It may also be proper here to state that, in view 

 of the fact that whatever influence exists, it is 

 dependent on local conditions, the attempt to fix 

 a certain general percentage of forest cover as 

 necessary for a country is childish, and also that 

 there are conditions where the existence of forest 



